Someone suggested I post this question here.

Transplanted '91 FI 302 into a Jeep. After it sets overnight it starts but lopes really bad. If I cycle the key 4 times to let the fuel pump build up it starts up fine and runs pretty good. After warm up all is well. It has to set for 8-10 hours to loose fuel pressure and give this symptom. Anyone ran across this before and fixed it?

Thanks for any help!

 

sounds like the fuel pump isnt working properly, or the fuel filter is clogged

 

Is it a complete mass air conversion? did you put the whole computer and wiring into it? It might be getting some odd reading from either a TPS sensor or the O2 sensor. Have you tried to pull the codes?

 

I had a similar problem at cold starts in the morning before when i had my Ranger. But my problem was because of the oil viscosity I used. I used 20W-50 since it was an old vehicle.

 

Yes, total mass air conversion. Running a new stock Jeep fuel pump in the tank. Thought maybe that was it but it runs fine after it gets warmed up even after letting it set for a couple of hours. I think the pump is providing enough fuel.

 

then I would have the codes pulled from it to give you an idea of where to start looking for hte problem

 

do you have a fuel poressure gauge hooked up to the fuel line to see what the actual fuel pressure is doing? or hooked up a regulator to make sure it is maintaining proper fuel pressure the whole time. also might want to go back and check all the wiring and make sure everything is on its proper place