I recently installed the Walbro 255 pump in my LT1. After I had it good to go, I started the car and immediately checked the fuel pressure. It was about 40 lbs with the car running, and about 38 at WOT. I then changed the fuel filter and gained about 2 more lbs. The car was running great for about 2 days and then it started acting like it did with the stock pump that only put out 25 lbs. The new Walbro pump was putting out 12 lbs.

Anybody had a pump go out like this?

 

sounds like you have some type of debri in your tank. maybe rust or leftover parts from the first pump. wot fue; pressure should be between 41 to 47 (hose off at idle). at idle vacuum line on 3 to 10 psi drop from first reading with the line off.

 

Check for junk in the tank or check to see if the fuel line slipped off of the pump......thats what happened to me.

-B

 

When the hose slipped off, did you still get a small amount of pressure (I'm getting about 12)? I will definitely check it tomorrow. Thanks.

 

I believe I still had some pressure because the car would still run but it would sputter and stumble, when I dropped the tank for the third time it was barely on the tube. So I cut off of the snap fitting from the stock pump and used a hose clamp to hook it up to the new fuel line....no more slipping.

-B

 

I probably do have the same thing going on. I'm going to check it this morning. Thanks .

 

That was it!!!!!!!!!! The hose had come off of the pump and was just sitting on top of it sort of half-cocked. I think this is a good argument for the trap-door method. If anything goes wrong, it's a heck of a lot easier to get to than removing the tank! Thanks B !