electrical question

[thrtyhz]

Hello all, first post. Ive got a 91 s10 and it got a strange problem. It almost stranded me about 2 weeks ago. I was going down the highway and the motor quit, it's a 2.8, anyway after it set about 20 min it restarted and got me almost home (i towed it the rest of the way). i noticed the throddle body wasnt spraying fuel and I didnt hear the fuel pump working. I straight wired the fuel pump through a switched ign relay and changed the fuel filter. Now the throddle body is getting fuel but its still not spraying. My question is:.. Is there one thing that would cause the fuel pump and the injecters not to work? One cause? Im thinking the "brain" possibly, what do you think?

[destroked blazer]

the distributor could be doing it take the cap and rotor off unscrew the module bolts turn the key on while the key is in the on position jiggle the module and watch the injectors if they start to spit get a distributor

[thrtyhz]

ok Ill try it tomorrow

[fastr68]

try wiggling the pink white wires from the distrib to the coil while its running see if it stumbles or misses or anything sometimes one or both wires break inside the insulation

bad coil

worn distributor or bad module

will cause same issue as broken wire

[thrtyhz]

Thanks for the sudgestions. Ive tried wiggling the wires and module with no response. Currently is not running. Ill keep messing with it. Is there a fuel pressure switch that I can bypass just to test it?

[fastr68]

the only thing there is for the pump is the ign switch to the ECM that clicks the relay on for a few seconds to prime the pressure up then the ECM allows both igntion spark AND fuel injector firing at the same time during cranking to start it and then the oil pressure switch takes over the fuel pump

so if it doesnt start then its gotta be ignition, pump, relay, ECM, power wires to ECM and fuse panel, or a fuse.

eliminate each one

most common is dead pump

next common is bad cap rotor wires plugs,

and then after that it could be anything

but relay would be next best thing to check


another possiblility is dead wire to pump from relay/oil switch

in which i have seen happen.. but not common.

is the pump humming priming with key in run position..

listen for it.

if so check pressure

if no sound from the tank then check FP wire, relay, power to ECM/fuse panel etc.
ign switch

it will be most likely something dumb minor stupid though

if not the fuel pump

[Bill Wheats]

Another PITA that could cause this is the ing switch that the key switch connects to. I've seen the starter work fine while the RUN becomes intermittent.
You need to track it down from the injector back using a test light and a meter.
Hint: at the injector - one side gets +12 volts all the time. The other side gets pulsating negitive 12 volts from the PCM through the ignition module. But you wont get it if the RUN on the ignition switch is bad. If you are getting power to the ign mod then you should see neg to the injector when the starter is running.

[thrtyhz]

Looks like the fuel pump was going bad (although it worked when I tested it the first time)it eventually quit and blew the ecm-b fuse which I hope has something to do with the injecters not working. I wont know for sure until I get the new fuel pump. Im going to get the sending unit also so Ill have a gas gauge. Looks like about $200 for the whole unit. May have to wait a couple weeks though. Thanks for all the help