North American Turbocoupe Organization



fuel pressure flutter
grovelj Offline
Junior Member
#1
I was wondering if it is normal for there to be a lot of flutter in the fuel pressure. I have a gauge hooked up so that I can see it while driving. When the car is idleing it's pretty steady and I get 38 PSI with the vaccum hose disconnected. But at WOT and 15 PSI of boost it flutters between about 45 and 60. Is this normal? And could all this flutter cause some occasional knocking?

Thanks.

Levi
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Pete D Offline
Administrator
#2
At 15 psi you should be seeing 53 psi and it should be fairly stable. There might be a couple psi fluter but if you are seeing a 15 psi flutter, there is a problem. Have you run the fuel system diagnostics?
Pete Dunham


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grovelj Offline
Junior Member
#3
Yeah everything in the fuel system diagnostic was okay except for the high speed test where I saw a lot of flutter. I get a little bit of knock at WOT, I'm thinking it may be related to the fuel pressure problems. Like, when the pressure is low whatever cylander is firing then doesn't get enough fuel. Any suggestion about what I could replace to fix the fuel pressure and the occasional knock that I get at WOT would be greatly appreciated.

Thanks,
Levi

[This message has been edited by grovelj (edited 09-21-2004).]
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Pete D Offline
Administrator
#4
Usually pressure just runs low when the pump can't keep up with the boost. I'm not sure what to say with a flutter. I'm not sure you problem is just pump but my guess is the answer is in the tank. If you still got the stock pump, you ought to consider an upgrade anyhow but I hate to say that without being able to pinpoint the problem. I'm thinking maybe contamination choking off the filter screen in the tank.
Pete Dunham


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grovelj Offline
Junior Member
#5
Thanks for the input Pete. It will probably be a while before I replace the pump since the car still runs pretty well. I'll be sure to post a follow up when I do take care of it though.

Levi
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mh23turbocoupe Offline
Junior Member
#6
I encountered the same problem with mine and a auto meter mechanical gauge pipointed the problem to the pulse dampner and replaced it with another I had layin around and it still did it parked the car for half the summer while riding my street bike to and from work got back in the car and guess what it doesnt do it anymore lol dont ask!! but anyways had mone on a dyno while it was doing the symptom you are talking about and all was well with the air fuel perfect all the way across the board so I wouldnt worry about it
87 TURBOCOUPE some mods 92 ranger
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