This weeks problem, need help here! !

[T-Type Mike]

Seems like something new happens to me every week with this car!!
Problem just started happening last week...First off my fuel pump started to scream extremely loud after I was rear ended lightly. I posted on here, and with some help we determined that probably there was some dirt dislodged somewhere in the line..I replaced my fuel filter and dropped the tank to check my fp sock, which turned out to be collapsed. Put it all back and went around the block.....Pumps still loud as hell, but when I get into boost the guage reads increase in vacuum not boost. What gives here???A 2 month old 340 done again??? I will order a new pump tomorow and make sure walbro warrantees it,
I was extremely concerned when I looked at the guage which was reading 18lbs vac. Could that have caused any other issues that I should deal with?? Thanks...Mike

 

[Blown&Injected]

IIUC

You are not getting boost? - "gauge shows vacuum"
Your fuel pump sounds different after a light hit in the rear.

The boost problem is probably not related to the fuel pump sound.

Have you done a fuel pressure test?

Did anything move under/behind the bumper when you were hit?

 

[T-Type Mike]

Thanks for the quick reply, Nothing was moved behind the bumper, other than myself dropping the tank to change out the sock. I will be doing that again tomorow to replace the pump.

The car goes into boost, but fuel pressure guage reads that it is going into vacuum>>>>????

I will do the fuel system check later today also, thanks for the tip. Anything else I should be checking out? TIA

 

[Blown&Injected]

I did not understand what you meant by "The car goes into boost, but fuel pressure guage reads that it is going into vacuum>>>>????"

You mean when you hit it, the FP goes (from typically about 45psi) to 0? And seems to want to go lower?

Just off the top of my head: To get an idea of how the fuel system is working, after running WOT through the gears and monitoring the pressure, Attach a line to the end of the fuel rail and put 12v. to the FP and check the flow and pressure. There are several points between the lines coming from the top of the tank to the fuel rail where you can check.

One of the points in the system you may want to look at is where the line disappears above the rear - just a few inches up stream of where the steel lines from the tank meet the rubber lines attached to the car. This place can be a problem especially if still on the stock body bushings.

 

[T-Type Mike]

Steve, you make some good points. I will have to have a look tonight. I am completely unsure as to why this all of a sudden is happening. My fuel filter was completly clogged, couldn't even blow through. I am going to go ahead and swapped in another 340 tomorow and see where I am at then, I am interested to see if I possibly mixed up a hose on the tank when I pulled the pump yesterday. I'll let you know what I find. Thanks again.
Mike

 

[Richard Inglett]

If the suction side of the pump is plugged or crushed as Blown&Injected is indicating, cavitation will continue to wipe out your pumps.

Richard