2003 mustang lx 3.8 high fuel pressure when warm. - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 11 Old 06-04-2019, 12:45 PM Thread Starter
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2003 mustang lx 3.8 high fuel pressure when warm.

Hey guys i have had this problem for a while now. As the car warms up it will start running very rich and loads up and tries to die. I have verified that the fuel pressure is going up around 70 psi when this happens. Pressure is tested at the rail and the frps reference voltage matches the pressure. I have replaced almost every sensor except the frps. Any help would be appreciated.

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93 hatch midnight blue 2710lbs 2890 with me
302 flipped stock trw's ,typhoon intake,70mm tb,gt40pheads,crane beehives,bbk lt,x-pipe,1chambers,safc,24lb inj,255 pump,76mm C&L,f-cam,4.30,t-5,king cobra clutch
best 1/4 time: 12.68 best 1/4 mph: 108.18
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post #2 of 11 Old 06-04-2019, 07:48 PM
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attach a scan tool and look at fuel pressure the ecm is seeing


89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #3 of 11 Old 06-13-2019, 12:11 PM Thread Starter
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Pressure in my tuner matches actual pressure at the rail. I replaced the frps with no change. Ive also replaced the fuel pump assembly and driver module.

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93 hatch midnight blue 2710lbs 2890 with me
302 flipped stock trw's ,typhoon intake,70mm tb,gt40pheads,crane beehives,bbk lt,x-pipe,1chambers,safc,24lb inj,255 pump,76mm C&L,f-cam,4.30,t-5,king cobra clutch
best 1/4 time: 12.68 best 1/4 mph: 108.18
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post #4 of 11 Old 06-13-2019, 07:20 PM
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what are the fuel trims, 02 voltages when this happens?

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #5 of 11 Old 06-14-2019, 08:28 AM
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Can you get a adjustable fuel pressure regulator?

https://www.summitracing.com/search/...-size/3-8l-232
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post #6 of 11 Old 06-14-2019, 01:55 PM
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Quote:
Originally Posted by ZEN357 View Post
Can you get a adjustable fuel pressure regulator?

https://www.summitracing.com/search/...-size/3-8l-232
fuel pressure controlled by computer. Adjustable FPR won't do no good. Different animal than "typical" 87-93 fox body stuff.
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post #7 of 11 Old 06-15-2019, 03:05 AM
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70 is a touch on the high side but the base fuel pressure should rise when the engine gets hot so it doesn't vapor lock. This is why you'll see many manufacturers well actually most manufacturers just run a higher base fuel pressure 55-65 psi or so. Back in the day 40 was common.

What your seeing is normal-ish.

However, it should not be going rich unless the ecu does not accurately know the actual base fuel pressure.

Sounds more like a bad FPDM over-volting the pump which should set a fault code.

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post #8 of 11 Old 06-15-2019, 09:46 AM
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poster has not posted any data that would suggest its 'rich'

there was no reason to change any of the parts that were changed.

but that is just spilled milk

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #9 of 11 Old 06-16-2019, 04:21 PM Thread Starter
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The car has shown a rich code a few times. It also blows black smoke oit when it starts loading up. I will check the fuel trims next. As for the parts change i had the fpdm as a back up. The fuel pump Assembly was in bad shape when i replaced the pump with a 255. The car is turbochargeg so i replaced the frps as i have heard that positive pressure can cause the sensor to start reading wierd. But it happens at the same point everytime as it warms up. The car does have a custom tune so i am talking with the tuner to see if something is off in the tune itself as it has done it since the initial tune.

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93 hatch midnight blue 2710lbs 2890 with me
302 flipped stock trw's ,typhoon intake,70mm tb,gt40pheads,crane beehives,bbk lt,x-pipe,1chambers,safc,24lb inj,255 pump,76mm C&L,f-cam,4.30,t-5,king cobra clutch
best 1/4 time: 12.68 best 1/4 mph: 108.18
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post #10 of 11 Old 06-16-2019, 05:31 PM
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turbo charged? tuned?did this after the tune?

WTF?

why only mention this now?

perhaps there are other mods, you are not mentioning...

stock injectors, maf? ecm?

this is a perfect example of how garbage in equals garbage out.


89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #11 of 11 Old 06-17-2019, 07:58 AM
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Quote:
Originally Posted by toddturbo View Post
fuel pressure controlled by computer. Adjustable FPR won't do no good. Different animal than "typical" 87-93 fox body stuff.
Gotcha, didn't realized it was controlled by the computer.
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