Kevin! By any chance would you be able to locate the wiring diagram schematics for the 2005-09 Mustang GT fuel pump driver module... I just recently discovered that the original owner replaced the stock fuel pump relay with an aftermarket relay which he then connected to the stock fuel pump driver module/wiring harness... He then ran a 10" gage wire from the aftermarket relay all the way up front connected to the battery which also has a 20 amp fuse connector spliced in... Needless to say, I have no idea what his purpose of replacing the stock fuel pump relay with this aftermarket relay, but my guess is he did this as a cheaper alternative for boosting amperage to the stock fuel pump in order to deliver more fuel to the Saleen supercharger... However, what I don't quite understand is if this was the previous owners purpose, then why didn't he just either purchase a Kenne Bell Boost a Pump or better yet, just did it right the first time by upgrading to the 2007-09 GT500 dual fuel pump kit from Ford Performance, to begin with?

At any rate, before I'll be able to return back to the stock wiring and do any type of fuel pump upgrade, I'll first need to understand the wiring of both the stock fuel pump driver module, wiring harness in the trunk section and fuel pump itself...

Thanks in advance,

-Rocky

I've also attached pics of the stock fuel pump driver module and aftermarket fuel pump relay below...


OEM/stock fuel pump driver module assembly

Aftermarket fuel pump relay spliced into OEM fuel pump wiring harness and connected directly to the battery with a 20 amp fuse connector spliced into a 10" gage wire..

 

Here You Go My Friend!

Is There Any Reference To This Relay Mod in the Saleen Blower Install Instructions??

For What it is Worth I Do Seem To Recall on the Roush Blower Upgrades They Said The 427R Horsepower Levels Were the Edge of the Stock Fuel Pump Set Up. Just an FYI! But I Also Seem To Recall a Fuel Pump TSB Way Back on Early S-197-S For Fuel Starvation.

Kc

 

Thank you, Kevin! To my knowledge, there is no mention about upgrading the fuel pump relay in the Saleen blower instruction manual... But then again, this is more than likely that Saleen assumes their stock/base 4.0" pulley which is included in the kit doesn't require upgrading the fuel system... However, the original owner swapped out the stock blower pulley and upgraded to the smaller 3.4" pulley to increase the boost from stock 5-5.5" psi to 8-8.5" psi.. Soon after I purchased the car, I went ahead and swapped out the 3.4" pulley and upgraded to a larger diameter 3.6" pulley which lowered the boost to approximately 7-7.5" boost out of concern for maxing out the stock fuel pump, but as I mentioned, I just recently discovered that the previous owner replaced the stock fuel pump relay with the aftermarket relay which is spliced directly into the stock fuel pump wiring harness and to the battery with a 20 amp fuse connector spliced into the 10" gage wiring that was also added...

So once again, I have no idea what the previous owner was attempting to accomplish by replacing the stock fuel pump relay with an aftermarket relay...

 

Whatever The Reason That was Added On It Seems Fairly Well Thought Out & Executed!


I Wonder if Paul Has Seen This or Could Shed any Light! @svopaul

Kc

 

What I don't like about the setup is the other end of the wiring is connected directly to the positive battery terminal which has that 20 amp fuse connector spliced in... If in the event that fuse should happen to blow while the car is being driven? Guess what, it shuts down the fuel pump and stops delivering fuel... I already tried pulling the fuse just out of curiosity to find out what would happen and sure enough, it cut off the fuel supply and I had to shut down the engine...

I also wonder if Paul has seen this and could possibly shed any light on this as well... @svopaul

 

Sorry for the delayed response. I have not seen that exact setup; it makes me wonder if the previous owner was chasing a problem where the fuel pump driver was losing or not getting power. That is a generic relay they installed, good that they installed that and a fuse but I suspect an underlying problem that they bypassed rather than diagnosed and fixed. I have had 2 problems with an S197 in regards to fuel pump driver modules, one was a problem that was traced back to the PCM and the other was a problem with the Ford Racing GT500 module setup....the car would intermittently lose fuel pumps and went to 4 Ford Dealerships who all charged him but never fixed it...since it was intermittent they sent him on his way and happily charged him for a "repair" they never actually made. In the end we put the IDS on it and watched the voltage and saw a spike and drop off intermittently....so we started looking into the wiring and when we started playing with the wires in the Ford Racing harness, a power wire came loose. Turns out that it had never even been crimped so the wire was intermittently making contact. This was a fault of Ford Racing's supplier of that component, we correctly crimped it and taped everything back up and here 10 years later it's still fixed.

In this case in order to find out what is going on you would need to undo what they did and connect it as original and see if there is a problem with the pump running and if there is then this was a band aid to fix a problem quickly rather than taking the time to diagnose and fix it correctly.

A TSB from Ford would not have used these parts to fix a problem so that is why my suspicion is that they were trying to fix a problem.

As far as Saleen goes, I don't have any of their instructions at my disposable but while it wouldn't surprise me considering the running joke is that they are held together with zip ties and duct tape (because they have actually used both among other things) but that power wire looks to be of a higher quality than I would expect to find with a Saleen kit and then again, why would they not use a tried product like a boost-a-pump or just use the FRPP GT500 kit which would make the most sense. So, looking at the pictures this appears to be a shop or individual trying to fix an issue in my opinion.

 

@svopaul

Paul, thanks for responding back... I totally understand how busy you are with the Mustang Museum Of America, so I totally understand the reasons for the delayed response...
Anyhow, as I mentioned in the previous responses above, the reason the previous owner had a speed shop install that fuel pump relay was to increase voltage to the stock fuel pump in order to deliver more fuel due to having installed a smaller S/C pulley which requires more fuel when increasing boost from the stock 4-5lbs boost to 8-9lbs boost...

Before discovering what the purpose of installing that fuel relay was for, I uninstalled the 3.4" S/C pulley and replaced it with a larger 3.6" pulley which lowered the boost down to 6.5-8lbs...
I also contacted Jim III from JDM engineering who did confirm that by swapping out the 3.4" S/C pulley for the larger 3.6" pulley that I could run to what the limits of the stock fuel pump is able to provide safely without the need for having to upgrade the fuel pump system...

What I do know is before recently discovering the fuel relay device, I didn't even realize what it was to be honest with you and during the entire 11 years of owning this car, I never encountered any fuel related issues...

Unfortunately, I have no clue as to how the fuel system was wired up from the factory before the previous owner had the speed shop in question install the fuel relay, but I most definitely agree that he should have done the fuel system upgrade the right way, the first time by either installing a Kenne Bell Boost-a-pump or installing the GT500 dual fuel pump kit thus leaving the OEM fuel wiring fully intact...

As for the Saleen S/C instruction manuals, I do have them saved on my PC and can post attachment links for you to look over, but keep in mind the instruction manuals are for the Saleen series VI S/C standard upgrade kit with the 3.875" pulley which produces approximately between 5-6lbs of boost at 475HP that doesn't require upgrading the fuel pump system...

In the meantime, let me know what your opinions and thoughts are on this and look forward to your next response... Thanks once again,

-Rocky

https://www.soec.org/manuals/superch...02-C11517L.pdf

https://www.soec.org/manuals/superch...02-C14338C.pdf

 

OK, sorry if I missed that. I reached out to a good friend of mine who is a Ford Master tech just to make sure my thoughts were on the same page as his and we are in agreement. This is really a bad idea to increase voltage, the systems in these cars are different than the earlier return systems with a fuel pressure regulator in that it uses voltage to regulate fuel pressure so there is no fuel pressure regulator and by sending a constant 12 volts or when running over 14 volts to the pump, the fuel pressure is uncontrollable as it is running the pump wide open...so you could see spikes in Fuel pressure up to 125psi. With the way this is set up you have no control over fuel pressure, it's just wide open with voltage to the pump. Fortunately, you never experienced any issues all this time, so I'd consider that a stroke of luck.... but the system just isn't designed to work this way. I would imagine that it was on the rich side with this setup and while you've had no issues, I would think that this could shorten the life span of a pump...especially if run low on fuel regularly where the pump is not submerged in fuel to help cool it which I doubt is the case since it's lasted this long. The bottom line though is that you're not regulating fuel pressure with the way this is wired putting full voltage to the fuel pump. My recommendation if the car demands more fuel is to run the M-9407-GT05 kit, it's plug and play and designed to work as intended with the fuel system design. The lower cost option is the Boost a pump, that at least does still regulate fuel pressure instead of giving it 100% voltage all the time. Also important is that the Boost a pump is a voltage regulator, so it maintains the set pump voltage/fuel delivery and engine lean out in the event you have voltage reduction from an alternator failure or system overload from overcharging. Right now, the way it is wired if you had an alternator failure under WOT, or an overcharging condition you could end up with a catastrophic lean condition at WOT.

 

Ouch!

Great Research! I Know Rocky Drives The Car Sparingly and Has Collector Plates Which Restrict Longer Trips, So I Assume That Has Helped Him get By!

KC

 

@svopaul
Paul, I cannot thank you enough for going through the trouble in reaching out to your good friend who's also a Ford master tech... Needless to say, both you and your friend have confirmed my suspicions and concerns from the very start...

As a matter of fact, I'm actually very surprised that the stock fuel pump has lasted as long as it has now that we know for certain the stock fuel system does not use a return system when compared to previous generations which included fuel pressure regulators... Therefore, I totally agree about being extremely lucky just as you mentioned... Just as I suspected, my doubts were right about the potential of shortening the lifespan of the fuel pump by installing the relay device by the speed shop in question at the request of the previous owner...

What really boils my blood more than anything else, is this speed shop in question should have known full well that the fuel systems in these cars do not have return systems which include fuel pressure regulators as the previous generation cars had, so you would think if this speed shop in question which by the way is Powerhouse411, who is supposedly an S197 Mustang tuning specialist, should have known better and realized that by installing a fuel relay device which sends constant voltage to the fuel pump and running it at wide open with no control of fuel pressure is a disaster just waiting to happen, knowing full well that an S197 Mustang does not use a fuel return system which includes fuel pressure regulators...

Once again, I find myself analyzing back and forth asking the same question over and over again, why in the hell didn't this speed shop do the right thing by either upgrading to the M-9407-GT05 kit or if the previous owner was so concerned over saving a few dollars could have had gone the Kenne Bell Boost-A-Pump route and did it the right way from the very start, to begin with...

Anyhow, as I mentioned earlier ever since I swapped out the previous 3.4" S/C pulley for the larger 3.6" Saleen pulley, the Saleen VI S/C is compatible to be ran at the limits of the stock fuel pump with no modifications necessary to the stock fuel system, but I would however feel a bit more secure by adding the Kenne Bell Boost-A-Pump for additional piece of mind... But as also mentioned earlier in the thread, I have no clue as to how the wiring was set up before they wired up the fuel relay...

Perhaps you could reach out to your friend once again on my behalf to help figure out how to go about putting the fuel system wiring back to OEM stock in order to clean up all this mess which should have never happened from the very start...

In the meantime, thanks once again for reaching out to your friend and helping me understand more clearly on how the stock fuel system operates...

-Rocky





@05stangkc
And thank God, Kevin as we do indeed know the main reason behind the fuel pump for getting by... As you're absolutely 110% spot on!