fuel pressure guage
 

Those that have a fuel pressure gauge under the hood and mech pump.

How do you read it? Mine bounces between 6-9 then when I shut engine down it holds at 8 for a few minutes the slowly goes down to 0. Is that about right? Around 7 or 8 psi I am guessing?

Re: fuel pressure guage
 

Should Be 6.5-8 Tops :)

Re: fuel pressure guage
 

Usually if I bring mine off idle, it smooths out so I can get a reading......at least until it warms up and then reads 0!...POS!

I'm running an Edelbrock 800 AVS and they say (instructions) not to run over 5.5 - 6 lbs at idle.

Re: fuel pressure guage
 

Jim I got an air filled one and does not 0 out when hot but it bounces alot If I take it off idle it bounces like 6.5-8 so I am guessing around 7 psi.

Re: fuel pressure guage
 

Also jim you have a regulator on yours right? How long after you shut down before you start to lose pressure in line, mine is only a short time is that good? does that mean the pressure is bleeding out the vent in gas cap?

Re: fuel pressure guage
 

My holley mechanical fuel regulator with mechanical pump is set at 5.5 - 6.0 and when it starts thats what it reads. But, after driving it a while it comes down to about 4.5 and stays there. So, I guess all I know is that it is between 4.5 and 6.0! I am running a 600 edelbrock though and they don't like high fuel pressures so I guess I'm okay.

Re: fuel pressure guage
 

unless you have an LS1....then it would be in the 40-60 PSI range :D

Re: fuel pressure guage
 

76Bonanza,

Mine holds pressure for a bit too when I shut it down, but not long and I do have a regulator with a return to the tank which would also lend to it bleeding down a little quicker. You must of traded out your liquid filled for the one you got?......almost a "no win" situation. The liquid fill doesn't work right and the other is "jumpy".

Probably the best thing to do (I'm thinkin I might) is put one inside, but if you do it right (using an isolator) it ain't cheap!

Re: fuel pressure guage
 

Or a ramjet :)

Re: fuel pressure guage
 

Almost forgot - fuel pumps naturally move in cycles, so jumpiness on a non-regulated system would be normal, I think. Example: if I just put power to my pump, the needle on my FP gauge will bounce from 48-54psi as the pump cycles (it's pretty rhythmic). Not sure if this could be what you're seeing. I'm new to electric fuel pumps.

Re: fuel pressure guage
 

That is what I was thinking shifty, that it was the rythem of the pump riding on the cam. And bounces faster but closer the higher the rpm.

So since it bounces between 6-9 I was guessing my psi would be around 7-8.

which would be good with my pump and holley dp.

Re: fuel pressure guage
 

Jim as a side note I found my liquid gauge had a rubber plug in it I drained all the fluid out and reinstalled it, it seems to work the same to me? but no problem when hot. I just am not sure if it will have any bearing on it being acurate or not? The air one I got does not seal good I have to get some teflon tape for it that is what you should use right? Same as plumbers tape?

Re: fuel pressure guage
 

Yes, but only use enough just to cover where threads contact threads. If some of that tape gets into the guage opening it might mess up the reading.

I may have to try draining the liquid out.

Re: fuel pressure guage
 

I hate to drag this up again. Got my air gauge on good. Here is the senerio when truck has been shut down for a while gauge bounces wildly untill warm like 5 minutes of just idling. Then levels out around 6-7 no bouncing. Does it take that long for the lines and tank and all to pressurize then the pump just holds it at that staic pressure?