i am having troubles with my fuel pressure. it is right around 60psi at idle. im thinking that it's because diameter of the passages of stock FPR cant return enough fuel to the return line, and thats why im getting about 60psi of pressure. it might be fine with a stock pump but with the walbro 255, the FPR just cant keep up. has anyone seen this problem before, i am going to test some random nissan FPR's to see if i can get a decent fuel pressure at idle. thanks for the help
can you max out a stock FPR with a walbro 255
- Thread starter materchan
- Start date
Have you read about drilling out your J tube? I'm not positive when you are supposed to do the J-tube mod (not done my research) but it might be something you could look at as well.
EDIT: http://www.supramania.com/forums/showthread.php?t=34548
EDIT: http://www.supramania.com/forums/showthread.php?t=34548
There are some cases that when people use the 255 with the stock FPR the pump will blow up the regulator, be careful, I sugest getting an aeromotive AFPR kit 
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I used the stock fpr for years on a 255 and had great afr's just make sure you drill out or bypass the j-tube as Sawbladz suggested
In agreement with Sawbladz. It's most likely your J-Tube if you haven't bypassed or drilled it. I'd recommend just bypassing it to take it out of the equation all together. Do a search for J-Tube (or jtube) bypass and you should find plenty of info on this. Aftermarket FPR's flow much more and the J-Tube restriction doesn't allow the fuel to return to the tank quickly enough. The FPR should have nothing to do with this as once the pressure is reached, the additional fuel should be then sent to back to the tank if I'm not mistaken. The J-Tube acts as a pseudo back-up FPR in case your FPR fails. This restriction however abnormally increases the fuel pressure if you are running an aftermarket hi-flow pump.
