Hello this is my first post. I am working on an 87 Wrangler with the 2.5L EFI. It has had a history of sometimes not starting after an hour or so drive. Let the Jeep set overnight and it will fire right up.. During this condition the fuel pump sounds like it is struggling to run if it runs at all. I replaced the pump, strainer and fuel filter. Ran it for 3 hours and now the new pump is locked up. I have ordered a complete pump module and I am waiting for its arrival. I show around 11.5 volts at the fuel pump plug when cold and this last time I checked the voltage at the plug after the 3 hour run it was around 10.5 volts. The jeep was still hot when I got that reading. Can't figure this out and hate to burn up anymore pumps. Is low voltage a problem here or is the ballast resistor junk? Don't know where to go from here.. Any help is appreciated.
Jeep wont run when hot
- Thread starter Buff71
- Start date
Optimally you should have the same voltage throughout the entire vehicle which is typically between 13.8 and 14.3 when its running. For starters make sure your charging system is up to snuff. In a nut shell the lower the voltage the more amps are required to do the same job and at some point if it drifts low enough things will stop working. In your case Id suggest you have a bad ground or several of them. A bad ground will cause heat, heat will cause more resistance and lower voltage to the pump and other systems. Cleaning ALL the grounds is where Id start for one.
Thanks guys. I appreciate your advise. I will give the grounds a cleaning. Finding them all will be the challenge I am sure. The charging system is ok. 14 volts when running. So the pump should be receiving full voltage. The manual mentions a ballast resistor in the fuel pump wiring so I thought the voltage to the pump would be lower than full voltage.
Change the cam positioning sensor. ( it takes the place of the distributor if you don't have one) A few bucks and it wont hurt a thing. Had the same issue in my Cherokee with 4.0. Took me 2 days but I figured it out. I rebuilt the sons engine that torched a piston. I reused the cps. Same issue right away. Once hot would not restart until it sat for awhile. After getting 2 rebuilder short blocks from the junk yard realized they had the same cylinder damage. I carry a new sensor in the glove box now. Give that a shot.
CPS is also on my to do list (though I'm just going to get the whole distributor) as are injectors, cap & rotor.
My Jeep left me and a buddy walking a mile and 1/2 out of the desert yesterday, just died on trail trying to retrieve a spare tire fell off his kids truck.
No good deed unpunished? Right..
How am I ever going to trust this thing on trail when I don't even trust it to go get cigarettes.
Speaking of solving that problem, how is your little wiring project progressing?
Yeppers..the down side of computer controlled stuff . I agree 100% once the shadow of darkness shows its face its hard to regain confidence when miles from anything and its 20 or 110 out. Another problem for me is the fact 90% of the parts we get is Chinese made short lived garbage. Anymore I carry a tent, S bag and supplies in case mine craps out in BFE. Might save a or our life some day.
Certainly is, been looking for the warm and fuzzy, but it's eluding from me.
My old '43 was Disney'd together with junk yard parts, but I trusted it implicitly.
Whenever I walked away from that one, it was My fault.
Also got survival bags like that myself for that exact reason.
My old '43 was Disney'd together with junk yard parts, but I trusted it implicitly.
Whenever I walked away from that one, it was My fault.
Also got survival bags like that myself for that exact reason.
its moving along but slowly. I had some steering column issues I found and since it is out I can change the turn signal switch the non locking key switch and tighten the tilt assembly so until I get it back in I'm just temp hooking things up to test fire then once all the wiring issues are resolved. I'll go through and solder and shrink tube things to fit as needed. In other words DONT GET A CHEAP HARNESS SET LMAO. I did find American Auto wire seems to have their stuff locked on and very detailed directions and assistance. even their website lets you down load their manual and it is full of knowledge. They are still abit salty on price but its virtually plug and play with their harness. I also bought a sealed factory set of wiring diagrams off Ebay a few weeks ago. Thats been a huge help decyphering wire colors and wire locations in the harnesses
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