Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
You can accept whenever you would like to. I will continue to follow up with you until you are satisfied. The engine should continue to run when the fuel pump relay is removed. The power should be supplied through the oil pressure switch. The oil pressure switch is at the back of the engine behind the distributor.
hi. ok great. As soon as i get it back running i will do that test. Im going to go ahead and try to pay now. So you know im happy with your help. Then i'll ask a couple more questions. thanks ron
p.s. How about this question? what do you think?
Does the ecm get its power from the ignition switch when its turned on? Or does it get its power from somewere else reguardless if the ignition switch is turned on or working?
Hi david. Thanks for the email. ok great. Well. let me tell you what has happend from the begining and see what you think. Im driving down the road. everything is fine. Then bamm!! engine shuts off... Coast to the side of the road. Crank crank crank.....Nothing... Minute later... crank crank crank.... Nothing. Couple minutes later.. crank crank bamm engine starts..ok.. Drive a mile. same thing...Then get it started again. Idle for 30 seconds. Engine dies. couple minutes later. Get it stated again. drive 4 miles and get it home in the driveway.. let it idle for a couple minutes.. Then it dies... wait a couple minutes. It starts and idles for a while. During that time. I pull the fuel pump relay. engine dies. Put it back it. crank and engine starts and idles.. ok. I turn it off and leave it til the morning. Next morning. go out and it starts and idles for a while. I hook up a timing light and hook it to #1 plug wire and set it off to the side. Pull fuel relay still dies. Put it back in starts and runs. Then after 2 minutes it dies again. So i zip tie the trigger on the timming light and point it tword the cab so i can watch it. As i crack the engine it flashes everytime that plug fires. ok. Im getting spark but when i put my ear to the gas tank filler neck. I dont hear the pump buzzing. So i turn off the ignition switch for 20 sec. Turn it on. Dont hear the fuel pump run for 3 seconds like normal... But the timing light still flashes when i crank the engine. ok. Then all of a suddon. it stops flashing when cranking... And hasent flashed when cranking since. and... i also took out the relay. And put a test light to that green and white wire and grounded it. I was told when you turn on the ignition the green wire should get power from the ecm for 2 seconds and then turn off. But it doesnt get power now at all. for no seconds. and no spark at the plugs. And no power to the pink wire at the coil when key is turned on. I thought the dist. control module took a dump. and maybe thats why the ecm wasnt sending out the 2 second power pulse to the green wire at the fuel relay to trip it. cause it wasnt sencing anything from the control module. And thats why i wasnt getting any more spark to the plugs. But then i descovered no power to the pink coil wire now. ... so i thought. .. Maybe a bad ignition switch was taking everything out and causing all the problems?? Thats why i asked about the power to the ecm. I thought maybe if the ignition switch was bad. Thast why it wasnt sending power through the green wire to the relay... Im sorry its such a big email. Im hoping to can make sence of it and let me know what you think. or be able to ask the question you need to in order to figure it out. I am a car guy. I have many older cars. GTOs firebirds camaros and mopars. and have restored them. So im very at home working on the cars. Just dont have knowledge of the computor stuff like this./ Like you do. thanks again ron
p.s. When the relay was out i did jump the orange wire that has power to the grey wire and the pump came on. So it seems the pump itself is cool.
p.s.. does the connector fro mthe harness to the coil have to be on the coil or can it be off with power just to the pink wire like i had it? maybe thats why? That white wire needs to be on there for some reason? if so. I can redo the test and figure out some way to have the connector on while testing.
The ECM (computer) is what turns the relay on. The relay is just an electromagnetic switch. The relay has a coil (electromagnet) that is turned on by the computer. This causes the contacts of the switch to close. The switch is fed power by the ECM B fuse and the other side goes to the fuel pump.
The low voltage code most likely set because of the failing ignition switch so I wouldn't get too worried about the code. Replacing the oil sending unit would be a good idea.
The fuel pump prime connector is located under the hood. It is a single red wire and should be near the underhood fuse panel. It does not go to the diagnostic connector under the dash.
Rechecked schematics and the red fuel pump wire may go to terminal F at the diagnostic connector. See diagram below. The wire at terminal G is the programming wire for the keyless entry system, jumper the A and G terminals together to program the keyless entry remotes.
Hi dave. ok. Well. I did something you might have done in the past. LOl I took the wrench and cut it in half. LOLOL So it cleared the firewall. I got the switch out without having to move the distributor. Put the new one in. Bingo. runs when you pull the relay. But i dont think the switch was bad. What happend was one of the prongs in the switch was bent over. Like it didnt quite line up when the plug was put on. And when the plug got pushed on. It just bent it out of the way. Not leting the orange and grey wire connect when oil pressure went up. who knows. It might have been that way the trucks whole life out of the factory. So that was the problem with that. So everything works great now. Thanks for all your help bud. ron
P.S. When i need help again.. Or if i have a friend that needs help. Is there a way to come on this site and ask for YOU to pay and work with?
The egr passage does not normally stop up on this engine. With the engine running, pull open the diaprhagm on the egr valve and see if the engine rpm drops. If it does, the passage is clear.
Next test, connect vacuum pump to egr valve and apply vacuum. Start the engine and immediately observe the egr valve and vacuum gauge. Reading should drop and the egr should move to the closed position. If it does not, then ther is an internal passage in the egr valve itself that is clogged, this will require replacement of the egr valve.
I just recently purchased a 2004 Tahoe with 155000 miles