Fuel pressure problem

[Vince]

Hi I'm new here fuel pressure slowly creeps up as car is warming up has 03-04 cobra fuel pump and tank - ran this set up for 2 years before the rebuild with no issues. New motor trans super charger kit fuel pressure keeps going up pump failed fuel pressure too high new fuel pump driver module new walbro TI 255lph pumps F10000302 in the cobra hat still have same problem fuel pressure went too high trigger pressure relief vavle in pump list fuel pressure . Help anyone have an ideal why this is happening

 

[I_LIKE_TURTLEZ]

Can't really understand what you wrote but your fuel pressure isn't being regulated.

There's about 10 reasons that might be and with the car being so modified, you probably would know the answer better than anyone.

 

[Vince]

Its the factory return less setup with the 03 04 cobra fuel tank and pump it's regulated by the fuel rail pressure sensor and ecu

Can't really understand what you wrote but your fuel pressure isn't being regulated.

There's about 10 reasons that might be and with the car being so modified, you probably would know the answer better than anyone.

 

[I_LIKE_TURTLEZ]

Its the factory return less setup with the 03 04 cobra fuel tank and pump it's regulated by the fuel rail pressure sensor and ecu

What's the year and trim for the car? I can try and procure a wiring diagram.


-Any hard fault codes currently stored?

-How are you verifying fuel pressure? It needs to be checked at the rail somehow with a mechanical gauge and then cross-referenced with what the PCM thinks it's seeing via data PID.

-Turn the key on, keep the engine off(KOEO). Set a multimeter to DC voltage, with a small needle gently back-probe the fuel rail pressure sensor to find the ground and 5v reference pins, you expect to see 5v. There will also be a signal wire pin that send voltage back to the PCM.

-After verifying you have a 5v reference/ground from the PCM, now back-probe the signal wire, start the car.. you should see fluctuations in the voltage reading as RPM/fuel demand changes. If voltage is not moving, the sensor is assumed faulty.



What you need to find out is if the PCM is getting the necessary data it needs to regulate your fuel pressure, without that control, your fuel pump is going to default strategy to 100% duty-cycle at all times. That would kill a pump pretty quick.

 

[ttocs]

I would probably start simple and replace the filter first. It will also allow you to trace the lines and get eyes on them and make sure there isn't a kink or something somewhere that is/got pinched.

 

[95opal]

I would probably start simple and replace the filter first. It will also allow you to trace the lines and get eyes on them and make sure there isn't a kink or something somewhere that is/got pinched.

Fuel pressure wouldnt elevate if their was a kinked line it would drop.

 

[I_LIKE_TURTLEZ]

Yes a restricted filter/line would cause pressure drop, not increase.

However if it were clogged, the pressure drop could cause the fuel to heat up and vaporize, that would have the PCM commanding the pump duty cycle % up. Assuming he hasn't replaced the filter with the other new parts, I would throw one in since it's cheap and easy.

It sounds redundant but he should still check at the sensor connector to rule it and the PCM drivers out even though the car starts and runs, it's a quarter-century old.
The more likely culprits are a corrupted tune or bad pump assembly but one shouldn't throw darts without gathering some data first. I'm not surprised a new pump driver module didn't fix it.

What's worse is the engine is boosted so now you have overwhelming positive pressure and that doesn't play well with a returnless system to begin with.

A lot of unknown variables when you start playing Legos with different model parts, I suspect a gauge reading the rail will tell the tale, I'd be interested to see the fuel trims as well.

 

[95opal]

Yes a restricted filter/line would cause pressure drop, not increase.

However if it were clogged, the pressure drop could cause the fuel to heat up and vaporize, that would have the PCM commanding the pump duty cycle % up. Assuming he hasn't replaced the filter with the other new parts, I would throw one in since it's cheap and easy.

It sounds redundant but he should still check at the sensor connector to rule it and the PCM drivers out even though the car starts and runs, it's a quarter-century old.
The more likely culprits are a corrupted tune or bad pump assembly but one shouldn't throw darts without gathering some data first. I'm not surprised a new pump driver module didn't fix it.

What's worse is the engine is boosted so now you have overwhelming positive pressure and that doesn't play well with a returnless system to begin with.

A lot of unknown variables when you start playing Legos with different model parts, I suspect a gauge reading the rail will tell the tale, I'd be interested to see the fuel trims as well.

Even then with PCM increasing duty cyclye pressure wouldnt be elevating when the fuel is being vaporized it would drop. Id be more inclined to look at the injectors or as you stated pressure sensor.

 

[I_LIKE_TURTLEZ]

Even then with PCM increasing duty cyclye pressure wouldnt be elevating when the fuel is being vaporized it would drop. Id be more inclined to look at the injectors or as you stated pressure sensor.

Yes sir that was my initial thought too but we don't know what his fuel pressure really is, likely only what some data PID is reporting, for all we know it's actually low across the injectors.
That's why I want him to find out what information is being fed to the magic brain-box, which I assume sends a signal down to his freshly installed pump driver module.

Let's keep in the back of our mind that this issue apparently occurred after the drivetrain R&R, heck of a coincidence. Maybe he smashed or scuffed something..

 

[Vince]

What's the year and trim for the car? I can try and procure a wiring diagram.


-Any hard fault codes currently stored?

-How are you verifying fuel pressure? It needs to be checked at the rail somehow with a mechanical gauge and then cross-referenced with what the PCM thinks it's seeing via data PID.

-Turn the key on, keep the engine off(KOEO). Set a multimeter to DC voltage, with a small needle gently back-probe the fuel rail pressure sensor to find the ground and 5v reference pins, you expect to see 5v. There will also be a signal wire pin that send voltage back to the PCM.

-After verifying you have a 5v reference/ground from the PCM, now back-probe the signal wire, start the car.. you should see fluctuations in the voltage reading as RPM/fuel demand changes. If voltage is not moving, the sensor is assumed faulty.



What you need to find out is if the PCM is getting the necessary data it needs to regulate your fuel pressure, without that control, your fuel pump is going to default strategy to 100% duty-cycle at all times. That would kill a pump pretty quick.

its a99 mustang gt 35 anneiversay limted edition bought it new . it has injector dynamics ID1050-XDS fuel injectors. the fuel pressure gauge i have is connected to the front driver side KB fuel rail . the tuner said the frps and the gauge were reading the same on his laptop. i started the car this moring it fires right up have to tap gas peddle to keep it running a couple of times then it will idle . fuel pressure at 30 psi if you stab the gas pedle a little fuel pressure gose up a little .as i was driving up and down driveway fuel pressure slowy increases to around 50 psi this was about 15 minutes. it seams to stay here around 50 psi. i have taken the car out for 20 minutes got on it hard ran fine got back home notice fuel pressure at 50 psi at idle thats high. it has the 3-3/4" pully on the super charger its only making about 6 or 7 pounds of boost the motor is low compression 8.8 to 1 it made 480 to the wheels at 6000 rpm

 

[Vince]

 

[Vince]

no hard fault codes. the only fault code i got was when i hit the go peddle and traction control was on engine light came on a couple minits later lean code. had tuner turn off traction control

 

[I_LIKE_TURTLEZ]

Now I see.. I had assumed you were having a drivability issue like rough idle, stumbling upon acceleration etc.


You & the tuner got tripped up by the atmospheric pressure reading at the rail(gauge) versus the delta pressure across the injector(s) so you thought something was wrong.

Your car is boosted, simply put you take the rail pressure and subtract the manifold pressure to read your delta, the PCM will command as much or little fuel as it needs to try & maintain that 40psi injector delta, it will require more rail pressure in your case.

As the tank/fuel expand from heat, you would expect to see pressure increase gradually to an extent as the car warms up.



Long story short, there's seemingly nothing wrong with the car, your fuel pump failing before was most likely coincidence.

 

[Vince]

no fuel pressure will keep climbing it killed the frist pump that was in the car before the rebuild and another which we thought was the kenne bell boostapump. fuel pressure went up agian with the new pump. disconnected boostapump and fuel pressure stabilized ran on dyno to test did fine without boostapump but it was to late it shut off iddleing on dyno no fuel pressure returned it and got the walbro 03-04 cobra fuel pump up grade kit installed got car back to tuner no issue fuel pressure good .change out iac to see if it would help idle at startup and drove car to tuner 20 minute ride shut car off fuel pressure was just under 50 psi thought we were done with fuel pressure issues and tuner got in car later that day with laptop out driving and fuel pressure went way up trigger the pressure relief vavle in the walbros no fuel pressure. he tried to start car next day would not start .droped car off to me next day was going to drop tank to check pumps . tryed to start car before i drop tank car fired up. for some reason the relief vavle stuck. something is causeing the fuel pressure to go way up after driving for a wile

 

[I_LIKE_TURTLEZ]

no fuel pressure will keep climbing it killed the frist pump that was in the car before the rebuild and another which we thought was the kenne bell boostapump. fuel pressure went up agian with the new pump. disconnected boostapump and fuel pressure stabilized ran on dyno to test did fine without boostapump but it was to late it shut off iddleing on dyno no fuel pressure returned it and got the walbro 03-04 cobra fuel pump up grade kit installed got car back to tuner no issue fuel pressure good .change out iac to see if it would help idle at startup and drove car to tuner 20 minute ride shut car off fuel pressure was just under 50 psi thought we were done with fuel pressure issues and tuner got in car later that day with laptop out driving and fuel pressure went way up trigger the pressure relief vavle in the walbros no fuel pressure.

Then you need to check the voltage being supplied to the pump, a BAP is supposed to be a switched-source, if it's applying more voltage than needed relative to engine load then it's going to increase heat and run the pressure high.

I could be wrong but I don't think a BAP is typically necessary on a terminator tank/pump setup around this power level. I didn't need one on my Terminator, wasn't running lean yet.


My best guess with the information you've given is the BAP is faulty, you have something wired in wrong.. or it's not necessary at all and causing your issue for whatever reason.

Like I said, just shy of 50psi atmospheric at hot idle is what I would expect to see for rail pressure on your particular setup. I'm not convinced it directly killed the original pump.


Hopefully someone experienced with a 480hp 2v(AKA ticking time bomb) with a Cobra tank return-less setup can chime in, personally I would move to a return-style fuel system & be done with this pressurizing headache.

 

[Vince]

No bap removed it when the second pump fuel pressure went high .the cobra pumps with out the bap had no problem supplying fuel at this hp with the big injectors I got the walbros for the upgrade

 

[I_LIKE_TURTLEZ]

No bap removed it when the second pump fuel pressure went high .the cobra pumps with out the bap had no problem supplying fuel at this hp with the big injectors I got the walbros for the upgrade

You're in luck. I contacted an old car buddy who is a Ford/Mustang nut and he said he's 99% sure the problem is your choice of pump.

Apparently the Walbro is not designed to be controlled by your PCM the way the turbine Ford pumps are, in other words it can't be regulated properly so it wants to flow much higher and you trying to run a returnless system at this power level is not helping.


Change to a Ford pump. Like I said playing Frankenstein is always trouble & you weren't being regulated, talk about rabbit trails here.. sheesh.

 

[Vince]

You're in luck. I contacted an old car buddy who is a Ford/Mustang nut and he said he's 99% sure the problem is your choice of pump.

Apparently the Walbro is not designed to be controlled by your PCM the way the turbine Ford pumps are, in other words it can't be regulated properly so it wants to flow much higher and you trying to run a returnless system at this power level is not helping.


Change to a Ford pump. Like I said playing Frankenstein is always trouble & you weren't being regulated, talk about rabbit trails here.. sheesh.

polmaxracing

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2 New Genuine Walbro TI 255lph GT Supercar fuel pumps upgrade kit for 2003-2004 Ford Mustang Cobra SVT Termi​

2 Walbro F10000302






SKU: F10000302 -2 Categories: 99-04 4V Dohc fuel injectors ,pumps , rails, TI / Walbro fuel pumps

• Description
• Reviews (0)

Description​

2 New Genuine Walbro / TI 255 fuel pumps F10000302 [ improved Ford GT supercar pumps] with installation kits . These pumps are designed to work with Ford returnless fuel systems that require variable voltage pumps . Awesome upgrade for 03-04 Cobra which had 135lph factory pumps
Genuine Walbro / TI pumps made in the USA as you can see the stamps on the pump .

E85 Compatible Manufacturer rated at 250+ lph Silent operation Best pump for electronic returnless Ford installations that require variable voltage fuel pumps

	Improved version of GT Supercar fuel pump. Identical except for the added relief valve and Delphi connector. Genuine USA made Walbro / TI fuel pump Near silent, 250 lph tubine design Ideal for electronic returnless fuel systems Use in return or returnless fuel systems

this is the kit i put in the cobra hat its made for the ford returnless fuel system

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[95opal]

polmaxracing

• 
  
• 
  
• 
  
• 
  

2 New Genuine Walbro TI 255lph GT Supercar fuel pumps upgrade kit for 2003-2004 Ford Mustang Cobra SVT Termi​

2 Walbro F10000302





SKU: F10000302 -2 Categories: 99-04 4V Dohc fuel injectors ,pumps , rails, TI / Walbro fuel pumps

• Description
• Reviews (0)

Description​

2 New Genuine Walbro / TI 255 fuel pumps F10000302 [ improved Ford GT supercar pumps] with installation kits . These pumps are designed to work with Ford returnless fuel systems that require variable voltage pumps . Awesome upgrade for 03-04 Cobra which had 135lph factory pumps
Genuine Walbro / TI pumps made in the USA as you can see the stamps on the pump .

E85 Compatible Manufacturer rated at 250+ lph Silent operation Best pump for electronic returnless Ford installations that require variable voltage fuel pumps

	Improved version of GT Supercar fuel pump. Identical except for the added relief valve and Delphi connector. Genuine USA made Walbro / TI fuel pump Near silent, 250 lph tubine design Ideal for electronic returnless fuel systems Use in return or returnless fuel systems

this is the kit i put in the cobra hat its made for the ford returnless fuel system

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​

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Shouldnt have issues due to those pumps. Did you ever test the FPS?

 

[Vince]

Shouldnt have issues due to those pumps. Did you ever test the FPS?

Put new frps in with the new pumps