fuel pressure? for the racers...

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stroked 340

stroked 340

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This past weekend i had to re-adjust the fuel pressure 3 times,set it at 7 1/2 made a few passes checked it,and it was down at 3 psi,re-adjusted and it was up to 10 psi,re-adjusted again to 7 1/2..what do you think?? fuel pump going bad regulator and pump going bad??...thoughts..i run the holley black pump and larger holley regulator..
 
Replace the regulator, maybe the seats got crap on it or worn out. When you adjusted it to 7.5 psi it should never have gone above that no matter what the pumps doing.
 
That was pretty much what I was getting at, replace the regulator with something other than a holley regulator, I had similar problem when I ran them and everything was great once I ditched the holley regulator(even brand new ones) and went with a little more expensive aeromotive style. I will never run a holley regulator again, pumps are okay though. When I said all holley regulators are junk I was implying that you have a faulty or bad regulator.:thumblef:
 
Aquick408 said:
That was pretty much what I was getting at, replace the regulator with something other than a holley regulator, I had similar problem when I ran them and everything was great once I ditched the holley regulator(even brand new ones) and went with a little more expensive aeromotive style. I will never run a holley regulator again, pumps are okay though. When I said all holley regulators are junk I was implying that you have a faulty or bad regulator.:thumblef:
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Gotcha..:cheers:
 
Are you sure the gauge is reading right? Is it in the engine compartment? A lot of them get wonky when they get hot, especially the liquid filled ones.

Say, it was 7.5, made some passes, it got hot and gauge read 3.5 (but pressure was really still 7.5). Adjusted it upwards (actual pressure 10), hot gauge still reads 7.5.

Later, gauge cools down and reads actual pressure of 10 psi.

Just a theory. Have had/seen many problems with engine compartment fuel pressure gauges in the past. Would suck to replace something expensive and still be showing the same problems.
 
LXguy said:
Are you sure the gauge is reading right? Is it in the engine compartment? A lot of them get wonky when they get hot, especially the liquid filled ones.

Say, it was 7.5, made some passes, it got hot and gauge read 3.5 (but pressure was really still 7.5). Adjusted it upwards (actual pressure 10), hot gauge still reads 7.5.

Later, gauge cools down and reads actual pressure of 10 psi.

Just a theory. Have had/seen many problems with engine compartment fuel pressure gauges in the past. Would suck to replace something expensive and still be showing the same problems.
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The gauge is new(as in just put on last week) i did notice the car was nosing over at the top end like it was going lean,so a Aeromotive regulator is being ordered..
 
CHeck voltage at the pump as well. I had a flattened postive wire that caused a higher level of resistance than normal and mad e the pump act kind of like yours. Replaced the pump with a known good one and it was good. I also am not a fan of Holley regulators.
 
stroked 340 said:
The gauge is new(as in just put on last week) i did notice the car was nosing over at the top end like it was going lean,so a Aeromotive regulator is being ordered..
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Doesn't this make it seem *more* likely to be a gauge problem? Put a new gauge in and now you're getting weird pressure readings...

Besides, new or not, lots of them get wonky when they get hot.

Won't hurt to get an Aeromotive regulator either way. Hope it fixes your issue.
 
I would second the use of a gage you can see during the run. Holleys are not premium parts, but they dont usually move around THAT much...lol. But you want to make sure on the top end you have a steady supply of fuel too. A good relay controlling the pump, decent size wiring to it and the power source, etc. Aeromotive is a beter part but you want to make sure the fuel pressure is good at speed. It's like setting the pressures on a nitrous kit... the plaste has to be flowing to get the right reading.
 
stroked 340 said:
,set it at 7 1/2 made a few passes checked it,and it was down at 3 psi,re-adjusted and it was up to 10 psi,re-adjusted again to 7 1/2..what do you think??
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This is another indication of a weakening pump.
 
Thanks for all the replies..looks like i'm changing both just to be safe...
 
Just throwing out ideas here - what about the volume test for the fuel pump? Disconnect the fuel line before the regulator, run it into a bucket for one minute then measure how much is in the bucket. Compare to spec. whatever it may be, guess you'd have to find that. Then at least you'll have narrowed it down. Maybe check to see if the filter is gummed up too?
 
I had this same problem when i ran the Holley red pump and regulator. I was chasing the pressure all over the place. (car ran fine regardless). I did however, have the cheap-*** skummit liquid filled fuel pressure gauge (was the cheapest they had). That might have been the problem all along. Anyhow, i pulled the red pump out and ran a blue pump that delivers 7psi. I dont run the gauge either nor the regulator. I dont race at all, if that helps.

In the end, I wouldnt say Holley regs are **** since I didn't really troubleshoot and confirm that it was the problem. However if I find something comparable, I'd give it a shot instead.

Cooter
 
Liquid filled gauge did the same to me,I finally set regulator to 6lbs cool,and forgot about it.Have checked it several times cool and its allways real close to 6lbs.Warm or hot it goes lower and lower.Bet your pump and regulator are fine.I would change the fast,cheap easiest thing first,to a non liquid filled one .Guzzi Mark
 
I had the bypass valve in one of my Holley pumps I ran in one of my cars stick at times. It turned out it was very fine debri from the tank causing it to stick. I took the pump apart and cleaned an polished the bypass plunger then put a filter before the pump.

The plunger is behind the spring behind the screw driver slot plug.

All cured.

Chuck
 
like mentioned.... pull the 4 screws out and inspect/ clean it . look for tears in the diaphragm .
ive never had a problem with any of the $20 Holley regs or even the generic versions ( i think thats whats on my car now ) . If i did , it was always a small chunk of debris inside it.
 
Cooter said:
I had this same problem when i ran the Holley red pump and regulator. I was chasing the pressure all over the place. (car ran fine regardless). I did however, have the cheap-*** skummit liquid filled fuel pressure gauge (was the cheapest they had). That might have been the problem all along. Anyhow, i pulled the red pump out and ran a blue pump that delivers 7psi. I dont run the gauge either nor the regulator. I dont race at all, if that helps.

In the end, I wouldnt say Holley regs are **** since I didn't really troubleshoot and confirm that it was the problem. However if I find something comparable, I'd give it a shot instead.

Cooter
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Holley red pumps are designed for 7psi and do not typically need to be regulated, where the blue pumps are 12 psi and need to be regulated before you catch fire under the hood.:cheers:
 
Slight possibility of color-blindness or just bad memory on my part. It was one or the other and well over 10 years ago.

And yes, fire is bad.
 
Update::..well i found another new regulator that i forgot i had,installed it set fuel pressure and watched it slowly fall off..called the Holley tech line he said it was the fuel pump,called Summit and ordered a new one should be here Saturday,in the mean time i removed the fuel filter before the pump and cleaned it,and blew out the line with compressed air all the way up to the regulator,we'll see Saturday if the pump was the culprit..
 
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