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

Ecomike said:

LOL, I named them Cloaked Jeep Gremlins, similar to cloaked Klingons (birds of Prey, leaving you praying they will vanish and not return), LOL, they just appear and then when you look for them they vanish.:shiver:

Good luck and have fun.

Are you 100% sure it is not still the hose/clamp issue? You could pressure test the pump and hose outside of the tank, next time, if there is one, before installing the assy.

Click to expand...

I didnt test them outside the jeep but today i tested after the filter. Put my gauge there with a makeshift of 2 atachments that where in my kit and some hose clamps. Same issue.

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I swear my neighbors think im crazy... Just installed a one way check valve and the second i key the ignition on it hit 49psi ish (good!) I key the ignition off BAM needle runs faster than a fat kid to mcdonalds, down to 11psi. AND within a handful of minutes itll climb to 9psi i am so fed up with Jeep/chrystler.

4 NEW PUMPS, 3 NEW PRESSURE REGULATORS, 2 FUEL FILTERS, INJECTORS, NO LINES ARE BROKEN, EVEN TRIED THE CHECK VALVE JIMMY RIG!


Any last ideas before i burn this p.o.s to the ground just for personal amusement. I am beyond crazed here lol.

I just did this 10 minutes ago, so ill see if it atleast holds that 9psi.


Many will say "ah give it up take it to a shop"

Well 4 reputable shops couldnt find the issue either. (I have a lot of mechanic shop friends).

I would give my LEFT LEG to find this issue

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Picture

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Update, its still dropping.

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Well i took the inline check valve out and it doesnt work anymore so... Maybe try a different brand check valve?

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If the pump internal check valve was bad(as i assume it is maybe? Losing my mind here) it would leak fuel back, how would i watch this, since the pump sucks the gas through the sock/filter. So it would leka it back into that correct?


Im thinking about maybe calling bosch...

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Welp i took off the sock/filter sucker upper. And made the pump suck gas strait from a cup, and watched it as soon as the key was cycled and turned off. The fluid did NOT drain from pictured hole, back into cup, so not bleeding off THERE. Boy have i ran in circles with this issue... Maybe ill buy a new fuel rail and waste money there next?

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I went with a 5/16 fuel injection hose from a different auto store... At the fuel pump, and it doesnt ibstantly drop to 15psi... Hmmm, i tried the oreillys fuel injection hose, the one with the bosch, and now autozones, now it has only bled 50psi to 42 psi in 8 minutes. Before in 8 minutes it wouldve been 0-10psi... Ill report back after it sits a long time, but if this was all hose issue, boy do i have bad luck!! (But lets not put our ducks in a row just yet) i wont set off the fireworks until i report back.

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Did you install the check valve backwards?

Did adding the check valve double the back pressure while running, as IIRC 39 is the top OEM fuel pressure for 1995???? It is 39 psi if it has a return fuel line.

The added check valve may raised the pressure enough to damage a hose seal, or damage the fuel pump CV or the FPR-check valve since you saw it reach at least 49 psi!!!!

You need to start from scratch looking for leaks from the pump to the injectors to the FPR itself. You pull the rail from the intake, make sure the injector clips are still holding the injectors to the fuel rail, then cycle the switch to see if any fuel at all leaves the end of the injectors.

Are you sure you got that fuel hose at the pump sealed 100%????

Now, one time, "if it ain't broke don't fix it!!!!"

Does it start right up all the time now????

Does it have proper fuel pressure when running???

Pretty sure mine bleeds down to 20 psi quickly with the engine turned off, and goes to zero over night, if not sooner. It runs and starts fine!!!

Lastly, is there a filter in the line!!!!! ???

You could have trash in the fuel line that is coming loose and sticking in the new FPR-check valve, or injectors, or from drain backwards into the fuel pump from decaying hose in the fuel lines!!!!

Did you just confirm the fuel pump check valve is holding pressure? You can dead end the pump to a pressure gauge, and cycle it on for barley 1 second (do not run it too long, as it might damage the pump, over pressure it??) and see if it holds pressure.

Ecomike said:

Did you install the check valve backwards?

Did adding the check valve double the back pressure while running, as IIRC 39 is the top OEM fuel pressure for 1995???? It is 39 psi if it has a return fuel line.

The added check valve may raised the pressure enough to damage a hose seal, or damage the fuel pump CV or the FPR-check valve since you saw it reach at least 49 psi!!!!

You need to start from scratch looking for leaks from the pump to the injectors to the FPR itself. You pull the rail from the intake, make sure the injector clips are still holding the injectors to the fuel rail, then cycle the switch to see if any fuel at all leaves the end of the injectors.

Are you sure you got that fuel hose at the pump sealed 100%????

Now, one time, "if it ain't broke don't fix it!!!!"

Does it start right up all the time now????

Does it have proper fuel pressure when running???

Pretty sure mine bleeds down to 20 psi quickly with the engine turned off, and goes to zero over night, if not sooner. It runs and starts fine!!!

Lastly, is there a filter in the line!!!!! ???

You could have trash in the fuel line that is coming loose and sticking in the new FPR-check valve, or injectors, or from drain backwards into the fuel pump from decaying hose in the fuel lines!!!!

Did you just confirm the fuel pump check valve is holding pressure? You can dead end the pump to a pressure gauge, and cycle it on for barley 1 second (do not run it too long, as it might damage the pump, over pressure it??) and see if it holds pressure.

Click to expand...

Ill answer all the questions in a moment... But my jeeps always had 49psi when running..

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I did not install the check valve backwards. 100% positive. It was $12 amazon special... Guy said it worked on his 77 camaro on a review but another review said it blew first use like mine. Go figure, shouldnt of cheaped out.


My fuel preasure has always been around 49 psi. Was told somewhere in 95 SOME return styles had 49 right before the switch to returnless. At one point the fuel rail where the pressure reg sits, was slightly bent, thats why it was lower psi on an old thread of mine. But once i bent where the pressure reg sits back "strait" (compared to friends 95 cherokees) it sealed nicely and started reading 49psi ish from that point on. The pressure reg sat fully seated from that point on.


The inline check valve was in there for literally 1 minute of run time total. I doubt it damaged anything. I took it out and put everything back oem under there.

I am 100% the line at the pump is sealed NOW, as i put a tighter hose on there and tighter hose clamps. It is SUPER snug. Plus pressure doesnt bleed off instantly (fingers crossed maybe this solved it) in the last hour it dropped to 29psi, usually in 1 minute it dropped to 9psi.


Until this fuel issue "if it aint broke dont fix it" was my motto for any vehicle ive ever owned. Ive been chasing this issue for so long its unreal. I did injectors as a last resort, plus i always wanted to do the 4 hole upgrade, so hey, 2 birds right?


When running fuel pressure pings around 49psi, it runs fine. (247,000 miles) but fine. Real good for a car with those miles. I literally run it 6 hours strait offroad. Knock on wood. And im fine. It is literally a bleed off WHEN IT SITS issue. I can drive it 200 miles on the interstate. Offroad it 6 hours. Drive 200 miles home. And no misfire. No hesitation. No starving for fuel. (Ive had a mustang that was garbage on the interstate with fuel issues, a bad pump, so i know how it would feel/act)


I didnt worry about fuel pressure until i had the issue of it not starting after sitting over night. If it cranked first try i wouldnt be here. Its not my daily. I dont need my 22 year old jeep to oem spec lol. Im not nit picking. I just want a first start, settle for second start lmao.


I do have a fuel filter. (Also new!)
And i doubt theres stuff in the lines causing this, it is for sure a bleed off issue, if i had stuff randomly clogging lines id have problems on the interstate and offroading and in the woods. But nope. Its fine. I put it to the test recently. Went 200 miles up north. Offroaded 5 hours. Camped over night. Next morning took playing with key cycling to get it going, offroaded 6 ish hours, came 200 miles home.



And yes i did just verify the pump check valved good (i think) i sat under the jeep. And had someone cycle the key, pump sucks fuel in. And it doesnt release it (atleast for the 5 minutes i sat under the jeep starring at it)




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2 hours later 20psi, fingers crossed! Im going to have it sit overnight and see if i get a healthy first time crank in the am

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I AM GOING NUTS. IT ONLY DROPPED TO 14 PSI IN 3 AND A HALF HOURS. so i figured, "oh great, didnt hit 0 psi!" But nope, go to crank it and no fuel, foot to floor.. POP POP OH BOOHOO IM A JEEP AND IM NOT GETTING SUFFICIENT GAS IMA THROW A FIT, oh wait you cycled the key a few times? Fine, now ill act like a good little jeep!


I AM SO FREAKING DONE.

Any downs to just putting the pump on a damn switch that i can flick on for a few seconds to the pump before i crank the jeep? A "system prime" switch?

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Ill see if it bleeds to 0 overnight... If it does, back to square 1. If it only bleeds to 15 ill consider the bleed off FINALLY fixed, and move onto the sometimes pump not turning on first or second key cycle issue.

Relays new.

Wouldnt surprise me if i had an issue at the under hood fuse box, when i did my ac the relay position from relay to battery was bad coming from the box, and had to run a new one... Maybe something in the fuse box/relay for fuel pump is half loostened so thats why itll only present itself half the time?


Before we go chasing electrical grimlens ill report back for the psi overnight... If psi is fine than id much chase electrical ANY DAY. Much easier. Can always run your own wiring for 75% of wiring issues.

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Minds got 100 things going through it, fingers crossed the bleed off doesnt happen overnight.

Onto the electrical issue. Before just slapping an ign switch in it. How can i see if its around the relay/underhood box. I did a visual inspection. But i just have a hunch its around that area, because of what i went through with my ac. The jeep ac never worked. I put new compressor, evap, drier, r134, condensor, etc. Had a multimeter everywhere and it wouldnt kick on. Low and behold a lot of diagnosing later... The relay under the hood, the female end in fuse box, had a bad relay to battery wire.

Maybe the fuel pump relay female end in box is similar? Ill have to see.


LORD DO I HOPE I HAVE PRESSURE IN MORNING

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Okay now this is interesting. I forgot to mention. I get code 13 once in a blue moon. Which if you google it means something to do with map sensor not reading different pressure during start up or something.


* The PCM reads atmospheric air pressure from the manifold absolute pressure (MAP) sensorand calculates the basic fuel strategy.

So this pcm shitting on me thing might make a little more sence.

Google code 13 to see what i mean.

110% not a bad map sensor, sensors are childs play.

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Unless the code 13 is a puzzle piece to ignore. Ive only got it twice after those long crappy cold starts where its begging for fuel. So it could be faulty and something to ignore. Could be caused by the other issue(s) so sorry to blabber on, just so much thinking on this matter lately. I will refrain from posting till the morning and hope at LEAST 15psi is maintained overnight.

(Thinking the damn hose in the tank mightve been this pesky pressure issue)

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Bad ignition switches are common on our jeeps. On the 87-90 they would go bad on the AC blower, AC power, Wind shield wiper, turn signal, electric window power through the ignition switch, with out causing starting or running issues. Did you not mention AC issues? Yes? But you fixed it already?

Also, the 87-90 was notorious for sloppy, noisy ground connections causing all sorts of issues. Like fuel power, sensor data issues to the ECU.

Lastly, are you aware that at WOT when starting, the ECU shuts off power to the fuel injectors, thus it cuts fuel going into the engine!!!! Your 2-3 comments about WOT "starting" and "flooding" etc make me wonder if think WOT is feeding fuel when in fact it cuts off power to the injectors so they can not deliver fuel (unless one is leaking???) ??? It actually is a trick when cranking to rapidly dry out a flooded fuel injected computer controlled engine!!!

Intellect said:

Okay now this is interesting. I forgot to mention. I get code 13 once in a blue moon. Which if you google it means something to do with map sensor not reading different pressure during start up or something.

* The PCM reads atmospheric air pressure from the manifold absolute pressure (MAP) sensorand calculates the basic fuel strategy.

So this pcm shitting on me thing might make a little more sence.

Google code 13 to see what i mean.

110% not a bad map sensor, sensors are childs play.

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Click to expand...

Intellect said:

Unless the code 13 is a puzzle piece to ignore. Ive only got it twice after those long crappy cold starts where its begging for fuel. So it could be faulty and something to ignore.

Click to expand...

I have never seem a bad MAP sensor, or read of 2 found here in 10 years. Super rare. That said, the vacuum hose to the MAP sensor is a common bad part!!! Mine was acting OK this year, most of the time, but it turned out it had a hidden dry rot, loose sloppy connection on the bottom side of the rubber-plastic tube connection, not visible unless you removed it and turned it 180 degrees!!! Mine is renix, your is HO, so IIRC yours is short and hidden, and know to develop an issue on the bottom side of the rubber from the intake throttle body to the MAP sensor.

I doubt it is your current problem.

So much food for though.. guess ill see where psi is at in morning and go from there. If psi is good ill start diagnosing the ecm, relay female on the box, ign switch.

Mines a 1995 btw. And yes i did mention ac issues (fixed) issue was at relay on fuse box under hood.

I did have my blinker switch go out, i replaced it months ago.

My blower motor does go out sometimes, nothing a good wack on the dash doesnt fix LOL.

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And maybe i was using the wrong words, whenever i have the cold start issue, i give it constant gas until it has a steady stream (from the bleed down) or gas issues in general.

In depth.

Crank. Nothing. Crank. Nothing. Engine wants to turn but no fuel.

Mr pump , oh hey guys im late to the party, whuuuuuuuuur, *check engine light comes on same time*

Crank, starts and dies, or starts and i hold gas.

Crank, feed it gas for a minute, drive it 6 hours just fine.

OR i could have turn the key 20 times.


Not those steps to the t everytime, but you get the picture.


I hope i painted a picture sort of. I have in my own head. It was two issues. Fuel psi, plus this electrical. Cause a bleed off issue (super common amongst old cars) you can just prime it 2-4 times. But since it wouldnt prime right away each turn, it was a electrical and bleed off combined

Normal car with bleed of youd... Half turn, prime 10-15psi ish? (Bullcrapping psi #s here),

Second Half turn. 30-40 psi

Third half turn, 40-50psi

Crank and fine.


BUT MINE. Bleed off

First half turn... Mr pump wake up

Second half turn... Wake up mr pump

Third half turn whuuur 10-15 psi

Fourth half turn.. wake back up (bleed off issue has drained back already)

Fifth turn, whuuur 10-15 psi again


So thats why it took much more playing to diagnose my bleed off.


I hope all that babbling made some sort of sence...


Whats weird is when the car has recently been running the pump always turns right on... I know its electrical... But never seen an ELECTRICAL issue that is only persistant on a COLD engine. .. florida... "Cold".....




Once again before we jump any guns im making sure it holds 15psi overnight.


But this bleed off wouldnt even of ever been a big issue if the pump had turned on everytime i cycled the key, cause i couldve just done the old poor mans prime...



I reread above post you made other day, can you help me diagnose to see if ecm/ign switch/relay box? (If psi is held in morning, but weve established psi issue and electrical issue are obviously seperate at this point)

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