Fuel pump has good flow. (I put a hose on the fuel line at the filter into a plastic bottle.)
I changed the filter yesterday. It was filthy and had some water in it.
The fuel pump turns on briefly (2 seconds)when I turn the key to the on position.
If I try to start it, it does start every time. (for about two seconds, then dies.
I can hear the relay click "off"
The fuse is good on the firewall by the relay. (I looked)
I'm at a loss and I could spend the time troubleshooting the problem, but I'm hoping someone allready has had this problem and knows what the fix is, and they would be so kind as to share it with me.
2006-11-29 11:39:50 · 8 answers · asked by Mr. KnowItAll 7 in Cars & Transportation ➔ Maintenance & Repairs
the relay is working if you have fuel pump for 2 seconds. if the ecm does not recognize oil pressure after start up, then it won't keep the relay energized. my guess is that either the ecm is bad, or most likely, the oil pressure sending unit/switch is bad. be sur the fuel pressure you have if even for only 2 seconds, is proper pressure. just flowing into a bottle isn't good enough of a test.put a guage on it.(after you fix the original problem)
2006-11-29 11:52:12 · answer #1 · answered by Anonymous · 2⤊ 0⤋
How long has it been since changing the pump. You can easily get defective ones as we have had several from time to time that didn't hold up. A scan tool will show clearly if the tps is working as should give even rising numbers of percentage of throttle as the pedal is depressed. Also should set a computer code as well. Crank Sensor can do this and not set a code. There is also major ground troubles with these pumps at the connector near the tank where they plug in. Don't forget to check the ignition coil. They can do this on a Chevy of that vintage easily. Also coil wire. Remember that it takes a lot stronger spark to fire the gasoline when the speed and compression are higher and the amount of fuel in the cylinder is more. A weak coil is having to charge up and fire much faster at rpm and while the weaker spark at high rpm might run okay with no load, you start dumping fuel down the cylinders and it might not work enough. You also mentioned that you had the throttle body system on that truck. Check the spray pattern on those as well and make sure that they are spraying cleanly and evenly. Last thing that I can think of is to check the gas itself and make sure that there is no water getting in it. Hope you can find the trouble soon!
2016-03-29 16:25:32 · answer #2 · answered by ? 4 · 0⤊ 0⤋
The 2 seconds is the programmed strategy of the PCM. When the key is turned on, the PCM will energize the fuel pump for 2 seconds and then turn it off if the PCM doesn't see engine RPM. The logic is not to run a fuel pump for an engine that isn't going to use the fuel.
Check the wiring diagram and see if the fuel pump is served also by the oil pressure sender. If so, it may be defective.
Good Luck & Merry Christmas
2006-11-29 11:49:51 · answer #3 · answered by Ironhand 6 · 1⤊ 0⤋
your on the right track. the pump is cycled by the computer and will remain on for about two seconds after released. there is also an oil pressure sensor in the circuit with the relay. it will close the relay and keep the pump energized if it is good. you can try another relay.which is probably the easiest.there is also a test wire under the hood for GM it is a single wire with a black plastic connector,and a female spade. supply this wire with positive battery voltage and the pump will run bypassing the con-trolls this is a test for the pump.my guess your relays no good
2006-11-29 11:52:03 · answer #4 · answered by samuel b 2 · 1⤊ 0⤋
i own a repair shop,and i run across this problem all the time with different gm products,,you might want to change the relay,and see if that helps it,,sometimes when the relay gets old they wont stat kicked in like they should,they keep kicking in ,and out,causing it not to run at all,i have see a lot of this lately since cold weather made its first appearance,,but id try that first,,it should make the pump stay kicked in,,if it don't,,you might need a pump,it might be shutting down on it,,this is cause d by age wear and tear,,and there's nothing we can do about that its just normal but try the relay for it,,i think you,ll find that to be the problem with it,,good luck,i hope this helps you with it,
2006-11-29 11:47:45 · answer #5 · answered by dodge man 7 · 0⤊ 1⤋
Fuel flow and fuel pressure are two diffrent things. Will it run on choke cleaner? Check the fuel pressure. It should have 9 to 13 pounds.
2006-11-29 12:30:30 · answer #6 · answered by TonynNC 5 · 0⤊ 1⤋
gearhead has it right.
GM built a safety feature in these motors.
no oil pressure and it wont stay running more then 5 seconds, after a while it wont start at all.
check the oil pressure switch,either a bad connection or bad sending unit, there are 2 on this motor, the one that you are looking for is on the front of the block and not in the rear by the distributor.
2006-11-29 13:14:33 · answer #7 · answered by Anonymous · 1⤊ 1⤋
Get a new fuel pump. Not enough pressure, who cares about volume or flow.
2006-11-29 12:24:42 · answer #8 · answered by RANDY C 3 · 0⤊ 1⤋