Problem with Fuel!!!

[Pedraza202]

I have a 99 4.3 automatic s10 blazer. I have shorty headers on it, 40 series flowmaster, hypertech programming but didn't pick engine tune so am not using 93 octane.(if you don't pick that option you don't have to use 93 octane) K&N filter, ngk plugs and taylor 8mm wires. On Wednesday I filled up my tank went to work came home. Friday went to work and came home again. It was Saturday morning when I went to my truck and it didn't turn on. Everything seemed fine it cranked well but wouldn't start. I pressed the gas to give it a little gas but still didn't turn on. I unplugged the coil and plugged back in tried it again but still didn't work. I checked my battery it was fine and charged so that couldn't be the problem. The only thing that I can think about was when I filled up my tank I put more gas in it than I should. You know how you fill up your tank and the pump atomically turns off, well after it did that it put more and more I guess you can say forcing in but I don't think this would be the problem gas is just going in. My truck has 125k miles just to let you know and since I’ve had it I haven't had any problem with the gas tank or done any work to it. Well about ten minutes later I realized my fuel pump wasn't turning on. (I think that’s what it would be) You know how you turn you key forward but not turning the car on your truck will make a noise for about 2-3 seconds well mine doesn't make that noise anymore. (i think that noise is the fuel pump opening on or preparing gas to be thrown into the engine) Well mine isn't turning on or making that noise anymore and when I press the gas pedal I don't smell gas around the engine. Do you guys think my fuel pump died on me or could it be probably my fuel filter is clogged. If my fuel filter is clogged would it cause my fuel pump not to work? Am assuming since my truck isn't making the 2-3 second noise anymore that has to be the reason. Please help me out guys I need my truck running my Sunday April 2 because here in California in Pomona the super Chevy show is in town (March 31- April 2 just to let you guys know) and I need to take my truck there because I was planning on racing it. Please help me out guy’s sorry for the long story thanks a lot.

[Sparky2263]

Overfilling the tank will not shut the pump off. Period.

First, ck. for spark. Pull the coil wire off the coil. It'll jump 3-4" and make a VERY audible popping noise. Then, verify fuel pressure at the schraeder valve.

The fuel pump relay is located in the underhood fuse box and clearly labled. You can jump pins 87 and 30 (ensure voltage with a test light) to verify fuel pump operation. Provided you have voltage (using a 12V test lamp), you can then verify all the way back to the tank.

Now, back to my first statement. Even though filling up the fuel tank has no bearing on fuel pump operation, it damn sure seems like all the fuel pumps I replace the tank just got filled up!

Besides, 125k is a bit above average for fuel pump life.

[mrmidnight]

Brother, I wish I could say that I could come up there before the super chevy show and help ya out, but my first opportunity won't be until April 2nd, to me it sounds like the pump went out, but try what sparky said, he is Mr. Gasket

[T Man]

Overfilling the tank will not shut the pump off. Period.

First, ck. for spark. Pull the coil wire off the coil. It'll jump 3-4" and make a VERY audible popping noise. Then, verify fuel pressure at the schraeder valve.

The fuel pump relay is located in the underhood fuse box and clearly labled. You can jump pins 87 and 30 (ensure voltage with a test light) to verify fuel pump operation. Provided you have voltage (using a 12V test lamp), you can then verify all the way back to the tank.

Now, back to my first statement. Even though filling up the fuel tank has no bearing on fuel pump operation, it damn sure seems like all the fuel pumps I replace the tank just got filled up!

Besides, 125k is a bit above average for fuel pump life.



A couple of things. I believe he was talking about the pump at the station, not on his truck. What sparky said about diagnosing the problem is spot on. Follow that. If you have a digital ohm meter you will be in good shape. Also, gm fuel pumps have a tendancy to just **** out. No warning signs of it going out, all of a sudden at around 100k or a little more it just stops.


And sparky, its gotta quit after the tank gets full.....gotta give those mechanics some kind of workout ;)

[Pedraza202]

thanks a lot guys for helping me out its been raining here i replaced my fuel filter thinking maybe it will do the trick (am into denial hoping its not the fuel pump) but it didn't. Am going to check the rest of the lines tomorrow but i don't think it might be ready by the chevy show. Thanks a lot guys ill let you know how it goes.

[Joker2040]

If it's not making the little whine noise when you turn the key on the pump is out. When I was younger I went out with a buddy in his 'rado and we were cruising then parked in a lot to hang out. About an hour later we go to start the truck and.... nothing. It would crank and everything but just wouldn't hit. When he turned his key over it wouldn't make the little noise either. Turned out it was his fuel pump. It just died.

[T Man]

Mine quit in the suburban with a full tank.....a 42 gallon full tank. He he, or mechanic LOVED me for that one.

[Texashorsepower]

I had a chronic problem just as stated above but mine would work some days and not others... In my situation it was the actual connector on the fuel pump that had a poor connection. I could crawl under the back of my blazer and just reach up and grab the harness on top of the gas tank and push the connection together tighter and it would start.

Once I had a little time to fiddle with it, I got the connector undone from the top of the fuel pump (which is right at the top of the gas tank towards the rear) then removing the driver's side rear tire, that gave me access to the harness that I just undid from the tank (the wires run along the top of the frame rail). It's tight in there but if you wiggle a few of the wires you'll see which one goes to the harness you just disconnected and you can pull it out between the body and frame rail into the wheel well, and that way you can have it right in front of your face to work on it. In my case it was the little tabs in the female portion of the connector that were not pressing tightly on the male pins that slide into it, so I actually took the entire connector apart and rebent the tabs to provide the correct contact (althought i'm sure you could use a dental pick and carefully bend the tabs so that they would be snug against the male pins when the connector is put back together).

Just route the wire with that harness back where it came from and reconnect it to the fuel pump.

Now in my case this was the only problem and I haven't had a single problem with it yet and that was a year and a half ago.

It might be something to try if you have the time to check it out before you dump the big green on another fuel pump.

Hope this gives you another way to check and see what the real problem might be -



THP