fuel pump prob

have a 1987 gmc jimmy fullsize....i have a problem with my fuel pump.. that it cuts out over rough terrain...im going thru boxes of fuses...some told me about a recall or a dealer notification on a ground prob... any one else have this prob...could use the imput ...thanks

 

If you're blowing fuses it's most likely NOT a ground problem. Since it happens on rough terrain I'd be looking over every inch of the wiring from ignition switch to fuel tank. I suspect that the wiring is between cab and frame somewhere and when you bump things right you get a short. Never had it happen on the fuel pump line bit I chased an elusive and intermittent short on tail lights that was caused by a crushed harness.

 

i have replaced all wiring form fuse box to tank ..... still same problem..

 

OK,, so it's not between the fuses and the pump, but it is STILL a short to ground somewhere in the system. Find the lead from the ignition switch that triggers the fuel pump. It may go directly to the fuse panel but I'd sooner think it triggers a relay somewhere in there. Check the whole harness for a bad spot. Don't rule out a bad ignition switch. I'm not sure just hwo one would short out but at this point you can't eliminate any possible problem until you have physically examined it.<p>There is also a safety switch in there somewhere that sees oil pressure. When the switch sees no oil pressure it assumes the eegine as stopped running and in turn it shuts the fuel pump off. There are a crapload of related wires and switches that control that pump. Any one of them could be shorting.<br>