I posted about this problem a few years ago...I still cant seem to find the fix.

Truck always starts on the first crank, Always.
But when its cold in the morning, it will start as normal, but will idle really rough and even stall unless I give it fuel. It will continue to do this until it warms up enough. Usually after a 10 minute drive it will idle smooth enough that Im not worried about it stalling anymore.
This used to happen only in really cold temps (20* or less), but now Im getting hints of it at even 35 degrees....the first stop sign I come to in the morning the engine speed fluctuates a bit for just a few seconds.
There is also a spot on the accelerator pedal where if I hold it there, the engine will run a little rough, just above idle about 1000-1100 RPM. This never used to happen (warm or cold).

I have tested the KSB and it gets the proper voltage and it moves as it should.
Its not bad fuel because I fill up my diesel VW at the same place. I use fuel additive in winter.
I also have an electric filter heater, which seemed to help decrease the warm up time, but did not fix the rough idle at start up.
We have had a few cold mornings already, and I would like to fix this before it leaves me stuck somewhere on a cold winter morning.
Any suggestions would be great, thanks.

 

Try turning the idle up a tad. And check the fuel lines for air leaks.

 

make sure your grid heater is working

 

Thanks for the suggestions.
I dont think it could be air leaks in the fuel line because it ALWAYS starts on the first crank....I would think if I had any air leaks in the fuel system it would first show up as hard to start with longer cranking of the starter. Do you agree? Also, this problem only happens when cold, an air leak would would cause problems all the time.
The amount of fuel I have to give it to keep it running when cold is way above idle. And the idle is set correctly when warm. If I turned up the idle then it would idle way too high after it is warmed up. I shouldn't have to change the idle for cold/warm weather...isnt that what the KSB is supposed to do essentially?
Heater grids are definitely cycling on and off as they should.

 

If you have an air leak back by the tank, it would show up a few min into the idle. Cold fuel is thicker than warm fuel. More resistance pulling fuel down the line=possibility of pulling air through small cracks cold.

 

Something is expanding in the heat, and making it run better. But it's probably not a metal part as atmospheric temps aren't really enough to make metal expand that much. It's not out of the question I suppose, but unlikely.
So, start at the start. Supply lines from the fuel tank? If your rubber fuel hoses contracted that could do it, restricting fuel supply. What next? Gasket on the lift pump? Probably not. Fuel filter? Not really feeling that, but maybe. Something on the IP? I don't know enough about them to make a judgement. Fuel lines? Mmm, probably not.
Oh, what's your timing set at? I was wondering also whether you had good compression. Check for blowby right when you fire it up. A little is normal, a lot is not. How much is a lot? How long is a piece of string? I'm sure there is an actual measurement, but I don't know what it is. If your rings are a little worn that could be it. Much smoke when it's cold? That'll be the tell-tale. And if your burning oil.
I don't know if I've helped or not!

 

Good idea on the air leak. I will check/replace the connections at the tank and see if there is any difference.
Are these just standard fuel hoses with hose clamps? Can I replace them easily without dropping the tank?

 

They are quick connectors.

Dodge used rubber flexible line from the engine to the chassis, then steel down to the fuel tank, back to rubber at the tank.

All flexible line would have cost $8 more per truck, so they used the steel.

I went with USCG approved diesel rated lines from the lift pump right to the tank. (2) 11' runs IIRC. 3/8" supply and 1/4" return IIRC.

 

Check the condition of your wires and connectors on your fuel pump. Mine had aged and rotted and I lost my fast idle.
Course I'm only dealing with -30's and -40's temps up here!!

 

You could pressure up the fuel tank ...5 psi max or kaboom!
and see if you have a fuel leak when its cold it sounds like its got air in the line and as the fuel warms up its expanding the fuel lines/oring and resealing its self. fuel heater are a known leat after they get old

 

This fuel heater cant leak, its electric.
So it looks as though the tank has to come down to access the fuel lines?

 

It may be electric but it can still leak...... the square cut o ring above the heater is prone to leaking........


Tank down or bed up. Your choice.......

 

No actually this is like an electric blanket for the filter. It just wraps around the outside of the filter.
I just filled the tank today, so I'll wait to drop the tank.
Anyone got pics of the tank connections?...If im going to drop the tank, I might as well just replace them, whether they are leaking or not.

 

I have some similar problems but not nearly so severe. Mine's a Cummins conversion.

I ran a piece of clear vinyl tubing from the steel line for the last foot before my lift pump. I can tell at a glance any time whether there's any air bubbles coming through fuel lines. This was ordinary hardware store clear plastic vinyl tubing, the stuff they sell off of big rolls, nothing special at all and it's been holding up fine for 4-5 years?

Also many told me to bump my timing 1/8" to help the starting problems. On a used truck it's impossible to tell if the injector pump was rebuilt & installed correctly for proper timing, or if somebody in the past screwed something up on the timing & got a gear off a notch or whatever. Fairly easy & worth a try to bump timing.

 

Thanks. I was wondering why Cummins didnt put a section of clear fuel line before the pump. My VW has one from the factory, and its very helpful.
Again, I dont have a starting problem. The engine always starts on the first compression stroke, even in the coldest temps. It just idles rough after starting.