Fuel Pressure Issues

95_XR7

Registered User
Hooked up quite a few of my modifications, and unfortunately when I prime the pump pressure jumps to 35 and bleeds off to 8-10 within a second or two.

Fuel pressure regulator is brand new Aeromotive A1000-6 and injectors were slightly used 60lbsers from David N. I've checked EVERYTHING. There is no fuel leaks anywhere, and I highly doubt the injectors are hanging open dumpiung that much fuel. But can a fuel pump leak back that much?

The car will start fine, idle for a bit and then start to bog down unless you give it a bit on the throttle. I do have some datalogs showing the 02 sensors just start going lean as soon as it's bogging.

-Corey
 
Does it hold steady pressure while the engine is running? Have you confirmed that the loss of pressure and lean condition are concurrent?

While it is not desirable for pressure to bleed off immediately after the pump shuts off, I would not consider it a problem. Aftermarket FPR's often fail to hold pressure after the pump shuts off. It could also be the pump but only if it was already doing that before you installed the regulator.
 
Thanks for the reply David. It holds steady pressure while it is running at 8-10 psi. Looking at BE the Pw shoots up as the O2s hit lean. Once the o2s show lean the car.starts bogging. If you blip the throttle the o2 goes stoic and the car.recovers.
When you prime the pump it shoots to 35 and then drops to 8-10.

-Corey
Does it hold steady pressure while the engine is running? Have you confirmed that the loss of pressure and lean condition are concurrent?

While it is not desirable for pressure to bleed off immediately after the pump shuts off, I would not consider it a problem. Aftermarket FPR's often fail to hold pressure after the pump shuts off. It could also be the pump but only if it was already doing that before you installed the regulator.
 
Replaced fuel pump. The old pump had a cracked housing and the check ball fell right out. Now, even with the 340 pump, it won't hold an idle longer than twenty seconds.
Has anyone had issues before with -AN lines not sealing correctly? I know most are against it but why not try some gasoline safe thread sealer?
Personally I don't see them leaking. You would expect to see it somewhere. What about an issue with the tune? I trust D.D. but maybe something was missed?:confused:

-Corey
 
Is the regulator an adjustable one? If it is, it looks like it needs to be set up properly. You should be seeing around 31 psi or so at idle.

Fraser
 
You got the regulator for fuel injection right? 8-10 psi is way low for idle. Like Frasier said mid 30s with vacuum hooked up, 40 with vacuum disconnected. You should have aeromotive part number 13101 or 13109 if its an a1000 model. I don't even think an injection model will even adjust that low.
 
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Sounds like you just need to increase the base pressure on the regulator. Start the car and keep increasing pressure until you get 40 psi at idle with vacuum hose disconnected. It's normal for it to spike up some on the initial prime.

David
 
At first I thought it was that. As it turns out, the AN fitting I managed to partially crush was in fact leaking. Replaced it and good to go. Now having a completely different issue. Almost feels like tq converter but.only in drives 1st gear. Manually put it.in drive and it works perfectly.
 
New issues: car is up on jackstands. Start thr car and put it in drive. Slight grinding noise. Reminds me of abs kicking on. Put the car in 1st, runs good. But.if you let the car spin up to 20mph on its own you get a nice abs like shudder. mph instantly goes to 0. I'm thinking its ds, but who knows at this point. I'm exhausted and supposed to be driving back to Carson at midnight so any help is appreciated.
 
Cory, some of your sentences don't always make sense. I'm trying to figure out what you mean exactly.

If you tried to run the car on jack stands, did you turn off traction control?

You can't use thread sealer on AN lines because the threads are not what seals. The seal is in the taper seat, not the threads. Always use anti-seize on the threads and don't over tighten. It doesn't take a lot of torque to seal an AN line.

Is fuel pressure holding steady now? The things you have said really don't make sense. I don't see how a loose fitting could cause fuel pressure to drop to 8-10psi when the engine is running. Did you verify that fuel pressure is now holding steady?

I didn't miss anything in the tune, but it will have to be dialed in via datalogging. Yes, when you do this many mods tuning will be required, there is no "plug in and go" tune that can compensate for the many things that may or may not be impacting your results. As long as you have the mechanical issues handled, the rest will go quick and easy.
 
Cory, some of your sentences don't always make sense. I'm trying to figure out what you mean exactly.

If you tried to run the car on jack stands, did you turn off traction control?

You can't use thread sealer on AN lines because the threads are not what seals. The seal is in the taper seat, not the threads. Always use anti-seize on the threads and don't over tighten. It doesn't take a lot of torque to seal an AN line.

Is fuel pressure holding steady now? The things you have said really don't make sense. I don't see how a loose fitting could cause fuel pressure to drop to 8-10psi when the engine is running. Did you verify that fuel pressure is now holding steady?

I didn't miss anything in the tune, but it will have to be dialed in via datalogging. Yes, when you do this many mods tuning will be required, there is no "plug in and go" tune that can compensate for the many things that may or may not be impacting your results. As long as you have the mechanical issues handled, the rest will go quick and easy.

David, I know alot of them don't always make sense. Two days with no sleep trying to get the car back together will do that to you. I mean hey, it's been a year and a half since I had even sat in it.


That's a good point about the thread sealer, and very little amount of torque to tighten the fittings. The car does indeed hold steady at 40PSI. It doesn't really make sense to me either. Replaced fuel pump and still only 8-10PSI. Now, this was only with priming the car twice as I was getting a little low on fuel in the tank. Fixed the -AN line while I had someone go pick up 5gallons worth. So it MAY have been the fuel pump, and only the fuel pump. Sorry if it doesn't make sense. 4hrs of sleep and heading out to Colorado in a few hours.

I didn't mean to say you had missed it. And I knew everything had to be dialed in by datalogging. Unfortunately, with a few issues that cropped up, and them cutting my leave I'm gonna get all of 1-2hrs to datalog.

As far as the mechanical issue is concerned. I had deju vu when it first happened, but couldn't quite remember the circumstances. On my 94, the ABS sensor would intermittantly stop reading the ring. The reason for it back then was because of a bent, and seized CV joint. The WHOLE halfshaft would wobble. I also seen a post from David N. where one of his halfshafts became unseated. Honestly though, I'm just gonna take the car to Ford and let them fix it.

-Corey
 
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