8.3 cold starting

[adamsoffroadperformance]

Of the 2 M931A2 trucks we bought with the 8.3 cummins one starts almost instantly in cold weather but the other one has to crank a while. The one that starts right up has fair blow by and the hard starter has none. Both just had the same spring and screw turning mods which made both run waaaaaaayyy better. They both started the same as they do now before the mods. I fired them the other morning when it was about 15 degrees out and the one fired in less than a turn or 2 of the engine. the other I probly had to crank 15 to 20 seconds till it fired then it had to chug and carry on for a bit before it was happy. It blew perfect smoke rings out the pipe though, but I'd rather have quick start versus pretty smoke rings. lol Any cold start tweaking tips. I hate to use the ether start. I'm thinking of tweaking the timing some which I know will make a difference too. One difference between the trucks is the hardstarter has a big fuel filter in the fenderwell and the other doesn't have the big filter it has an inline filter spliced into the inlet line to the lift pump.

 

[74M35A2]

Have the fuel delivery hose(s) from the tank to the lift pump been replaced? They are know leakers, and since it is a suction line, it will suck air vs leak fluid out. Also, the OFV (Over Flow Valve) in the injection pump may need to be cleaned, it controls the amount of fuel pressure between the lift pump and injection pump, then returns the rest as cooling. If it is opening sooner than it should, or is stuck partially open, it will do almost exactly as you describe. A shade tree way of cleaning it is to pinch the return line (front of pump) shut for 10 seconds at and idle, and then release it. Repeat several times. RV boards say this will bring it back to new over 90% of the time, vs having to buy a new one. It is just a simple ball and spring device as a banjo fitting on the return outlet of the IP. Though Cummins usually does not publish compression or leak down figures (they measure engine health with a crankcase vent flow meter, measuring blow-by air flow), the engine with blow-by speaks for itself, especially considering diesel is compression (heat) ignition. The aftermarket does make a hollow injector to attach both a compression and leak down gauge to, but it sounds like the slow starting engine is begging for a cylinder kit. Mine starts the same way, and I wish it didn't, but OK after about 10 seconds of idling.

 

[adamsoffroadperformance]

The hard starter has no blow by. the one with blow by fires right up. I'll have to try pinching the hose

 

[74M35A2]

The hard starter has no blow by. the one with blow by fires right up. I'll have to try pinching the hose

Sorry, I mis-read it.

 

[JohnnyBM931A2]

For what it's worth, mine starts extremely fast and it also does not have a fuel filter inside the fender. Starts in maybe 1 turn of the engine. When it's really cold it starts the same way, but does chug a bit at first.. Sometimes makes the smoke rings too I usually throttle it up a little with the hand throttle, and within 30 seconds it's running flawlessly.

 

[adamsoffroadperformance]

hmm ok. I've been thinking of getting a spin on fither base and changing the fender mount one out to something more common.

 

[Cinman37]

The hard starter has no blow by. the one with blow by fires right up. I'll have to try pinching the hose

Are you using a block heater? It was 20 degrees here the other day, 8.3 would crank fine but would not start. I had to plug my block heater in for 4 hours or so to get it started.

 

[adamsoffroadperformance]

no block heater. I mean I'm amazed at it starting in that temp anyway but when the one beside it takes right off it makes say hey wait a min. lol

 

[seano11]

mine with zero blowby doesn't start worth a rats ass in the cold.......

 

[JohnnyBM931A2]

mine with zero blowby doesn't start worth a rats ass in the cold.......

I'm curious.. Does yours have the additional fuel filter inside the wheelwell? Also, what is the status of your batteries?

 

[adamsoffroadperformance]

Ok so when it was cold this morning I held the throttle wide open and then started to crank it. almost instantly it started to chug and fire. I left off the throttle as soon as It acted like it was gonna start and it chugged for a second or so then was running. So seems a tweak of the fuel pump may solve the problem. possibly some pre boost fuel adjustments would help. acts like it needs more fuel to get started.