Fuel pump wiring/relay/pcm question
10-11-2004, 01:10 PM
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Fuel pump wiring/relay/pcm question When I turn the ignition key on, the pump comes on then cycles off after a few seconds. This is normal from what I'm told. I am using the pcm fuel pump wire to the pump relay.
Now, when I turn the key farther and the starter hits, the pump seems to cycle on and off VERY fast - making the fuel pressure gauge dance back and forth from 0-60 psi. If I don't start steadily applying pressure to the gas pedal, it will not start and eventually flood. But can be started by flooring the gas pedal if it does flood. Once the car is started it runs just fine. And when I kill it, I can immediately crank it again without applying any pressure to the gas pedal. But - if I wait a while, I have to go back to the gas pedal to get it started.
I have a full Aeromotive fuel system - A1000 pump, regulator, rails, etc.
Anyone else have this problem? Should I just wire an ignition power wire to the pump relay instead of the pcm wire - which someone suggested to me?
*Also - I think I've got a fuel slosh problem because when I slow down or back up fast the pump cavitates, but when going down the road it's fine. Would the Aeromotive voltage regulator fix this? Or is it strictly a sump tank issue - I've got the Aeromotive sumped tank that came with the system. This is all on a Fox Mustang btw.
Thanks for any help!!
Now, when I turn the key farther and the starter hits, the pump seems to cycle on and off VERY fast - making the fuel pressure gauge dance back and forth from 0-60 psi. If I don't start steadily applying pressure to the gas pedal, it will not start and eventually flood. But can be started by flooring the gas pedal if it does flood. Once the car is started it runs just fine. And when I kill it, I can immediately crank it again without applying any pressure to the gas pedal. But - if I wait a while, I have to go back to the gas pedal to get it started.
I have a full Aeromotive fuel system - A1000 pump, regulator, rails, etc.
Anyone else have this problem? Should I just wire an ignition power wire to the pump relay instead of the pcm wire - which someone suggested to me?
*Also - I think I've got a fuel slosh problem because when I slow down or back up fast the pump cavitates, but when going down the road it's fine. Would the Aeromotive voltage regulator fix this? Or is it strictly a sump tank issue - I've got the Aeromotive sumped tank that came with the system. This is all on a Fox Mustang btw.
Thanks for any help!!
10-11-2004, 02:03 PM
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Sounds like an injector may be stuck open. When its running is it running rich? You can lift the fuel rail, the injectors will be attached, and turn the key on. The injectors should pulse once leaving a wet area but should not be leaking after the first pulse.
10-12-2004, 11:57 PM
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Talked to Aeromotive about the 'slosh' problem - with their sumped tank - and they said 'if it's two years old or so, it was a bad design - and that is what's causing the problem'. So 'you'll need to buy one of our newer ones'... Wha? No 'send it back and we'll fix OUR OWN BAD DESIGN I've already paid for'?!?! What crap...
10-13-2004, 12:09 AM
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Originally Posted by Lane
Talked to Aeromotive about the 'slosh' problem - with their sumped tank - and they said 'if it's two years old or so, it was a bad design - and that is what's causing the problem'. So 'you'll need to buy one of our newer ones'... Wha? No 'send it back and we'll fix OUR OWN BAD DESIGN I've already paid for'?!?! What crap...
Last edited by onehardmaro; 10-13-2004 at 12:29 AM.
10-13-2004, 12:09 PM
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Originally Posted by onehardmaro
Yeah, you need to bitch more about that. But how are you getting slosh on start-up?
But can't be good for the pump either.
10-13-2004, 09:26 PM
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That sounds to me like a problem with the electrical system. It sounds like as you go into "crank", the system voltage is pulling down so low that everything is resetting.
Try it with a big battery hooked up with jumper cables, or check for a bad connection at one of the battery cables.
Try it with a big battery hooked up with jumper cables, or check for a bad connection at one of the battery cables.
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91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
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91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
Latest numbers: 9.71 ET, 141.42 MPH, 1.40 60' , 610 RWHP Mustang Dyno
www.speartech.com
10-14-2004, 10:39 AM
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Originally Posted by Speartech
That sounds to me like a problem with the electrical system. It sounds like as you go into "crank", the system voltage is pulling down so low that everything is resetting.
Try it with a big battery hooked up with jumper cables, or check for a bad connection at one of the battery cables.
Try it with a big battery hooked up with jumper cables, or check for a bad connection at one of the battery cables.
Thanks!
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10-25-2004, 06:19 PM
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Just out of curiosity... Could it have something to do with me having a return line, but using an '01 computer(single fuel line)?
Everything is wired right - heavy gauge ground, heavy gauge from battery, heavy gauge to pump - and the green fuel pump wire from the computer. Checked all connections and they're fine. The relay is behind the dash - so it's not right by the pump or battery - that's the only other thing I can think of is happening. The power is just having to travel to far?
Everything is wired right - heavy gauge ground, heavy gauge from battery, heavy gauge to pump - and the green fuel pump wire from the computer. Checked all connections and they're fine. The relay is behind the dash - so it's not right by the pump or battery - that's the only other thing I can think of is happening. The power is just having to travel to far?
10-25-2004, 07:47 PM
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Lane,
My relay is on the dash as well and I'm not having any problems. Are you sure that your grounds are good? I had a heck of a time starting the car until I found out that the ground from the block to the frame wasn't good. I fixed it and the car fires right up.
How big is "heavy gauge"? Maybe it's too big and the resistance is so great that the pump isn't getting enough current?!? Speartech gave me a ~14ga wire from the relay to the pump. I have a different pump, so I'm not sure of the current requirements on your Aeromotive.
Just throwing out some ideas...
-Matt
My relay is on the dash as well and I'm not having any problems. Are you sure that your grounds are good? I had a heck of a time starting the car until I found out that the ground from the block to the frame wasn't good. I fixed it and the car fires right up.
How big is "heavy gauge"? Maybe it's too big and the resistance is so great that the pump isn't getting enough current?!? Speartech gave me a ~14ga wire from the relay to the pump. I have a different pump, so I'm not sure of the current requirements on your Aeromotive.
Just throwing out some ideas...
-Matt
