4.0 liter runs bad at a slant? like a carb??

[RUTH]

ok, so i have a 86 bronco 2, did the 4.0 swap out of of a 93 explorore, used complete manual wiring harness, but not under the dash, so i dont have the option of sticking a scaner on it, at least i dont think.

ran awsome for about 2 weeks, then started acting up when i would try to climb any steep hill once engine was at running temp, when it is cold it runs fine, but know after tryin to find the problem and it growing into cutting out and sometimes dieing just drivin around, i need help.

i thought it was a fuel problem, i am running a fuell cell and the stock bronco 2 pump/ filter, which i replaced both of those hoping it would help, it did not.

any help would be awsome, thanks.

 

[Nhaz]

The 86 was a carb right?

the 4.0 is a pure fuel injected vehicle. the fuel pressure required for the engine is alot higher then the fuel pump from a carbed vehicle can deliver.

my guess anyways.

 

[trail B2]

The 86 B2 has two fuel pumps one in the tank and one mounted on the frame.When it gives you problems check the fuel manifold shrader valve.If there's a fuel delivery problem it might show.Mines been giving me problems in the heat and the latest theory is the in tank pump isn't working properly and it's creating low pressure with the heat the gas is boiling in the line.When I check the shrader valve air comes out under pressure.Thats one more thing to check anyway when you said you had one pump.Going up hill would put the air at the motor end of the line.

The 86 is the first year of fuel injection.

 

[RUTH]

yeah 86 so it did originally have the fuel injection, and i did put another pump at the fuel cell to get the fuel up to the high pressure pump, with the 2.9 i never had a fuel delivery problem.

i will check that shrader valve and see if its got air coming out, and if so i dont know why, maybe a small hole in my pickup tube in the fuel cell??

 

[wahl_7s]

Check the cell vent make sure your getting air to the cell. check the fuel pressure should be around 45 PSI. i dont think its vapor lock unless your fuel line is really close to exhaust or other extreme heat source gas boils at a much higher temp under high pressure.nedd some more info on fuel delivery with a fuel cell you dont need 2 fuel pumps make sure your "high pressure pump" is below the bottom of the cell!!! fuel pumps dont suck very good. what kind of pump are you using, is it high pressure enough?

 

[RUTH]

yes the pump is below the cell, and checking the valve on the lid i didn't think of that, ill check that too, and Ive done it before, and may sound stupid but just a regular tire gauge is fine for checking the fuel pressure at the rail correct, pressure is pressure and the fuel line is not close the the exhaust at all, i was hoping someone might think its a sensor of some sort,


heres a question, i put the low pressure pump at the fuel cell to help suck the fuel up and to the high pressure pump, do you think that the low pressure pump could regulate the flow??? but wouldn't explain why it ran really good for a while and slowly got worse.

you cant really see it bu my outlet for fuel is at the left side, and i tried filling it completely to the rim, doesn't matter.

ill check the fuel pressure again and let you know what u get.

 

[wahl_7s]

sounds like fuel delivery take the gas cap off and see if that makes it better, than its a problem with the vent. also most fuel cells have foam the foam can be falling apart and clogging the pick-up in the cell, i have also seen the butterfly filter in the cell get clogged. now take this for what its worth the foam is basically to minimize slosh if it were me i would take it out and throw it away, if your not racing the truck it really serves no purpose! by the way check your fuel filter for any little bits of debris thats not normal. and the filter should be before the fuel pump to catch crap before it gets to the pump causing failure.

 

[trail B2]

I just got back from 4x4 ing this weekend and my car ran perfectly.On Fri I pulled the in tank pump and it did not work when supplied with power.Put in a pump that I had on hand no more cutting out.

 

[RUTH]

I just got back from 4x4 ing this weekend and my car ran perfectly.On Fri I pulled the in tank pump and it did not work when supplied with power.Put in a pump that I had on hand no more cutting out.

good deal, im glad its running good now, i haven't had much time to look at mine, i just moved to Nevada, and just been doing a lot of forum reading till i get a place cleared to actually dig into it, im hoping ill have low fuel pressure and it will be a simple replace the pump again, or maybe the pressure regulator on the fuel rail is bad?? don't know how to check it though.

here is how my junk is sitting now... well the pic wont upload to photobucket.. wtf

 

[alwaysFlOoReD]

ok, so i have a 86 bronco 2, did the 4.0 swap out of of a 93 explorore, used complete manual wiring harness, but not under the dash, so i dont have the option of sticking a scaner on it, at least i dont think.

ran awsome for about 2 weeks, then started acting up when i would try to climb any steep hill once engine was at running temp, when it is cold it runs fine, but know after tryin to find the problem and it growing into cutting out and sometimes dieing just drivin around, i need help.

i thought it was a fuel problem, i am running a fuell cell and the stock bronco 2 pump/ filter, which i replaced both of those hoping it would help, it did not.

any help would be awsome, thanks.

I had similar problems in a f-150 truck. It ended up being the ignition module.
Richard

 

[RUTH]

thanks richard, ill keep that in mine, which something i didnt mention before just completly forgot, was when it started to runb bad, i could shut it off for a min and then it would run good again for a min. but i think its a fuel pump issue.

 

[alwaysFlOoReD]

That's what I thought too with mine. Exact symptoms as yours. Actually not mine but I could use if I got it running correctly.This was on a '80 f-150 race truck with an '86 302. It had a home built fuel cell that had cast components.There was definitely a fuel problem as the fuel came out like mud originally but the following didn't fix all the problems; I swapped out;cast for brass, installed fuel filter before fuel pump[ OP didn't have one], low pressure pump, high pressure pump, flushed fuel system. Still not running right. Then I swapped out entire harness and related electrical components, [granted they were used], and couldn't solve the problem.I gave up and the truck got passed on to someone with better diagnostic skills while I built my own race truck. I spent over 80 hours last summer on his truck. I raced against him two weeks ago and he told me it was the ignition module Oh well, it was good to see the truck racing plus I learned a lot.
Richard

 

[RUTH]

you have any pics of your race truck??? would like to see it.. thanks for the input too

 

[alwaysFlOoReD]

you have any pics of your race truck??? would like to see it.. thanks for the input too

Click on the link in my sig.
Richard