blown fuel pump fuse '92

[gold10go4]

The '92 stopped running one day; just died. Had it towed. It would crank, but not start. Thought it might be the fuel pump. But before replacing the pump, decided to check the fuse panel. Sure enough, the fuse for the fuel pump was blown. Replaced this, and it ran - for about 2 minutes, then another blown fuse. Did this again; same results. Any ideas as to what it causing the blown fuses? Can a faulty fuel pump relay cause blown fuses? Or is it more likely a bad wire in the fuel pump or the sending unit? Or perhaps a short somewhere else? Thanks.

[dmbrisket 51]

start tracing wires for a short

[AJT1961]

Bad fuel pump is my guess without seeing the car. Before they fail totally, they draw a lot of power to overcome the bushing wear.

[jackass#1]

check your ground from the tank, make sure its still good. while your there check the pump connection ontop of the tank to make sure good connection, maybe dissconnect and clean both ends. if that dont help, start tracing wires from pump to fuse box. make sure no bare wiring is exposed. if all is well there trace from fuse box to relay to power supply. i bet there is a break in your wiring some where.
what else does that fuse control?

[BlazerLT]

sounds like a dead short in the wiring.

[goldengopher]

Just adding on to this post since I'm also looking into this particular vehicle..Is it possible for the fuel pump to cause the 15A fuse to blow in the fuse panel when initially it would kick out gas on the other side of the fuel filter..Now even turning the key to the on position causes the fuse to blow..The fuse slot also is an ECM B/ fuel pump control. It seems to me that an electrical issue vs a faulty pump would be the cause..any ideas or help would be apprecited...Replaced the Fuel Pump relay with no success..Haven't dropped the tank yet and would hope to isolate the issue before going that far if at all possible..Thanks

[bear paws]

[quote=gold10go4]The '92 stopped running one day; just died.

Fuel Pump? poss. but unlikly,Relay? V Doubtfull, Shorted wire? YES!!
Wire diagram very usefull here. Get a bunch of fuses and with motor stopped, ignition on , yiggle all the wires and harnesses especially behind the dist. where the big harness goes down thru the metal strap clip held by the bell house bolt. The dual purpose low oil press / fuel shut off switch [ green-? ] wire runs in there. Unplug oil press 3 way plug and testicle light the fuel pump circut while u wiggle and jiggle. [The light keeps this job down to 1 1/2 people.] when lite goes out /fizz wapp/fuse blew u are getting close to short. If short is down behind bell houseing u need, to pull dist.and a few other things and some small hands and 4 letters to get into harness.
If u can't find short or just can't touch it,It may be easyer to just simply cut both ends of shorted wire and back wire pump relay circut to fuel pump. [I think F/P relay closest to fender on f/wall driver side] Again wire diagram real helpfull here. Chilton Electronic Fuel injection and Ignition book {autozone etc.} good or a friend at garage with access to repair manual services.
Keep in mind that wiring is not a black art and if you cut a live wire, electricity won't leak out unless u short it to it's own ground and only then u get FIZZ WAPP. Bear Paws!!!

[bear paws]

NO NO NO don't pull tank yet!!!
There is a plug conector for F/Pump behind bumper [lic plate area ]that will disconnect pump from circut and let u determine if pump is morta.

Bear Paws.

[goldengopher]

Kind of a tough tell here considering when you turn the ignition to the on position(not starting it)the 15A fuse immediately blows. This also negates the luxury of hooking up a code reader to the diagnostics port under the dash...thank you for the reply any other pointers?

[jackass#1]

it is an eletrical issue. realy need to trace wiring that is connected to this fuse. if it opperates the fuel pump and ecm, those are the components that need to be focused on. hooking up a code reader really isnt going to be very useful at all. check grounds and wiring of the components controlled by that single fuse. it is not a hard job, anddoesnt take a brain surgeon to do it.

[bear paws]

Sorry, thought you said it ran for 2 min so figured if motor stood still it woundnt blow fuse.jackass right about ALDL/ diag port worthless at this point. Note ECM/b or #2 fuse powers fuel pump relay driver [Read as power transistor] in Ecm only along with pump itself and relay.Basicly the ECM turns on pump relay for 2 sec. when ign. energized to prime system or over rides oil press switch in start poss. untill oil press above 2-5 lbs and then the oil press switch handles load to keep pump on. That said you may as well forget what i just said cause it won't really help you.There is only pump, relay, oil press sw., and ECM driver in this fused circut.The rest is all a bunch of wires. Orange poss w/blk tracer wire {prob 12-14 ga} is 12 v source to system and brown or gray wire to rear of car to pump via that connector i told you about. Again, the most vulnerable area for wire short is behind motor or the chassis harness to pump itself. If you unplug relay it does not take chassis harness out of play.Pump still fed by oil press sw but however if u pull oil press sw plug off with Ign. on and then put new fuse in, it will isolate pump and wire [brown, maybe gray ] out of the circut.With plug off oil sw and fusev still blows i would look real hard at that orange/ blk ? wire. Bear Paws

[goldengopher]

Thank You Bearpaw for the very detailed information you have responded with. Will tackle this at some point today

[gold10go4]

Thanks for everyone's help. Turns out that the wires from the oil pressure switch had insulation burned off by the exhaust pipe. The bare wires touching the exhaust did in the fuses. As soon as the wires were reinsulated, the problem stopped. I couldn't tell until I got under the truck and saw the wires below the oil switch next to the exahust. Thanks for everyone's help, again.

[BlazerLT]

Amzing, glad you are on the road.