The truck had been running and idling rough. I replaced spark plugs, this did not help at all. I drove to gas station put in 15 gallons of gas. Started,set at rough idle for a few minutes while I was on phone. Took off down the road,truck spit and sputtered then died. Tried to restart, it tried to hit a few times but never started. Since then I replaced the fuel pump, fuel filter, cap and rotor, and the above mention spark plugs. The engine turns over but will not start. Check for fire and appears to have fire. As engine is turning I do not see fuel coming out of the injectors. I also can't hear the new fuel pump running, I do hear a click after a few seconds from fuel pump with the key just being turned on. I am stumped right now. The problem started slowly and got to running rougher, then would not start at all. Any help with this would be greatly appreciated. Thanks 8hawg>>>
First thing I would do is try squirtin some gas into it and see if it runs. If so then at least you know where to look for the problem. I have the same truck(454 TBI) I just did the fuel pump in mine too, one thing i noticed while doing it is that the ground was real corroded, may want to check that out, it attaches to the frame rail right where the electrical plug is that goes to the tank. You should be able to hear that pump on, if you don't hear it, it ain't goin, that sucker is loud. If the pump isn't running and the ground seems ok, try dropping the tank(i know i know it's got gas in it, drain that first :)) then run 12v to the pump and see if that kicks it, if it does check the relay and after that the computer i guess.
First on the firewall on the passenger side, near the heater hoses. There is a relay and fuse panel. It should have a plastic cover (sometimes missing). In there should be a wiring connector that looks like it is just plugged in to a cap. Unplug it, and there should be a 20 AMP fuse there for the fuel pump. Verify with a test light that you have power across both sizes with a good fuse in place. Test the wires on both sides of the connector. (I have found a bad fuse connector a few times on high mileage trucks). Next Verify that you have power at the fuel pump Relay, and that the relay is good. On the Relay it will show you which pins to ground, and which pins to apply power to to test the relay, and the circuit. You should also test all the fuses in the fuse box inside the truck with a test light. Make sure none of the wires has pulled lose from the back side of the fuse block.
Next go to autozone or advanced. Get a Injector Pulse Tester aka Noid Light. Remove the plugs from the injectors (compress the two tabs lift straight up). Plug in the test unit. Have someone crank the engine, while you watch the tester. Light Solid = Injectors have power, but will not work. No Light = No power to injectors Light Flashing = Injectors receiving 'Pulse' Signal.
The Pulse signal is what tells the injectors to Spray fuel.
If no Pulse do the Simple ECM test with a code clip. Make sure you get the ECM good code. If no ECM good code, pull the ECM and have it tested. Do not just replace, it could be a wire in the harness going to the ECM.
IF ECM is Good & you have Pulse I would check out the wiring at the sending unit, and test back from there.
If you have Constant power but no pulse, test the signal from the distributor. There are magnetic pick ups in there. One set on the shaft, one on the housing. If they register weak, or do not register, you will not get a pulse signal for the injectors to Spray.
If you have No Power at the Injectors (verify this with a test lamp as well as a Noid light), You will need to get the wiring Diagram and test back until you find power.
If you can not Obtain a Noid Light, you can make one your self. a 194 style bulb with some cut off 16 penny nails soldered to the wires will work for GM TBI. More of a pain in the but to make if you can buy a cheep one. Charles
First of all I want to thank you guys for your advice with my problem. I have just replaced the fuel pump relay. YES, you guessed it , IT STILL WON"T START. I will continue to pursue this problem until I fix it, I will not give up. Really thanks alot for your suggestions. If you think of any more let me know. I will be sure to post a reply here on my progress. Thanks again, 8hawg>>>
First of all I want to thank you guys for your advice with my problem. I have just replaced the fuel pump relay. YES, you guessed it , IT STILL WON"T START. I will continue to pursue this problem until I fix it, I will not give up. Really thanks alot for your suggestions. If you think of any more let me know. I will be sure to post a reply here on my progress. Thanks again, 8hawg>>>
Had the very same symptoms on my 88tbi last year. You're due a new fuel pump. Try this to get it to the garage. Turn on the key, get out and beat on the fuel tank. You may then hear the fuel pump whine. Start and drive to place of fixing ... your garage or your mechanic.
Hello guys, "IT IS ALIVE" I just wanted to let you know I got my truck running. It is running as good as it ever has. I thank you all for your suggestions and advice. "89 GMC" I wanted you to know that my ground wire from the tank to the frame,"like you suggested", was in fact the reason why my new fuel pump was not working. It was dirty, I cleaned the wire connection and cleaned the frame where the ground bolt is installed. After that, it started. It still had a miss or roughness to it, but not as bad as before.SO, I installed a new set of spark plug wires. That did the trick, truck is running great. After a new fuel pump, fuel filter, fuel pump relay, cap and rotor, sparkplugs and wires, alot of thinking, reading, researching,asking questions, a few skinned knuckles, sore neck, and yes alot of choice words, my truck runs great. Thanks again guys. 8hawg>>>
Others may disagree, but I like to paint over chassis connections with nail polish after cleaning and reassembling. I just feel better knowing it's sealed from the elements.
The nail paint isn't tough enough to lock the bolt down, and can be quickly removed with acetone if needed. Really though, once it's properly cleaned, installed and sealed, you shouldn't need to remove it again.
Glad to hear you got it fixed, glad we could help. I know I find a lot of good advice on here when I'm looking at a problem so I like to "pay it forward" when I can too. Sounds like a lot of the fuel pump problems are similar, nothing like that feeling when it finally fires back up for ya....
And if any other girly men out there have forgotten there nail polish (j/k), you can also spray the connection down with form-a-gasket spray. It comes out of the can super runny so it gets down in the cracks, then hardens almost instantly.
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