I have a 2000 Blazer, 4 dr, 4 x 4 with 120,000 miles. Early this year the fuel pump went out, this was confirmed by the dealer who wanted $1,000 to change the pump. Towed the vehicle home bought a $400 replacement and swaped it myself. It wasn't that difficult, we also changed the fuel filter, wire harness connector and fill hose, had to cut old one off. The vehicle ran well for about 2 months then became difficult to start, onceit started it ran well,pump finally failed. There waslittle or no pressure whenit wastrying to start. Got the second fuel pump under warranty, ran well for about two months then the same thing, got number three under warranty ran well for several months then the same thing. This time we started trying things before we replaced it and found that if you primed the throttle body with a little gas it would start and run fine, pressure was between 55 & 60 when running and little or no pressure when trying to start. While it was running I took the vehicle to a friends shop and his mechanic replaced the fuel pump with number 4, still under warranty. Well last week it got difficult to start again and failed over the weekend, once again if you prime the throttle body it starts and runs fine. It is my understanding that there is a starting circuit and once oil pressure comes up it switches over to a second circuit for driving, this is how GM handles shutting down the fuel pump in case of an accident. I believe the starting circuit is causing the problem with the pumps, does anyone have any information or ideas on how to solve this problem. I need to find a fix to this problem because warranty is almost up on the pump.

 

Have you been using GM fuel pumps?
You shouldn't have to prime the fuel, there is a check valve in the pump and the fuel pump primes as soon as you turn the key. You should have about 60 psi within seconds of turning on the ignition, before cranking.
Do you run your tank low on fuel or ever run out of gas?
If you are running the fuel pump and starving it for fuel it will wear out the brushes very quickly.

 

as a rule of thumb never let the tank go below 1/4 because then the fuel pump is not fully submerged in gas, which is its coolant.

if you have already been doing that, then wow you must have really bad luck.

 

In addition to looking into the starting circuit you mightwant to check out the fuel pump relay. Not sure of what is causing your pumps to go bad so quickly but sounds like you may not have the correct current going to it. Too much or too little current is not a good thing and the relay may be the culprit.

 

The pumps have been NAPA units, I now don't believe any of the pumps were bad, the problem is clearly with the starting circuit but I don't know how to fix it. I have replaced the fuel pump relay. When I say prime the Throttlebody I mean pouring a little fuel in it. The engine then starts easily and runs fine, fuel pressure is correct and all is great until the next time I need to start the thing.

 

What is the fuel pressure with the the key on but not started? Attach a fuel presure guage to the port on the fuel rail, turn the key to the on position and check the fuel pressure. Should go to 60 psi. If not, the pump is bad, OR you are loosing pressure somewhere. Have you checked the fuel pressure regulator? you might have leaky injector(s), is the fuel filter clean?

I don't think you have a starting circuit problem since you clearly state that the vehicle will start and run if you prime the throttle body. Sounds like a fuel delivery problem more than anything else. Good Luck.

 

my father had the SAME exact problem years ago with his 1st GEN blazer. Took it to the dealer everytime, cost him a ton! They never found what was wrong with it. 7 fuel pumps later he got rid of it.

I would def check the size of your fuses, check your relay, look in the harness for shorts. If the Fuses are too large, they are letting too much current through causing it to burn up. Make sure the connector to the fuel pump is water tight also. Getting water in a connect can cause you heck.

Keeping it above a 1/4 tank is a VERY good idea also. Im in the process of replacing the fuel pump and relay on my 1st Gen right now :-/ and i only let it drop below 1/4 once.

 

Check the pump wiring harness... Sometimes they have issues...