I've got 200k on my Lariat. Engine was replaced 60k ago. It's in outstanding shape and is driven a lot. Suddenly this morning I start as usual and it runs about 5 seconds then stalls out. Every start, same thing. So it seems I am getting fuel pressure to start but it doesn't last.

I did replace the Fuel Pump Module within the past two years, due to corrosion of the FPM housing. At that time the truck would no start at all. Could it have gone bad already?

Any ideas? I'm thinking this must be an electronics failure. It was perfect all day yesterday.

 

Is it really cold where you are? Too much moisture in the fuel line can freeze and cause a temporary restriction or blockage in the fuel line.

 

Yes, it's been cold, and as it has warmed a little the truck will idle a little longer. I did re-fuel yesterday morning, then drove 50 miles to work, and 50 miles home, then around town last night. It was not fully cold with this new fuel until this morning.

 

What have you done to determine that to a confidence level of 100% and that it is not something else?

 

absolutely nothing. I said it "seems to" have fuel to start but not to run.

 

Temperature is up to 26 from about 19 when I first started the truck this morning.

I was just out starting and trying to run it and had better results. Since this morning I have started it about 30-40 times with the same result, stall after 5-10 seconds.

Now, I attempted to keep it running with light throttle and it held at 1500 rpm then stalled. After a few more tries I got "engine in safe mode" on the menu.

A few more tries and it has held idle. Now it has been idling for about 5 mins. and seems back to normal.

 

You might want to get some dry gas in the tank just to be safe. Everything you've described makes it sound like a frozen fuel line, but it could be something else related to the cold...time will tell. I figure the dry gas is a pretty cheap and easy solution if moisture is the problem.

 

Thanks. I have added some HEET to the gas. As the day went on it got to a point where I could drive it and it ran fine. Shut it down once doing a few errands and it stumbled a little upon restart but otherwise was fine. After it cooled down I started it and it stumbled for about a minute but kept running then smoothed out the idle. Hopefully as it gets colder tonight it will be ok. Going down to 14 overnight.

 

So it chilled overnight and I have the same issue this morning. 5 seconds of run time then stalls. I won't be home to keep trying it as the day warms. Tomorrow should be warmer and I will be able to get whatever codes are showing. I will also be able to check fuel pressure (hopefully).

 

There's an outside chance the coolant temperature sensor is no good, but it usually doesn't cause such extreme conditions.

 

It sat yesterday and when I got home late in the day (warmer outside) it started and stalled once then started and stumbled for a long time before smoothing out. I drove it 30 miles, parked it and started it a few times while I was out and it started and idled every time. Runs perfect once the idle smoothes out.

 

Drop the spare and pull the FPDM off the frame and look at it. Was the replacement module the newer style with the spacers? I'm suggesting this as a means of eliminating a variable, because I agree with alloro, it does sound like water condensation freezing in the line somewhere. You have to use a HEET at (or even a little above) the recommended dosage to get results.

 

I will take a look at the module. I think I put washers behind it when I mounted it. Either that or it had them built in. I definitely did not mount it flat to the frame.

About moisture in the lines, I'm doubtful about that, unless it is somewhere that would thaw as the engine attempts to run. See, when the outside temperature rises to about 28 it will stumble and stall, but after a few tries, and sometime me applying throttle it will eventually stabilize and idle. From that point on it is mostly ok, but even once warmed it has stumbled a bit upon restart - after sitting for a while.

I definitely think it is affected by temperature, but not sure I can say it is frozen moisture as opposed to an electrical fault. I hate to start throwing electronics on it without knowing. Is there a way to test the FPM? Or any other sensors that could be intermittent?

I have to drive this truck to PA tomorrow so I sure hope I can figure this out.

 

This morning I tried at 34 deg. and it started and stalled twice, now it just cranks, no start. I have a feeling it is the FPM. Planning to replace and see if that does it. Unless there are any other suggestions.

 

You might want to check and see what the fuel pressure is before throwing a new FPM at it. If the PSI is up to par then the FPM is okay and the problem lies elsewhere.