Geo Tracker Starting Gremlin

[Jonathan]

Good morning! So glad I found this group. I'm a noob with a starting problem. I have a 93 Tracker 4wd, 5spd, 8v, 140K with a starting issue. Engine was rebuilt 10k ago. When leaving Lowe's, the Tracker wouldn't start. It ran fine while driving there. It's newer to me and has worked great up until this point. The fuel pump quit working but now it's developed another starting problem. It's has new plugs, wires, fuel filter and pump, ICM, injector and other parts. There is fuel getting to the injector and plenty of spark but still wont start even though it cranks well. All of the fuses are good and there isn't any codes being thrown aside from 12 (normal). It will start with test fuel added through the TBI. When trying to start it, it will flood out rather quickly. Actually have had to pull the plugs due to too much fuel in the cylinders preventing turnover. My mechanic buddy is scratching his head as to what the issue is. The Tracker won't talk to his Solus scanner or his older "brick" scanner. He disconnected the battery for a while and it started up for a few seconds then died.  My buddy is thinking that the new injector isn't pulsing but rather just shooting a constant stream of fuel into the TB. He's wondering if the injector isn't getting the correct signaling. The ECM is working correctly and timing is correct.  He is thinking the distributor pickup isn't sending the correct injector pulse to the injector? Any help you or suggestions you guys may have would be greatly appreciated to prevent blindly throwing new parts into it.

Thanks, 

Jon

 

 

[Knyte]

Hello, and welcome!

Hm, I've never encountered a fueling issue such as you describe, but, from the sounds of it, your friend is likely on the right track.  If it's hydro-locking, it's absolutely getting too much fuel, for whatever reason.

Keep us updated!

[Moses Ludel]

Hi, Jonathan...It sounds like too much unregulated fuel going through the injector.  I would first-off make sure fuel is properly returning to the tank.  When a TBI system builds excess pressure, which you're describing, a pinched or clogged return line can be involved.  So can devices that are supposed to open and aren't, like valves and solenoids.  Restricted return lines will spike the fuel pressure, and this would deliver way more pressure than the injector can handle.

My first mechanical test would be a fuel pressure check at the TBI unit.  Check for normal fuel pressure.  If high, again, look to the fuel return.  You replaced the pump, verify pump output and actual pressure.  An overly high pressure pump in a TBI system can cause havoc...If necessary check the actual pump pressure separate from the TBI regulated pressure.  This can all be done without dropping the fuel tank again.

If the return is clear and pump pressure is correct, I would focus on the fuel pressure regulator.  It may not be dropping the pressure enough and is instead pressing too much fuel into the injector.  The injector would flood the engine.

Of course, as your friend suggests, electronics could be at play.  I would still want to scan this engine for troubles, in particular the pulse to the injector.  If anyone has an automotive oscilloscope like the Autel MaxiScope MP408 or even an inexpensive Hantek, you could back probe the injector and check for a voltage pulse to indicate whether the injector is switching on and off.  That's a quick one.

Let us know whether this helps.  We'll go from there...

Moses

[Jonathan]

I have a 93 Tracker 4wd, 5spd, 8v, 140K with a starting issue. The Tracker will flood itself out and hydrolock with fuel. If I pull the plugs, crank it to clear the cylinders, it wills start but run rough with a lot of exhaust. When restarting after, it won’t start as the cylinders get flooded. New parts include plugs, wires, fuel filter and pump, ICM, injector, pressure regulator and other. ECM is fine and timing is correct. The previous owner rewired the fuel pump relay as the old one developed electric issues (I’m guessing. He had it on a toggle switch you flipped on and off to drive it. I have driven it for 6 months with no issues, problem just showed up on a trip to the store. Basically, the fuel pump is just constantly dumping fuel into the engine.

My mechanic buddy is thinking the fuel pump is not receiving the proper signaling anymore and the previous owner’s relay need to be redone. Can anyone point me in a direction as to how to accomplish this (detailed instruction would be great)?

My buddy and I are at a dead end aside from rewiring the relay. And not sure how to do that in the first place. Any help or ideas would be greatly appreciated. 
 

[Moses Ludel]

Hi, Jonathan...This is similar to your earlier question.  Did you go through my August 11th reply above? 

Your buddy's thought about pulsing and sync to the distributor reminds me of a quick troubleshooting technique I used years ago on TBI units...If there is no risk of backfiring, remove the air intake hood above the TBI unit.  Have the engine in the shade or hood shadow...With a timing light hooked to #1 spark plug wire, hold the flashing light toward the TBI intake and the injector.  While watching the injector with the timing light, have someone crank and start the engine.  Continue watching the fuel coming from the injector, using the timing light as your pulsed light source.

Engine cranking and idling, you should see a uniform, cone-shaped spray pattern.  Increase the engine speed while continuing to watch the injector spray pattern.  It should remain uniform and conical.

If there is a pouring of fuel (with no spray cone), the injector could be defective or stuck open.  You can actually see the fuel exiting or leaking from the injector, whether there is a leak at an O-ring, gasket, fitting, injector body (a crack) or the TBI housing. 

The timing light, as your single source of light, is sync'd with the ignition.  If there is no fuel pulse or cone, try hooking the timing light to another cylinder.  See whether the pattern changes.  A faulty trigger could be distributor timing out of sync with the crankshaft and crank position sensor.  Someone may have removed the distributor housing and altered the rotor's position from its sync with the distributor housing. 

TBI engines typically have a fixed distributor housing position in the engine block.  Time the engine by the factory method with #1 piston at TDC on its compression stroke and the distributor housing in its correct position.  The rotor must point to the correct clock position.  Spark wires must be in the right distributor cap sockets.  Firing order is set accordingly.  All of this is in the factory workshop manual for the Geo Tracker.  You may also find this information online.

If valve timing or ignition timing is off, there will also be a faulty pulse.  Begin with a look at the injector spray pattern for leakage, using the timing light technique described.  Verify the ignition function, distributor clocking and base/idle spark timing with a timing light.  Lastly, check the valve timing.  The timing belt may have jumped time.

Moses