fuel pump question 02 suburban

[hickmysta]

I can hear the fuel pump engage when i turn the key to the on position ; does that mean the fuel pump is working? It comes on for about 3 seconds and shuts off before i try to start the engine.

[gkindub]

This is a normal sound: the fuel pump is repressurizing the fuel system prior to start up. If the pump does not run at all or runs too long then you may have a problem.

[hickmysta]

The dealer told me my fuel pump was going......blamed it on the ethenol in the gasoline. My truck failed to start twice while parked on a slight downward grade ..Both times I could hear the fuel pump come on for 2 seconds then shut off when I turned the key to the key on position.The second time this happened I had about 8 gallons of gas in the tank.
CAN I CONNECT A PERMANANT FUEL PRESSURE GAUGE IN THE LINE IN ORDER TO CHECK MY PRESSURE WHEN MY TRUCK FAILS TO START AGAIN ?

[gkindub]

I think you should get a baseline reading of fuel pressure while the truck is running well and then when you get a no-start check it again and compare. Find the fuel rail pressure fitting and get a fuel pressure gage and check your pump pressure against the pressure spec for your vehicle and engine.

[Ryan685]

It's not a good idea to run a fuel line into the cab to connect a fuel gage too. I would think what you are hearing is normal. When you turn the key on, the fuel pump comes on and then goes back off if the engine is not started. Fuel pumps do not stay on for very long unless the engine is started. There may be certain times when the key is turned on, fuel pressure is already present. The fuel pump will not come on until the engine is started. I think what you are asking is, if every time you turn the key on, the pump is coming on for 3 seconds is there a problem? I would say yes. The pump is not making enough pressure or pressure is lost somewhere in the high pressure side. So every time you turn the key on, the fuel pump comes on. In other words, the first time you turn the key on (don't start the engine) the pump should be heard. After switching the ignition off and back on again, you shouldn't hear the pump come on.

[MT-2500]

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.
MT-2500

[maxwedge]

Originally Posted by MT-2500

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.
MT-2500

Hey, mt-2500 we're on tour together tonite!!

[MT-2500]

10-4 on that Maxwedge
Mt-2500 /alias Sherlock/Crunch

[hickmysta]

thanks again to everyone who has tried to help me...My original problem was ; My suburban would not start at all while parked on a downward grade with less then a quarter of a tank..One time i got it started by simply hitting the gas tank with a rubber mallot.The second time the rubber mallot trick didnt work. What did work was rolling the vehicle to level ground...the dealer said my fuel pump was probably hanging up and therefor starting to go. However i could hear the fuel pump come one when i turned the key to on. The starting problem doesnt seem to happen when my tank is full. The last time this happened i had 8 gallons of gas in the tank, parked on a downgrade
(gas gauge read less then 1/4) (nose lower then rear) and within 30 mins i couldnt restart vehicle.....ANY THOUGHTS? could my fuel
pump be hanging up?Ineed to get a fuel pressure gauge at auto zone so i can check the pressure next time this happens....SORRY SO LONG.......

[MT-2500]

Quote
Ineed to get a fuel pressure gauge at auto zone so i can check the pressure next time this happens....SORRY SO LONG.......
GET THE GAUGE ON IT AND IT WILL TELL THE STORY
Good Luck and let us know how it goes.
MT-2500