Hey guys, after sorting out my plug fouling issues I've been having, I've been driving my car around. It runs really good / responsive. Now here is my problem. Originally, I set my fuel pressure to 6 psi at idle. I'm running my stock tbi fuel pump with the Mallory return style regulator. It seems to run at 6 psi for a while, but I went to the auto parts store and I popped the hood only to reveal a dwindling 3 psi at idle. Why would it change. I got the car home and I waited for it to cool. I started it up again and it went right to 6 psi. Can I adjust it up to 8-8.5 psi so when it does run for a while it will drop to 4-5 instead of 3?

Whats my problem?

 

First, make sure you can trust your gage. Readings varying with temp aren't uncommon.

If that isn't the issue, then your fuel pump getting weak with temp could be.

Adjusting high to accommodate low isn't a good idea. You can overpower your needle/seat in the "high" mode by doing that.

 

I thought I read somewhere Holley's can handle 8 psi? I'm not sure how to find out if it is the gauge vs temp? I mean the car still ran really well.

 

http://www.holley.com/data/Products/...199R7923-2.pdf Page 5 "General Information". 7 psi max at idle, 4 psi min at redline.

About the only way to make sure the gage isn't being affected by heat is to use a remote gage.

TBI pumps aren't known for their high performance capabilities, though. But, if it isn't causing any performance issues, you probably don't have a problem.

 

I'd do some more testing before dropping the tank, dropping the tank sucks. You need to pull the rear end, remove the exhaust, then finally get to it. It's a 3 day job to me, because I enjoy sleep and rest (lazy).

I ran a 3 way T at the carb inlet, and ran a line to my vacuum gauge (doubles as a pressure gauge up to ~10psi), and strung that into the car. Just watch it doesn't leak, or you'll be covered in gas FAST. Or tape it to the window. Drive around and watch it for a bit.


Out of curiosity, what did you do to fix the plug fouling?

 

My baseplate was from a different car. It had no idle discharge holes in the secondaries. Causing the front four cylinders to run pig rich and the rear 4 to run really lean, I'm currently borrowing my buddies baseplate off of his car with the discharge holes in the back w/ my idle mixture screws out about 1 turn each. Runs very well right now minus my fuel pressure problem.

Maybe its my gauge location? I have it right at my regulator?