Fuel Pump??

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Jan 9, 2006 | 01:05 PM

BIG K

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Pro

Joined: Nov 1999

Posts: 659

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From: Woodland Ca

Fuel Pump??

I am experiencing rough running upon start up (cold), but will keep running. The longer it runs, the less power I can get with lower and lower top speed.
I have used fuel teatment, fuel and air filter replaced.
There is no codes however, the aux fan is always running.

Could this be an intermidtant fuel pump problem?

How do I test?

Any ideas?
Thnaks!

Jan 9, 2006 | 01:22 PM

rick lambert

Le Mans Master

Joined: Oct 2003

Posts: 6,130

Likes: 2

From: seattle WA

Can't say for positive-but I doubt it's an intermittent fuel pump problem. Do you have cats-they maybe clogged-and that's kinda how they act.As for the aux. fan always running-I have no idea.Anyways this will get you to the top.

Does an 89 have a cold start injector? and have you done a leak down test for the injectors?

Last edited by rick lambert; Jan 9, 2006 at 01:24 PM.

Jan 9, 2006 | 02:05 PM

CFI-EFI

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Joined: Sep 2000

Posts: 17,298

Likes: 32

From: The Top of Utah

Quote:

Originally Posted by BIG K

Could this be an intermidtant fuel pump problem?

How do I test?

Any ideas?
Thnaks!

Possibly. Put a pressure gauge on the fuel system and go for a tide. If the pressure drops, you have a fuel delivery problem that needs trouble shooting. If the pressure stays up, move on in the trouble shooting chart.

RACE ON!!!

Jan 9, 2006 | 03:09 PM

skateparkdave

Melting Slicks

Joined: May 2004

Posts: 2,524

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From: Lufkin Texas

St. Jude Donor '05-'06

CTS is something else I would also check. If the ECM thinks the motor is hot when cold it will trim tune accordingly and fans will run. The result is petty much the conditions you describe.

Jan 9, 2006 | 04:56 PM

CFI-EFI

Race Director

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Posts: 17,298

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From: The Top of Utah

Except, when the engine warms up to match the erroneous CTS info, the engine should start running better, not worse.

RACE ON!!!

Jan 9, 2006 | 06:20 PM

skateparkdave

Melting Slicks

Joined: May 2004

Posts: 2,524

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From: Lufkin Texas

St. Jude Donor '05-'06

Quote:

Originally Posted by CFI-EFI

Except, when the engine warms up to match the erroneous CTS info, the engine should start running better, not worse.

RACE ON!!!

Yeah, I thought about that and you have a point, unless the sensor is stuck somewhere in inbetween land or fluctuating. Not saying this is the problem just "something else I would check".

Jan 9, 2006 | 06:21 PM

Rick86

Burning Brakes

Joined: Nov 2000

Posts: 855

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Big K, I have a FP guage. IM me I might be able to help you test your fuel pump some evening this week or this weekend.

Rick

Jan 10, 2006 | 08:57 AM

AGENT 86

Team Owner

Joined: Jan 2003

Posts: 20,254

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From: Summerland B.C. Canada

I agree with checking the cats also. As for the aux fan running, i would fix that before it burns out. The aux fan should be switched on and off by the temp switch in driver side head. The lead may have come off and is making contact with ground , or shorted somewhere between head and relay. Switch could also be bad or someone previous to you may have modified the wiring.
Now if you have your fans mixed up and its the main fan running, then there is a good chance that your car is in limp home mode, thus the poor performance.