2001 GMC Sonoma No start

This is my dads truck but I have the fun of working on it. We have tested the relay(well it clicks when the ignition is turned on) I didnt see a fuse designated for this, I have also made sure by putting a few extra gallons of gas in it because his gauge has been going bad, no avail. I also took off the line that goes to the fuel filter from the pump and the fuel just trickles out. No pressure there at all. There used to be a loud buzz when we started the truck and now no noise at all. Im thinking that it would for sure be the pump, but I know that some of you guys may know better. Either way I am going to loosen the bed and scoot it back to replace it, im not dropping the tank. From what I have heard from a couple of local guys thats what they also say but I thought that I would get an answer from some guys that may tell me more than a local guy(repair shop). What do you guys think? Should we just replace the pump?

This sounds like a pump problem. If you have no pump prime, when you turn the key to start it, chances are the pump is bad. You can test the pump by finding the test wire and energize it and see what happens, or you could unplug the pump and probe it from there with a voltmeter to see if its getting the proper voltage before you go throught the trouble of taking it apart. But in my opinion, this sounds like your in need of a new fuel pump.

Also, make sure if you do have to replace the pump, buy a quality pump, a Delphi unit is a good example of a good pump. Don't go cheap on this, or chances are you'll be doing it again sooner than later. Good Luck!

Sounds like your fuel pump is toast, but you may not be seeing the whole picture. You need to see what the max fuel pressure is by doing the following to check out the fuel pump. Or, if you have 300 -400 bucks you don't really need, just jump in and replace the pump and see if it solves the problem.

1 ) Check the fuel pump maximum pressure at the schrader valve with a fuel pressure gauge. Be aware the fuel pump only runs for 2 seconds when you turn the key on (engine off). Then the key has to be off for 10 sec before the pump will run again. (Fuel pressure gauge is about 35 bucks if you need to buy one)

With a properly working pump, the fuel pump reaches its max pressure during that 2-seconds, which should be something over 61 psi. When the pump shuts off the fuel pressure will immediately fall 5 or 8 psi. (This is normal) It should not fall below 50 PSI.

To see the max pressure put the gauge where you can see it when you turn the key on (engine off) or else get someone else to turn the key or watch the gauge. You need at least 61 PSI to start the engine.

2) If maximum fuel pressure is low: Check the battery with a load type tester. AutoZone will do it for you. A weak battery will cause a no start, as the fuel pump needs max voltage to get the fuel pressure up to and above 61 psi, which is needed for the engine to start.

3) However, before giving the fuel pump its last rights try this:

Under the hood, on the driver's side fender towards the firewall, there should be a red fuel pump test wire, it should be hanging down by the electrical junction box. It won't be connected to anything, just hanging there with a gray or black plastic insulator on the end of it.

After you find the test wire, disconnect the fuel pump wire connector at the gas tank, apply a 12v supply to the red fuel pump test wire and leave it there while checking for current on the 12v feed wire in the wire connector at the gas tank. (On my 95 the 12v feed wire going to the tank is gray) Test the current with a voltmeter, while using the ground wire in the connector for a ground. It should read between 12 & 13v or something more than 12v.

4) If you don’t have at least 12v on the Gray wire try using a different ground. If you have 12v, then make sure the wire connector at the gas tank is making a good connection to the fuel pump wire connector.

5) If you have 12v+ and the pump still doesn't put out 61+ PSI when you have 12V applied to the red test wire, the pump is toast and needs replaced. (Make sure the battery has 12V+ when doing this test)

6) If you need to replace the pump, get a Bosch, Delco or Delphi – in that order. The rest are junk. Here’s a link for a good price on a Delphi fuel pump, but also check out the on-line prices at AutoZone and O’Reilly’s.

http://store.getgmparts.com/index.html

Good luck and let us know what you find, as it will help others.

Hey guys thanks for the replies. We are going to go ahead and replace the pump. He bought the relay and as I told him to start with it was ok. We are getting plenty of voltage there also. There is no whine with the pump at all even after towing it home. There was just a trickle of fuel at anytime no matter if the key is on or off. As to expense, well just for starters I call advance and they say 318+. So he is not going to fool with it till after christmas. So we normally go to autozone or we may have an outlet for cheaper GM parts from the dealer we are also going to check out. So thanks for the list of trouble shooting!!! You guys are the best!!

Try pricing the Fuel Pump with this site. They sell high quality Delphi Pumps, not the cheap ones you'd get from Advance Auto and I'd bet it's cheaper than the $318 at Advance and they're great to deal with. I just bought one from them for my Blazer.

BTW, the fuel level sending unit is all part of the fuel pump module so his gauge problem should also be fine once you replace the Pump.


http://store.getgmparts.com/fuel-pumps.html