Yea, left out in the cold. The high idle won't work unless it is enabled in the ECM. I think you can do that with the smarty. Just a mater of digging through the sub minuses. Once it is enabled, it will come on if the IAT is below 32°. The switch from Moparman bypasses the IAT with a fixed resister, tricking the ECM into thinking it is cold. However there are other parameters like coolant temperature and APPS that have to be correct before it will come up. My old 81 with the 440 had dual 750 watt block heaters. 30 minutes and it was reading on the temp gauge, even at -40°.

 

Well, still behaving its self. Except my lousy fuel mileage is back.

 

This is officially annoying.
Hard start again. Cranks and cranks and cranks and cranks (normal speed), then boom its running like nothing ever happened. No hesitations or hits and misses, it's running normally. Gotta be something electrical.

 

This is a long thread so I cant remember if anyone discussed starter speed. I understand that a mere 20 rpm reduction in starter speed will cause starting issues.

 

It has lit off before with a much slower cranking speed (see posts 37 and 38). In those cases I got a couple hits and misses then it would start running poorly at 1st then cleared up after a few seconds. Last night and again this morning is just cranked then suddenly it was running normal. The temperature was above freezing in both cases.
Remember on the old gassers that had secondary contacts on the starter motor to bypass the ballast resister to the ignition coil? When those would fail the engine would just crank until you let off the key then it was suddenly running. It's kinda like that except i'm not letting off the key, but about to.

 

All I can say is that the Cummins ISB is fully electronically controlled and is VERY sensitive to electrical differences. Any reduction of voltage/amperage and the system can give off phantom issues which wont be detectable as they truly dont exist but are a result of those electrical variances.

I know this is frustrating but if you search around the forums you'll occasionally find someone who posted that they couldn't solve something until they either replaced the batteries, the cables, the alternator, or cleaned up corroded connections. Then all of a sudden the truck started and ran beautiful.

Lastly, if I remember correctly the starter solenoid will work down to about 9 volts before the Bendix wont engage, but that said, the VP requires 9 volts to function as well otherwise the pintle valve wont trigger and deliver fuel to the cylinders.

Cranking over these engines takes considerable electrical power.

 

Funny you should mention this. I was reading another thread that fuel pressure could also effect the pintle. When the temperature got cold my fuel pressure started going up, still under 20psi though but above 15.

 

What The H!. The truck sat for 5 hours and it's colder now than it was this morning by 5°. I bump the key after the WTS light goes out and it's running, just like that.

 

Hard starting because of fuel pressure is only when the engine is hot. This is because the VP tolerances change as the engine and VP warm up and high fuel pressure stops some functions. This doesn't sound like your issue.

 

Truck sat in a heated hangar for the last 3 weeks while I was "out of town". Started cranking and nothing, so i stopped and let the lift pump cycle out. Hit the starter again and it lit right off.
DRAIN BACK!
Shut it off and let it set while I spent the next couple of hours shoveling out the door.
Went to start it and guess what,,, repeat!
My thoughts at this point is stopping the supply line from draining back. I'm looking at a check valve on the inlet side of the lift pump to counter this.
Also while I was "away", I ordered a more reliable fuel pressure gauge.
I need a double gauge so I can get the one off the steering column. It blocks my view.

 

Cougar there is NOTHING to stop drain back in the fuel lines other than a leak. And the fuel lines never hold pressure when the fuel pump isnt running.

The truck will start perfect even if there's no pressure in the fuel lines AS LONG AS the prime is maintained. Trying to add some kind of one-way valve isnt going to solve anything since you have no idea where this drain back is occurring. Meaning, you could add it up by the VP but if the fuel line is empty of fuel behind the one-way valve then as soon as you start the truck it will only run for a second and then bobble and stop because of the huge pocket of air in the system. Then you'd have to crank some more and get the fuel pump pumping again in order to re-start.

So if you cant find a leak then there's other issues causing this problem. But really.....it just sounds like a leak.

 

I have used a spray developer on the lines that will show up as wet if there was the slightest leak and nothing is showing up externally.
This all started after I replaced my fuel filter drain because it started leaking. To be clear, I had no problem before or while it was leaking, and it was wizzin pretty good. It is not leaking now, but there is nothing that could stop it from sucking air except the plug I put on the end of it. I'm putting the check valve at the tank outlet (my draw straw) to minimize any volume (I hope) should drain back be occurring in the supply. side.

 

What plug are you talking about?

And a leak doesn't always mean "fuel escaping" but rather "air entering".

 

Oh, PS
I filled the tank before I parked it.

I agree, it's a leak. But were? The developer I use is from a die penetrate kit. If there is the slightest fuel leak, it will draw it out. Vacuum is a bit more involved. I can isolate sections of the lines and pull a vacuum on them. If vacuum doesn't hold, I have a leak.

 

A plug on the end of the fuel drain. And yes I know a leak works both ways.