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Fuel pump won't turn off/red hot manifolds by TylerB11
Started on: 01-15-2004 08:47 PM
Replies: 7
Last post by: JazzMan on 01-15-2004 09:47 PM
TylerB11
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Report this Post01-15-2004 08:47 PM Click Here to See the Profile for TylerB11Click Here to Email TylerB11Send a Private Message to TylerB11Direct Link to This Post
Hey guys,

Just tried to start my 85GT in the bitter cold and went and got gas and came home - the fuel pump kept running after i turned it off, and the exhaust manifolds were glowing red.

There doesn't appear to be a blockage in the exhaust - it is flowing pretty well.

I thought maybe it was red from running rich at startup, so I let it heat up, no difference.

any ideas?

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Report this Post01-15-2004 08:57 PM Click Here to See the Profile for PURPLE REIGNClick Here to Email PURPLE REIGNSend a Private Message to PURPLE REIGNDirect Link to This Post
It has a bad oil pressure sender. The sender controls signal to the fuel pump & when bad will keep the fuel pump running, & possibly leaking fuel into the cylinders flooding it making the manifolds glow. Pull the fuel pump fuse to get it quit temporarily. Get a new oil pressure sender in it. Sits on the engine adjacent to the battery.

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TylerB11
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Report this Post01-15-2004 08:59 PM Click Here to See the Profile for TylerB11Click Here to Email TylerB11Send a Private Message to TylerB11Direct Link to This Post
I was thinking that, but wouldn't the regulator send the excess gas back to the tank?
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Report this Post01-15-2004 09:13 PM Click Here to See the Profile for PURPLE REIGNClick Here to Email PURPLE REIGNSend a Private Message to PURPLE REIGNDirect Link to This Post
Correct..............but it sounds like fuel is leaking either from an injector or the regulator. Unless it has a timing issue when running, but then it would run real bad.
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TylerB11
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Report this Post01-15-2004 09:30 PM Click Here to See the Profile for TylerB11Click Here to Email TylerB11Send a Private Message to TylerB11Direct Link to This Post
where is it located? i heard its down by the AC compressor..
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Report this Post01-15-2004 09:36 PM Click Here to See the Profile for PURPLE REIGNClick Here to Email PURPLE REIGNSend a Private Message to PURPLE REIGNDirect Link to This Post
Above the A/C compressor, like I was saying, right across from the battery. Take the right grill off and look for a large bell shaped plastic sensor sitting atop a line with a 3 pin connector on top.
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Dropzone
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Report this Post01-15-2004 09:38 PM Click Here to See the Profile for DropzoneClick Here to Email DropzoneSend a Private Message to DropzoneDirect Link to This Post
On 2.8, it is next to the EGR solenoid, if I'm not mistaken. Sitting vertically, the body looks to have a hex design to put a cresent wrench onto it. Its a big, beafy looking thing.... Should have 3 wires coming from the top (anyone confirm?) When you go to remove it, but another open-end wrench or cresent onto the fitting that the sender is threaded into. You'll need to keep that oil line from twisting as you try to twist it off....

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-jason
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Report this Post01-15-2004 09:47 PM Click Here to See the Profile for JazzManClick Here to Email JazzManSend a Private Message to JazzManDirect Link to This Post
On V6 cars with A/C the sender is here:

On non-A/C cars the sensor is screwed directly into the block, just above the filter:

Note, this is the '88 sender, it looks slightly different than the previous years but is still in the same location. Do not use a big socket to engage the hex at the top of the sender, that will destroy it. Use the proper size wrench on the fitting next to where it screws into the adapter. Use an adjustable wrench to grip the block that the sender screws into, otherwise you will crack the tube.

To test if the sender is indeed defective, at least as far as the fuel pump circuit goes, just unplug it. If the pump stops, then the sender is bad. The cause of this type of failure is actually a failed fuel pump relay, oddly enough. When the relay fails the parallel circuit in the oil pressure sender will provide power to the fuel pump after a few moments of cranking to get the oil pressure up to trigger level. Since the sender isn't designed to do this duty full time the contacts eventually fail, usually by welding themselves closed.

JazzMan

[This message has been edited by JazzMan (edited 01-15-2004).]

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