Posted prior that my 03 f350 5.4 would intermittently stall. Like the key was just turned off. Seemed like it would happen when off the gas and rpms dropped. So far I have checked for any kind of vacuum leak, replaced the iac, replaced the Pcv valve, cleaned the maf and throttle body, new air filter and fuel filter , new cps twice, full syn oil change, checked all fuses and wiring. I'm lost now! Still happening and at any speed. Typically fires right back up ,sometimes takes a couple tries. No cel and no codes.Wish it would just throw 1 to point me in the right direction. Its happening more often now Any thoughts? Crank sensor? Any help apprechiated.

 

Not sure this will help, but three or four years ago I had a problem where when I let off on the gas the engine would die but I could start it right back up. Turned out it was a bum Throttle Position Sensor, but for some reason I'm thinking you don't have a TPS.


Another long shot might be the actual fuel pump. For instance, maybe when you're down to a quarter tank of gas the pump overheats..... Anyway, knowing the fuel pressure when the problem occurs couldn't hurt.

 

I had a problem like this on a 94 dodge and the throttle body needed to be cleaned but you have already done that. I think there was also an issues with my radiator fan relay that cause this issue to on my Dodge.

 

Fuel pump and delivery seem fine. Pressure was in spec when issue first happened a few months ago. I do have a tps but I always thought anything faulty with the tps sensor or connection would throw a code ??????

 

Didn't throw a code for mine. The dealership didn't initially have a clue, and first reflashed the computer hoping that would help. Then they kept it a few days, and ultimately replaced the TPS. Engine has never died since then.


However, I have a manual, and the problem would happen at the same place on a specific route, as I was coasting to a stop, while the vehicle was at an uphill angle. It never happened while the engine was at rpm.

 

I think your fuel pump is on its way out.

 

I once had a truck with similar symptoms, turned out to be a clogged fuel tank vent. Do you notice any sucking sound (aside from your wallet) or puff of pressurized air when you take the gas cap off?

 

Did the tps today. Holy $&@" she's like a f1 off the line now. Throttle responses is unbelievably better. What I did notice was a filthy and loose connection at the crankshaft sensor. Cleaned and greased that sucker up and the truck is running better thisafternoon then it has in a long time. I'm kinda thinking its the crank sensor since the symptoms are as is the key was just turned off. Or so the PCM thinks. Anyways I'll keep my fingers crossed and if it happens again. I'll be replacing the crank sensor. I think ya gotta move the ac comp out of the way to do it so I hope I'm all set now.

 

Update

Well it happened again. Ran sea foam and it seemed to run much better. Now I noticed a decline in gas mileage? And a higher idle at start up? Even a little erratic idle in general. Stalled 2times last night and has been fine today so far. Could it be the egr or dpfe sensor???? Still no cel.

 

Okay my turn. I have a 2001 F250 Superduty 5.4. About a month a go, my truck stalled at a red traffic light. I couldnt get it started, and needed it towed back to my local garage. It was a bad fuel pump. Low and behold, a couple weeks later it died again while waiting for a car to turn in front of me. I was able to drift to the shoulder a restart with no problem. It drove well again for about a week. Last week I was headed out, and it stalled while driving at normal cruising speed. Again I got it started and drove for another couple miles and it stalled yet again. Got it started, then parked for a about an hour and drove back home with no issues. I toook it to the garage and had all 8 coils replaced based on their hesitant recommendation. They had codes that 2 packs were bad and was misfiring.

I drove it for a week and all was good. Ahh, on Saturday morning my truck started to "sputter" then stall. I managed to get it to my garage where error code P1299 and P0451 were present. The owner of the garage took my truck for the weekend in order to get the same thing to happen, but to no avail. So I 'm asking my fellow mechanics, would you help me out on what could be causing this issue?

 

I keep getting a P1299 code, which is a cylinder over heat error. So far I have replaced the sensor, clutch fan and washed out the front of the radiator. Yesterday, I had the same problem and getting the same code...Not sure what my next move is either.

When the engine shuts down, it is actually doing it to protect its self. It is normal to shut down, but why who knows