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80 PSI of fuel pressure, regulator is good, where to next?

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neat

Member
Joined
Sep 27, 2005
Messages
273
The Buick in my sig started to lean out on the dyno a little in the upper RPM's, so we put a fuel pressure gauge on the car to see if the pressure was dropping. To our suprise, the engine was seeing 80 PSI (!) of fuel pressure at idle, and it drops all the way to about 42 in the upper RPM's at WOT.

I double checked the pressure with another gauge, and sure enough the engine is seeing 80 PSI of fuel pressure at idle. I replaced the regulator this weekend with no change in pressure.

I figure something must be clogging/blocking the return line. Any advice on where to start looking for that? I checked the rubber line beneath the regulator for kinks and didn't find anything.

Anyone got some idea's on where to start looking?
 
Hi,
Walk it back to the tank, and see what can be seen.I guess it is possible that the obstruction you are seeing is in the fuel rail, or that the second regulator you installed is stuck closed, but I doubt it. Pull the return line hose off in the filter area, put a bucket or something under it, see what happens.
 
You may have 2 problems here. One with return and one with feed. Your pump might be hurt from pushing against the 80 psi most of the time. Do as instructed above and check return flow as close to the tank as possible.
 
Fuel pressure regulators almost never go bad. Make sure the hard line(s) that runs down the front of the engine isnt kinked. Check (or replace) the rubber lines at the tank.

Good luck...
 
And the other problem is, at WOT, you should see 1psi increase per pound of boost. So it should be at around 60 psi if you are making 20lbs of boost.
 
I just had this problem with my GN and the issue was something clogging the return line. Took it apart and blew the return line out, no more 80psi fuel pressure and the car runs WAY better - duh. (Thanks Otto!!!:rolleyes: )
 
If blowing the return line out doesn't work, try locating the hard line to rubber line fitting which will come apart.

It necks down in size at that point and can get blocked up or frozen up there.

It's right underneath the power steering pump area and steering shaft area.

Got to go from underneath the car, on ramps is easiest with a good light.

Once you have it separated a coat hanger type rod can be used carefully as a pipe cleaner.

And you can try the air in both directions from there too.
 
Huh??

Blowing, and/or digging crap out of a fuel line, and then blowing it into the tank??:rolleyes:
It could also be the liner has let go, and is adding a restriction.
Replace the lines, B4 you find it on a rollback...
Easy test:
Run a temp return line into a jug, jump the pump lead, and see what the FP is.
Another clue: If you can't turn the FP down at least 5 psi below correct operating psi, then 1, [or more], of the following is likely:
1.Regulator is too small for the pump GPH.
2. The return line is too small, or plugged.
3. The reg is FUBAR.
 
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