Ok guys I try to explain the problem...

Im tuning a customer car right now and Ive had problem with the fuel pressure when boosting....

1st time I tuned the car, at idle I had 40psi fuel pressure, at wot it went up to 54psi, and after getting full boost (15psi) the pressure was dropping rapidly to 25psi before I let the trottle go.

The car was equiped with a walbro 255. I installed a brand new one, the problem was gone.
the car made 320whp @ 14psi

Now im retuning the car about 2 months after I tuned it the 1st time. guess what? pressure is dropping exactly like 1st time....

things you need to know:
1: The fuel tank is stock using stock line, and the tank is always full of fuel.
2: I tried putting direct power with big gauge wire, same problem.
3: injector are 780cc
3: motor is GSR with garret full t3-1


if someone has any idea what should I look next....

Ill remove the fuel pump tomorrow and look if there is rust or something in the strainer to see if there is junk in the fuel tank...


THX!!!!!

 

Might sound crazy but do you have another fpr u could try?

 

x2 for trying another FPR, especially if it's a stocker.

 

mine did the same thing, the fuel filter was clogged

 

change fpr, fuel filter, pump strainer. at that power levels the walbro will hold pressure well..

some customers of mine drop pressure at around 500+whp

 

I'm having the same problem, fuel pressure drops to 50psi by 7k. I'm already running power directly off the battery to the pump via relay so it's not that either.

So far, changed FPR, dampener, fuel filter. I'm going to drop the tank and see if there's anything in there that could be causing it.

What car is it on? My car (CRX) has a little fuel pump pickup extension piece so it sits in a more "stock" location and I've been worried about it possibly sucking air past the extension. Also possible that the customer didn't tighten down the hoses inside the tank on the walbro correctly.

Also possible it's a faulty pressure relief valve inside the pump itself.

 

its in a DC4....

Already changed fuel filter, the fuel tank is full of fuel, Ill change fpr right away....

 

I just recently had a similar problem and it turned out to be the fuel line inside the tank going from the pump to the cover. It was all swollen and leaking like crazy. The previous owner had thrown in a piece of regular fuel line instead of submersible fuel line. Just wish I hadn't discovered this problem on the side of the road...

 

is it a real walboro pump? seems about 90% of them now a days are fake. ive seen so many issues with walboro pumps.....thats why ive never been a big fan of the dual walboro deal

 

i ad a problem like this. turned out to be rust in the tank. got it tuned made a little over 400. 2 days later it started leaning out. put a new pump in worked fine. 2 more days go by starts doing it again. the pick up screen was getting clogged up. ended up swapping tanks.