Hard starting cold..... All of a sudden....
 

It's been getting cold here. It's not AWFULLY cold but it's been in the lower mid-20's to 30's at night. Last few times I've gone out to start in the morning, it has had an awful time of it. I've cycled the WTS a couple of times, it'll crank fine and fire but not start. When I stop cranking I can hear the hum of the LP. No codes are being thrown (I know because I've cycled the key on and off three times at least without starting). My fuel filter is relatively new. Eventually, with a little application of the throttle, it will sputter to life in a cloud of smoke, idle rough for a short period of time and then eventually settle down. After that, starts are a cinch.

My truck is about to become my daily driver and this won't do. Not at all.

you may have a problem with the grid heater system, but if that's the case most likley a code will be set

Thats what I would have expected as well. I disconnected my FP gauge line from the IP schrader valve. The gauge hasn't been working for a while (I've had issues with air in the line with the AF fluid). I wondered if there was a leak at that point, perhaps relieving pressure in the system enough, esp now with the cold weather to create this situation. I'll find out tomorrow.
Today when I went to start it, It cranked fine, LP whirred for the requisite 20+ seconds. But no fire. It took a couple cycles and a small application of throttle to get fire. Then it was the same. Several cycles, fire but no start. Puffs of smoke. then finally start, rough idle that subsided quickly.

are you running winter blend in it?

I would suspect thick fuel. Check heater in fuel filter.

Does it sound like its running on three cylinders when it starts? I had an issue with my truck when it had the VP, the overflow valve stuck open and would drain fuel out of the IP, only three cylinders (I'm guessing from the three ports in the bottom of the pump) were firing. Took a lot of cranking and a lot of smoke before it would run on its own.

Filled up about a week ago so the fuel isn't old - it's what every other diesel in the area is running.

Stuck overflow valve??? How do you know?? The VP is not that old (couple years +-)

The symptoms said OFV, and replacing it fixed the problem, so I am assuming it was the culprit. My VP was only a year or so old when that happened.

How much of a job is it to replace? Where is it?


Here's a new wrinkle. I did the two things I wrote about above. Removed the FP line to the diaphragm and plugged in over night.

Was COLD (~20) this morning and the truck fired right off like nobody's business!

Update: Last night I left it unplugged. Got cold again. And the hard-start problem came right back. To me that is leading more to a grid heater problem??

So it stayed unplugged all day. It was cold (low 40's). Went out when I got home, cycled the grid heater and touched it off. It started, a little roughly but quickly settled into its regular idle.

Still thinking grid heater.

Other opinions?

It is simple to ohms check the grid heater and see if it's open. You can also hook up a volt meter to the grid heater connection before you try to start it and see if it's getting voltage.

What are you running for a lift pump? If the lift pump has given up or is running intermittently, I'm not sure a code would be thrown until the VP44 chews itself to pieces.

If you don't already have a low fuel pressure warning light installed, I'd suggest one as some insurance.

You might want to consider checking out your lift pump to verify the VP is getting positive fuel pressure when you turn the key. If it's not, the VP has to pull fuel from the tank when it's not designed to. This could account for the hard starting and chugging that ensues after it finally starts.

Just an idea if the grid heaters and fuel pre-heater are functioning properly.

--Sk

The LP was new about 5 years ago and i hear it run on every bump of the key. But if fuel pressure were the issue why, when the block heater is plugged in would it start right up, as it did this morning from nearly the first kick of the key?

Plug it in. Really good for it. I put mine on a household timer at the receptacle on the wall. Set it to come on for 2 hours before I need it. That's even in -30*C weather. No point wasting electric power. Sounds also like someone has stated - check your grid heater. When you start you should see the voltmeter cycling from about 12v low to 14.5 high while the grid heater cycles. That will tell you if it is working. Also first turn on of the key prior to start you should see the voltmeter really low to indicate the grid heater is drawing current. Then the preheat light should go oiut and see the voltmeter rise.