HELP! Fuel/Electrical problem.

[Rabbit]

I'm hoping someone here has dealt with this issue before. Ok, for starters, the basics: '88 B2, 2.9l, A4LD auto, 4x4. I have recently replaced the following in response to the problem: Fuel pumps, filter, and fuel control relay. Now for the problem: the damn thing will run just fine for a few weeks and with no warning at all the fuel pump will lose power. It doesn't matter if it was turned off and then back on or if i'm cruising down the highway, it will just stop working. After leaving the truck parked overnight I can go out in the morning and it will respond as if nothing had ever happened. It will go fine for 2-3 weeks then do it again. I'm completely stumped. It's actually losing voltage at the pump and I can't seem to find a short or a loose connection. Any ideas?

 

[Shran]

The wiring to the rear tank in my '86 was worn almost all the way through where the brake line runs through the frame. I'm not sure how the B2 is set up, but maybe it's similar.

 

[IMenriched]

Yep +1, hints of wiring/connection issues.

may also want to check your TFI, (aka ignition module), they do not like heat and if they get too hot they tend to get erratic...yes there is a fuel control component with them as well.

 

[djurs]

+1 on TFI/ICM module
If that doesn't do it, then OHM your wires.

Someone really needs to add a sticky about the ICM/TFI modules. I would suspect there are probably about as many rangers sitting in junk yards that just need an ICM or TFI module as rangers needing a new mitsubishi 5 speed, or explorers needing a new A4LD.

 

[Rabbit]

Ok I tested the Ignition module theory and the results lead me to believe that is not the problem. While the truck was actually working I unplugged the module. I then turned the key to the on position without actually starting it. The fuel pump still came on and primed the system. Unless the module has a function that will disable the pump I would think that if it were the problem the pump would not operate with the module unplugged. Does what I'm saying make any sense? If the module is at fault then when the problem presents itself I should be able to unplug the module and that would allow the pump to operate. Right? I think it's getting really close to time to just do an engine swap and do away with the 2.9 altogether.

 

[IMenriched]

the TFI is only suspect after it is warmed up...that is up to operating temp...yes they can be tempermental/problematic.

so was it fully up to temp??....I taken several TFI's to the local part store they checked them out on a niffty testing machine, they ran the test multiple times for each....I have heard/read that some have gone as far as taking the hair dryer too to get them as warm as possibale and then test right there at the parts store and had some that at 1st checked OK, then blasted it with hairdryer....then recheck to find the it bad.
this may sound extreme...but with your issues of randomness...it maybe in order.

It is not to say that your's maybe fine??....check wires for a bad or broken spots and check the connections on the harness...& grounds

 

[gbadgley]

Connection or ground problem comes to my mind first. Intermittent problems can drive you nuts. the only way is to wait untill you have the problem and hope you can find it before it fixes it's self.

 

[Natedog]

The wiring to the rear tank in my '86 was worn almost all the way through where the brake line runs through the frame. I'm not sure how the B2 is set up, but maybe it's similar.

X3........gotta find a good replacement plug with short wire leads on it and splice it to mine.

Is that how you fixed yours and if so where did you get your plug with good wires?

I';ve had TFIs that tested good, but were bad....it''s a cheap try and you should have a spare with you anyways.

 

[nazareth2002]

Check emergency fuel shut off switch.I had just about the same problem and it turned out to be the fuel switch was bad.I haywired it and it ran fine till i parked it 3 yrs ago