2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

fuel pump isnt pressurizing?

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Old May 14, 2006 | 08:32 PM
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fuel pump isnt pressurizing?

hello all, i have an 88t2 and did the fuel pmp rewire some months ago, i went replaced 2 brand new pumps cause i thought they were faulty. when i put the key in the ignition and turn it all the way without starting it i can hear it whining but it never stops whining like my old 86 and 88 na's did. i have wentover the wiring several times and i did verything right when i rewired the pump, any suggestions? thanks.
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Old May 15, 2006 | 03:41 AM
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You haven't actually told us what's wrong. How do you know there's no fuel prssure? Is the engine not starting?

The fuel pump only runs if the engine is cranking or running. To check it you need to put a jumper wire in the yellow check connector by the FR strut tower and turn the ignition on. Open the fuel filler and listen for it running.
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Old May 15, 2006 | 10:31 AM
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What made you think the prior pumps were bad?

Got fuel in the tank?
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Old May 15, 2006 | 02:28 PM
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im sorry i dont think i said it right. my car is fine, runs, boosts, all is good, but when you first get in the car and turn the key all the way with out starting it, the fuel pump comes on but never ever stops, usually it should whine for a second and then stop right?
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Old May 15, 2006 | 07:06 PM
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Nothing should happen if you just go to ON. Nothing at all. Zip. Nadda.
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Old May 16, 2006 | 06:56 PM
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all my other rx7's pumps have made a whining sound (which is the pump pressurizing) for about 3 to 5 seconds before starting the car. does no one else have any thing like this go on?
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Old May 17, 2006 | 01:03 AM
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The S4 pump does not run when you just turn the key on. There is no way they can. S5 pumps are controlled by the ECU so they might do that, but S4's can't.
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Old May 17, 2006 | 03:53 AM
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my pump does that, yes they all make a sound, mine doesnt stop either since i installed a new pump
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Old May 19, 2006 | 05:05 AM
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The pump in your S4 does not run when you turn the ignition on unless someone's messed with the wiring or left the jumper wire in the check connector. Go look at the wiring diagram and you'll see that it's physically impossible with unmodified wiring.
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Old May 19, 2006 | 07:09 AM
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It would HELP if some reliable source, say ICEMARK, could tell us if the Series FIVE have the pump run just by putting the key to ON. That would be a nice thing for him to do.

Series four do npt run when the key is put to ON. At least not the Factory installation.
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Old May 19, 2006 | 07:26 AM
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http://s8.photobucket.com/albums/a47...uelControl.jpg
http://s8.photobucket.com/albums/a47...maticTurbo.jpg

If you can understand that...

If I'm following it right (doubtful) then the IG1 position goes to the Engine Fuse (15A) which controls the Fuel Control System. The Fuel Control System picture confuses me. Damn squiggly lines and ****

Last edited by My5ABaby; May 19, 2006 at 07:30 AM.
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Old May 19, 2006 | 04:27 PM
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Those are S5 wiring diagrams, so they're not relevant to this discission. S4 and S5 fuel pump control is different like I said before.
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Old May 19, 2006 | 04:35 PM
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I was responding to Hailers. It's already been stated about 5 times that the S4 fuel pump isn't supposed to be on unless your car is running. Therefore, the discussion is pretty much now about S5 fuel pumps.

However, my bad on not stating that they were S5 diagrams. I meant to quote Hailers in my post which would of made it obvious, but forgot to.
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Old May 19, 2006 | 04:39 PM
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As NZConvertible is trying to say, the S4 fuel pump will NOT run when the key is set to IGN unless someone is messing with the wiring (ie. by jumping the test connector). There is a physical switch inside the AFM that MUST be activated by the engine sucking air for the pump to run.
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Old May 19, 2006 | 04:59 PM
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Originally Posted by My5ABaby
I was responding to Hailers. It's already been stated about 5 times that the S4 fuel pump isn't supposed to be on unless your car is running. Therefore, the discussion is pretty much now about S5 fuel pumps.
The original poster and all the people who clain there pumps run with the key on have S4's. No S5's owners have posted yet so we're still talking about S4's.

The S5 fuel pump wiring diagram shows that it's phyically possible for the S5's pump to run as soon as the key is switched on, if the S5 ECU is programmed to do that. But that doesn't prove that it does. What we want is someone with an S5 to verify if that really does happen, preferably by measuring voltage at the fuel pump. I don't entirely trust other people's ears...
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