random stalling issue

[pat247]

did your truck stall out too? or was it just idling like if it was sucking up air?

It was acting like it was going to stall then the computer would try to compensate by raising the rpm's. Like I said disconnect one side of the PCV, if nothing changes you will know it is a vacuum leak.

 

[Gryphon313]

i did the fuse recolation and the problem is still there. im thinking maybe a bad fuel pump that shorts out or is not sending enought fuel. i have no codes for a bad fuel pump tho

That was my thought with the fuel pump driver module. It’s on the old Fuse 27 circuit and could have been damaged prior to the relocate. I found a video that showed the fuel pump driver losing voltage on the output side to the fuel pump. I replaced mine, but it didn’t fix the stalling issue.

 

[mrbaird2022]

That was my thought with the fuel pump driver module. It’s on the old Fuse 27 circuit and could have been damaged prior to the relocate. I found a video that showed the fuel pump driver losing voltage on the output side to the fuel pump. I replaced mine, but it didn’t fix the stalling issue.

I may be way off on this I had 2016 xlt sport same issue random stall traffic lights and such after warmed up especially..cam phasers tend to cause this to..just a thought f-150 forums have some writeups about it mkcluco auto tech guru done some videos as well...I'm no expert I bought that truck from Alfa Romeo fiat dealership that got shut down for not paying off traded in vehicles so when my appointment came I went they were closed for good called Chrysler capitol told them to come get it I'm done!

 

[Gryphon313]

Update- I went through all the vacuum lines last night checking for leaks. I pulled the check valves and verified that they still worked. I did not discover any obvious leaks. When I created a leak by removing the check valve at the manifold vacuum supply line, the engine idle loped as you would expect.

While I was looking for vacuum leaks, the engine shut off multiple times. As usual, it was as if someone just cut the ignition off. I replaced the throttle body and that made no difference. The engine would idle fine and then just turn off.

I ran a diagnostic test on the long and short term fuel trims on the way into work and nothing seemed unusual. I watched the MAF readings as well. Still doing some research on what those should look like. I was monitoring changes in g/sec as well as hertz. Voltage was at zero the entire time, but I am not sure if this style MAF reads out voltage. I’ll try spraying the MAF with electronics cleaner to see if anything changes.

On the fuel pump side of things, I swapped the fuel pump relay out since it’s the last easy thing before dropping the tank and changing the fuel pump.

I never thought I would be wishing for DTC’s to pop up on my rig, but dang…

 

[FordTechOne]

Update- I went through all the vacuum lines last night checking for leaks. I pulled the check valves and verified that they still worked. I did not discover any obvious leaks. When I created a leak by removing the check valve at the manifold vacuum supply line, the engine idle loped as you would expect.

While I was looking for vacuum leaks, the engine shut off multiple times. As usual, it was as if someone just cut the ignition off. I replaced the throttle body and that made no difference. The engine would idle fine and then just turn off.

I ram a diagnostic test on the fuel long and short term fuel trims on the way into work and nothing seemed unusual. I watched the MAF readings as well. Still doing some research on what those should look like. I was monitoring changes in g/sec as well as hertz. Voltage was at zero the entire time, but I am not sure if this style MAF reads out voltage. I’ll try spraying the MAF with electronics cleaner to see if anything changes.

On the fuel pump side of things, I swapped the fuel pump relay out since it’s the last easy thing before dropping the tank and changing the fuel pump.

I never thought I would be wishing for DTC’s to pop up on my rig, but dang…

It sounds like you may want to get it professionally diagnosed before throwing more parts, especially if they’re aftermarket. I have seen instances where the causal part was replaced with an aftermarket one and the issue was not resolved, leading to further replacement of functional OEM parts with aftermarket ones. That’s not a good path to head down.

 

[pat247]

The shotgun approach is good for the economy though.

 

[Gryphon313]

@FordTechOne. Thanks for stopping in. I agree with your advice. I am trying very hard not to go down the path of tossing parts at it. Some of what I have done is just maintenance items, but the throttle body was definitely a “let’s see if this works” attempt.

 

[Gryphon313]

The shotgun approach is good for the economy though.

More like “whack-a-mole”

 

[Evil Peaches]

That was my thought with the fuel pump driver module. It’s on the old Fuse 27 circuit and could have been damaged prior to the relocate. I found a video that showed the fuel pump driver losing voltage on the output side to the fuel pump. I replaced mine, but it didn’t fix the stalling issue.

Is there any particular way to check for damage to the driver module? or is the best way to check the voltage to/from the pump?

 

[Gryphon313]

The video I watched showed the tech checking voltage going into the FPDM (pin 1) and then going out of the FPDM to the FP (pin 5). It had good input voltage, but as the vehicle continued to idle, the output voltage of the FPDM would steadily drop until the vehicle stalled.