Fuel Pressure Problem

[WardenTex26]

Hi all,

My father and I are having a problem with our 1996 Chevrolet K1500 Pickup. It is a 4x4 with a vortec 350cid.

 

We looked in all manuals and they all said that the fuel pump should put about 60-66psi of pressure into the lines in order for the truck to run. We are currently getting 52 psi. Is that good enough? We replaced the fuel filter twice and it still is at 52 psi. However, when we try to start the truck, it just keeps turning over and over without starting up. We have lots of spark and we have air. I am thinking the fuel pump is dying.

 

So, for the last resort, can we blow air through the fuel lines back to the tank to get any dirt out of the lines and clean the screen in the tank? It has an electric fuel pump and I want to know if it will cause any damage to the fuel pump if we blow air into the tank.

 

Any thoughts?

 

Edit: I see a lot of other people have the same problem, but none tell me if it is a good idea to blow air back into the tank from the fuel filter area.

 

Thanks

[zaac]

The fuel pressure regulator could be the problem also. A whole lot cheaper to replace. The thing to do is block off the return line and check pressure. If pressure increases above normal spec the pump is ok. On my 5.3 the reg is $90 and the pump is $550 with a whole lot more labour. Don't ask me how to plug the return line cause I've never done it myself. I asked on here but got no response but it is the way to test pump and reg. Seems funny that 52psi won't start it. My truck was trying to start with 35psi until it used up the fuel as the pump wasn't working at the time.

[WardenTex26]

We have already replaced the fuel pressure regulator. Every sensor is also brand new. New fuel injectors and also a new tune up. Like I said, we have also replaced the fuel filter as well. The only thing we can think of is the fuel pump.

 

But I want to know if it is safe to blow air into the fuel line from the fuel filter back to the tank to clear and debris from the screen or lines in the tank?

[zaac]

But I want to know if it is safe to blow air into the fuel line from the fuel filter back to the tank to clear and debris from the screen or lines in the tank?

I don't know if that is safe or not. If you regulated the air pressure down to say 30 psi I can't see what it would harm. The truck won't start anyway so how much worse could it get. You're probably gonna end up replacing the pump anyway. What I did was left the filter off and turned the key on to see how good of a flow there actually was. How many miles are on the pump? With my 2000 5.3 the pump failed at 35k and 115k so they seem to be a weak link. I'm told it's a good idea not to let the fuel level get to low as the pump relies on fuel to help keep it cool. That and replace the filter often.

[markw8]

I'm not a tech, but fuel injected engines seem to need the pressure they were designed for, to start and properly run. Injecters won't fire without the proper pressure. A bad regulator usually causes high pressure, a bad pump - low pressure.

 

Mark.