1990 i6. Was just going around a corner slowly and the jeep just plain died. Tried to restart it, fired up like usual but then right away just died. It fires up but wont stay on. My first thought, its a fuel issue. So i pressed the nipple on the test port and there was almost no fuel coming out. When i turned the key to on position I dont hear the pump prime either.

What could be going on? The whole sending unit is brand new, its got new fuel pressure regulator and the truck was running fine all day today.

 

here what the jeep does

 

you check the linkage for the throttle? im not 100% sure but my friends focus did this when the stop that keeps the engine at an idle broke so it would just cut its own gas

 

Since u did not hear the fuel pump....check the fuel relay.....fuse
Check the dc supply to the fuel pump....
Hope this help.

 

I 2nd this check your fuses and your fuel relay... Check your fuel injectors make sure none are leaking also I would check your Iac and throttle body...
If you hold the gas pedal does it stay running?

 

If I hold the gas down it keeps running, yes. Fuel pump makes no noises at all. It does not prime. There is no pressure in the rail at all. I swapped the relays around and still same thing. If I totally remove the fuel pump relay it just won't even start, just cranks. Where is the fuel pump fuse on a Renix jeeps?

 

If it runs by holding the gas pedal down, then it is likely not an electrical control problem.

The fuel pump itself is #1 suspect.

With an 87-90, you should have 31 psi while idling. Then disconnect the vacuum line leading to the fuel pressure regulator and the pressure should jump to about 39 psi.

 

Yeah thats kind of what I was thinking. I just went through this whole issue with a fuel pump before and actually replaced the whole sending unit. The unit only got about 1000 miles on it.

 

Ok, a little update. Was able to get it into my drive way, with a help of a good friend. We did a few testings. Pump does
Not prime at all. Key on no sound no buzz. It does start normally like it always did. I han my hand on the supply line right at the fuel pump, key on, no noise, line is limp. When Sean started the car the line got hard he kept it reved up at like 4-5k and then as soon as he let off the line went limp.

So there is pretty much no fuel pressure. The pump gets power and runs for a little bit and then just dies.

So pump is bad?

 

is there anyway to just make the pump come on manually? like short the wiring in a way?

 

ya i'd test your fuel pump. you can "hot wire" it and try and narrow it down to part or electrical.

 

sounds like a bad pump, even though it dont have manymiles on it, if it was a cheap unit, it could definitly be bad already

 

What's the easiest and safest way to hot-wire it? That way I can see if its the pump itself or some wiring deal. Just two things I don't understand why it's working when I floor it but wont prime when the key is on and won't run at idle, but the truck starts fine.

 

Seriously?? Stick i frickn voltmeter or test light to it, start at the relay, check your fuses and narrow it down to the pump, put the leads on the pump , have someone crank, see how many volts you have when cranking. Check all your connections/wiring, it can be frustrating and expensive to just throw parts at something until you have a result, faster to prop diagnose it, follow the steps, and it could be a simple fix.

 

I tested the harness on the pump already it gets 5 volts when ignition is on for priming.