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Old 08-26-2014, 02:23 AM   #1
Join Date: Dec 2013
Posts: 8
Low fuel pressure and has no power

When I start up my jeep it always takes a lot more cranks to get it started and I'm waiting for maybe about 5 or more seconds till my jeep will start. When I drive the car, doesn't matter if it's warm or cold, and I try to step on it passed 2000 RPM's in any gear the engine will hesitate, make a bogging down noise, sometimes backfire and slowly speed up. When I climb up hills I can't keep my speed unless I have RPMs over 3500.

I rented a fuel pressure kit and tested it on my jeep. I hooked it up and turned my key just before the ignition start, I see the gauge go up to 1 PSI and then declines back to 0. I go to start the engine and the pressure slowly climbs up to 13 and will finally start up at about 13 PSI but will be very rough. After a few seconds it will run fine and the idle is Smooth but the fuel pressure is running at about 20 PSI now and when I remove the rule vacuum it will only go up to about 21 PSI. When I turn my car off the pressure immediately drops to zero within 10 seconds.

Does anyone have any ideas what this might be I think it is the fuel pump but just want to check first before I have to drop my tank. I put in a new tank and sending unit about 2 years ago but has always seemed to have that problem but recently just keeps getting worse.

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Old 08-26-2014, 01:22 PM   #2
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Join Date: Mar 2012
Location: Ridgway, Pa.
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That fuel pressure is definitely low. But could be caused by a clogged or partially clogged fuel filter. Or even a clogged pick up sock on the bottom of the fuel pump.

When you changed the tank, did the new one have the plastic cone in the bottom? Sometimes over time they break loose and cause problems with the pump by starving them from getting enough fuel to operate correctly.

Even a clogged vent can cause the problems that you are having, if the tank cant get air into it, the pump cant build any pressure.

In any event, it looks like you are changing the fuel filter and if that doesn't cure it, dropping the tank.

'87 YJ, 4.2L built and bored, 8.5" of lift, 8.8 rear, AX15/NP 231, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...
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Old 08-26-2014, 03:21 PM   #3
Join Date: Dec 2013
Posts: 8
i will defiantly change the fuel filter and see if that changes anything. i know that almost every time i head to fill up my gas tank, i take the gas cap off and it sounds like it releases a lot of pressure and creates a vacuum.

And i do think that there was a plastic cone in it but will check that if nothing else seems to fix the problem. Thanks
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Old 08-26-2014, 11:30 PM   #4
Join Date: Dec 2013
Posts: 8
So I Checked the fuel pressure with the gas cap off of it and it didn't change the PSI. Then i replaced my fuel filter and that didn't fix the problem either. So then i just figured i would just replace my distributor cap and spark plug wires just to put some new ones on. but still the pressure stays right at 20. I think i just got to drop the tank and check to see if the fuel pump is clogged or replace it.

If anyone has another ideas please let me know.
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Old 08-26-2014, 11:36 PM   #5
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Join Date: Jul 2014
Location: PHX, AZ
Posts: 121
check your fuel pressure regulator.. Mine did this same thing.. If you see or smell fuel in the vacuum line coming off of it to the intake manifold replace it its shot..
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Old 08-26-2014, 11:37 PM   #6
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Location: PHX, AZ
Posts: 121
also look for vacuum leaks

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