Truck Shutting Off

[88 GMC Truck]

I have a 1988 GMC Sierra 3/4 extend/cab that I have owned since new. About 5 years ago it was stolen from my home and recovered a few hours later. Needless to say the thief broke into the steering column to start the truck. In doing so ,some wiring was damaged and needed repairs at the dealer. All seemed ok until the truck, a couple of years later, started to shut off like someone reaching over and turning off the key. It was initally diagnosed as a failing fuel pump. The truck had a little over 200K on the ticker at that time. So in went a new fuel pump from NAPA with a new wiring harness that goes inside the tank and which is connected to the new pump.

 

Well since that time another three pumps have been installed in as many years because of the same symptoms and now in less than a year it appears that its fuel pump time again. To be honest I don't think its the pumps anymore. I believe there is a short so here is my question. Is there anyway possible that a cruise control switch/ arm could cause this to happen if it had a short in it? I had lost the ability to engage the cruise control. But after installing a new ignition switch it started to work. I thought great I found the problem NOT !!! . As soon as I wiggled it it would quit working again. The truck stayed running but the cruise quit. Then it wouldn't reset again like before.

 

Now sometimes it does and sometimes it doesn't. I can disengage it just by moving the turn signal/cruise control arm ever so slightly. I'm not sure if there is anything related but the truck is still shutting off randomly. I was wondering if electrically there is ANYTHING in the steering assembly that could short out turning the engine off!

[boothybunch]

I'm from UK. I would bet the problems have got to around the steering column.

 

I repaired my fathers old ford transit Diesel van few years ago, it didn't have cruise control but someone had messed with wiring big time. At some point before my father purchased the vehicle, it had an alarm fitted and they had taken the instrument cluster apart to get to the wiring that came upto the column. they have soldered joints on the existing wiring and made a right F**K up of it. It intermittly shorted out and shut the van down. left it 2 mins and then no problems till next time. sorted out that problem then the ignition switch gave up the goat. That to shorted out internally ( as i took the darn thing apart to check)

 

What i would do is carfully take the electrics off the column and check all the connections. What i have found out recently on modern cars is where wires go in to switches etc they tend to break internally.

 

Also if there is a BIG multiplug that goes through the firewall, pull it apart and clean it. May have crudded up due to age.

 

It's one of those jobs that if you can do it yourself, it's a ball ache but not cost you anything . But if you take it to a dealer, leave them a blank cheque!!!!

[dwags]

About a year ago my buddy who has a 1997 Tahoe had the same problem. The computer spit out the fuel pump code. In went a NAPA pump and guess what? It continued to shut off then about 30 min. later it would start. It turned out that any aftermarket pump is junk. He got an ACDelco pump and away went his problem. My pump on my old 96 Silverado went bad and I got an ACDelco pump and never had any problems. My guess would be if your wiring turns out ok, it's your junk NAPA pump. NAPA had no problem refunding his money for the pump, but he had to eat labor for three pump replacements. Good Luck.

[88 GMC Truck]

I wanted to share my findings with the group about my truck shutting off after 3 fuel pumps installed. It turned out to be the wire that leads from the positive side of the battery (The Small One) to the junction box on the fire wall on the passenger side. The reason it kept appearing to be a bad fuel pump was because the wire had frayed on the frame rail over twenty years and wasnt sending the proper current to the junction box which effects all your sensors and fuel pump relay. Therefore, the intermittent problem .

 

The Fix: Wire changed and (very Important) the truck had to relearn its sensor parameters and now it runs like a new truck again. This problem wasn't found by shops or myself for four years.

 

So check your small wire to make sure it is good and also check the small alternator wire that also runs to the same junction box..

 

Finally Fixed ...... Whew !!!!