I have had a serious idle problem. Due to recent gas prices, I had swaped out my 30lb injectors for my 24lb injectors and then increased the fuel pressure. When I drove my car it ran ok, but I noticed my car started to have an idle issue. It started to cut out and die. Checked for codes, vacume leaks, IAC....nothing found! I had fuel coming out the vacume line off my fuel pressure regulator and my fuel pressure was 100 when checked the fuel pressure. I swapped out the fuel pressure regulator diaphram & I swapped my injectors back to the 30lber's. Start my car and my car still will not idle! I pull the vacume line off the fuel pressure regulator and no fuel is coming out, but the car will idle. I check my fuel pressure and it's reading 100psi! When I connect the vacume line back on to the fuel pressure regulator, the car dies??? I searched for high fuel pressure with our search option and I have found noting on this situation????? HELLP!

 

Key on Engine on = 100 psi fuel pressure

Key on Engine off = 40 psi fuel pressure


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Try an new fuelpressure gauge, then check your fuelpump, and lower the pressure again, over 50PSI is real bad for your stock fuelpump. it will cause damage to the pump, 100PSI really not good.

 

Check for a plugged/pinched fuel return line. 100# is the pump at max pressure, no regulation (check regulator internals).

40# at key off is the check valve pressure, could be anything.

No/low vacuum higher fuel rail pressure, high vacuum lower fuel rail pressure (+/- 5#). 43.5#-38#

 

Well, The BRAND NEW fuel diaphram I got from autozone has a leak that is dumping fuel out the vacume port. I don't even thing the diaphram was on the running car more than 5 minutes total! I would not doubt that was the problem all along!

 

Changing to the 24#'s and raising the fuel pressure is real close to the 30#'s and lowering fuel pressure. If the blm's are between 108 and 160 (closed loop) there will be no change in the fuel comsumption.

 

 

In theory, I would agree with you. However, when I run my 24's vs my 30's there is a significant difference in gas mpg. I can maybe get 10mgp with the 30's. Granted, I have a lead foot when I drive it When I run the 24's, I get an average of about 16-18mpg....driving it the same. I Just can't wait to get it running again I'm going to check the fuel lines for kinks...which I've found none.

What do you guys think about me using an air hose to purge out any clogs in the fuel lines? Just a thought???

Thanks for the help!!!!!!!!!!!!!

 

Blow the return line back to the tank. Listen for the hiss at the fuel cap (don't smoke).

A word of wisdom either the 30# are too rich (check Afr) or the 24# are too lean (at wot) the first wastes gas and power, the second melts pistons.

 

Also, bad gauge, Don't think stock pump capable of
putting out 100psi let alone the 255s
Played with mine while tuning and think 58# was the
peak and thats with a 340M in the tank.
JMHO

Later

 

My fuel pump is a walbro 255lph pump. And ya don't have to worry about me smoking That would be bad...Kaboom!!! My car runs really strong..really strong with the 30's! If I pump my fuel psi up to 52, the 24's do ok, but I notice a huge power difference! I need to get it tuned for the larger injectors!

I just hope my only problem is my fuel pressure diaphram! Thanks for the help!

 

My FMU was not working right. I disconnected it and fuel pressure is where it should be. Thanks for your help