Old Komatsu Forklift will not start or idle

MigGunslinger

MigGunslinger

Red Skull
Joined
May 21, 2020
Member Number
909
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693
Loc
Sacramento
My company owns an old Komatsu FG20ST-4 With a Propane Nissan H20 engine.

This forklift was abused by an ex employee that was burning the rubber off of the tires doing circles and probably over revving it just before it quit working.

Our service company has been throwing parts at it for a while now with no end in site, they just killed the starter after cranking it for 3 solid days with no progress. They have been making backhanded comments for a while now about selling us a new forklift.

Take a look at their report below and let me know if you are seeing what I'm seeing. It says returned to service but it **** the bed again immediately.
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Has it jumped time? I asked the tech and he said it had a geared timing set, a quick google search shows a timing chain with tensioner :shaking:
How would I check that if I found a few hours this weekend to check it out? Valve cover is very accessible and easy to remove, the front of the engine (back of the forklift) will be difficult but not impossible to access.

Also, anybody have a good source for an electronic FSM for this machine? Not sure if one even exists.
 
I have a bigger version of that machine that I think has the same engine. How old is it? What type of propane system does it have? Post pics.

Mine has a propane "carb" that starts flowing propane when it sees vacuum from the intake. The more air that flows, the more it opens and feeds more propane. Mine ran when I bought it, but pretty poorly and was hard to start. I found that carb thing new on ebay for a couple hundred bucks and it made it way better. I later found rebuild kits, which is really just a diaphragm and gasket for way cheaper. It ran better and started way easier after replacing it.

Will it fire on ether?

If it's dual fuel, will it run on gas?
 
bgaidan said:
I have a bigger version of that machine that I think has the same engine. How old is it? What type of propane system does it have? Post pics.

Mine has a propane "carb" that starts flowing propane when it sees vacuum from the intake. The more air that flows, the more it opens and feeds more propane. Mine ran when I bought it, but pretty poorly and was hard to start. I found that carb thing new on ebay for a couple hundred bucks and it made it way better. I later found rebuild kits, which is really just a diaphragm and gasket for way cheaper. It ran better and started way easier after replacing it.

Will it fire on ether?

If it's dual fuel, will it run on gas?
Click to expand...
See the ticket above, EVERY fuel related thing has been replaced by the techs because diagnosis is hard.
 
Well, it kind of sounds like it’s occasionally starting and running. That doesn’t really sound to me like it’s jumped time.

Compression, spark, fuel. Sounds like compression is verified, the other two are still open to interpretation as far as me reading that report goes.

They’re using the term mixer for what appears to be the regulator/evaporator. I have always associated mixer with the propane “carb”.

I would start by verifying regulator function. Even though it reads like they replaced it, you can definitely have too much or too little fuel coming out of it. In my latest case, the regulator was supplying way too much propane to the machine for it to run. It had somewhat similar symptoms in that would initially start and then “flood”. It would start up again later as the pressure in the mixer dissipated.

I think the evaporator/regulator freezing is a clue.
 
Check the fuel hose going from the vaporizer to the carb. I’ve been beat by a hose that was plugged. Propane is a pretty oily fuel. It can build up tar over time, not letting the fuel flow. Or the diaphragm is blown out in the vaporizer.
 
Bacho said:
Well, it kind of sounds like it’s occasionally starting and running. That doesn’t really sound to me like it’s jumped time.
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In their report they verified timing was correct, replaced a bunch of fuel parts, and then went back and found that timing was off and reset it. Either they don't know how to verify timing or it changed right?

It will only start when the planets align and then only if you keep it revved up, it will not idle. Messing with the distributor sometimes gets it to start.
 
Bacho said:
I would start by verifying regulator function. Even though it reads like they replaced it, you can definitely have too much or too little fuel coming out of it. In my latest case, the regulator was supplying way too much propane to the machine for it to run. It had somewhat similar symptoms in that would initially start and then “flood”. It would start up again later as the pressure in the mixer dissipated.
Click to expand...
I'm pretty good with gas engines but my propane is a bit iffy. Is there any procedure I can do to verify too much or too little fuel?

Impco model J regulator, looks like it uses different springs for different vacuum amounts. There is a test port.
 
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Bacho said:
Well, it kind of sounds like it’s occasionally starting and running. That doesn’t really sound to me like it’s jumped time.

Compression, spark, fuel. Sounds like compression is verified, the other two are still open to interpretation as far as me reading that report goes.

They’re using the term mixer for what appears to be the regulator/evaporator. I have always associated mixer with the propane “carb”.

I would start by verifying regulator function. Even though it reads like they replaced it, you can definitely have too much or too little fuel coming out of it. In my latest case, the regulator was supplying way too much propane to the machine for it to run. It had somewhat similar symptoms in that would initially start and then “flood”. It would start up again later as the pressure in the mixer dissipated.
Click to expand...

MigGunslinger said:
I'm pretty good with gas engines but my propane is a bit iffy. Is there any procedure I can do to verify too much or too little fuel?

Impco model J regulator, looks like it uses different springs for different vacuum amounts. There is a test port.
Click to expand...

Well, I think the output of the regulator is only supposed to be 3 psi or so. In my case, it was pretty obvious to conclude there was more pressure than that by pinching the hose or observing the force it came out with when the hose was disconnected.

As suggested up higher in the thread, trying to run it from a bottle of gas sounds like a good idea.
 
Vacuum advance hose looks to be falling off, the wiring on the coil seems new, the distributor looks to be rotated all the way in on direction, does the distributor rotate counter clockwise? I see a lot of online manuals for that engine
 
cj3a said:
Vacuum advance hose looks to be falling off, the wiring on the coil seems new, the distributor looks to be rotated all the way in on direction, does the distributor rotate counter clockwise? I see a lot of online manuals for that engine
Click to expand...
Now that I know the engine model, manuals are easier to find, I was searching the lift itself.
 
Check the propane fuel solenoid. I had one that seemed fine but the wires were iffy inside the unit so only making contact once the unit was running. The viberation was making the ground connection once it was started with starting fluid.
 
Duc said:
Check the propane fuel solenoid. I had one that seemed fine but the wires were iffy inside the unit so only making contact once the unit was running. The viberation was making the ground connection once it was started with starting fluid.
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I believe this one is vacuum operated and it was replaced.

I have a list of **** to try now so thanks guys.

First step will be getting the starter replaced so I can test stuff. They have been working on this thing near the office and basically running the starter non stop for days driving my accounting department batty:lmao:. One of them probably sabotaged it for some peace and quiet. :lmao:
 
Is it sucking air somewhere throwing the fuel air mixture off? Had a man lift do right before the carb at the mixing tube intake hose.
 
PAToyota said:
I give your accounting department credit if they have the wherewithal to sabotage a forklift. Rare is the office worker who can figure out which is the business end of a screwdriver these days.
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Hey now, some of us accountants are useful.

Way long ago a buddy of mine commented that I was probably the only CPA that knows how to weld.
 
Well, I did say such people were rare... They're not non-existent.

I have to say that for the decades I've spent in the Architecture and Engineering fields, I've been majorly disappointed at how few of my coworkers have been at all mechanically handy or inclined.
 
I had that engine in the TCM I sold to m016324. Same as an 70's Datsun pickup.

Propane stuff is super picky about enough voltage to fire off. When the battery is weak it would crank over fine and not fire, and as soon as the key released it would fire off.
 
Dumb Update. The techs came back today with a starter. After having the valve cover off ****ing with the timing some more and misidentifying the rocker shaft as a camshaft the tech finally tried to install the starter.

It's the wrong starter... :shaking:

I really don't have the time to mess with this thing, but I think I'm going to have to if I ever want it to run again.
 
Seriously. Sounds like you got the window lickers of the techs
 
Alright we fired our service company so I loaded up some tools and put in some hours today on this thing.

First thing was to check the hose between the regulator and mixer to make sure it was clear and had no leaks. That checked out good.

Next was to verify spark. I get strong distinct sparks from the coil wire but the spark from the plug wires are weak and inconsistent. Pull the cap and rotor and everything looks ok. The points were replaced at some point by a PerTronix unit. I checked the install instructions for those and it seems to be wired correctly.

The vacuum advance is crunchy as **** so I go down the rabbit hole of rebuilding this stack of thin plates in the top of the distributor that are separated by the tiniest ball bearings I have ever seen, like the size of grains of sand. Reassembled and lubed the vacuum advance moves way smoother.

I found TDC and restabbed the distributor. Did a lot of messing around with the timing and the spark at the plug wires was more consistent. Seemed like the ignition was in a better place Got it to start a couple of times but it would run for about 10 seconds max. A little snoot of starting fluid would get it started pretty consistently.

I thought I had narrowed it down to a fuel issue so I went and picked up a vacuum hand pump and got my timing light and vacuum gauge I forgot at home. I suspected the fuel shut off solenoid so I put some vacuum to it and tried to start but no improvement. I hooked my gauge to the vacuum port on the mixer and it only pulls around .5-1 in hg while cranking. Not sure but that seems low?

I noticed that it was not starting as often or running for as long as it had been so I tested the spark again and the weak and inconsistent spark at the plug wires was back. The spark at the coil wire is still strong. There is some very light corrosion on the contacts inside the distributor cap and I went after it with a scotch brite pad but that didn’t seem to help.

I got pretty frustrated and cleaned up my **** at this point. If it was a car I would throw a cap and rotor at It for ****s and giggles and probably replace the plug wires because the ends were kind of bent up from the techs and don’t give a positive click when you connect them. Problem is that this engine is almost exclusively used in forklifts and auto parts houses don’t have jack **** for it.

I am considering a tuneup kit with cap and rotor and wires. I need some type of resource for how to test the fuel system components but YouTube is failing me. Everything on there is for newer machines with a ton more electronics.
 
I bet that's a j15 engine and there is nothing on that engine that fits anything in an old Datsun pickups ever sold in America, it's only overseas stuff and forklift stuff inside the US .

Okay there may be some stuff that interchanges like the distributor or whatever I'm not sure, but the j15 is a different animal .

If spark is weak at the plugs I'd be looking at the coil, if you have a fuel solenoid eliminate it, replace the fuel regulator if you haven't already, you can get new one on eghey for 75 bucks, make sure rotor isn't burnt through going to ground or cap isn't cracked .
 
Valley Rock said:
I bet that's a j15 engine and there is nothing on that engine that fits anything in an old Datsun pickups ever sold in America, it's only overseas stuff and forklift stuff inside the US .
Click to expand...
This. Figure out the automotive equivalent and most parts will interchange.


I have a 60's Nissan Patrol with a P40 engine and I buy parts for the forklift equivalent because they're way more common.
 
bgaidan said:
This. Figure out the automotive equivalent and most parts will interchange.


I have a 60's Nissan Patrol with a P40 engine and I buy parts for the forklift equivalent because they're way more common.
Click to expand...
There are some obscure nissans from the late 60s that share some parts but they are all special order at the parts stores. Even searching rockauto and summit with OEM part numbers turns up nothing.

Luckily Amazon seems to be flooded with Chinknasty tune up kits for the H20, I have one on the way. I'd buy OEM quality if I could but as far as I can tell the forklift parts sites are selling the same chinese garbage for more. Maybe Nissan supports this engine more in Japan but there is just not much here and almost nothing local.
 
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