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Old 05-29-2011, 09:54 PM   #1
Join Date: May 2011
Posts: 5
fuel issues

I own a 1987 YJ and I am experience fuel pressure problems. When I disconnect my fuel line going into my carb I am not pushing out fuel all the time. I disconnected my fuel pump and put the hose into a can of fuel to see if indeed it was pumping...it did. When I hooked the lines back up and turned my key on I could hear the fuel being pumped into my into my fuel filter which is located just prior to my carb. When I try to start my jeep it turns over and runs for a very short time then dies. I have noticed that when I let it sit for a few moments it seems to fix itself momentarily by allowing the fuel to flow into the carb until I start it again and the fuel is burned up. Also, the fuel pump has just been recently replaced. I am not sure if there is a pressure problem or not since it seems like when I disconnect the lines or let it sit fuel will begin to flow once again. I am unsure where I should go from here but some help would be fantastic!
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Old 05-30-2011, 06:00 AM   #2
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Location: Newport, Tennessee
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What about the fuel filter? It sounds like it's clogged up to me. Replacement is quick, easy and inexpensive. Good luck!


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Old 05-30-2011, 11:52 AM   #3
Join Date: May 2011
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Fuel filter is new. the trouble lies somewhere before my electric fuel pump I believe.
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Old 05-30-2011, 01:14 PM   #4
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blow the line into the tank-could be trash,,,,
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Old 05-30-2011, 01:58 PM   #5
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Location: Loveland, CO
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I assume it is a 4 cylinder TBI if you have an electric fuel pump or it is an after market alteration. But you are saying carb which should be a 4.2 with a mechanical pump.

I agree with the above you might have something in the tank that is clogging the feed line and floats away when you stop pumping, only to get sucked back in after a bit.

The other things to look at are:
Wiring connections, especially if this is aftermarket and just recently replaced)
Make sure the hoses are hooked up correctly. I think with an electric pump you have a feed tube and a return line. The return line should feed back whatever fuel isn't used by the engine to the tank so you fuel pump isn't over working.
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Old 05-30-2011, 09:58 PM   #6
Join Date: May 2011
Posts: 5
The jeep is in fact a 4.2L 258, the electric fuel pump was an alteration that was put on prior to my purchase but then needed replaced in January. I will disconnect my lines running into my tank and blow them out to see if they are clogged...very good possibility.

As for the wiring, right now I have my pump with direct wiring to my battery (not permanent) to make certain that there is no mix up with the wiring. I assume that the lines are hooked up correctly on the fuel pump (inflow and outflow are the only two and the arrow on pump is in the right direction). There is a return line coming out of my fuel filter and looks to be hooked up correctly.

I do want to note that I do have what I think is a vapor lock? When I pump fuel into my vehicle I have to hold the pump half way (always have from purchase date) to fill it up and I am not sure if perhaps that is causing an issue? But I never had problems with my fuel until recently.

Will double check all the info you guys have sent me and check those lines to the tank. Thank You for the tips and I hope she will be out scooting soon...this nice weather is giving me the itch!
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Old 05-30-2011, 10:08 PM   #7
Join Date: Oct 2010
Posts: 203
That's not what vapor lock is. And having to refuel at a slower speed is not what's causing your problem. Sounds more to me like you have an obstruction somewhere in your fuel system. Your electric pump should put out a pretty healthy fuel flow when you run it into a bucket.
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Old 05-31-2011, 02:24 AM   #8
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Location: Loveland, CO
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Yeah, vapor lock is an engine issue not a tank issue. You may have vent hose issue in the tank which could be why you have to hold the pump half out, or an obstruction in the fill hose.

Neither of these would cause your issue. Unless for some stranger reason you tank is hermetically sealed and does not allow any air at all in the tank in which case you fuel pump would be fighting the vacuum created by removing the gas. Since gas caps are vented, this seems unlikely.
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Old 05-31-2011, 10:41 AM   #9
Join Date: Jan 2010
Location: Las Cruces, NM
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Did you replace the fuel pump with the same model? Some electric fuel pumps will not "pick-up", how about the screen at the pickup, is it clean? Make sure your gas cap is good.

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