I need help, my car is stranded at work. I'm pretty sure my fuel pressure regulator has died. When you turn the key to 'on' you can hear the fuel pump prime, but the FPR won't hold the pressure. It goes up to 40lbs but drops to 0 with in 5 seconds. If you crank the car the pressure will stay steady but when you stop cranking it, it drops to 0 again.



Its an Aeromotive A1000 and it's got to be less then a year old. Has anyone heard of these things dying all of the sudden? Could it be something else like the fuel pump letting the fuel flow back thought it?

is there fuel in the vacuum line?

not sure, it was about 10pm and pitch black outside so I wouldn't been able to tell anyway. When I go to meet the tow truck guy tomorrow I'll check.



Could it still fail and not have fuel in the vacuum line?

Could be, leaking injector or bad check valve in the fuel pump also. If the pressure stays steady while cranking I'd say you have another problem becides a bad FPR.

yes, but if it does have fuel in the line, its definately bad

I'm starting to think its a sticking fuel injector, we switched out FPR's and it still does the same thing. Now I've just got to go rip my manifolds off and find out which one it is.

i pulled the manifold off and the checked the impeadance on the injectors and they checked out fine. I then proceeded to hook up a 9volt to each one to make sure that they fired, all did. The results of these tests seem to say that the injectors are working properly.



Is there a good way to test the check valve in the fuel pump to make sure that is working properly?

https://www.nopistons.com/forums/pub...#>/biggrin.png I think you've already conducted that test, no? https://www.nopistons.com/forums/pub...#>/biggrin.png

indeed, it would appear so https://www.nopistons.com/forums/pub...IR#>/smile.png



however, i didn't come up with another possablity, the connection between the haltech and the injector clips could be lose and casuing the injector to open. https://www.nopistons.com/forums/pub...1047683664.gif

If it's coming out the injectors your car would be swimming in gas by now.

Its probably the fuel pump itself. Good time to change the filter too.

Nothing is WRONG with your fpr , thats how they are designed to work , mine does the same thing and its a PAXTON of the same design. Those regulators are normally closed , when the pump starts the fuel pressure pushes it open , whatever pressure you get is based on the spring pressure you put on it with the adjustment screw. The vacuum pressure at idle has little or no effect on it especially on rotarys (lower vacuum , mine is -7"Hg), the reference line and diaphragm are for RAISING the fuel pressure when under boost.

You have another problem , if you have fuel pressure then what you need to look for is your spark (there could be two problems which cause the "lack of spark" , bad coil / wire or no ignition pick up signal to the Haltech) it can even be bad plugs , you just have to check over everything, most times its something very simple. https://www.nopistons.com/forums/pub...DIR#>/wink.png

the FPR is susposed to hold pressure after the system is primed and according to the paper work that came with my Aeromotive it should hold pressure for up to 20 minutes once the system is primed. The problem is that my fuel system isn't holding pressure at all.



Its not that the car won't start, it will, but you have to really pump the gas. Once you get the car started it will not idle unless you've got your foot on the gas. I'd imagine this is do to the lack of fuel pressure. The plugs, coils, and CAS are all fine and working properly.

well is the fpr bypassing, or do you have some other leak?

Is the pump stock? Maybe you ruptured the line in the tank? My wouldn't start for a while because the fuel pumps were swelling the lines in the tank.. Once I put in the SS Braided line, all was good.



https://www.nopistons.com/forums/pub...#>/biggrin.png

What type of pump and regulator you have ? . I had an A1000 and it never worked like that , I have friends with them and the areomotive FPR's and none of them hold the pressure in the system. Were you runnin the car hard prior to that problem ? , hate to be the one to say it , but if you were and nothing else was changed it could be your motor (I know , similar **** has happened to me !)

i was sitting in the parking lot messing with my haltech maps when the started acting up.



Right now I'm running a stock FD pump, as soon as I get a day off I'm going to go swap it out for my old TII pump.

Now you're saying something differently ......., once you mess with your maps and you screw them up , you would be fouling plugs , hard starting and having idle problems , pull your plugs and check them .

His plugs did have lots of gas on them since it's running so rich. That's why we thought it could be a stuck injector. We should know more tomorrow afternoon when we try it with the new pump.

OK then , but let us know what happened. Just fwiw , I tried tuning my Haltech for about a year using only a narrow band a/f ratio meter and needless to say I was unsusessfull, one thing I learned though is that the motor is VERY particular with the ratios durind starting and idle , and the plugs foul very easily without an ignition amp. , I kept about four sets of plugs so that I could just swap them out quickly. i Don't think its your pump , once you are getting 30+ psi then its working . Presently my pumps and regulator works exactly like that , after the initial prime the pressure goes back to 0 , when I tumble to start it , it goes back to the preset 39-40 psi.

well, i replaced my fuel pump and its still doing the same thing.



It just seems odd to me that since last year my regulator has alway held pressure, after the prime or after a drive, and come to find out that you guys are saying its not susposed to.



I always make a back up of my working fuel map before I start making changes to it. That night was no different. I wound up leaning the mix out to much at idle and the car wouldn't stay idleing, so I tried to richen it up back to where it was. I never could get it right, so I reloaded the orignal map that I was working from. After that the car wouldn't start back up. I poped the hood and thats when I noticed I had now static fuel pressure.



Now that you guys say that I'm not susposed to be holding pressure, all my maps are based off the fact that I was. Could it be that there was some type of restiction in the line that took a year to work though the system and now that its gone my maps are all f*cked up?

I received my new regulator from summit today. The new one holds pressure like the old one used to before it messed up. The car now starts and runs ok but won't hold idle but I believe I know whats casuing that.



The pitch of the exhaust note has changed though. It has a lower exhaust note now. Any ideas on why the sound of the exhaust note would change?