Jump to content
Carlos

1988 Jeep YJ Wrangler 2.5L TBI with no gas coming out of fuel injector

Recommended Posts

jeep just died the other day.  Wont fire up.  Checked the injector and nothing is coming out.  I have spark, and fuel pump is working.  changed the injector and still nothing.  I am getting 3.5 volts at the injector plug.  Is that the right amount?  My diagnostic chart says battery voltage?  Help.  

Share this post


Link to post
Share on other sites

Hi, Carlos...Thanks for making the conversion to Subscriber Member, we have valued your participation at the forums!  

So, are you getting fuel flow to the TBI unit?  Try this:  Unplug the TBI pressure test port plug.  (Route pressurized fuel away from hot engine areas or any ignition source.)  Turn on the key briefly .  There should be a steady stream of fuel flowing from the port under pressure...At 14 or so PSI, you should clearly see fuel flow at the test port.

If there is no fuel flowing from the TBI test port, see whether the fuel filter is clogged.  It only takes one tank of fuel from a gas station that has a watery holding tank to clog a fuel filter.  You can disconnect the fuel filter and again turn on the key briefly.  If you see a steady stream of pressurized fuel from the disconnected (tank side) of the filter, you have a functioning fuel pump.  Next, confirm that the filter is flowing fuel through it.

If the fuel pump is flowing fuel and there is no fuel at the test port, you either have a clogged fuel filter or the pressure regulator is clogged.  If the pressure regulator and fuel flow seem normal at the TBI pressure port, the problem could be between the regulator and injector or you may not be getting a sufficient fuel injector voltage pulse like you hinted.  Make sure the fuel pressure regulator is adjusted to proper pressure (14-15 PSI). 

Confirm that you have fuel flow to the regulator, and the regulator is set properly.  If there is no flow restriction between the regulator and injector, there should be fuel flowing from the injector if the injector has a sufficient voltage pulse and the injector's solenoid is working.  Make sure voltage is correct at the injector and test the solenoid function.

Injector pulse voltage is strictly from the ECU.  I would want to see 5 volts here, the typical ECU output voltage to the MAP and TPS.  Lower voltage can be a poor ground or loose connection with too much resistance.  As we have discussed at the YJ/2.5L TBI topics, the 2.5L engine is notorious for poor grounds if you have not checked them.  In particular, check the ground near the dipstick to the body/firewall (also engine to firewall and body to frame and battery).  Check grounds for resistance, as resistance can lower voltage.

Let's work through this Carlos.  Let us know if you find the trouble source or need more information...

Moses 

 

Share this post


Link to post
Share on other sites

Moses,

 

Thanks for getting back to me.  I think I am getting fuel.  I pulled the fuel line at the back of the TB and it spits gas.  I ran the fuel pump when the injector was out and gas came out.  I am thinking it is the plug.  I am only getting 3.46V at the plug and the ground is showing 2.3 ohms of resistance to the battery negative.  I refreshed all the grounds last year but will do it again tomorrow night.  And for the record best 12 bucks i have spent in a long time being a subscriber.

 

Carlos

Share this post


Link to post
Share on other sites

Thanks for the subscription comment, Carlos...

The fuel supply system passed the quick test for fuel supply.  If you're concerned, verify the regulator pressure adjustment when you've solved the basic problem.

The ground resistance reading is a real clue.  Good diagnostics approach on your part, taking the local ground at the TBI and make it loop back to the battery negative...In the scheme of how grounding should work, the real test is just what you did:  test from the device all the way to the battery ground.  Superficially, this accounts for circuit continuity, but more importantly you've confirmed the resistance in that circuit.  High resistance is, simply put, a source for voltage drop in a 12VDC system.

You're on the right track.  Consider all grounds including the ECU.  I'm confident you'll find the trouble spot.  This is a great illustration of how much voltage drop can take place due to a weak ground or too much ground resistance.  Excess ground resistance could be from an open, a poor connection or a frayed ground lead—even at the battery.  Corrosion wicking and oxidation, or corrosion at a ground connection, even as simple as the battery post to the cable terminal resistance, can drop voltage significantly.  Poor surface contact between the battery cable terminal and its post can be a trouble spot. 

One test that works very well on the ground circuit is a lamp load test.  This can be done by making a 12VDC bulb into a diagnostic tool.  The bulb becomes a "device", much like any electrical drain or driven device (a heater motor, headlamps, a cigarette lighter/power supply source, etc.).  The link below is to a useful paper on automotive voltage drop with mention of a simple lamp load test.  The lamp load test is optimal on the ground side of a 12VDC system.  You understand ohms-resistance well;  voltage drop to a "device", including a simple lamp load tester, is a symptom of excessive resistance*:

http://www.fluke.com/fluke/uses/comunidad/fluke-news-plus/articlecategories/electrical/diagnosevoltdrop 

*Causes of excess resistance can be under-capacity/smaller gauge wire, loose or corroded connections, strands of wire not making contact, crimp "butt connector" wire splice connections that create poor contact with all the wire strands, corroded wire, corroded terminals, poor grounding on a D.C. system, or virtually any resistance that increases load on a circuit.

Footnote: Fluke has some remarkable, albeit expensive, test equipment.  The test meters that I like can perform an insulation resistance test.  The Fluke 1587 is one DMM example.  The low amperage of four AA batteries is converted into very high voltage at a very low and non-destructive amperage.  This source of current is sent through the circuit or wire(s) being tested, and the high voltage will find its way through leaky insulation.  Depending on the probe contact points, the DMM readout provides an ohms resistance reading to either a ground point or between parallel wires, detecting a leak through the wire insulation of the two wires.  (These test meters can run voltage up to the 1000V level with no other power to the circuit. Visualize running this non-destructive test on automotive 12VDC wiring harnesses with the vehicle's 12V battery disconnected.  Of course, a 50V insulation resistance test setting would be plenty on sensitive circuits.)  A Fluke 1587 insulation resistance test can include circuits buried inside remote wire harnesses that would otherwise require guesswork or labor intensive stripping out of wire (hot leads or grounds) within the circuits in order to make a visual inspection.  The leaking voltage or voltage resistance (measured down to milli-ohms) is easily read by the meter.

The lamp load test is very simple and can be done on light wire circuits with a smaller automotive bulb and on heavier circuits with a head lamp.  Read through the Fluke information at the link above.  The paper addresses automotive electrical systems, and at the bottom of the text you'll find a short section discussing "ground gremlins".  I also hyperlinked the Fluke 1587 if you're curious about that meter.  Spendy but what an instrument for chasing down hidden wiring troubles!

Let us know what you find, Carlos...

Moses 

Share this post


Link to post
Share on other sites

hi Moses.  So I spent some time on this tonight.  I found freyed wires on the actual TBI connector.  I replaced the connector and still noting.

 

Couple of things I found interesting.  

The orange wire at the injector is shared with the EGR solinoid and the fuel pump relay.  This is the wire I get 3.46 volts on.  The other wire at the injector (blue wire) goes to the ECU.  Here is where it gets strange.  I get 3.46 volts on the orange wire at the injector but not at the EGR solinoid.  The orange wire at the injector and the orange wire at the ERG solinoid have perfect continuity.  AND if I test for voltage across the 2 I get 3.46 volts.  Very strange.  I think.  I am way past my pay grade on this one.  I checked and cleaned all grounds.  Thoughts?

 

image.thumb.png.1c83cbf0578784e7f9d320e60200c342.png

Share this post


Link to post
Share on other sites

Hi, Carlos...The wiring diagram is graphic.  You have a 35-way connector to the ECU.  Keep that illustration in mind...

Devices like the TBI injector are KEY ON hot.  Typically, an ECU/ECM/PCM controller does not provide "hot" voltage but rather completes the ground to these D.C. devices.  If the Orange lead (common) is KEY ON hot and provides a clean voltage reading, your aim is to verify whether the Green wire to solenoid and Light Blue to the injector are completing the ground. 

Disconnect the Light Blue and Green leads from the injector and EGR solenoid.  If the Orange leads each read KEY ON hot with your voltmeter, you should be able to activate/test either device with a simple jumper wire to ground.  If these devices each operate normally with a brief, temporary direct ground at the Light Blue and Green contacts, and if the injector is still not flowing fuel, then the ECU lead is not completing the ground properly.

You're testing in this way:

1) When isolated,  the Orange lead (common to both the EGR and the fuel injector) should be a KEY ON hot wire.  Test the Orange (common) lead for voltage with the key in the ON position.  If the Orange (common) lead provides KEY ON voltage, grounding the Light Blue or Green pole at each of these devices should activate them.  Do this only briefly, as they normally operate at approximately half the KEY ON voltage.  Do not damage the devices. 

2) If you have KEY ON Orange wire voltage to each device, disconnect the plugs at the EGR solenoid and injector.  Use your meter as a jumper between the Light Blue and Green plug pins and each device.  Read the Light Blue and Green wires for both voltage and ground resistance.  What do you get? 

3) With the device plugs disconnected from the EGR solenoid and injector, check for voltage and also check for ground continuity on the Light Blue and Green plug connectors.  Test with the KEY ON—you may need to crank the engine to get an injector pulse signal.

3) Connect or jumper the KEY ON Orange leads to the EGR solenoid and the injector.  If grounding the EGR solenoid (Green wire contact on the solenoid) and injector (Light Blue wire contact on the injector) directly at the device activates the EGR and the injector, check the wiring continuity and resistance between these devices and their ECU contacts.  On the 35-Way ECU connector, Pin 5 is the EGR signal.  Pin 21 of the 35-way connector is the injector signal.  (The plug is not easy to reach for continuity testing!)  See whether there is too much resistance in the injector lead to the ECU.  If not, the ECU itself could be at fault.

Rebuilt ECU units are available if you isolate the problem to the injector's ECU signal.  Although I always caution against taking a "parts replacement troubleshooting" approach, we have many examples of these circuits breaking down in the ECU, and thorough troubleshooting can isolate the ECU as the culprit.  You could get creative and inspect the ECU like some have.  Here is an example of what can go wrong in an ECU.  See CSMART's great troubleshooting and photo of an ECU board burnout:  

 

Moses

Share this post


Link to post
Share on other sites

Moses.  So much has happen since my last post.  :(.  The 3.46v is coming out of the BLUE wire.  The orange wire has no voltage.  So I started digging in my electrical.  The orange wire runs back to pin 87 of the fuel pump relay.  I have 12v at 30 and the rely is working.  So I started testing continuity looking for a fault.  The orange wire that goes to 87 has continuity with the yellow wire that comes from the ignition and ends up at pin 85 or 86 (I forget we will call it 85) the other pin gets ground from the ECU.  So without the relay in I get 12v (pin 85) to the yellow wire as well.  So I tore my wiring loom up looking for a frayed wire.  :(.  I traced the wires all the way back to a large plug in the firewall right next to the clutch master cylinder.  I disconnected that switch and the continuity went away.  There is no where in the wiring diagram where yellow and orange do cross and based on my limited understanding of car electrics they should not cross.  So if I unplug the plug and the continuity goes away is that safe to assume that the problem is somewhere on the other side of the plug and everything before that is ok?

 

here is what I think is happening.  Correct me if I am off track.  

85 and 87 have continuity. (Bad)  When 86 gets its ground from the ecu it completes the circuit with 85 and effectively grounds 85. Since 85 and 87 have continuity it is also grounding 87 which is why I don’t see 12 v at the injector.  Find where 85 and 87 are coming in contact and repair.  Then 85 can be grounded to move the coil in the relay and 87 can get its 12v to the injector.  

Share this post


Link to post
Share on other sites

Your reasoning is sound, Carlos.  Keep in mind, however, that the injector only pulses on when there is an ECU signal from Pin 21 on the ECU.  The ECU signal requires that the engine is either cranking or in run mode.  There is never a steady opening of the injector, if there were, the injector would continually flow fuel.  The injector only flows fuel when the ECU provides a signal from Pin 21.  The current to open the injector, signaled from Pin 21, is both the injector open/close and the injector's pulse width.  Pulse width is the duration (time interval) that the injector stays open. 

Note: Remember that fuel is under constant pressure, the fuel flow is strictly controlled by the pulse width of the injector. Width or time interval for the injector pulse determines the amount of fuel flowing, a response to the throttle position and other sensor feedback.  When fuel demand is high, the injector open/pulse rate or width is higher.  There is no pulse or flow at the injector without the ECU getting a signal from the crankshaft position sensor.  The CPS tells the ECU that the engine is either cranking over or has achieved a running state.  Make sure the CPS is functioning properly.

To your point:  The Yellow lead is "Ignition" (a true 12V source), which is the #3 pin at the 35-Way ECU connector.  You describe "30", "85" and "87".  These are common Bosch relay poles: 

70198785_large.jpg

The relay is a standard Bosch-type numeric, and the poles represent various conditions.  The goal of the relay is to energize and create continuity between the intended poles when activated.  This is a magnetic relay.  It requires a ground and hot to close the circuit or magnetize the relay.

Here is the wiring schematic for your YJ Wrangler's 2.5L TBI injector circuit:

2.5L TBI Injector Wiring.pdf

I have included an extra page to address the Power Steering switch and other devices involved with the injector circuit.  Check out the Power Steering Switch and other circuits for faults, opens or shorting:

2.5L TBI Injector and P.S. Wires.pdf

Note that 14 gauge Yellow is the ignition ON source for 12 volts.  According to this diagram, the EGR/Evaporator canister purge solenoid ("front of left shock tower") should be fed from a 14-gauge BR (brown) lead that feeds from a junction with 14-gauge Orange wires.  Those Orange wires include a feed to the Fuel Injector.  You should get continuity between the EGR /Evaporative canister's Brown wire and the injector's Orange wire.

Note the pins on the ECU (6, 5, 21 and 18 on Page 8W-107).  This should clarify how the ECU pins apply.  The firewall bulkhead connector that you discovered includes many of the wires that feed to the 35-Way connector.  The 35-Way connector should not be confused with the bulkhead connector.  The 35-Way ECU connector is at the ECU unit under the dash.

The Fuel Injector needs two signals to activate:

1)  The fuel pump relay must function for the Fuel Injector to function.  Try another relay in its place.  Swap relays or try a new one.

2)  The Injector must get a signal from Pin 21 on the 35-Way connector at the ECU.

3)  If either the Light Blue signal from Pin 21 or the 14-gauge Orange wire feeding to the injector is not performing properly, you have no Injector flow.

4)  Both the fuel pump and injector require Orange circuits to perform properly.  The same is true of the Brown lead to the EGR/Evap canister solenoid.  The fuel pump working is a good sign as long as all of the Orange wires at the junction have continuity.

5) The EGR/EVAP canister solenoid needs the Blue wire signal from the ECU at Pin 5.

6)  The Injector needs the Light Blue wire signal from Pin 21 on the ECU.

You can identify these wires at the firewall bulkhead connector.  This may save the time and energy of crawling beneath the dash to locate the ECU 35-way connector.  If you suspect a break in continuity between the bulkhead and the ECU connector, you'll need to go beneath the dash.

See how my comments compare with your thoughts and conclusions...Keep us posted.

Moses

Share this post


Link to post
Share on other sites

Moses,

 

1.  my theroy requires this to be true. The orange wire connected to the 87 pin on the  fuel pump relay should have a CONSTANT 12v when connected with the negative terminal of th battery.  This would eliminate any pulse requirements form the ecu.   This should be true when connected to the injector, to the brown wire at the egr purge and to the orange wire at the fuel pump.  Is this correct?

 

2.  Should there be continuity under any circumstance between the orange wire and the yellow ignition wire?

Carlos

Share this post


Link to post
Share on other sites

Carlos...Open up the PDFs from yesterday and below...The Yellow wire feeds from the ignition key circuit to the relay.  Yellow should read 12V hot with the key in the ON position.

Test the relay's functions.  If no clicking with a hot pole and a ground, try swapping relays to see if you can get a relay to work.  There is a second relay called the "B+ Latch Relay" that also interacts with these circuits.  You might try replacing that relay.  Review that circuit in this PDF:

B+ Latch Relay in 2.5L TBI Circuit.pdf 

The cover in your hand is the bulkhead wire bundle that goes through the firewall.  On the dash side of the firewall, some of those wires feed to the ECU.  (RD is also to the starter relay switch as shown in the B+ Latch Relay PDF above.)  The other Orange leads depend upon the fuel pump relay to close and provide them with a voltage reading.

Below is a PDF of the Bulkhead connector wiring identification and each wire's location on the bulkhead connector.  The bulkhead view is from the inside of the firewall, you can follow the color coding from there through the firewall to the engine bay.  I also included the 35-Way ECU pin layout with all color coding.  See each of the two pages:

YJ 2.5L Bulkhead Connection and ECU Pin Readout.pdf

If you're not finding poor connections or burned wires, you should focus on the relays and possibly the ECU.  Getting the Fuel Pump Relay to function, whether in a simulated test or through the underhood wiring circuits, should get the injector to open.

This should help clarify...

Moses

 

Share this post


Link to post
Share on other sites

If I understand the relay correctly, when the relay opens the constant 12v to relay pin 30 should flow through pin 87 and create a constant 12v at the orange wire which is connected to the injector and eventually to the fuel pump.  The relay is working and there is no 12v at the injector.  My belief is that the orange wire is being grounded somewhere but if it was why would the fuel pump cycle on.  

Share this post


Link to post
Share on other sites

Carlos...First let's confirm whether these Orange wiring circuits are hot voltage feeds or not.  Using a volt-ohmmeter, with the Key On and Key Off, test the Orange wiring devices on circuits that you know are working—like the fuel pump itself.  On that circuit, read the voltage for the Orange feed.  We need to know whether Orange wires are hot positive feeds and what voltage they read.  If they are hot leads, 12V or otherwise, then Pin 6 to the ECU should also be 12V hot when the Yellow wire activates the fuel pump relay.  This test depends upon the fuel pump relay working properly.  If you think the fuel pump relay is defective, try another relay in that slot.

Using a volt-ohmmeter, test the Orange lead at the fuel pump relay or at the fuel injector for a path to ground.  Probe one end of the meter to the Orange lead and the other end to a good ground.  If there is continuity, the Orange circuit is grounded.  You can test other Orange leads for continuity to ground as well.  This will indicate whether all of the Orange leads are connected as shown in the wiring schematics that I provided as PDFs. 

Also try testing the injector Orange lead to ground with the bulkhead connector disconnected.  If the Orange lead showed a path to ground before the bulkhead connector was separated but does not show a path to ground with the bulkhead connector separated, then the Orange circuit is likely grounded at the #6 Pin of the ECU.  If there is no sign of a path to ground on the injector's Orange lead with the bulkhead connector disconnected, also check other Orange leads to see if they now show no path to ground.  If the ground only takes place with the bulkhead connector attached, the ground source is the ECU via Pin 6. 

Another troubleshooting route:  At the fuel pump relay, which poles show a voltage reading with the ignition switch in the On position?  Does the EGR/EVAP solenoid work but the fuel injector does not?  The injector is an electro-magnetic pintle.  The injector requires positive voltage on one side and a ground completion on the other.  If Orange is the hot 12V feed, then Light Blue to the injector must be the ground provided by ECU pin 21.  Isolate the injector.  If Orange is a hot lead, apply hot current to that pole of the injector.  Use a jumper lead to ground on the other pole for testing the injector.  If the TBI unit is fuel pressurized, you should see fuel flow when this circuit is complete.

Again, first confirm whether Orange is consistently 12V hot/positive voltage when you turn the key to the On position.  This would show that the relay is connecting Yellow 12V current to the Orange circuits.  If other Orange feed devices work (fuel pump, EGR/EVAP solenoid, etc.), and only the Injector does not work, then either the fuel pump relay is defective or the injector is not getting a signal from Pin 21 of the ECU.  Remember, the ECU will send an intermittent (not constant) signal to the injector.  The injector does not stay on, it pulses when triggered by the ECU.  Remember, too, that the Pin 21 ground signal only occurs when the engine is cranking or running.  The CPS is a reference signal for this circuit.

If the wiring, the relays and ECU are not defective, and if the injector works when you isolate and test it, look for something that could be blocking fuel between the fuel regulator and the injector.  If there is no signal from Pin 21 on the ECU to the injector, the ECU could be defective.  You could inspect and clean the ECU 35-way connector plug and inspect the pins and slots before condemning the ECU.

Moses

Share this post


Link to post
Share on other sites

Had a mechanic come out.  There is no ground coming to the light blue wire on the injector.  Ugg.  So much unnecessary work.  Pulling the ecu now.  

Share this post


Link to post
Share on other sites

ok.  I pulled the ecu.  There is perfect continuity between the light blue wire at the injector and pin 21 on the ECU.  There is no ground coming out of pin 21 ever.  Does that confirm that the ECU is bad?  Or could something else be keeping the ECU from sending the signal?  When we put gas down the throttle body it fires up so there is spark.

Share this post


Link to post
Share on other sites

Carlos...Glad you followed the Pin 21 signal and Light Blue wire lead.  An extra pair of eyes was likely helpful, too.  Nothing has been lost but time...

So you confirmed that Orange is KEY ON hot and the Light Blue lead provides the ground to the injector?  Did you try jumping the Light Blue lead directly to a good ground point to see whether the injector flows fuel?  If grounding the Light Blue lead operates the injector, the injector is good, and you're missing the ground signal from Pin 21.

I would try this:

1) If Orange is KEY ON hot, unplug the injector leads.  Make a jumper wire using a low amperage (5-10 amp) inline fuse to protect the device.  Run this jumper to the injector's Orange pole.

2) Take another jumper and ground the injector pole where the Light Blue wire attaches.

3) When you turn the key to the ON position and hear the fuel pump running, there should be fuel flow from the injector.  Do this briefly to prevent flooding the engine.

This approach would confirm that the injector itself is working but the Light Blue ground wire is not getting an ECU signal at Pin 21— as you suspect.

The only things that could keep the Pin 21 from sending a signal are 1) your suspicions about  a burned circuit on the ECU or 2) the long shot that the crankshaft position sensor signal is weak.  The CPS issue is unlikely because you are getting spark, which also requires a CPS (crankshaft position sensor) signal.  The sensor is readily accessible at the bellhousing.

You could check the CPS for dirt, debris or a poor connection.  Sometimes rear main seal oil will reach the sensor.  If there is nothing to indicate a problem with the CPS or wiring, and if the injector circuit wires are all intact, and if the fuel pump relay is new or clearly functioning properly at each pole, then a rebuilt ECU would be a worthwhile investment.  A number of forum members have narrowed their 2.5L TBI system troubles to the ECU.  This is a module that sees a considerable amount of work, load and vibration over time.  They do fail.

Moses 

Share this post


Link to post
Share on other sites

Moses,

 

Will a comanchee ECU work in a YJ?  I can find a comanche one from 1987.  2.5 with TBI with manual transmission.

 

Carlos

Share this post


Link to post
Share on other sites

Hi, Carlos...Pleased that you're making progress on your Wrangler.  The used ECU sounds like a good investment.  To be sure the Comanche ECU is compatible, you'll want to get the part number from your current ECU and the Comanche ECU.  I can help break down the interchangeability.  If the numbers are compatible, you have a prospect.

Provide me with the part numbers, I'll help run down the interchange...If the ECUs do interchange, this will be a good, cost-effective test.  Otherwise, there are rebuilt units available. 

If you cannot get reliable numbers from either of the ECUs, provide me with information from the underhood emissions sticker/decals.  I need the year, transmission type and whether the vehicle is EPA only (49-State) or EPA/California (50-State) emissions.

Glad to assist...

Moses

Share this post


Link to post
Share on other sites

Hi, Carlos...ECU information below:

1) All 1987-90 Jeep YJ Wrangler 2.5L TBI models with manual transmissions use a common 50-State ECU.  This is a "FENIX" system from the AMC/Jeep era that carried into the Mopar years.  The Mopar part number is 53005023.

2) The 1986-87 MJ and XJ 2.5L TBI engines with manual transmission use a common 50-State FENIX controller, Mopar part number 53004763.

If your YJ Wrangler is a manual transmission, this should be compatible.  Fit/coverage is the same: 1987, 1988, 1989 and 1990 (YJ).  Is this an inexpensive used item, and is there a warranty/guarantee that it will operate?  This is an electronic device.  If inexpensive and guaranteed to work, it would be worth trying.

What is your YJ's model year and transmission type?

Moses

 

 

 

Share this post


Link to post
Share on other sites

Should work, Carlos...As a point of interest, the current ECU in your YJ Wrangler is a remanufactured unit.  That means very little, a rebuild could be just as likely to fail as an OEM controller, depending upon the rebuilder.  Some would argue that you're better off with a used OEM unit like the Comanche ECU.

I'd give the used OEM unit a go...It should quickly answer questions.

Moses

Share this post


Link to post
Share on other sites

Carlos...When you get the engine running, make sure the fuel regulator is set for the right fuel pressure:  14-15 PSI.  You mentioned changing the injector.  Do a PSI check if you have a pressure gauge for the port.

I'm optimistic about the ECU curing the injector flow problem.  This has been a trying and time consuming process, and you have been thorough in your approach and troubleshooting.  The injector needs a Light Blue wire completion signal from the ECU, you should have that signal with the "new" (used) ECU.  If the Comanche ECU is in good shape, you'll have some answers shortly!  

Moses

Share this post


Link to post
Share on other sites

fired right up this morning with the new ECU.  Best lesson to learn from this.  Get another pair of eyes and don't assume anything.  Thanks for your help.

Share this post


Link to post
Share on other sites

And sold it two hours after i fixed it.  On to my TJ.  Second lesson of the day, get out while the getting is good.  Thanks again for all your help.

Share this post


Link to post
Share on other sites

You're welcome, Carlos...The takeaway from this is to not waste time avoiding what might be the more expensive fix.  In this case the ECU itself.  The lesson will stand here at this thread for the benefit of the many.  Yes, an ECU can fail!

Enjoy the TJ Wrangler.  We'll look forward to hearing more about it when you have time.

Moses

Share this post


Link to post
Share on other sites

Hi, Carlos...I was researching an auxiliary transmission cooler for our Ram 3500 truck and saw this wiring diagram for a typical Bosch type relay.  I immediately thought of your YJ Wrangler 2.5L fuel pump relay.  Check out this PDF illustration of the relay in this wiring circuit.  It helps clarify how the current flows and the relay switching.

Illustration of a Bosch Type Relay.pdf

I trust you're enjoying your TJ Wrangler after seeing the YJ's taillights for the last time...Looking forward to your posts.

Moses

Share this post


Link to post
Share on other sites

×
×
  • Create New...