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Author Topic:   fuel pressure
posted March 25, 2002 08:21 PM
at idle the pressure guage was showing 6lbs of fuel pressure, when i'd get out on track and at full throttle the pressure would drop down to 1-3lbs. The motor purrred like a kitten, never hesitated or stumbled so I wasnt backing off figuring if the motor was only getting 1-3 lbs at full throttle it wouldnt run very good. I run a regulator on the return line and we ran the adjuster scr$w all way down and all way up and the fuel guage read 6lbs at idle. Any suggestions on what it could be? The guages are brand new this winter along with the barry grant mechanical fuel pump.

[This message has been edited by 2nd2none (edited March 25, 2002).]

posted March 25, 2002 09:39 PM
You may try taking off the regulator and capping off the return line. We run a mec. pump on ours, and dont run a return line and we have 6# at idle, and about 8 1/2 wide open. We had a similar problem with ours, but ours didnt drop that low.

posted March 25, 2002 09:45 PM
it is possible the filter is blocked, or even a loose fitting that is allowing air to be sucked in (a few of my past experiences with this type of problem).

posted March 25, 2002 10:08 PM
it depends on what kind of regulator you have. Some have an idle jet to set the fuel pressure at idle and others dont. if you have the latter then you need to set the regulated fuel pressure at about 4500 rpm to get close. This is assuming that every thing else is plumbed correctly and yu have a good new fuel pump. Mech. fuel pumps wear out! plain and simple. I go thru one at least one every year. hope that helps.

posted March 26, 2002 12:41 AM
Call Barry Grant, they will be able to tell you what to expect. I ran all BG stuff and none of it was bad. I had a mechanical fuel pump with a bypass that shut the flow off when I was under acceleration and let the bypass flow as I let off the throttle. the tank was just a regular tank and the vent was working. It was a great system and the pump didn't develop very much pressure. but, boy did it work.

posted March 26, 2002 11:34 AM
What dodgeboy said....mechanical pumps use mechanical bypasses not the diagpram style..your mechanical pump does not produce the volume or the pressure that a belt drive other thought is I have had brand new gauges that were bad,..the best thing to do is go to an auto parts store TOOL section and get a good quality hand held oil pressure gauge(usually reads 0-50 lbs) and use that to set fuel pressure and then compare to your car gauge to set a baseline

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