thafaz

Gents,

Finally getting back to my beast!!! For you young fella's, enjoy all that free time....life gets in the way big time.

Having some issues with my 4309; fuel pressure will not adjust no matter what I do with the screw....worn out diaphragm? I took it apart and nothing looks broken.

Buy another one or is there a better recommendation for a TPI to carb application?

Thanks,

Faz

thafaz

...some more observations...

I unhooked the line to the carb and the return; even with the adjustment screw completely removed, gas shoots out of the out port at alarming rate and nothing out of the return.

So, it's not regulating at all. I set out to buy a replacement....$220!!! They have gone up.

Holley 12-887 seems a better priced alternate: https://www.holley.com/products/fuel...s/parts/12-887

Fuel pump was replaced with the following:


Am I missing anything obvious? All feedback appreciated.

bluegrassz

iTrader: (3)

I am having the same problem at the moment. I was running the stock intank TPI pump with the 4309 and Holley 750 Street HP carb. I had no problems keeping it at 6 psi. My pump went bad after setting for a while and I replaced it with GM EP381 which is a TBI pump. Now with the same setup, I cant get the fuel pressure to adjust. I purchased a rebuild kit for the 4309 and installed it with the same problem. I am currently trying to clean out the stock return line and make sure it is not blocked.

Was thinking of going with the same holley regulator you linked.

I tested the fpr with a pressure tester and with the adjuster screw completely out, I still got 6 psi. I may try running the return directly to a gas jug to rule out the return line.

Here is the link to the rebuild kit.
Mallory 29859 rebuild kit for 4309 FPR

thafaz

Looks like there’s blockage in the return line right at the pump….thankfully I cut the inspection hatch. I’ll take the pump out to see what’s going on….