Also, if you can check the pre-heater, some engines have it, some don't, some have 1 and its not connected.  I use a Coleman tent heater, slide it under the motor, and let it heat the motor for about 45 minutes, and most any engine in good repair starts right up...  (Do not use this technique on an oil leaker, though!)

My 180 has two of these, rings are getting weak or cylinders just glazed horribly with notable blowby, have had pump rebuilt where once running has plenty of power but I can smell the unburned fuel from the exhaust tells me nozzles need to come OUT.  Old gal needs a freshen overhaul about as much as I do!!

Anything below 40 my 180 is set up that way.  Timer was for old incandescent lighting so can carry the amps.

My BUDA BD153 in the forklift needs 3 short squirts of ether to start it AND 2 good batteries to spin. OK, it has so much 'blowby', I've rigged ABS plumbing to 'recycle' the fumes from the oil filler cap to the intake. yes, I KNOW it has low compression but the 5K estimate is a LOT more than a few cans of ether !

I was told years ago that Freightliner trucks do NOT have  glowplugs or intake heaters, just turn the key and start them up.....

Yep, mine easily handles the correct amps, been using it for years.  I start using mine when around 30 or less, depending.  

PS the latest 2800's with the bosch injectors and last timing advance program would CRANK... and sounded different, and didn't smoke..  

That being said…I have drove compact construction(idi with glow plugs) equipment across the lot on either when it was gelled up and it didn’t seem to hurt it!  But wouldn’t recommend it!

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Engine spin.

Good battery, thick battery cables, clean contacts, dielectric grease after cleaning, good switch.

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When I put the new battery in it I cut an inch off the ends of the cables at the battery end due to corrosion and put new clamps on that end. This forklift is a mid to late 80's and was city owned. It sat for several years before they auctioned it off. They didnt say how many years it sat for only that it sat for several years. I changed all fluids and filters. The battery was a junkyard battery they put in it just to get it from the city lot to the auction yard. Anyway one thing I havent looked at is the other ends of the cables at the starter and ground. Ill take those ends off and give them a good cleaning. Great running forklift otherwise. My other forklift is an 1980 ACP60 Allis Chalmers and a dang fine one at that. Gas though.

SteveM C/IL wrote: I believe  JD juice is"higher strenght" than most others. Think it has been discussed here before.

Wonder if that is a good thing?Seems to me the more potent the ether the more damage it could do to a motor.

So to correct the digression, here's the OP's core question:

" I have a Case forklift with a Cummins 4 cylinder engine that will not start at all unless it gets a shot of ether. It is a strong running engine, but wont start without it. What possible causes could make this machine not start without its shot of ether?"

We dont' know WHICH Cummins he's got... I can't give him immediate direction of any CUMMINS design, I can only comment on the basics:

Diesels need to crank at at least some particular speed in order to fire the engine.

If you run large volumes of fuel rack on cranking, you are NOT likely to get an ignition as early BECAUSE the unburned fuel is just absorbing latent heat.  Crank it with the throttle to full slow.  Once it's been constent in cranking, crack open the sum and see if it'll wake up.

The owner's manual for my subcompact diesel tractor says to open the throttle to a fast idle position and crank over a couple times, then activate the glow plugs for about 20 seconds, then crank the engine. 

Like everyone else, I didn't read the owner's manual until I had it for a couple years. It starts much better that way than leaving it at idle like I had been. IIRC, the owner's manual for one of my AC diesels had similar instructions.

I urge you to read your manual and follow the instructions for your particular engine.

WF owner wrote: ...read your manual and follow the instructions for your particular engine.

YES YES YES!

And while diesel engines are all the same with respect to 'compression ignition'... they're not all the same with respect to HOW they accomplish it.

There's direct, and indirect injection... there's different concepts in head design, rod length to stroke ratios, and compression ratios... so they all have a little different character.

Starting a cold engine, regardless of WHAT type it is, is really one of the hardest events on an engine.  Oil is cold, oil pressure goes from nonexistent, to insane... the starting unit is under tremendous load to just TURN it, and trying to get it spinning FAST enough to bounce past TDC swiftly... the battery is cold... a little trace of moisture in the connections... cold air coming in...   accomplishing that pressure spike hot enough for compression ignition to occur ENOUGH to kick the flywheel hard enough to clear the next several compression events...  the fuel is cold... injection pump and injectors hate that.

Listen to how an old aircraft V12 or radial starts, and you'll notice that it doesn't all start at once... some cylinders hit, while the others are still missing... eventually they pick up, after they've spun a bit and cleared out whatever was fouling.

One of the first diesel-starting challenges I had, was the pony-motor 6cyl Cat mentioned above.  I don't know if they're ALL that way, but the one I worked on had a lever that opened up the valves, so that pony motor exhaust was blown through the cylinders to WARM them.  While it was doing that, it was circulating lubricating oil and coolant (both shared with the prime mover) to get both up in temperature for an easier start.  Spinning the engine for all that time seems silly, but in terms of long life and starting assurance, it's the right thing to do- they designed it that way, and that's one of the biggest advantages of a pony-motor start.  Unlike an electric starter, that pony motor could roll the engine over all day if you keep the starting fuel tank full.

On the locomotives I taught on, four 72vdc electric starting motors were wired up in series-parallel switching so that the crank could be rotated slowly to check for a flooded cylinder.  A leaking injector can put enough stray fuel in a combustion chamber to hydraulically prevent a piston from crossing TDC, and if forced, the cosine angle of crank against the rod can easily bend the rod and crank... so they have a programming sequence in the system to turn it slowly with the electric starter through four complete revolutions of the crank, after that, they bring it up to cranking speed, make sure they have oil pressure (it actually uses a booster pump for 20 seconds or so before cranking) then they tell the fuel management system to processed with fueling.  The fuel management system is full authority, and uses peizoelectric sensors on each head to detect when ignition occurs, and it watches each cylinder for misfires.  It brings on fuel to each cylinder individually, and adjusts it to get ignition, because each cylinder is slightly different, both in initial state, and in running character... so it's like having a mechanic assigned to each carbeurator of an individually carbeurated engine.  Once the engine is running, then it goes through a short warming cycle before it will allow running load (basic power generation), followed by a considerable warmup cycle before it will allow the prime moving load... all to make sure that million-dollar engine exceeds a 5 million-mile lifespan.

On a side note the Case forklift I posted about has a Cummins 4-390 engine in it. Now it does have a slight fuel leak at the fuel injection pump which the mechanic took a look at and said he could fix no problem. I also ordered up an owners manual for this machine. So with that said could a leak at the fuel pump have anything to do with the motor not wanting to start as easily?