While my mechanic is still trying to figure out why the is no power to my new fuel pump, I have a question. The wiring harness underneath the carpet on the drivers side has got water in it due to bad molding around the door and letting ALOT of rain in. Anyway, does anyone know if this entire wire system can be replaced easily. I can't even find the part !! I am sure this is what shorted out my FP. Thanks

 

year-I think that you're on the right trail-your 12v pump feed should run thru that area. You more than likely want to splice and wire it correctly as opposed to a wire loom or thru GM as the price will floor you if available. If to 12v at tank I would look closely at these wires you've mentioned and you shouldn't have much trouble figuring out where 12v is and isn't. (and which of the many wires is the fuel pump) good luck let us know what youze guys find PS check out all other accessories in the rear as the fuel pump may not be the only thing effected. JP[sm=groupwave.gif]

 

Thanks JP. I will call the shop monday and let them know. I will check out all the other accessories too.

 

Follow the wiring from the fuel pump to underhood. I doubt you will find that it goes into the cab...

 

kyle-what year is this and where, if not drivers side underfoot-where do you think they run it?jp[sm=icon_stickpoke.gif]

 

From other posts, it is a 98.

Most commonly, a wiring harness for a component outside of the cab of a vehicle will be outside the cab of the vehicle. Things like lights will run through the cab and out weather tight connectors, but those pass thrus are on vertical surfaces, not horizontal ones.

 

The blazer is a 98. I am just at a loss. The mechanic said he even took apart the underhood fuse box and found no problems. For some reason though, there is just no power going to the FP. Also, I am assuming that there is a short which may have made the FP go out in the first place. Of course I have been wrong once or twice before. This is just frustrating and I want my truck back !! I really appreciate all of the help you guys have been.

I did a little searching on here and correct me if I am wrong. Could the ignition switch be the reason the FP is not getting power?

 

doubt it's the ignition switch but...I've been wrong b-4...Kyle-are you thinking that the Blazers wiring isn't in the cab? I haven't checked my GM manuals yet but...I did have a 96 as well as a 97 that had fuel pump and rear light issues and the wires under drivers foot(MANY) had gotten corroded and needed cutting out the bad, putting in the new(wires that is). Now maybe a 98 is different than the years I've stated-cause there are many changes between those years but-I'm not aware of the wires running anywhere else.(but under foot) And if they are run under drivers feet-I would be checking which one is the pump feed wire(up near the brake pedal) and see if it's hot 2 seconds key on, then see where it looses it. Again, I don't have a manual in front of me to tell you the color of this fuel pump feed wire and searched(googled)awhile ago, with no success. Nor could I find anything helpful on Autozones site(but that could be my lack of expertise). good luck. JP[sm=icon_stickpoke.gif]

 

JP- that makes sense to me. I know those wires have been exposed to repeated soaking by the leaks in the molding. By the way......I have replaced the door molding. Anyway, that bundle of wires right under the drivers right foot seems logical to me too. I will look in my Chiltons manual and see if it shows what color the wires are to the FP. If those wires are for the rear lighting too, that explains more also. I swearI have never replaced so many taillight bulbs in my life!! Coincidence?? I'll call the mechanic in the AM and see how it's going. Thanks again for the help and I will keep you posted.

 

1998 was the first year with the underhood fuse block which housed the fuse and relay which supply power to the fuel pump. All of the wiring for triggering and powering the fuel pump is outside the cab. It seems logical that the wire back to the pump would be as well. With the 96 & 97 trucks, everything was inside the cab.

Pin 86 should be solid ground. The relay should have +12V at Pin 30. If that checks out good, then you can check the continuity between the fuel pump relay output and the +12V wire at the fuel pump. A jumper wire from a known good +12V source and the switched output of the fuel pump relay (pin 87) should turn on the pump. You can check to see if the relay is being commanded on with a 12V test light. Test on pin 85 of the fuel pump relay. The light should turn on when you turn the key on.