4.6L 3v Swap - Return Style Fuel System - doesn't run

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06-14-2021
mastersmith

1 Attachment(s)

4.6L 3v Swap - Return Style Fuel System - doesn't run

Hey guys, new to tuning here so please bear with me haha. I've got an F100 that I have swapped a 4.6L 3V into, from a 2006 mustang. The motor is all stock even using the factory airbox. The only thing I have changed is set it up with a return style mechanical fuel pressure regulator and stripped down the wiring harness. EVAP has also been removed. The issue I am having is that the engine will sometimes fire and run for a second or two, then die. Other times it will not fire at all.
I did get the donor car complete and the motor ran great before removing it from the mustang
As far as the tune, I have disabled PATS, disabled EVAP, turned off the rear O2?s and tried to set the fuel settings for return style. It seems like a fuel issue, so I probably did something wrong here: Aeromotive Fuel pressure regulator is set to 40 PSI.
Desired Voltage set to 15 across the board (I am using the power output from the FPCM only to control the fuel pump relay) - Note: I also tried just powering the fuel pump relay from the ignition, with no change to the starting/running conditions
-Note: fuel pump comes on with key and stays on (never shuts off) ? this should shut off after a few seconds right?
P, I, D, all set to zero
Should I turn off adaptive voltage?
Should I set it to fixed duty cycle?

It seems like its getting way too much fuel. I have attached a log of trying to start the truck. Just trying to figure out if this is a tune issue, or a wiring issue....
Attachment 110771
06-14-2021
mastersmith

1 Attachment(s)

Attachment 110772

Here is my tune as well
06-15-2021
B E N

What your describing sounds like a mass air meter issue. Is it using the stock MAF in stock location?
06-15-2021
mastersmith

Yeah MAF and air box/filter are all stock. Unplugging the MAF doesn't change the symptoms....neither does unplugging the FRP, cam sensors, etc... I spent some time tonight with my multimeter, and I have 10 volts in my VREF circuit at the fuel rail pressure sensor. Also found a couple others online with very similar issues, and it turned out to be a bad PCM. Could this be likely? It was running in the donor car two moths ago. Maybe I somehow damaged it?
06-16-2021
B E N

It is possible, but seems unlikely. Verify all of your ground locations are solid and direct to metal with no paint or rust in the way. Also make sure nothing in the harness got pinched or cut.
06-16-2021
mastersmith

I double/tripple checked all of my grounds and sanded all the terminals tonight... no change. I can't find any pinched or damaged areas in the harness. And I can't seem to repeat the 10 volts in the FRP VREF circuit, now it is reading 5.05 volts, as are each of the other VREF circuits. I did try un plugging both cam position sensors at once, and that will make it run for a few more seconds, and fire up more consistently. it also has an audible misfire with both sensors unplugged.
06-18-2021
mastersmith

Any other thoughts on things to test, log etc... I'm running out of ideas haha. I'll play with it some more this weekend, but I think next week I'll send my PCM out to get tested. Anybody ever deal with SIA electronics? Their test/repair process seems pretty reasonable. Send them the PCM, they test it, if it is all good they will charge me $90 and they'll send it back and I can rule that out... If it's bad and unrepairable they only charge for shipping, and if they can repair it the price starts at $169.
06-19-2021
B E N

Its worth a shot.
07-14-2021
mastersmith

So I ended up installing the factory mustang pump in the truck and set it back up as a returnless system. So now the fuel system is back to stock form using the fpdm. and I also tried another PCM, and ran all of my grounds directly to the negative post on the battery. None of these changed the symptoms:banghead:

Has anybody on here successfully swapped a 3v into something else using the stock PCM/Harness? I am at a loss of what to try next. I have come across a couple of other thread on different forums of people with the exact same issues, none of which have been able to get it running. Could there be something in the cluster/BCM/PATS/other modules that the PCM needs to see?

After doing some more research, unplugging both cam sensors puts it into some sort of "failure" mode and will then fire the injectors and spark on both cycles, thus why it will run for a couple seconds but has a bit of a misfire. Also to note, with the cam sensors unplugged, I can press the gas pedal and get a response (engine revs like it should). It still shuts off after about three seconds though.

with the cam sensors plugged in, it will only run for about a half second, and has no response to the throttle pedal.
07-14-2021
decipha

Ive done several thousand of them never an issue

logging would show you exactly whats going on

sounds like you have a custom maf and dont even know it
07-14-2021
mastersmith

2 Attachment(s)

would you mind taking a look and see if anything stands out?
Attachment 111659 Attachment 111660
The tuning/logging is new to me so if there are other things I should be logging, please let me know.

Also, the MAF is the factory Motorcraft MAF.
07-15-2021
decipha

I dont use hp but it should be obvious. Look at the maf counts and see what you have.

Is it in the factory maf housing ?
10-04-2021
Dman64

Quote:

Originally Posted by decipha

Ive done several thousand of them never an issue

logging would show you exactly whats going on

sounds like you have a custom maf and dont even know it

What do you use? Do you run factory harnesses?
10-04-2021
Dman64

Did you figure it out yet?

D
10-04-2021
Alex5.0

I did a 3V swap into a 67 Mustang , fit the factory fuel pump in the tank, keeped the returnless but on the fuel pump you need to block the syphon that feed the right side in the S197 tank .

one thing I had to deal is if you splice the tps wire signal for a transmission stand alone or anything else , it will fail start and no throttle .
10-05-2021
Dman64

Quote:

Originally Posted by Alex5.0

I did a 3V swap into a 67 Mustang , fit the factory fuel pump in the tank, keeped the returnless but on the fuel pump you need to block the syphon that feed the right side in the S197 tank .

one thing I had to deal is if you splice the tps wire signal for a transmission stand alone or anything else , it will fail start and no throttle .

That raises another question. Could you run a return style set up with an aftermarket pump that is PWM and use the factory adaptive voltage setting? Or would you have to block off the return style line back? I can't see why you couldn't.

D
10-06-2021
Alex5.0

Quote:

Originally Posted by Dman64

That raises another question. Could you run a return style set up with an aftermarket pump that is PWM and use the factory adaptive voltage setting? Or would you have to block off the return style line back? I can't see why you couldn't.

D

Yes I did , you have to find the output on the fpdm that control the pump with the fuel prime , there is 2 or 3 ignition positive on the fpdm , dont remember which. You still have to change the returnless parameter , fpvt , PID ... etc but you dont turn of the switch for the fuel pump. That way you can keep your fuel rail pressure sensor and have a prime Key ON and pump will not run continiously .