Code P1233

[tmcphail]

You mean 4 pumps.

Brian, my understanding is that both pumps are always running, moving fuel in parallel. When one of the relays fail, one pump has to do the work of two and when you need higher fuel flow (under load, high RPM) one pump cannot maintain the pressure so the car probably misfires and loses power.

From looking at the wiring diagram both FPDM are always under power, but there are two different logic lines that tell each FPDM the duty cycle to run on each motor. It wasn't clear to me were the pump ran at the same duty cycle or different ones. TonyG (the man who tuned Joe's TT monster) was the one that told me that both pumps run the same. He also said in Joe's car he had to shoehorn into the tank in 3 pumps instead of 2.

 

[BlackICE]

You mean 4 pumps.

Isn't it nice to be young without a failing memory. :lol

 

[tmcphail]

Isn't it nice to be young without a failing memory. :lol

Ha right. I was on site for all of it so that helps as well. 6 years ago wow. Actually this is about the weekend I lost my mind in that car. The initial dyno work was done on 4-22-06, Joe was kind enough to throw me into the passenger seat for a ride that night and I completely lost my mind and picked up my car on 4-28-06.

 

[GT350H]

I had the same fuel delivery problems twice. It seems the relay problem may rigger more that one code. And the codes may differ if you have a tuner? Not sure just guessing on that.

I would have swapped out the relays before going to the pump. There have been lots of relay problems and very few pump failures. I am not saying your pump wasn't bad but if you incur the problem again go straight for the realys. I am not sure how hard you drive the car but this will only happen on hard pulls above 4000 rpm when the seconadry pump is needed

Here are my posts and if you see the relay contactor point it's easy to see why they seem to go away early. I wish there was a HD relay that would fit in the slot ..

Fuel Pump relays :

Detailed diagnosis post :
http://www.fordgtforum.com/forums/s...ble-Code-P1235&p=255925&viewfull=1#post255925


Photo:
http://www.fordgtforum.com/forums/s...ble-Code-P1235&p=255923&viewfull=1#post255923



Main Thread :

http://www.fordgtforum.com/forums/s...ble-Code-P1235&p=255923&viewfull=1#post255923

Brian,
The first step I did was to replace the relays, which did not fix the problem I was having. In my situation, it appears that the fuel pump was the culprit.

 

[STORMCAT]

Brian, my understanding is that both pumps are always running, moving fuel in parallel. When one of the relays fail, one pump has to do the work of two and when you need higher fuel flow (under load, high RPM) one pump cannot maintain the pressure so the car probably misfires and loses power.

From looking at the wiring diagram both FPDM are always under power, but there are two different logic lines that tell each FPDM the duty cycle to run on each motor. It wasn't clear to me were the pump ran at the same duty cycle or different ones. TonyG (the man who tuned Joe's TT monster) was the one that told me that both pumps run the same. He also said in Joe's car he had to shoehorn into the tank in 3 pumps instead of 2.

Hello Clinton. The tech who looked at my car told me the primary pump runs all the time. The secondary pump only come on when the demand is required. Which made sense to me as far as the relay failing . The primary relay would pull in and stay contacted. If you are in the upper power band and in and out of the throttle the secondar relay would pull in and out and that would cause more where and tear on the relay. Torrie would probaly know... Torrie are you listening ??

 

[STORMCAT]

Brian,
The first step I did was to replace the relays, which did not fix the problem I was having. In my situation, it appears that the fuel pump was the culprit.

Thanks for sharing your issue and cure.. It sounds like I got off easy !!

 

[STORMCAT]

Ha right. I was on site for all of it so that helps as well. 6 years ago wow. Actually this is about the weekend I lost my mind in that car. The initial dyno work was done on 4-22-06, Joe was kind enough to throw me into the passenger seat for a ride that night and I completely lost my mind and picked up my car on 4-28-06.

And now you know the rest of the story !! or and please clarify post 25 please .. :biggrin

 

[BlackICE]

Hello Clinton. The tech who looked at my car told me the primary pump runs all the time. The secondary pump only come on when the demand is required. Which made sense to me as far as the relay failing . The primary relay would pull in and stay contacted. If you are in the upper power band and in and out of the throttle the secondar relay would pull in and out and that would cause more where and tear on the relay. Torrie would probaly know... Torrie are you listening ??

That is why I don't go to a Ford dealer to work on my car. Look at the wiring diagram both relays are always powered as long as the key is on and the inertial switch is not tripped. I studied this before installing the BAP. I never heard my BAP relays turning on or off other than when the ignition is turned on and they are triggered by the regular fuel pump relays. Constantly turning relays on and off is a good way to wear them out.

 

[Wwabbit]

So what happens to the instantaneous mixture when a pump goes intermittent due to poor points? At high power settings (manifold pressures) sudden lean conditions are serious issues in the combustion chamber. Has anybody seen what their exhaust is doing when this happens?

 

[Wwabbit]

...is the ECU and throttle body fast acting enough to manage a sudden drop in fuel flow at high power?

 

[jcthorne]

That is why I don't go to a Ford dealer to work on my car. Look at the wiring diagram both relays are always powered as long as the key is on and the inertial switch is not tripped. I studied this before installing the BAP. I never heard my BAP relays turning on or off other than when the ignition is turned on and they are triggered by the regular fuel pump relays. Constantly turning relays on and off is a good way to wear them out.

You are both right, sort of. The PCM only runs the primary pump normally and low throttle. Look again at the wiring diagram. The PCM controls the GROUND side of the circuit (most transister based controls do). The fuel pump is pulse width modulated output to control fuel pressure in the fuel rail. There is a pressure transducer there to provide feedback. Near 4000 RPM at WOT, the PCM runs out of effective pump capacity on one pump and begins using both. There is no pressure or flow spike, the pressure is still controlled at the fuel rail. Neither pump is at 100% output.

The relays only supply the +12v power and cut off on loss of ignition switch or inertia switch. The speed of the pump is controlled by the PCM. Hope this helps.

 

[Wwabbit]

You are both right, sort of. The PCM only runs the primary pump normally and low throttle. Look again at the wiring diagram. The PCM controls the GROUND side of the circuit (most transister based controls do). The fuel pump is pulse width modulated output to control fuel pressure in the fuel rail. There is a pressure transducer there to provide feedback. Near 4000 RPM at WOT, the PCM runs out of effective pump capacity on one pump and begins using both. There is no pressure or flow spike, the pressure is still controlled at the fuel rail. Neither pump is at 100% output.

The relays only supply the +12v power and cut off on loss of ignition switch or inertia switch. The speed of the pump is controlled by the PCM. Hope this helps.

Now there's a good class in GT fuel systems. Thanks for that. I'm just starting to study it, but the use of a fuel 'buss' is interesting and makes sense. But what about any sudden loss of pump output due to pump drop out for any reason at high manifold pressures? What protects the engine from sudden lean conditions. This occurrence and condition seems pervasive. Please tell us.

 

[STORMCAT]

That is why I don't go to a Ford dealer to work on my car. Look at the wiring diagram both relays are always powered as long as the key is on and the inertial switch is not tripped. I studied this before installing the BAP. I never heard my BAP relays turning on or off other than when the ignition is turned on and they are triggered by the regular fuel pump relays. Constantly turning relays on and off is a good way to wear them out.

I never studied the diagrams.. There are relays in for the turn signals and wipers. The points are like the old distributor points they are a weak link but are designed to cycle in and out. From what jcthorne describes I am not going to bash my dealer tech.. :biggrin

You are both right, sort of. The PCM only runs the primary pump normally and low throttle. Look again at the wiring diagram. The PCM controls the GROUND side of the circuit (most transister based controls do). The fuel pump is pulse width modulated output to control fuel pressure in the fuel rail. There is a pressure transducer there to provide feedback. Near 4000 RPM at WOT, the PCM runs out of effective pump capacity on one pump and begins using both. There is no pressure or flow spike, the pressure is still controlled at the fuel rail. Neither pump is at 100% output.

The relays only supply the +12v power and cut off on loss of ignition switch or inertia switch. The speed of the pump is controlled by the PCM. Hope this helps.

Thank you for the further detail. That's sound closer to what the GT tech described to me. I guess the fuel pump driver modules are an additional controller and control the pumps like a VFD

 

[BlackICE]

I don't know for sure how the pump are driven could be one at a time. I just relayed what Tony G told me and I haven't tested it myself. That would require monitoring either the signal into or preferably output of the FPDM. The ECU has the control wire to run each pump independently. However I wouldn't be suprise if he is right, it saves the designer from using another output line from ECU that isn't needed. The relays are always on and only cycle with the key.

The fuel pump motors driven using pulse width modulation, or PWM. Usually the control signal is a fixed frequency square wave of varying duty cycle used to drive a MOSFET or IGBT which gates a high current load to the pump motors.

 

[Waldo]

Could a bad relay also throw a P0611 code? My GT was throwing an intermittent P0611 code during a dyno session yesterday.

Is there an easy way to check and confirm a bad relay?

Best Regards,
Waldo

 

[tmcphail]

Totally unrelated. As I stated yesterday I believe that was a fluke :

P0611 FUEL INJECTOR CONTROL MODULE PERFORMANCE

Possible causes
- Open or short fuel injector control module circuit
- Fuel injector control module power or ground circuit
- Failed Fuel Injection Control Module (FICM)