skyhigh4by

iTrader: (1)

Im using a holley 502-6 with the newer style injectors that are rated 60lb/hr @12psi 85lb/hr @21psi and Im feeding it with a walbro gsl393 pump mounted under the hood.

The brass plug is still in the top of the regulator so I know previous owner never messed with it but I plumbed a gauge in to the line between the pump and TB and I'm getting a solid 16psi. Im pretty sure it should be around 11-12psi from factory....

I have a few mods...intake, cam, headers but nothing major enough to need that high of fuel pressure I think. Its running rich, can see and smell it in the exhaust and sometimes get code 45.

So my question is... Why is the pressure that high? Is that pump pushing right through the regulator? Can I drill out the brass plug and adjust to FPR to lower the pressure or can it only be adjusted higher from factory setting?

ex-x-fire

Put a hole in the plug & pop it out. If you don't have any restriction in the return line then you should be able to adjust the pressure down, even as far as 4-5psi.

skyhigh4by

iTrader: (1)

I tried to adjust it down but I went as far as pulling the adjuster screw right out and it wouldn't go below 15psi. I was able to turn it up to 22psi. Holley tech says it should be 11-12psi. I don't think my return line is restricted but I suppose its a possibility. I did a carb to TBI conversion and Im using the stock return line that was for the Q-jet. Is it too small?

skyhigh4by

iTrader: (1)

Well to solve my own problem...

I put a 3/8" line from the TBI in to a jerry can and was able to lower it down so low that it wouldn't even run. So I guess I need to tear in to my return line.