fuel pressure?
05-03-2007, 11:53 PM
#1
1st Gear Member
Thread Starter
Join Date: Oct 2006
Location: New Canaan CT
Posts: 94
fuel pressure?
could some one please tell me what the pressure should be in the fuel rails of my 94 gt? i got the car about a month ago and just want to make sure that this part of the car is okay. i did the test today and got 32psi, does that seem about normal?
Also, could someone help explain why this is happening:
for some reason my engine likes premium fuel and with the other lower octanes (regular and super) it will ping. im pretty sure its from premature detonation. it happens in most gears at different RPMs but even more noticeable at lower RPMs and when the engine is under a strain like going up a hill. also (if it helps) i noticed that my spark plugs show the wear of running hot. could this have anything to do with the pinging and possibly could the fuel pressure in the rails have anything to do with the pinging?
Also, could someone help explain why this is happening:
for some reason my engine likes premium fuel and with the other lower octanes (regular and super) it will ping. im pretty sure its from premature detonation. it happens in most gears at different RPMs but even more noticeable at lower RPMs and when the engine is under a strain like going up a hill. also (if it helps) i noticed that my spark plugs show the wear of running hot. could this have anything to do with the pinging and possibly could the fuel pressure in the rails have anything to do with the pinging?
05-04-2007, 12:07 AM
#4
5th Gear Member
Join Date: Jul 2004
Location: Westminster, MD
Posts: 4,343
RE: fuel pressure?
The fuel pressure regulator is vacuum operated. When you remove the vacuum line then it acts like the car is at wot and increase the fuel pressure to the max amount. This way you can adjust your fuel pressure to max amount at wot. 38 at idle is way to high, should be around 32 at idle.
05-04-2007, 12:09 AM
#5
1st Gear Member
Thread Starter
Join Date: Oct 2006
Location: New Canaan CT
Posts: 94
RE: fuel pressure?
i did do a timing test and it did not seem advanced. if anything it advanced 1/4-1/2 a inch when it was reved up. wouldent it move a lot more than that? Also, i did it with my dad who has rebuilt a few cars (69 GTO and a 31 Model A) and when he saw it he said it did not seem advanced that much. how much should i expect the engine to advance when i am doing a timing test?
so what could be causing me to have a lower fuel pressure? (32 instead of 38-41) old fuel pump, lines not that clean? it is a 94
so what could be causing me to have a lower fuel pressure? (32 instead of 38-41) old fuel pump, lines not that clean? it is a 94
05-04-2007, 12:11 AM
#6
Banned
Join Date: Dec 2005
Location: Lil' Rhody
Posts: 22,376
RE: fuel pressure?
ORIGINAL: EVO32
i did do a timing test and it did not seem advanced. if anything it advanced 1/4-1/2 a inch when it was reved up. wouldent it move a lot more than that? Also, i did it with my dad who has rebuilt a few cars (69 GTO and a 31 Model A) and when he saw it he said it did not seem advanced that much. how much should i expect the engine to advance when i am doing a timing test?
so what could be causing me to have a lower fuel pressure? (32 instead of 38-41) old fuel pump, lines not that clean? it is a 94
i did do a timing test and it did not seem advanced. if anything it advanced 1/4-1/2 a inch when it was reved up. wouldent it move a lot more than that? Also, i did it with my dad who has rebuilt a few cars (69 GTO and a 31 Model A) and when he saw it he said it did not seem advanced that much. how much should i expect the engine to advance when i am doing a timing test?
so what could be causing me to have a lower fuel pressure? (32 instead of 38-41) old fuel pump, lines not that clean? it is a 94
take your car to a shop that has a clue and tell them you want you car set at 14° btdc
05-04-2007, 12:18 AM
#7
Join Date: Feb 2007
Location:
Posts: 47
RE: fuel pressure?
Not for nothin but isn't the base timing set at 10 degrees on those motors. 14 degrees is the most you want to advance it. Shouldn't you start at base first and make sure everything is kosher and work your way from there. Plus dont forget to pull the spout connector on the harness of the distributor or all your work is worth nothing
05-04-2007, 12:21 AM
#8
Banned
Join Date: Dec 2005
Location: Lil' Rhody
Posts: 22,376
RE: fuel pressure?
ORIGINAL: AngryFloppy
Not for nothin but isn't the base timing set at 10 degrees on those motors. 14 degrees is the most you want to advance it. Shouldn't you start at base first and make sure everything is kosher and work your way from there. Plus dont forget to pull the spout connector on the harness of the distributor or all your work is worth nothing
Not for nothin but isn't the base timing set at 10 degrees on those motors. 14 degrees is the most you want to advance it. Shouldn't you start at base first and make sure everything is kosher and work your way from there. Plus dont forget to pull the spout connector on the harness of the distributor or all your work is worth nothing
05-04-2007, 12:25 AM
#9
Join Date: Feb 2007
Location:
Posts: 47
RE: fuel pressure?
I totally understand that, but he seems to want to get his fuel pressure set good and he is pinging so I figure he should probably start out at base timing and work from there.An old trick is to bring the car to 2000 rpm and slowly start to bring the timing up, when the car starts to break up a little bring the timing back a couple degrees. Usually that will keep things in check.