1999 Blazer won't start

[LaidEBug]

My blazer wont' start. My daughter had an idea to "pound" on the gas tank, then it started. My bright idea to shut it off to test it, well now it won't start at all. I'm figuring it's the fuel pump, are these hard to do ourselves? the garage can't fix until late next week.

[DINO55]

LaidEBug....

Before you think of any fuel pump swapping, You need to check some things out first.

When you turn the key on, do you hear the fuel pump priming (whinning) for 2 seconds?

Are your battery cables CLEAN?

When was the last time your fuel filter was replaced?

Installing a new fuel pump involve's pulling the gas tank off the truck, The fuel pump alone, AC DELCO (the only one you should use IMO) will cost you somewhere around $200 -$300 ... The fuel pressure needs to be checked on the old pump if it's primming, before replacing this expensive ass part.
Good luck and post back here with any questions and your findings...

Dino

[DelCoch]

If you would like to Check out your Fuel Pump before laying several hundred bucks for a new one, do the following.

1) Check that you have at least 1/4 tank of gas.

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.

2) With a jumper wire, apply 12V to the red fuel pump test wire while checking the fuel pump pressure at the schrader valve with a fuel pressure gauge. (Fuel pressure gauge is about 35 bucks if you need to buy one) If you have less than 50 PSI goto step (4) below.

3) If you do have at least 61 PSI of pressure, (which is needed for the engine to start) disconnect the 12V jumper wire and test the fuel pump pressure at the schrader valve with just the ignition key on, (engine off). 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.

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.

4) If the 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.

5) However, before replacing the pump, 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 and the ground is black) Test the current with a voltmeter, while using the ground wire in the connector for a ground. It should read 12 to 13.5v or something a little more than 12v.

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

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

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

If you need to replace the fuel pump, do a search in the FAQ’s of this board and you can find step by step instructions. For a ‘99 you will need a special wrench/pliers to disconnect the gas line at the fuel pump. Before removing the three lines on the pump, you might want to mark them using colored zip ties.