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Discussion Starter · #1 ·
Ok, got some time to dink with the car tonight. I got the pro m maf and installed it. It ran ok and then about 5 minutes later it started surging and then died. The car was tuned with a 70mm tb, and 76mm maf with 42lb injectors. I installed a 75mm accufab tb and an 80mm pro m maf sensor and housing. Didn't re tune it. I figure that it will need to be tuned to the new setup. I took it out to warm it up and pull codes and it ran terrible so I took it back inside. It was stalling out and not wanting to start back up. I finally put the old tb and maf back on and fired it up. It ran without stalling, but my fuel pressure was bouncing between 15 and 20 at idle. I unplugged the vacuum line on the regulator and it didn't bump up the pressure like it should. I didn't see any fuel coming from the vacuum port. I replaced the fuel filter a couple of days ago also. Could this be a fuel pump issue? I can hear it kick on when I turn on the key.
 

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Well, goes without saying that 15-20 is way too low. I've had a couple strange fuel issues that I wouldn't have been able to solve without troubleshooting. First, my main fuel line from the tank was bending itself and restricting fuel.the bend occured right near the passenger rear wheel, the hard line inside the rubber had developed a kink. Easy replacement. My only other fuel related issue was my in tank sock. After 22 years and untold amounts of gas, it was deteriorated completely. When I was swapping the pump out I played with it a bit, I could get it to pull the fragments over the inlet in a way that it would also restrict flow.

While I'm not saying these are your issues, i am saying it will need some troubleshooting. I didn't have a fuel pressure guage but the car ran like garbage under load. Might give them a look?
 

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After you fix your fuel issue, im thinking that your going to need to get the car retuned with the new maff, but im not positive on that, maybe NX ill chime in on that one.
 

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You have a vac leak then. Most likely causing your surging issue also. Check the pcv (if you still use the pcv system) to make sure it's still working and restricting airflow some when you, for lack of better words, suck air through it. Also, hopefully you didn't lose an intake gasket and you're pulling air from the lifter valley, cuz you're not going to be able to see it. Have you tried spraying carb/brake clean all over while it's running to see if it changes your idle? Also, try capping off all vac lines except the fuel pressure one to see if you have a vac leak down wind of the motor.
 

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Discussion Starter · #5 ·
Why would it have gotten worse after changing back to the original setup? I bumped the fuel pressure up a touch about a week ago. Where all do i spray while checking for leaks? All around the upper and lower intake, then where else?
 

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Discussion Starter · #7 ·
ok, cool. I turned the key over to listen to the fuel pump. It took a few key cycles to register pressure on the regulator gauge. Shouldn't it kick up to pressure on the first turn?
 

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Discussion Starter · #9 ·
it only went up to 25 or so with key on. I read that it's supposed to be higher than that. Does key on, engine off pressure matter a whole lot?
 
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