When installing a new fuel pump, any computer changes needed?

Pokageek

Active Member

Jun 10, 2005

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MA, USA

Dec 2, 2005

#1

• Dec 2, 2005

• #1

155 fp. I am going to re-attempt installing my trick flow heads on Sunday with a new pair of heads that were shipped to me from Summit. Other than the possible bad valve in one of the new heads, could there be any other reason my car was running extremely rough?

If you remember, it was impossible to keep my car running without my foot nearly flooring the gas pedal. It also seemed to be running impossibly rich. I installed new 24# injectors, new fuel pump and Brothers Performance had sent me the wrong MAF. The one they sent me was programmed for 19# injectors.

SO...now that I have the RIGHT MAF, new heads, (checking every cylinder for clearance 1st), is there any other reason y'all can think of that the car might be running so rich that it can't hold an idle or have I checked everything off?? Thanks..

 

WhiteDevil

New Member

Feb 4, 2003

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San Diego

Dec 2, 2005

#2

• Dec 2, 2005

• #2

I dont think a fuel pump would be the problem. Because the FPR still keeps the same pressure and the injectors still fire the same amount of fuel. Are you sure that its not timing related or anything and thats why it wont run? What evidence do you have that its running rich?

 

Black95GTS

Active Member

Jan 8, 2004

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Marlborough, MA

Dec 2, 2005

#3

• Dec 2, 2005

• #3

The fuel pump can be installed and you won't notice a difference. At least I didn't notice a difference when I did mine.

Just make sure to depressurize the fuel system and disconnect the battery. And wear gloves and eye protection because gas will get everywhere.

 

Pokageek

Active Member

Jun 10, 2005

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MA, USA

Dec 2, 2005

#4

• Dec 2, 2005

• #4

Thanks for the reply guys..

"Are you sure that its not timing related or anything and thats why it wont run? What evidence do you have that its running rich?"

The timing was right on the money. No, it was a faulty head I think (bent valve).The plugs were black and wet and I had to floor the car to get it to run basically "dis-engaging" the injectors but that could have been because of a bad valve or wrong MAF I guess?...can't think of anything else.

 

final5-0

Mustang Master

Apr 6, 2003

6,817

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79

DFW Texas

Dec 2, 2005

#5

• Dec 2, 2005

• #5

Your car was running like poop before cause:

your pcm was being told by you to use a transfer curve for 24lb inj

the maf was really caled for 19's

however ......

you were using 24lb inj's

Could things be more possibly hosed up???

When you get all that kind of stuff matched up hardware and tuning wise ........................

I kinda suspect you will be able to make some headway with your tuning efforts.

Grady

 

Pokageek

Active Member

Jun 10, 2005

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MA, USA

Dec 2, 2005

#6

• Dec 2, 2005

• #6

Thanks for the input Grady. I will keep you posted on results!

 

Methodical

15 Year Member

Dec 1, 2003

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Clinton, MD

Dec 3, 2005

#7

• Dec 3, 2005

• #7

Yeah the computer was confused. Better rich than lean I guess. Once everthing is right start datalogging and adjusting the MAF. Adjust either the slopes or flow figures - not both at the same time.

Oh, why a 155 fp and not a 190 or 255? Just curios.

Peace
Al

 

G

Green 94 5.0

Founding Member

Mar 25, 2002

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Ft. Lauderdale, FL

Dec 3, 2005

#8

• Dec 3, 2005

• #8

no changes are necessary at all with a fuel pump swap. however, you do need to change things around with the addition of larger injectors or the MAF, unless they are calibrated to one another.