Re: 1999 4.3 4-door Blazer

Just trying to get a second opinion. I replaced my fuel pump last weekend after the pump failed to operate. After the replacement, the car runs but after sitting for a while, it take longer to start.

I tested the pressure under the hood and get (about) 60 psi but I lose 15 psi per minute (ie., it fails to hold the pressure). Since I was replacing the fuel filter, I hooked up the pressure gage to the output of the new fuel filter and I still get a pressure drop after the key is turned off. Does this confirm the fuel pump has the problem?

Speaking of fuel pump, can someone tell me the purpose of the 3 outputs on the fuel pump. One is obviously the fuel to the engine. I know (now) that the fuel is cycled back to the tank so one is the return to the tank but what is the 3rd one?

Looking at my pump, the outer two connector have the same quick disconnect connectors but the middle one is different.

I purchased the fuel pump from a company on eBay. When I told them about the pressure loss, they are telling me to go to a certified mechanic to find out why it is losing pressure. Of course, a certified mechanic is not going to do this for free and I'm sure this eBay company won't pay for this. According to the eBay ad, this pump is made in America and has a guarantee. I just need some information to present to them that their pump is bad and I need a replacement.

The car did not have any problem starting before so I figure that I have a bad fuel pump unless someone else can give me something to check out.

 

The 3rd line is a vacuum line to the evap system which is used to check the seal on the tank.

It definitely sounds like you have a problem with the pump.