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Discussion Starter #1
Car won’t start and here’s what I know so far. When I turn the key to run, the pump comes on and stays on. I’m running an Aeromotive A1000 pressure regulator and have a gauge installed on it. The gauge never even moves off zero pounds. Just a bad pressure regulator?
 

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Was the gauge working before? Do you have a filter inline that may be clogged? Sometimes the gauges simply just don't read, especially if they get hot. Will the car start? If so then I'd say the gauge isn't working. Many fuel systems have a port to put a test gauge on, you could check that if you have one.
More info would help if you are not able to start. Carb, EFI? Where is the gauge in the system? Do you have filters and where? Can you smell gas in the carb (assuming it's carbed)?
 

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FFCobra Craftsman
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If you are running a Ford ECU that is the symption of a bad ECU. We need more info on your setup
 

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Discussion Starter #4
I’m running an A9L ECU, It’s not a clogged filter, I can hear fuel running through the pressure regulator and back to the tank. The gauge has worked in the past. I’m running an in tank pump and an inline filter. The fuel line feeds the rails and then the regulator and the gauge is on the regulator. Let me know if you need any other information.
 

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FFCobra Craftsman
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Can you remove the regulator from the rail and temporarily plug the outlet from the rail? That should give you whatever the max pump pressure is on the gauge.
 

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Discussion Starter #6
CraigS, I'm not sure how I could do that. The gauge is on the regulator. From the pump the line goes to the front of the left rail, the rails are joined in the back and the return port on the right rail goes to the regulator and then back to the tank.
 

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Discussion Starter #7
If the regulator is faulty wouldn't that cause the pump to not turn off if the key was set to on? Also, I would think the gauge would show at least a small amount of pressure even if the regulator was completely open.
 

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FFCobra Craftsman
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When my A9L ECU was bad the fuel pump would run aill of the time and motor would not start. I didn't have a fuel pressure gauge so I don't know if I had pressure or not.
 

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FFCobra Craftsman
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Can you get to the return line fitting at the tank to undo and plug the hose?
If the regulator is faulty wouldn't that cause the pump to not turn off if the key was set to on? Also, I would think the gauge would show at least a small amount of pressure even if the regulator was completely open.
It would except that the A9L (as well as most most ecu's) has a 10 second or so pump run programmed in for every start. Remember this is an old ecu from long ago in terms of computer capabilities so not too sophisticated. It gives the 10sec shot and then looks for either oil pressure or crank speed/ignition (I forget which) to assure the engine is spinning. If it sees that, then the pump comes back on.
 

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Discussion Starter #10 (Edited)
I don't have any way of plugging the return line. I was just thinking, I had a different ECU when I stripped down the donor years and years ago. I'm thinking it's stored in a box somewhere in my shop or storage warehouse. I'm going to try to find it and if I swap it out with the A9L that should give me at least something to A/B test with. right? Won't another Mustang ECU not a A9L still work?
 

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Discussion Starter #11
Well, that was easier to find than I thought. The other ECU I have is a DA1, will that swap in place of the A9L at at least start the motor as a test?
 

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A9L is MAF, the DA1 is speed density. If it runs, it's not going to run well.

With the pump running, it should still build fuel pressure. The EEC IV knows nothing about what the fuel pressure is doing. Pull the dipstick and make sure there isn't a lot of gas in the oil. Wondering if a bad EEC is holding the injectors open?
 

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Car won’t start and here’s what I know so far. When I turn the key to run, the pump comes on and stays on. I’m running an Aeromotive A1000 pressure regulator and have a gauge installed on it. The gauge never even moves off zero pounds. Just a bad pressure regulator?
I had my brand new fuel pump that had about 10 minutes time on it fail. It would run and it sounded like it was doing something, but I just disconnected the fuel line at the tank and nothing would flow
 

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Can't believe it's going to take an A9L question to pull me out of the woodwork . . . a "properly working" A9L commands the in-tank fuel pump to run for 3 seconds in the absence of valid Crank Position Sensor input. Then the fuel pump relay will shut off, so as NOT to create the situation you are experiencing. Assuming you are NOT cranking the engine AND the fuel pump continues to run after the ignition is in RUN for 3 seconds, then you likely have a bad A9L (probably bad capacitors, very common problem in an ECU that old). IF you are NOT cranking the engine and the fuel pump continues to run, there is a possibility (although slim) that your fuel pump relay is bad. Pulling the relay only proves that EITHER the relay is actually bad, or the ECU has commanded it on. Not a real precise test. The fuel regulator is designed to bypass excessive fuel above it's set limit by returning fuel to the tank. It sounds like it's doing what it's supposed to do; I suspect your pressure gauge is not monitoring the correct point in the fuel system. I'd take the high road and suggest changing the caps in the ECU first, they are cheap and it's not a terribly hard job. Google for A9L cap replacement. If you don't feel comfortable working on a PC board, find a local ham radio operator; he'll know what to do and probably help you out. I stopped rebuilding A9L's some time ago, but I did a bunch of them for forum members "back in the day". HTH

Videodude
 

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I had those exact symptoms - my MassFlo relay board had burned the 12v line to the coil. Check your under-hood voltage.
 

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That is not condescending at all. It's called "basic troubleshooting". It has been mentioned that you should check your fuel rail pressure. I would make sure there is enough gas in the tank then use a remote pressure gauge to check the fuel rail pressure. If you believe the installed pressure gauge reading, you most probably have a bad fuel pump. But checking with a remote pressure gauge will verify there is a mechanical failure. AutoZone or Checker will let you use their's for free. Once you verify fuel rail pressure and it is holding (no injector problems) then go on to the potential electrical solutions. Good luck.

WEK
 

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I had those exact symptoms - my MassFlo relay board had burned the 12v line to the coil. Check your under-hood voltage.
I had a Mass Flow system fail after 149 miles. The digital/analog converter for the air flow meter would short when it got warm and open the injectors continuously. I went back to an analog meter. If anyone needs a Mass Flow meter, I have a good one.
 

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I had a Mass Flow system fail after 149 miles. The digital/analog converter for the air flow meter would short when it got warm and open the injectors continuously. I went back to an analog meter. If anyone needs a Mass Flow meter, I have a good one.
Tom,I would be interested in the Mass Flow Meter for a spare. Mine is off of a 1991 Mustang so it is getting OLD! Let me know how much and I will get you shipping info. Thanks Dave
 

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Tom,I would be interested in the Mass Flow Meter for a spare. Mine is off of a 1991 Mustang so it is getting OLD! Let me know how much and I will get you shipping info. Thanks Dave
Just to be clear, this is the air flow meter that is sandwiched between the throttle body and the air cleaner, not the intake duct mounted one. Is that what you're using. I also have a billet air cleaner which was cut to fit the meter.
 
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