fuel pressure
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feul pressure
i am having some trouble maintaining feul pressure. i believe that an '85 tpi system should maintain pressure after the car is shut off, mine doesn't. I have an adjustable feul pressure regulator. yesterday i put a replacement diaphram in the regulator and today i replaced the feul pump. the problem persists. has anyone had a similar problem and how did they solve it . the car really runs like crap, it won't idle, it pops and snorts and i'm getting very frustrated :mad thanks :cheers:
Le Mans Master
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From: Sachse Texas
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Re: feul pressure (atotalnincompoop)
If it is not holding pressure and you have replaced the regulator and the pump, the only thing left is A) a leak, or B) the injectors are leaking and bad.
You are using a mechanical gauge correct? (Just making sure)
You are using a mechanical gauge correct? (Just making sure)
Drifting
Joined: Aug 2002
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From: Birmingham AL
Re: feul pressure (atotalnincompoop)
Check the resistance of the injectors. Pull the plug off of each injector (lift ears on metal clip and slide off) and make sure each one reads 16-17 Ohms. The original Multec (greenish-grey) injectors are bad about breaking down in resistance over time. I didn't have the leak problem, but the popping and stuff you describe sounds exactly like what my car did with one bad injector. You should be able to get to 6 of them without removing anything. One of mine read like 2.7 ohms. I unpluuged it while the car was running (barely) and everything went to almost normal. hope this helps. :)
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Re: feul pressure (Siveck)
I have a new feul gauge mounted right on my feul rail ( at the shreader valve) as far as my injectors go, i tested all of them and they all have between 16.1 and 16.4 ohms. I have inspected the entire feul system and can find no leaks at all, I"m stumped :confused: I even have new o-rings on all of my injectors. I have 175 lbs. compression in every cylinder on a brand new engine. thanks :cheers:
Le Mans Master
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From: High Plains Drifter Fayetteville, AR
Re: feul pressure (atotalnincompoop)
Might want to take a look at this thread:
http://forums.corvetteforum.com/zero...010258#4010258
Hope that helps.
J :seeya
http://forums.corvetteforum.com/zero...010258#4010258
Hope that helps.
J :seeya
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Re: feul pressure (atotalnincompoop)
i just tried it with pinching off the lines, the pressure still dropped when either line was pinched, obviously I have a leek. I can't smell feul and have inspected the entire system, any suggestions? :cheers:
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From: Johnson Kansas
Re: feul pressure (atotalnincompoop)
The other day someone posted about the same situation. He found out that his fuel line was cracked inside the gas tank above the pump. He had pulled his pump out and set it in a 5 gallon bucket and watched it squirt.
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From: Sun City West Az
Re: feul pressure (atotalnincompoop)
If the pressure is leaking off with both lines pinched off, (I assume your pinching them off at the fuel tank) and your FPR is good,then your injectors are leaking. The OHM test is to see if the solenoids are good ....apparently your's are ok but the injectors still can leak even with good solenoids...I'll bet that's your problem.....cause if the pressure DIDN'T leak, then the problem is before the clamp and in the tank. Hope that makes sense....
[Modified by ittlfly, 6:15 PM 9/18/2002]
[Modified by ittlfly, 6:15 PM 9/18/2002]
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From: Duluth MN
Re: feul pressure (atotalnincompoop)
That was me with the fuel leak inside the tank. I would just inspect the metal line on the sending unit.. Mine was acctually rubbing the inside of the tank on the side closest to the rear of the car... On the sending unit it would be the first bend on the line directly behind the two welded on strips of metal.. You could see where it had rubbed through... I just took the pump off and dried the whole unit with a hair dryer then had it welded (have to be carefull when welding because the metal is thin don't want to melt through it). Then I bent the lines a bit to avoid the rub. My car starts instantly now every time. Also and I almost forgot does the sending unit have a pulse dampener on it that the pump plugs into before the metal line?? if so examine it for a torn diphragm on both side this too could be the problem.. I replaced mine it was 22 dollars.. and changed it with the pump..
[Modified by Ericthewolf, 4:50 PM 9/18/2002]
[Modified by Ericthewolf, 4:50 PM 9/18/2002]
Burning Brakes
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From: Duluth MN
Re: feul pressure (Ericthewolf)
The pinch rule is as follows if you pinch the return line and the leak stops it is your fuel pressure regulator. If you pinch both togethor and it still leaks its your injectors.. If you pinch the feed only and it still leaks it is behind where you pinched it IE pump, pulse dampner, hole in the line in the tank..This last one I added. :jester
Drifting
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From: Latham NY
Re: feul pressure (Ericthewolf)
The pinch rule is as follows if you pinch the return line and the leak stops it is your fuel pressure regulator. If you pinch both togethor and it still leaks its your injectors.. If you pinch the feed only and it still leaks it is behind where you pinched it IE pump, pulse dampner, hole in the line in the tank..This last one I added. :jester
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Re: feul pressure (Bluevette85)
from what I understand it is suposed to hold pressure alt the time, there is the shreader valve mounted on the feul rail to bleed off the pressure for servicing :cheers:
Instructor
Joined: Sep 2002
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From: Waycross Georgia
Re: feul pressure (Ericthewolf)
I heard that you can do somethin to obtain more pressure. As in take the vacume hose off your regulator, plug it, and plug the reg. Is this true. Would it help on My 85 i have Air Foil, Cut Lid, MAF screens removed, Hollowed cat. Fresh motor. Thanks
C4Dreams
C4Dreams
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Re: feul pressure (C4Dreams)
i had read somewhere that you can get about 4 more pounds of pressure doing that, i have an adjustable one. but supposedly your way works. you don't need to go overboard modifying your tpi, unless you have unlimited cash. i have a very basic set-up and it is plenty fast :cheers:
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From: Johnson Kansas
Re: feul pressure (C4Dreams)
You have a vacuum hose running to your fuel pressure regulator. This works to reduce fuel pressure when you have lots of vacuum. When you crack your throttle your vacuum drops and fuel pressure increases. At WOT you have no vacuum so you have max fuel pressure anyway. I don't see it changing things a lot but it would only cost you the cost of a screw to plug the vacuum hose. Just put a piece of electrical tape over the regulator hole Then see how it runs.
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Re: feul pressure (Kendall)
if i would have known what an adjustable regulator kit was, i would have made my own, all that they are is a taller lid with a machine screw in it to adjust the hieght of the diaphram. i must admit i was shocked when i opened the box and saw only that, my first reaction was that there was something missing. if there is a next time, i'll make my own :cheers: