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Have an odd carb swap question
#21
When I take the vacuum line off the fuel pressure regulator, the PSI jumps from 31-ish to 40PSI.

I tried to drive the truck with the pressure gauge attached, but the hose is so thick that when i close the hood so it won't blow open, the hose gets pinched.
'95 Bronco -- 351W-435-205, D44 SAS, Cromos, Truetrac, E-Locker
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#22
It sounds like one of 2 things. Either the vacume to the regulator is incorect or the high press pump is bad. Try driving it with the vacume line for the press regulator undone and plugged. See how it does.
Broncomatt
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#23
broncomatt Wrote:Try driving it with the vacume line for the press regulator undone and plugged. See how it does

It does relatively the same with the FPR vacuum line disconnected and plugged Confusedcratchhe:
'95 Bronco -- 351W-435-205, D44 SAS, Cromos, Truetrac, E-Locker
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#24
With out a pressure reading it is hard to be sure but it does sound like a fuel pump.
Try and find some way to rig the fuel press guage up to get some driving readings(especaily when it acts up).
Broncomatt
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#25
It is possible that it will make a difference.
With low fuel pressure it is not getting as much in there when the injector opens.
Because obviously more fuel will flow at 40psi as opposed to 30 psi given the same opening size and duration.

I am not sure how to run the fuel pressure gauge either, I have had that exact same problem.

I think that is what the pressure regulator is supposed to do.
At idle you will have good vaccum, so pressure is reduced, at full open throttle you should have little or no vacuum, so pressure goes up.

If it didn't run better, you can still have an issue with it not moving enough fuel, but I still dont really think that is the end all solution.

Actually, Audra may have an extra pump laying around if you wanted to try it out. I know we have removed a couple and went to single pump systems.
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#26
Traveler Wrote:It is possible that it will make a difference.
With low fuel pressure it is not getting as much in there when the injector opens.
Because obviously more fuel will flow at 40psi as opposed to 30 psi given the same opening size and duration.

I am not sure how to run the fuel pressure gauge either, I have had that exact same problem.

I think that is what the pressure regulator is supposed to do.
At idle you will have good vaccum, so pressure is reduced, at full open throttle you should have little or no vacuum, so pressure goes up.

If it didn't run better, you can still have an issue with it not moving enough fuel, but I still dont really think that is the end all solution.

Actually, Audra may have an extra pump laying around if you wanted to try it out. I know we have removed a couple and went to single pump systems.

With the vacuum disconnected, it did seem to have more power but it may just have been me wanting it to have more power--ya know? The difference wasn't enough to be definative.

Now you kinda have me leaning towards that frame-mounted fuel pump, too. If Audra has time to dig one of those pumps up, i'd really appreciate it. I know how busy you both are, however.
'95 Bronco -- 351W-435-205, D44 SAS, Cromos, Truetrac, E-Locker
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#27
Not a problem, I know I have at least one in the garage if not two... I'll try to find it this weekend. I think the one was practically brand new and I have the original running around somewhere too which I had swapped out but it turned out it was fine.
The Trucks
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The Kompany Kool AKKountant
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#28
You two are the bestest! :xyxthumbs:
'95 Bronco -- 351W-435-205, D44 SAS, Cromos, Truetrac, E-Locker
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