I read these forums a lot, some very helpful advice on here. Did some looking and couldn't find the answer to my question..

Short Form:
Plugged in, starts great
Not plugged in, wont start in -10C or colder
Replaced fuse and relay for fuel heater, didn't help

I've got an 2003 3500 with 346,000km on it. Been a weird winter with temperatures changing from -40C to +5C and anywhere in the middle. Averaging around -18C (0 in Fahrenheit? i think).

Truck was running just fine, no issues, for most this winter until a week ago. Went to fire it up (was only -10C, wasn't plugged in) and it just cranked and cranked and cranked but wouldn't fire up. Held it for about 10 full seconds, stopped, let it sit for a minute, tried again, and it fired up after about 8 full seconds. Normally, my truck is 3seconds tops.

After that, if it wasn't plugged in, even in +5C weather, crank times were right up around the 10secs. If it was a cold day, it wouldn't even fire up, just crank for awhile (solid, healthy sounding, no weakness or slowness in it). But if it was plugged in, started right away with no problems at all.

Just using the code display on the dash, its not throwing my any codes. Replaced the fuse and the relay for the fuel heater, still no help. Not sure how to check or locate my grid heater. Truck has original batteries, alternator, and injectors. Not sure if any of those could be causing this?

Thanks for the help! I'll be checking this frequently, so I'll be able to answer questions right away.

 

Check and make sure your fuel isn't gelled to start with. If it's still in liquid phase at those temps I would almost say it's and injector problem. A lot of folks state that they have hard starts on cold days but after truck has run a while they don't have the issue until the truck sits overnight. Kinda holds true for your story as well.....cold, no/hard start. Plugged in (warmer block and internals) starts up.

I would say it's injectors but I'm sure someone else will have more info for you. These folks on here are a wealth of information!!!!! Welcome aboard and fill out your sig so we know what you've got so we can better help you.

 

Thanks for the quick reply! Will fill out sig, but just in case anyone missed it in my first post

2003 quad cab 3500, Laramie, short box, 4x4, 346,000km

Fuel was definitely not gelled and you summed it up pretty good there. Once its started, she runs great during the day, no issues. But when left over-night, the hard/no start will happen again the next morning.

Injectors hey... well that sucks.. heard those are expensive to replace

 

What oil weight are you running right now? When the temperatures get really cold and it sits overnight without being plugged in it can make that oil thicken, not wanting to let the engine turn over as fast as it should to start. This happened to me one day when it got down to -20 F. Your manual will tell you the lighter weight oil you can run in order in the colder temps. Just a thought.

 

Original batteries? If the batteries Load test OK, talk to one of F1's distributors about testing, rebuilding and maybe re-tipping your injectors.

On a 2nd note, too bad F1 couldn't keep their old web site LIVE while building the new one on the side. Not much info there on their sticks.

 

I've got the winter stuff in (that sounds terrible, but I'm pulling a complete blank on weight). Oil shouldn't be the issue, wasn't anywhere near cold enough for it to thicken to that degree. It was doing a hard start in the warm weather, 0C, give or take 5C.

Just had the batteries tested about 3months ago, was given a solid clean health of bill for them. Was getting suspicious of them, lasting 8 years and with winter coming up.

Back to the injectors though. Truck runs great, no smoke, no mis-fire, gives me all the power I ask for when I ask for it without stuttering or anything. Does that make sense with injectors starting to fail?

Could it be as simple as the solenoids went on the grid heater unit?

 

What you are describing sounds like the onset of an injector failure. This issue is very common with the 03 model year when cold starts are concerned. If you plug it in, the engine is warmed and starts fine. I have experienced this with a few of our 03 Dodge CTD company trucks.

Yes! The lack of smoke, no misfire, etc all sound too familiar when the injectors started to lose their recommended tolerance levels and returned too much fuel back to the tank. Have them bench tested or send them to F1 or purchase a new set from a DDP distributor.