New fuel pump, new regulator, still has fuel pressure issue..

[Intellect]

Do this:

With engine up to temp with fuel pressure gauge connected. Find the return fuel line where it is rubber and is accessible to clamp with flat blade pliers. Start engine, read gauge, clamp return line. Pressure should jump up to 70>90 psi, turn engine off with line still clamped. If pressure drops fast it will indicate fuel pump check valve. If it stays up or drops a small amount it will indicate regulator or injector leak, if it steadily drops it will be injector.

To recap. 3 new fuel pressure regulators (different brands, even tried 2 junkyard oems), 2 offbrand pumps, a bwd pump and a bosch, 6 injectors, tried a one way check valve (which blew first use). All lines are solid not broken. I got the bleed of minimilized to not hitting zero for 4.5 hours.

Bledd off is inevitable :gee:

 

[comanche91]

I have a stroker and am using the 96-99 Mopar 53030778 injectors with an adjustable FPR and run around the same fuel pressures as you do, 49 w/o vac, 39 w. vac. On the MJs there is a section of rubber fuel hose on the right side of the rear axle just before the supply and return lines connect to the hard front lines. I clamp the return line there for pressure tests. Maybe the XJ fuel lines run differently, but there has to be a rubber to hard line transition back there somewhere you can clamp.

My fast pressure drop turned out to be the fuel pump check valve, and the aftermarket inline check valve did the trick. Once my fuel pump dies and gets replaced, I'll ditch the inline check valve. Until then, it's doing fine.

 

[Intellect]

Ill try clamping there... Im circling back to the bleed off once i figure electrical. I dont mind waiting for the prime before i start. Mine isnt the pump check valve, i tested it out of the tank.

 

[Ecomike]

That is what I recall too, I think mine bleeds off to zero overnight, or after 4-5 hours...but I could not find where I made any notes.

Mine was a 50% pressure drop in 20 minutes earlier this year, cruiser54 said that was good to go,

so I moved on and found the real problem after way too much grief, it was shear pin in the Dizzy drive gear going bad screwing with the timing, very rare and hard to locate unless you knew what to look for. It was not obvious until the pin completely failed.

To recap. 3 new fuel pressure regulators (different brands, even tried 2 junkyard oems), 2 offbrand pumps, a bwd pump and a bosch, 6 injectors, tried a one way check valve (which blew first use). All lines are solid not broken. I got the bleed of minimilized to not hitting zero for 4.5 hours.

Bledd off is inevitable :gee:

 

[Intellect]

That is what I recall too, I think mine bleeds off to zero overnight, or after 4-5 hours...but I could not find where I made any notes.

Mine was a 50% pressure drop in 20 minutes earlier this year, cruiser54 said that was good to go,

so I moved on and found the real problem after way too much grief, it was shear pin in the Dizzy drive gear going bad screwing with the timing, very rare and hard to locate unless you knew what to look for. It was not obvious until the pin completely failed.

That makes me feel better about my bleed off. Maybe i fixed it than. If you could find that note i appreciate it ..

Also, new ignition switch... Pump delay is still there, i just finished up. Thinking of putting my old one back in and putting that $35 elsewhere.

 

[Intellect]

Pump delay with check engine light delay still there.. everything in column looks clean. No burn. No melt. No funky smells. Connectors all look great.

So wheres this leave me? How do i diagnose if its ecm/pcm or relay box under hood. (Like i said earlier, the ac relay spot in the box under hood crapped out and i had to jimmy rig something, so with the pumpy relay being beside it i wouldnt be surprised if that relay spot was funky too) (what was bas about ac relay spot was the wire position on the relay that went from relay to battery was bad.) Maybe similar situation for pump relay spot? Idk why it would delay... and not.. just not work at all.

 

[Intellect]

Using tap a talk so excuse me if images are big.

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[Intellect]

First 42 seconds shows the issue again (with new switch) ignore the rest unless you want to see an overview of my burnt free column.

https://youtu.be/6neEPmSL42I

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[Intellect]

Ok i should of made a video. 110% not a pressure issue. Wow i wasted a lot of money and time on that. With sitting pressure at 49 psi it still took playing with to get it cranked. I never thought to force prime it with cycling, make sure gauge is at 49psi and than crank. Even after i got the delay to catch up, it still took playing with, giving it gas and such. I imagine the pump has problem getting power when cold but when it gets warm power/electrical issue dissapears... So... Dang...odd....

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[Intellect]

Well doubt its the relay, jumping 30 and 87 makes the pump come on just fine.

Whatever it is controls the fuel pump AND check engine lights, AND tells the computer the pumps working. Cause like i said, when cold, even at 49 psi, it doesnt crank.


The plot thickens......

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[Intellect]

And before we circle to the cps i tested that many times with a multimeter via bleepin jeeps tutorial. Its good.

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[Intellect]

Side note, can i use a 2wd ecm in my 4wd? Local has a 94 ecm, figured i can diagnose with it.

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[Ecomike]

Post 107 photos show severe overheating of the red and purple wire insulation that has turned dark brown the last 2 or so inches. Have you tried wiggling them in run to see if the pump wakes up?

First 42 seconds shows the issue again (with new switch) ignore the rest unless you want to see an overview of my burnt free column.

https://youtu.be/6neEPmSL42I

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[Intellect]

Post 107 photos show severe overheating of the red and purple wire insulation that has turned dark brown the last 2 or so inches. Have you tried wiggling them in run to see if the pump wakes up?

Just tried that, no difference. I plan to buy a used ecm and see if thats it. (If so ill splurge on a new one). But ive had a guy on another forum walking me through a lot of multimeter tests. Nothings unusual, says everything points to ecm?

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[Ecomike]

When did the no cranking issue start?

Other than you getting cranky LOL.:laugh3:

Your Fuel pump time delay on/off issue, and not cranking are two different problems. Give us a the details on this new(???) no cranking issue!!!

New starter switch .... wire issue, as the wires/connector got moved????

Not sure about the Chrysler column, mine are GM 85-89 columns, but on mine there is a hair trigger location issue of the ign switch that needs fine tuning when you tighten the mounting hardware. It is the apx 12" long rod between the key hardware and the actual ignition switch. If it is not set in the sweet spot when you bolt it down, you get a no crank. Also the rod from the shifter does not allow the shifter to move properly if it gets out of sync, and then you have the NSS, Neutral Safety Switch. The NSS can get old, dirty internal contacts and cause a no crank, thinking the jeep in is gear. Needs to be in Park or Neutral to crank.

EDIT: Did you check the ECM fuse? maybe you blew it working in the Ign switch swap???

 

[Intellect]

When did the no cranking issue start?

Other than you getting cranky LOL.:laugh3:

Your Fuel pump time delay on/off issue, and not cranking are two different problems. Give us a the details on this new(???) no cranking issue!!!

New starter switch .... wire issue, as the wires/connector got moved????

Not a starting issue persay. In getting all these posts mixed up here lol, in the end, when i say starting i mean the fuel pump/ecm issue ive had since i first posted.

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[Ecomike]

Well doubt its the relay, jumping 30 and 87 makes the pump come on just fine.

Whatever it is controls the fuel pump AND check engine lights, AND tells the computer the pumps working. Cause like i said, when cold, even at 49 psi, it doesnt crank.


The plot thickens......

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LOL, word choices do matter, this is what got me all CRANKED up, LOL.

That said, when it does not start and has fuel, I would check the CPS during the cranking cycle for a signal (If that is possible?). Or check for a spark!!!! If there is fuel pressure and no spark, it may be the CPS going bad. I have been told the 91 and newer CPS test does not prove the CPS is good!!!! Ask Old_man

Use a hair dryer to heat the CPS, then other suspect parts, HV coil, ICM to see which one is not working cold?

Also I had no starts when cold ages ago with a bad Intake Temp sensor on my 87 Renix.

 

[Intellect]

Tried the cps trick. No luck. Nlow dryer broke though, #myluck lately... so didnt get to heat ecm......

BUT i read guys online that had the computer issue would turn the key to acc, wait 5-15 minutes, than come back and crank her up, well guess what, i turned it to acc waited 30 secs to hear pump whuuur,than primed 2 times to guerentee pump was well primed. Than i left the key in acc spot for 5 minutes on the dot. Came back, and cranked a LOT easier... The plot thickens. So leaving the key in acc helped whatevers up with this Jeep. Money on ecm?

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[Ecomike]

Once again, cranking is cranking, starting and running is starting and running, they are not the same thing, One follows the other, one must crank it to start it, but starting is not cranking.

You say you had it in the Acc position? Do you mean in the Run position or the Acc position? The too are not the same. The Acc position on the ignition switch does not to my knowledge power up the ECU at all. Thus it would have no effect on powering the fuel pump or the ECU, etc. It powers things like the radio...

I would track down power from the ignition switch to the ECU, test the wires at the ECU for power. Also be sure to consider the ASD relay mentioned on your new thread it too is notorious for no starts!!!

 

[Intellect]

Once again, cranking is cranking, starting and running is starting and running, they are not the same thing, One follows the other, one must crank it to start it, but starting is not cranking.

You say you had it in the Acc position? Do you mean in the Run position or the Acc position? The too are not the same. The Acc position on the ignition switch does not to my knowledge power up the ECU at all. Thus it would have no effect on powering the fuel pump or the ECU, etc. It powers things like the radio...

I would track down power from the ignition switch to the ECU, test the wires at the ECU for power. Also be sure to consider the ASD relay mentioned on your new thread it too is notorious for no starts!!!

Ill go back to my laymens terms than, my apologys. I put the key in the half turn position, half turned clockwise right before fully turning it clockwise.

Better? Lol

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