1989 Cherokee Laredo; fuel problem

[JamesJH]

I'm having problems with my 89 Cherokee (6 cyl) fuel pump. I have a new ignition module and spark, a new fuel pump. and 12 volts to the fuel pump, but when I turn the ignition on the pump doesn't work?? Anyone know what else could be causing this problem?? Help.

Thanks JamesJH

[Saudade]

By doesn't work you mean, it doesn't run? or it runs but doesn't pump? or it runs and pumps but still your car won't start?

Have you changed the fuel filter yet?

[JamesJH]

Originally Posted by Saudade

By doesn't work you mean, it doesn't run? or it runs but doesn't pump? or it runs and pumps but still your car won't start?

Have you changed the fuel filter yet?

JamesJH .. It's getting spark, has new fuel pump and I have 12 volts going to the fuel pump but when I turn the ignition on the pump does not pump fuel. It turns over fine, and has spark. Any idea why the pump is not pumping fuel?

[Edbrooks]

Can you hear the pump running when you first turn on the ignition? If you can, the pump relay is OK. Disconnect the fuel line at the fuel rail (be sure not to lose the o-ring! Take it off and put it somewhere safe for the moment!) Have someone turn the ignition switch on while you put your finger over the end of the fuel line from the pump. If you get substantial pressure, (it will force your finger away) the pump is working and the problem may be in the fuel pressure regulator, allowing all fuel to return to tank. If you get no fuel, or very low pressure, easily stopped with your finger, the pump is not pumping correctly, which seems to be your problem.

Inside the gas tank the pump connects to a short hose that runs to the fitting plate where the pump is mounted. That hose is held on with stainless steel hose clamps and is inside the gas tank. Those are screw type clamps. If one is loose, the pump simply pumps gas in a loop inside the gas tank. Fixing - or checking for - the problem requires removal of the pump from the tank and tightening/checking those clamps.

[JamesJH]

Originally Posted by Edbrooks

Can you hear the pump running when you first turn on the ignition? If you can, the pump relay is OK. Disconnect the fuel line at the fuel rail (be sure not to lose the o-ring! Take it off and put it somewhere safe for the moment!) Have someone turn the ignition switch on while you put your finger over the end of the fuel line from the pump. If you get substantial pressure, (it will force your finger away) the pump is working and the problem may be in the fuel pressure regulator, allowing all fuel to return to tank. If you get no fuel, or very low pressure, easily stopped with your finger, the pump is not pumping correctly, which seems to be your problem.

Inside the gas tank the pump connects to a short hose that runs to the fitting plate where the pump is mounted. That hose is held on with stainless steel hose clamps and is inside the gas tank. Those are screw type clamps. If one is loose, the pump simply pumps gas in a loop inside the gas tank. Fixing - or checking for - the problem requires removal of the pump from the tank and tightening/checking those clamps.

I put a new pump in and I know those clamps are tight. I also checked the fuel pump relay (on the 89 there is a bank of 4 relays right behind the electronic ignition module), I switched the relays around and it didn't seem to make any difference. I've always been able to hear the pump when I turn the ignition on, in fact it was loud, but I cannot hear the pump at all now, that's why I replaced it. This is a big mystery to me. Any ideas? By the way, the one thing I've been thinking about is the possibility that the polarity is not correct on the pump itself (inside the tank) is it possible that the polarity being reversed could keep the pump from pumping? If so, I can just disconnect the line outside the tank and switch the polarity to check. Just a thought.

Thanks for your input.

James

[Dale Aeppli]

Originally Posted by JamesJH

I put a new pump in and I know those clamps are tight. I also checked the fuel pump relay (on the 89 there is a bank of 4 relays right behind the electronic ignition module), I switched the relays around and it didn't seem to make any difference. I've always been able to hear the pump when I turn the ignition on, in fact it was loud, but I cannot hear the pump at all now, that's why I replaced it. This is a big mystery to me. Any ideas? By the way, the one thing I've been thinking about is the possibility that the polarity is not correct on the pump itself (inside the tank) is it possible that the polarity being reversed could keep the pump from pumping? If so, I can just disconnect the line outside the tank and switch the polarity to check. Just a thought.

Thanks for your input.

James

hi,,, i don't know weither onr not you got my mail on the resister on the fender i doubt if polarity is wrong if it had a two wire connector, don't want to make any sparks at tank. did you check the resister dale
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