Fuel Pressure
Thread Starter
Racer
Joined: Jan 2008
Posts: 291
Likes: 15
From: Virginia Beach VA
Fuel Pressure
I'm still running the stock '69 fuel lines to a BG 750. The car runs and feels great. However, my fuel pressure gauge installed just before the carb inlets (after the stock inline fuel filter) stays around 0-2 psi and drops to 0 when rev'd.
Is this normal with the guage installed past the inline fuel filter (with return line) or is my gauge defective? It's also a fairly new ZZ4 & fuel pump with less than 5000 miles...
Last question... That is a fuel return line off of the filter right? I think I read somewhere that its a vapor return line.. but I can't remember.
Thanks
Is this normal with the guage installed past the inline fuel filter (with return line) or is my gauge defective? It's also a fairly new ZZ4 & fuel pump with less than 5000 miles...
Last question... That is a fuel return line off of the filter right? I think I read somewhere that its a vapor return line.. but I can't remember.
Thanks
Drifting
Joined: Aug 2007
Posts: 1,924
Likes: 6
dont sound right to me.
If the gauge is accurate you're always toying with running too lean. ZZ4 pump? is that correct for the engine or is it an upgrade? I'd be curious to know if maybe the wrong rump rod is in there.
But, Mike's answer works too. (and faster)
If the gauge is accurate you're always toying with running too lean. ZZ4 pump? is that correct for the engine or is it an upgrade? I'd be curious to know if maybe the wrong rump rod is in there.
But, Mike's answer works too. (and faster)
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
fuel pressure !
If your running the orginal stock fuel line from a 69.
and you can not pump up to 5 psi, I would bet your gas line is leaking.
Gas leaks are not to be taken lightly, in a plastic car.
I highly recommend you find the problem.
I would cap off the carb and check your fuel pressure.
almost every orginal 69 gas line is a rusted steel line, and leaks.
forget the tape ideals... FIX IT.. 69 VETT
and you can not pump up to 5 psi, I would bet your gas line is leaking.
Gas leaks are not to be taken lightly, in a plastic car.
I highly recommend you find the problem.
I would cap off the carb and check your fuel pressure.
almost every orginal 69 gas line is a rusted steel line, and leaks.
forget the tape ideals... FIX IT.. 69 VETT
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Gimme a break here. People add aftermarket gauges to their cars, then fret over the readings they get- and then try to fix something that's not broken.
A defective gas line will always leak outwards (drips/smell) LONG before it leaks badly enough to suck air in and starve the pump.
Look at the endless string of posts where people spend most of their time staring at either the water temp or oil pressure gauges or both. The car apparently works fine, but they feel the need to stare at the gauge wishing it read something different.
GM put all the gauges in C3s for 'bling', not for necessity. Most of GM products of the era using similar engines had no temp or pressure gauges and somehow miraculously survived.
Adding more gauges now to measure more parameters achieves what?
A fuel pump in bad shape will show up with an engine going flat at max load and max revs. The poster indicates his car runs fine.
A defective gas line will always leak outwards (drips/smell) LONG before it leaks badly enough to suck air in and starve the pump.
Look at the endless string of posts where people spend most of their time staring at either the water temp or oil pressure gauges or both. The car apparently works fine, but they feel the need to stare at the gauge wishing it read something different.
GM put all the gauges in C3s for 'bling', not for necessity. Most of GM products of the era using similar engines had no temp or pressure gauges and somehow miraculously survived.
Adding more gauges now to measure more parameters achieves what?
A fuel pump in bad shape will show up with an engine going flat at max load and max revs. The poster indicates his car runs fine.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
Gimme a break here. People add aftermarket gauges to their cars, then fret over the readings they get- and then try to fix something that's not broken.
A defective gas line will always leak outwards (drips/smell) LONG before it leaks badly enough to suck air in and starve the pump.
Look at the endless string of posts where people spend most of their time staring at either the water temp or oil pressure gauges or both. The car apparently works fine, but they feel the need to stare at the gauge wishing it read something different.
GM put all the gauges in C3s for 'bling', not for necessity. Most of GM products of the era using similar engines had no temp or pressure gauges and somehow miraculously survived.
Adding more gauges now to measure more parameters achieves what?
A fuel pump in bad shape will show up with an engine going flat at max load and max revs. The poster indicates his car runs fine.
A defective gas line will always leak outwards (drips/smell) LONG before it leaks badly enough to suck air in and starve the pump.
Look at the endless string of posts where people spend most of their time staring at either the water temp or oil pressure gauges or both. The car apparently works fine, but they feel the need to stare at the gauge wishing it read something different.
GM put all the gauges in C3s for 'bling', not for necessity. Most of GM products of the era using similar engines had no temp or pressure gauges and somehow miraculously survived.
Adding more gauges now to measure more parameters achieves what?
A fuel pump in bad shape will show up with an engine going flat at max load and max revs. The poster indicates his car runs fine.
If you have a fuel leak, you will smell it pronto. And if it ain't broke, don't fix it. Just my 2 cents. 
Thread Starter
Racer
Joined: Jan 2008
Posts: 291
Likes: 15
From: Virginia Beach VA
I did put the gauge into the engine compartment mostly for looks... hey.. why not... It does look pretty sweet all chromed out on the feed line. Additionally, if I do run into troubles down the road thats an easy functional tool to rule out fuel feed problems.
I do not think I am leaking gas anywhere... but I will double check... the gauge read the way it did from day 1 and the car runs fine so I'm pretty sure from what you guys are saying its a defective gauge...
It just interested me because I didn't know if it was a possibility that the return line is affecting the pressure readings.
69Vette- No fear I have ordered a replacement gauge... Mike... In the mean time I have a black piece of tape over it with white writing that reads "INOP"
Thanks for the help
I do not think I am leaking gas anywhere... but I will double check... the gauge read the way it did from day 1 and the car runs fine so I'm pretty sure from what you guys are saying its a defective gauge...
It just interested me because I didn't know if it was a possibility that the return line is affecting the pressure readings.
69Vette- No fear I have ordered a replacement gauge... Mike... In the mean time I have a black piece of tape over it with white writing that reads "INOP"
Thanks for the help
Last edited by A8skyhawk; Apr 18, 2008 at 06:37 PM.
Advanced
Joined: Sep 2006
Posts: 94
Likes: 0
From: Modesto CA.
if your car runs fine then don't worry.... but i had two of the oem filters plug up in a very short time... i have a new fuel tank, lines, pump... saved the filters and checked them later and they were fine.... i think it has something to do with the blend of fuel in Calif.... Edelbrock has warning about the fuel in one of there carb instruction sheets....
Last edited by jack 69; Apr 19, 2008 at 01:24 AM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Melting Slicks
Joined: Jan 2003
Posts: 2,712
Likes: 31
From: Shreveport LA
LA Events Coordinator
I purchased a dual-feed chrome fuel line with filter and gauge from Summit Racing.
The only problem I have encountered is the gauge reads 5-6lbs then, as the engine warms up, it drops to 2lbs. The engine runs perfectly....Called Summit and they said that as the engine warms up, the guage will show a drop in pressure. Is this true??...I have never heard of that before. I have owned 2 Holley gauges and they never showed a drop in pressure....but just in case, Summit is sending another gauge out Monday and I should get it Wednesday.
Just checked it (engine cold)...shows 5 lbs.....will check it tomorrow.
Has this ever happened to anyone (gauge shows a drop in pressure as the engine warms up...)
The only problem I have encountered is the gauge reads 5-6lbs then, as the engine warms up, it drops to 2lbs. The engine runs perfectly....Called Summit and they said that as the engine warms up, the guage will show a drop in pressure. Is this true??...I have never heard of that before. I have owned 2 Holley gauges and they never showed a drop in pressure....but just in case, Summit is sending another gauge out Monday and I should get it Wednesday.
Just checked it (engine cold)...shows 5 lbs.....will check it tomorrow.Has this ever happened to anyone (gauge shows a drop in pressure as the engine warms up...)
Last edited by vetteguy75; May 9, 2008 at 10:50 PM.
