S-10 Forum banner
1 - 17 of 17 Posts

·
Registered
Joined
·
1,000 Posts
Discussion Starter · #1 ·
I think my fuel pump went out on my 94 cpi. It doesn't whirl when I turn the key. I pushed the schraeder valve and it didn't spurt out. I hooked a positive to the fuel pump test wire. I made sure electricity was at the fuse box. I jumped a wire on the oil pressure relay cut off. Fuel pump is not working, but the is voltage at these spots.

Is it possible to pull the wires from the fuel pump without removing the gas tank? I want to make sure the power is def making it to the pump. Removing the tank to get to it is gonna be a chore, so I want to make absolutely sure it is the pump.

Thanks.
 

·
Registered
Joined
·
10,909 Posts
I've heard of guys removing the bed bolts on the left side, loosening
the right side, removing the filler hose to the cap, and tilting the bed
enough to reach the top of the tank and then blocking with a 4x4
or whatever it takes. It's much easier to do this than pull the tank.

This way if you have to do the pump you should be able to reach it
with the bed tilted enough to the right..HTH's
 

·
life begins @ 20 psi
Joined
·
676 Posts
If you put 12 volts to the fuel pump test conncertor and it didn't work, either the ECMB fuse is blown, fuel pump is dead, or the ground wire that is on top of the fuel sending unit is bad. The fuel pump test connector bypasses everything and puts power DIRECTLY to the pump. ECMB fuse powers the fuel pump. The ground wire that goes on top of the fuel sending unit is attached to the frame. On my truck, the tab that held it to the frame was almost rusted in two.

If you have to pull the pump, the easiest way is to remove the bolts on the driver's side of the truck, there will be three of them. Loosen the other three on the passenger side. Penetrating oil and a breaker bar are gonna be your new best friends loosening/removing the bed bolts. They can be VERY stubborn to loosen... You may have to disconnect the wiring harness in the back for the license plate lamps also. There should be two or three bolts holding your fuel filler neck to the bed, they will need to be removed as well. With all that done, lift up on the wheel well and shove two 4X4's on top of each other on the frame and lay the bed on them. This will give you plenty of room to get to the fuel sending unit. Chances are you aren't gonna like what you see. The fuel lines are gonna be welded together with rust. HOSE them with penetrating oil and let it sit for awhile. Make sure that you spray not only the fittings but also where the fittings attach to the fuel lines. Use a backup wrench when removing the lines or else, you will twist them off. Removing the fuel sending unit cam (lock ring) can be a chore. You *should* use a brass punch to remove it so you don't produce any sparks close to the tank. This is a "stealership" item so, you will have to obtain one from there. Part number is 25124032 and it should cost around $6. In closing, grease the hell outta everything when you put it together so, it isn't such a PITA next time ;). HTH's

Mike Campbell
 

·
life begins @ 20 psi
Joined
·
676 Posts
On my truck it wasn't as it was bolted to the top on the frame directly under the bed :(. That's why when I redid it, I crimped on a ring terminal after I ripped the plastic insulator off. Then I soldered the wire to the terminal. I bought a stainless steel bolt and ground the frame down to bare metal where it attached. Everything was given a liberal coat of grease afterwards. Can ya tell I'm particular about my grounds ;)?

You could try to get an inspection mirror up there to see how it looks physically. If there's enough room, you could check it with and ohm meter too. Bottom line is if it's not the ground, you're gonna have the pull the pump. So, if you have to tilt the bed to check out the ground wire, it's not that big of a deal. Just make sure that you have plently of extensions for that breaker bar ;)... HTH's

Mike Campbell
 

·
Registered
Joined
·
1,000 Posts
Discussion Starter · #10 ·
Everything seems doable. I just wanted to make sure I exhausted every option, which sounds like I did. The thought of wrenching on the truck for a couple of hours and busting some knuckles sounds pretty relaxing after the day I have had.

SY2932, thanks a bunch for the info. You definately got me comfy with what I need to do.
 

·
life begins @ 20 psi
Joined
·
676 Posts
NP, if you run into any problems post them here and we'll get ya back on the road :)! Good luck and be safe!

Mike Campbell
 

·
B4U Task Force Admin
Joined
·
34,395 Posts
I see a lot of posts suggesting that you bump up the drivers side of the bed for access to your tank. If you don't mind a differing opinion here goes...Rather than bumping up the bed on just one side,,,do yourself a favor and remove it completely. Access is unrestricted and you can completely clean around your tank and pump. Use compressed air after getting all the dirt and crud removed. If you don't have a compressor, canned air from an office supply works well.It's an easy job and can be done in less than 3 hours start to finish. (as long as you have a friend to help with the bed...) Good luck....
 

·
Registered
Joined
·
1,000 Posts
Discussion Starter · #13 ·
Well. I got the bed off. Easy enough to do. There was a ground strap we missed the first time we lifted it off. I unplug the connector to the fuel pump and hooked 12 v's straight to the gray wire and it turned on. It worked. I then put the plug back together and turned the key on and it worked. I'm confused but glad. I'm gonna clean all the connectors and grease them as suggested.
 

·
life begins @ 20 psi
Joined
·
676 Posts
Hmm, you're not the only one who's confused... I thought when you put 12 volts to the fuel pump test connector, it didn't work :confused: ??? While you have the bed off, check for continuity between the fuel pump plug and the test connector on the firewall to make sure it's good and that you had the right one ;)...

Check out the fuel pump relay on the driver's side of the truck on the firewall next. On the 4.3's, the fuel pump relay is towards the fender and the AC relay is next to it towards the brake booster/master cylinder. You can just see the FP relay on the left side of this pic:
http://huryde.station180.com/gallery/view_photo.php?set_albumName=mikecampbellakaSY2932&id=aae
These two relays are interchangable so, you can swap them out to see if one is bad or not. Try that and report what you find.

Yup, I bet that you forgot to remove the ground wire that attaches to the driver's side rear frame. If a knew that you were just gonna take the bed completely off, I would have warned ya about that one. Sorry...

Mike Campbell
 

·
Registered
Joined
·
1,000 Posts
Discussion Starter · #15 ·
I got it all done. I guess the pump running was it's last hurrah, cause it quit working immediately after it worked. With the bed off I could test that electricity was def getting to it. Got me a replacement pump and sock and all is good. The bed is setting back on, I'll getted bolted back up tomorrow.
 

·
life begins @ 20 psi
Joined
·
676 Posts
Glad to hear that you didn't pull the bed for nothing :)! If you have a pressure washer, I would spray down the frame and wax between the cab and box while it's off. Hope that you are back on the road soon.

Mike Campbell
 

·
Registered
Joined
·
1,000 Posts
Discussion Starter · #17 ·
I sprayed soap on it and let it soak for an hour or so and then blasted it with hose pressure. It got it pretty clean. I'm letting the driveway dry before I bolt it back up. Next project is the brake lights not coming on. I'll be working on that in the next week or so. Luckily it's not my daily driver.
 
1 - 17 of 17 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top