383 NA using Racetronix pump

I am having problems with the fuel pressure being too high. The FPR is a stock GM part. It was replaced with a new GM FPR...didn't help the problem. I removed the return line in several different spots and ran it directly into a gas can. The pressure went down every time, but when reconnected it would go right back up. This lead me to think that there was an obstruction in the last segment of flexible hose going to the tank, or an issue with a clogged return filter in the tank. The pump was removed and there appeared to be no issues with the return hose or the filter inside of the tank. When the bucket for the pump was sealed and reinstalled, I did not reattach the return filter. (hopefully that was OK) I used compressed air and there was no restriction in the last segment of return hose. There were no obvious kinks that I could see....until I ended up kinking it myself.

I decided to replace everything from the top of the tank to the intake in hopes of resolving this current issue...as well as maybe preventing future issues due to having old hoses/lines. I used -6AN Teflon lined hose and AN fittings for both the feed & return.

Still having problems....

Pump primed - 42psi.
1250rpm idle w/ vacuum connected - 47psi.
1250rpm idle w/ vacuum disconnected - 50spi.
3000rpm - 42psi.



Any ideas as to why the stock FPR is not able to maintain a lower pressure??

 

What is the flow rating of the Racetronix pump?

What kind of pressure gauge are you using?

 

255L/Hr @ 43.5PSI @ 13.5V (300KPa)

Autometer 4463 fuel pressure, Ultra-Lite 0-100 psi, 2 5/8 in.

 

Get a manual gauge on it first, I bet the guage is off.

 

I haven't confirmed with a mechanical gauge this time, but I've done it several times before while chasing this problem and the readings were always identical. The car is running extremely rich so I'm guessing that the readings are accurate.

 

 

The only thing I could say is to get an adjustable FPR, or swap a known good FPR from another car.

 

The big brown truck should be stopping here tomorrow. I just foresee another new part that doesn't fix the problem.

Thanks for the help!