Chevrolet Repair: Replacing a 1992 Chevy Silverado 1500 fuel pump, fuel pump relay, fleet trucks

Question
Van,

This truck was running great until I went into a store and came out.  Tried to crank it and it sounded like it wasn't receiving any fuel.  It was trying to start but no luck.

I removed the carb and placed a little fuel in the breather.  It cranked then but died shortly thereafter.

Could you tell me where to locate the fuel pump and basically what is required to replace it myself?

If you have any other suggestions I would love to hear them.

Your help is greatly appreciated.

Thanks,

Laura

Answer
Hello Laura,
Well...I believe you don't have a carb, but rather a throttle body, with two injectors in it. Does kinda look like a carb.
You did the right thing so far...isolated spark vs fuel, and nailed it down to a fuel problem.
The fuel pump is inside the fuel tank. YUCK!!
First thing to do is listen to see if it comes on and runs.
You may need to get back by the tank, and have someone turn the key to RUN. Not crank.
When first turned to run, the fuel pump should buzz in the tank for three seconds approximately.
If it does, then a filter may be all you need. It is located in the line, just about under the drivers seat, in a clip on the inner edge of the frame.
A fuel pressure tester connected would also be nice, but that may come later, assuming the pump is running, and the filter is new.
If the pump does NOT run, check the fuse. It should be on the firewall, under the hood, in front of the passengers seat. There is probably a plastic cover held to the firewall by three long plastic nuts. Remove that cover,(I throw them away on my fleet trucks). It is probably marked fuel pump relay, fuel pump fuse, etc.
The fuse is in a little plastic clip. You can't see the fuse till you release the catch, and pull it out of that clip. It looks like it is something, but is just a fuse holder with two wires.
If that fuse is good,a test light touching the metal tabs in the fuse should light up for the same three seconds described above. Test both ends of the fuse.
If the fuse test lights the test light, but the pump doesn't run, connections back at the tank area, or the pump itself is where you go.
If the fuse doesn't light, the relay or ignition switch may be at fault.
If the engine cranks over, the ign switch is good.

If the fuse does not light, use a jumper wire from battery positive, to the fuse, and listen for the pump. That will bypass the relay, and if the pump runs then, check the relay and wires.

Now,,if the fuse lights, but the pump doesn't run, lay back by the tank, and just as someone turns the key to run, smack the bottom of the tank, about in the center, with your hand. About as hard as you can with the heel of your hand. That is where the pump is, and that might make it start to run. If it does, you can still expect to need to replace it, but it might get the truck home.

To replace the pump, you can either drop the tank, or move the bed back, which often is easier.
I have even heard of unbolting the bed except for the two rearmost bolts, which are just loosened, and raising the front of the bed, and blocking it up, but block it well if you are going to get in there.
The tank unit will be right there. Clean it all off, remove the retainer ring, and pull it all up out.
The pump can be replaced separately, but if a dealership does it, they usually want to replace the complete tank unit, at three to five hundred $$$.
Pump itself from a parts house is about 60 to 80$$$.

So, listen for the pump first, and then change the filter if pump is running.

Let me tell you one other thing I ran into once..
I had one that the pump was running, filter was new, but almost no pressure at the throttle body.
I dropped the tank, removed the pump unit, and there is a little hose inside there that connects the pump to the line coming out of the tank. That hose had split, and the fuel was just spraying inside the tank. A little piece of hose fixed the problem, but it still required dropping the tank.

Another similar problem was the wires inside the tank to the pump. We had replaced the pump, and the new one did the same thing...worked for a while, then you had to smack it. The wire connections in the top of the tank assembly, where the connector plugs outside, were riveted, and the rivets were loose. I soldered those connections, and the old pump was fine, although we left the new one in there, but never any more problems with it.
But it really hurts to replace a pump that has power to it, only to have the same problem after all the work, so at least check those wires. It was a 93 1500.

Make sure the ground wire that bolts to the frame back by the left rear wheel is clean and tight also...do that early in the testing.

Good luck,
Van