Location of the fuel pump relay?

Well, I took my truck out this weekend and had a blast the first day, but thats when the trouble started. I took in A LOT of water (and didnt hydro my engine!!)
and I think I fried the fuel pump relay. After going through a hole the truck fired right back up and was just chugging to get the water out, which was fine, it was later on the trail near the end of the day when the truck just died. We let the truck sit and dry out for a bit, checked my plugs and wires, checked for spark and what not but it still wouldnt turn over. We were standing near the back of the truck having a conversation when the fuel pump started to whine like it does when you turn the key to start the truck, except the key wasnt in the ignition, nor was the whine stopping. It went on solid for about 10-15 seconds and that was it. We pulled it back to camp and checked a few more things and we figured the pump just killed it self.

(800 words later..) I ran a 12v wire to the pump + plug and the pump started up. So the pump wasnt actually dead which leads me to think its the relay that got fried. Temporarily I have a switch wired to turn the pump on and off so I can drive it, but it cant idle anymore. Its almost as if its getting to much fuel and just cuts out.

Hopefully that was descriptive enuff.. Im not really sure what happened heh, but I do know I have an electrical nightmare on my hands at the moment. The dinging sound that comes on when the keys are in and the door is open is on constantly while the vehicle runs, and if I hit a bump my rear wiper goes off lol Water = bad!

on the '91 (and I think '92) the fuel pump relay is on the passenger fender.. "UNDER" the box with the big fuses.. on '93+ (first gens) its it on top with the big fuses.

~Mark

You wouldnt happen to know which relay is which under there eh? They dont have any markings (that I noticed) and I found 3 of them. I originally though my relay was shot.. But after searching, the problem may lie else where. Dont think its gonna get fixed before work tomorrow lol

The two common things I hear about that fail are the relay itself and the inertia switch. The inertia switch is under the carpet, by the passengers feet close to the transmission hump. That is what is supposed to turn off the fuel pump in the case of an accident. If that goes bad, no power to the fuel pump.

If thats not it, its time to start tracking the power to see where it dies.

~Mark

WOT = Wide Open Throttle
EEC - Electronic Engine Computer

Most common failures are relay, pump/wiring, oddball stuff. Inertia switch is a good place to start troubleshooting but rarely fails.

Good luck!

I tried all three of those relays (rather, I changed them all between each other to see if one was fried) and I checked my inertia switch (the red button, not the grey box under the ash tray). I also checked my voltages at the pump and had 7v on both positives when the key was off, I never thought to check it when the key is turned to on. I have it hard-wired to a switch on my dash going from the pump positive to the battery that I flip on to start the truck and leave on while driving, but it doesnt seem to help once the truck is warm. When its cold it'll idle, but when its warm it doesnt, you have to keep giving it gas.

I managed to drive it home from the trail 2 hours away, but Im still unsure as to what would be wrong... Its like the air/fuel mixture is messed up, and I know jack about engines I may just see if I can get a shop just outside of my work to fix it this week if they can. I mean, I can drive it.. Its just a pain in the ass since its a manual, gotta run the clutch/brake/throttle all at the same time, and when stopping it gets tricky lol

The other thing I noticed is, it idles at like 400rpm now... I think thats the cause of the stalling, because thats just to low, isnt it? I think it used to idle at 800-900rpm before this happened. Any ideas?

Thanks in advance guys, I've been doing some reading but I cant seem to find my problem exactly, since all my relays seem fine, as does the pump.. /shrug

Well I fixed most of my problems, but the fuel pump still wont start up with the truck. I've got a shop right next to where I work thats gonna look at it tomorrow and tell me what to fix after work.

My MAF was the culprit for the stalling/harsh idle and what not. I took the sensor out of the body it self and both the little wire conductor thingers were coated in mud. Cleaned that out and also fiddled with a few other things to just make sure they were ok, like my throttle body connector and the IAC valve connector (I think it was the IAC.. The cylinder looking thing behind the TB on the intake manifold?), both of which had mud inside them. My relays seem ok, but I have no idea... A new fuel pump relay appearntly costs $30.. So I waited on that, because I cant take it back if it doesnt fix the problem heh.

Threw my exhaust back on after the cats and its got tons more power now than it had before I removed them the day of the incident. Not sure if that was because of everything that was messed up in the engine bay or if its because of how much mud I managed to rattle out of the muffler...

Anywho, so far Im glad my problems werent the truck dying, and just caused by a lot of mud! I figured as much, but after I cleaned the obvious (what I thought was the obvious at least..) and it still was messed up.. I feared for the worst. Nothing like having EVERYTHING die all at once due to natural failure haha

Thanks for the help guys!