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Hello to All....

I wish to thank all the members and especially you Mr. Ludell for all the time spent on our endless problems....

I have reviewed all the posts that might pertain to my problem and do not wish to ask a question that can be easily answered by simple review...

My YJ has had an.. "on again / off again"   problem that may not be related to this exact problem but it just seems to have never been 100 % or maybe even 80%...

The current problem started on an outing in the woods ..drove fine climbing, downhill and 4wd.. coming back the engine began to act like it was starving for fuel..the harder you press on the gas the more it chocked out...would idle fine..no power..

So... I took it to mean a faulty pump and ordered same...pulled tank ..found sock off the pump..Problem solved ??..decided since I have a new one might as well drop it in.. "nice to have a trail spare anyway".. replaced tank with new filter... went to fire it up ...no start..no apparent fuel at the TBI....Now it wont run at all...

So... check electrical to pump ..fine..check lines..fine..

Ordered a Pressure gauge...slap it on the TBI access port ..No pressure.....Check pressure before the TBI... jumps to 50 psi...way to much..??  checked inline with " T "  Key on 25 psi..

Start..jumps to 50 psi..no apparent fuel returning to tank..

SO.... rebuild the TBI... bad regulator..Maybe...clean,  replace TPS , new injector, and filters while its apart... "  Nice to have trail spares anyway"  reassemble...try to start ...no fuel....

So....Back to ZERO.... No fuel getting past the Regulator... Remove TBI..reinspect , reassemble..try to start...no fuel

Also the CPS..MAT sensors replaced during the last session...Of unknown problems..."Nice to have trail spares anyway"

When fuel is manually poured in the carb. she fires right up and I can keep it running if i drizzle it in..

So... it runs if i can figure out how to get my wife under the hood with a squeeze bottle while I drive....Could work...Maybe.. Make a great hood ornament...Should switch that around encase she reads this..She Drives....ya sounds better...

 

The questions are.....will the pressure spike to 50 psi if there is no return to tank..? Is 50 psi just way to much ..?

Will to much pressure cause the regulator to shut down so to speak..?

Is it possible the spring in the regulator is bad ,The kit did not have a new spring...Seems a weak spring would allow to much fuel...did try to adjust with set screw...no Fuel...?

The TBI is clean no blockage in ports...so what could be stopping the flow... Other than the regulator... ?   "Did I just answer my own question..Maybe"

Why are my troubles worse now after the repairs..At least it ran at idle before?

 

Your Attention , Patience and experience with this matter will earn you my admiration and a box of Girl Scout cookies...of your choice

Jamie

 

 

 

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Jamie...Thanks for supporting our forums!  See my comments below on your TBI issue:

On 1/26/2018 at 8:09 PM, Jeep4Us said:

So... I took it to mean a faulty pump and ordered same...pulled tank ..found sock off the pump..Problem solved ??..decided since I have a new one might as well drop it in.. "nice to have a trail spare anyway".. replaced tank with new filter... went to fire it up ...no start..no apparent fuel at the TBI....Now it wont run at all...

Good decision and approach...

So... check electrical to pump ..fine..check lines..fine..

Ordered a Pressure gauge...slap it on the TBI access port ..No pressure.....Check pressure before the TBI... jumps to 50 psi...way to much..??  checked inline with " T "  Key on 25 psi..Start..jumps to 50 psi..no apparent fuel returning to tank.. rebuild the TBI... bad regulator..Maybe...clean,  replace TPS , new injector, and filters while its apart... "  Nice to have trail spares anyway"  reassemble...try to start ...no fuel....

Good troubleshooting so far...Glad you changed the filter.  Did you check the fuel flow volume when you T'd off the line for a pressure test?  Volume is a critical as pressure...

So....Back to ZERO.... No fuel getting past the Regulator... Remove TBI..reinspect , reassemble..try to start...no fuel

The regulator is mechanical, so this is not an ECU problem (yet)...Did you disconnect the return line when you tried to test the flow through the regulator?  You need an unrestricted return line (or detached temporarily) to test the regulator.  The regulator may be working, but if fuel is restricted at the return flow to the tank, you may not get any fuel supply.

Also the CPS..MAT sensors replaced during the last session...Of unknown problems..."Nice to have trail spares anyway"

Understood but, as you note, likely unrelated to your current issue.

When fuel is manually poured in the carb. she fires right up and I can keep it running if i drizzle it in..

Proof this is a fuel supply issue or an injector that is not flowing fuel.  Make sure fuel flow to the regulator is adequate, that the return is unrestricted, and if the problem persists, target the injector fuel flow.

So... it runs if i can figure out how to get my wife under the hood with a squeeze bottle while I drive....Could work...Maybe.. Make a great hood ornament...Should switch that around encase she reads this..She Drives....ya sounds better...

Diplomacy wins the day!  Yes, you need consistent fuel supply.

The questions are.....will the pressure spike to 50 psi if there is no return to tank..? Is 50 psi just way to much ..?

50 PSI is normal only if there is a restriction or the regulator is sticking.  The pump is not designed to bump up against a restriction.  There should always be fuel flowing back to the tank once the mechanical regulator reaches 14 PSI or so, which should be instantly.  The pump PSI design is normally well above the regulated pressure.  (50 PSI is not extreme even for the lower pressure limits of a TBI versus MPI system fuel pump.  Check the pump part number anyway, we can see if its the TBI pump and not an MPI type.)  This higher pressure/volume is intentional and enables ample fuel supply while steadily returning the excess flow to the tank.  No vapor-lock is an ancillary benefit.

There is a clue here:  The 25 PSI at the tee seems high, the regulator at the TBI unit should be opening at 14 PSI and instantly start flowing fuel back to the tank.  If the regulator is opening normally, there's a restriction in the return line to the tank.  Try this:  Safely tap off the return line port at the TBI unit and run the return fuel into a safe vessel with the Key ON briefly.  Pressure at the "Tee" should read closer to a normal 14 PSI.  A slight spike before the regulator opens would be okay, but a steady 25 PSI says that 1) the regulator is stuck or set too high or 2) the return flow to the tank is restricted or routed improperly.

Will to much pressure cause the regulator to shut down so to speak..?

Try the open flow at the return line test...The regulator is mechanical and doesn't have the sense to do anything other than bypass fuel at the adjusted PSI set point.  This is a spring balanced diaphragm pressure relief that opens at a preset, adjusted point.  If the regulator is adjusted too high, the reading will be high.  If the regulator opens low, the pressure will be low. 

That's why we adjust the regulator with a pressure gauge attached:  But it is assumed that the return to the tank is unrestricted—the fuel is flowing freely through the return line and flowing freely (internally within the TBI unit) between the TBI's regulator and the return line.  You cannot, and will not, get an accurate pressure regulator setting unless fuel is flowing into the regulator in adequate volume and pressure, and there is no restriction on the outlet side from the regulator to the fuel tank.

Is it possible the spring in the regulator is bad ,The kit did not have a new spring...Seems a weak spring would allow to much fuel...did try to adjust with set screw...no Fuel...?

Try the approach I've shared...You cannot make an accurate regulator adjustment if there is a restriction on the return side of the regulator or the volume/flow of fuel to the regulator is inadequate.

The TBI is clean no blockage in ports...so what could be stopping the flow... Other than the regulator... ?   "Did I just answer my own question..Maybe"

If you didn't, I did...Two heads better than one?

Why are my troubles worse now after the repairs..At least it ran at idle before?

This is a mechanical system, as you know.  Nothing metaphysical.  If the new pump works properly, you can follow through with the tests I suggested.  Adjust the regulator as necessary but only after you're certain there is no restriction (volume wise) on the return flow and the pump flow to the regulator provides both enough pressure and adequate fuel volume.

Moses

 

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Mr.Ludel

I want to start by saying thank you for your timely response to my problem....Your  is willingness to help and sharing of your vast knowledge is very rare...Kudos to you...

After review of your answers I decided to to take a step back and start over to gain a fresh look...sometimes its better to wipe the slate clean, and clear out the cob webs...Its easy to get so focused you cant see the problem....

As you stated above nothing metaphysical about this very simple and really very reliable system...I hope the following helps someone in the future with a very simple problem.....

The FUEL LINES WERE REVERSED..........

That's right....the lines at the TBI were reinstalled exactly as removed...The problem came at the tank...when reassembling I crossed the rubber hose to steel lines......very easy to do when laying on your back with dirt in your face.....

I just never spotted the problem up front as I was reassembling the TBI and doing the tests.....Not sure if this will resolve my original problem and will advise after some test drive time...

I have always enjoyed being the brunt of a good joke and I always learn more from my mistakes than anything else...

As for my eating crow...My wife says I have to ride in the back seat for awhile.....At least she's letting come along for the ride.....

Thanks Again for your incite......Now about those Cookies......

Jamie

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Jeep4Us...Jamie, I am so pleased to hear that you solved the problem!    This is great and certainly nothing to be self-conscious about...A retake, an outside citing of the basics, and you came around to "seeing the forest for the trees".  We all do this at one time or another.

My mind process, and pick up on this, is to refocus on what's supposed to be happening, followed by the likelihood that nothing drastic has changed beyond what I have done.  In your case, that was changing the fuel pump.  At least you now know now how high the pinched pump pressure will reach.  That short testing period should not have damaged the new pump.

I'm really glad that you found something concrete.  Did you use high pressure clamps on the pump fuel lines?  Are the tubes "bubbled" to prevent the hoses from sliding off?  Have you reset the pressure regulator to factory PSI?

So glad that you were willing to "put it out there" and share these details.  Now others with this issue will know where to look!

Thanks, Jamie,

Moses

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