wont start with MAF plugged in
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Supreme Member
Joined: Dec 2000
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From: California
Erg.. I changed the relays, which one is the fuel pump? far right? all three on my firewall look exactly the same... I can't tell the difference. Does it matter? Can't get it to start even with MAF unplugged, Im moving the relays around though.. Help please 
relay is good.. fuse good 
Supreme Member
Joined: Jul 1999
Posts: 5,183
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From: Oakdale, Ca
Car: 89 IrocZ
Engine: L98-ish
Transmission: 700R4
On my '89 the FP relay is different (least the bracket is?) than the MAF power and MAF burnoff relay's.
You could have a bad relay, but ususally when disconnecting the MAF allows the car to start and run better, the MAF is bad.
But, what may be occuring is the burnoff relay is bad (and you now have it where the FP relay goes) and maybe the MAF hadn't been gettingt he burnoff, which shortened it's life.
Just "supposing"
You could have a bad relay, but ususally when disconnecting the MAF allows the car to start and run better, the MAF is bad.
But, what may be occuring is the burnoff relay is bad (and you now have it where the FP relay goes) and maybe the MAF hadn't been gettingt he burnoff, which shortened it's life.
Just "supposing"
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Joined: Jan 2000
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Rezinn,
The MAF power and burnoff relays should be interchangeable, but not likely the fuel pump relay.
Dependins on which car you have, the relay locations vary somewhat. An '86 TA looks like this:
A MAF with no power applied will not provide any signal to the ECM, so the ECM may presume no air flow. The engine should still at least start briefly, however, since the MAF signal is basically ignored at cranking. The ECM should be providing fuel pulses to start the engine regardless of MAF signal. I'm guessign you have no voltage to teh fuel pump. You can verify this by testing voltage at the ALDL connector, terminal 'G'. This terminal is directly connected to the fuel pump power wire. There should be a 12VDC signal at this line for about two seconds when the ignition is first turned on. There should also be 12VDC whenever the auxilliary oil pressure switch is closed.
If there is no voltage to the pump you should check the fuse and the relay. Lacking that, the ECM controls the FP relay.
------------------
Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader
The MAF power and burnoff relays should be interchangeable, but not likely the fuel pump relay.
Dependins on which car you have, the relay locations vary somewhat. An '86 TA looks like this:
A MAF with no power applied will not provide any signal to the ECM, so the ECM may presume no air flow. The engine should still at least start briefly, however, since the MAF signal is basically ignored at cranking. The ECM should be providing fuel pulses to start the engine regardless of MAF signal. I'm guessign you have no voltage to teh fuel pump. You can verify this by testing voltage at the ALDL connector, terminal 'G'. This terminal is directly connected to the fuel pump power wire. There should be a 12VDC signal at this line for about two seconds when the ignition is first turned on. There should also be 12VDC whenever the auxilliary oil pressure switch is closed.
If there is no voltage to the pump you should check the fuse and the relay. Lacking that, the ECM controls the FP relay.
------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
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Joined: Oct 1999
Posts: 735
Likes: 2
From: Portales, NM USA
Car: 86 T/A
Engine: 5.0 TPI
Transmission: 700R4
I'm with Vader on this. Sounds like a fuel problem. The MAF Burnoff and Power relays call for a different part number than the fuel pump relay, however the numbers will cross reference as a substitute so they can all three take the same relay.
Unplugging the MAF should result in using pre-programmed default MAF settings and the car should run if it were a MAF related issue.
Unplugging the MAF should result in using pre-programmed default MAF settings and the car should run if it were a MAF related issue.
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