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Clark Propane forklift runs rough at start

Mud

Diamond
Joined
May 20, 2002
Location
South Central PA
I have a Clark GPS25 MC lift with a Mitsibishi propane engine that runs rough at a cold start. Once it has started and run for a short period it smooths out and runs fine until the next cold start. It starts a little hard then sounds like it is running on one two or 3 cylinders until suddenly it clears up. Occasionally it will start right up and run fine from cold. There's no discernable connection to air temp or weather conditions, or how long it's been sitting, except very cold weather makes it needs more cranking to get the first cough of ignition.

We've replaced plugs, wires, cap and rotor, vaporizer, regulator and carb diaphragm over the past year, with no real change. We've run out of people to ask locally for advice, and I'm reluctant to turn it over to a dealer with a blank check to sort it out. Leaving the key on for an hour before trying to start it makes no difference. The ignition coil is now wired directly to the key switch to bypass any harness issues, 12V at the switch goes to a ballast resistor then to the coil. I have not replaced the ignition module as of yet.

When I first bought it it started fine, this appeared after more than a year of 1 to 2 hours a week of use.

Thoughts and suggestions? Help!

Clark01.JPG
 
If it has hydraulic lifters, one might be leaking down and a valve not operating properly. My guess is that its in the valves. I had a problem with mine when it got warm, that a valve would stick open. Maybe you are having a cold valve problem.

Just a guess,
Josh
 
Were the plugs in bad condition?
One reason for your symptoms can be water on plugs/head gasket.
A compression chek might tell you something.
 
I have one that is gasoline that does the same thing .

Have to replace the #1 plug regularly.

If you jump it does seem to help.

I always thought it was the alcohol in the gas curious to se if there is another solution.

Tried the dealer and got a young punk that told me I didnt know how to change plugs!
 
As you already did the rest of it, why not pull the ignition modual/pickup from the dist. and check it, could be corrosion on the terminals or a bad ground to the dist. mounting plate, a little dielectric grease on the mounting surface would do wonders for the system.

Dave
 
Compression test comes up 155, 145, 155, 155.

Here's a photo of the plugs today, removed from the engine when cold.

Battery condition from low to on charge hasn't made a difference.

DSC05472-1200.jpg
 
I think I would go with the coil itself. Very "wet" combustion chamber because of the "perfect" chemically correct reaction. My opinion on ignition modules is they are more of a "switch"...but that probably would be next inline based on price...

The loss of lift on one or more valves seems interesting but I think you'd get some audible clicking or clacking if a lifter failed to pump up as there would be lash in the system. I had some problems on my Clark with continental flathead with valves sticking open, seems like an OHC engine would not have the same issue because lube would tend to flow downhill into the guides (with help or hinderance of the stem seals of course). Just for info, the thing that solved the problem for me was some marvel mystery oil. I actually remove the plugs when I feel like I have the time and put a couple of drops in each cylinder for "maintenance".
 
Same experience with propane here......

IMO you can't have too hot a spark with propane.
Propane just does not seem to 'light off' real great compared to gasoline.
It might be that heat in the engine helps this.

Non-helpful but related details:
My small hyster with the propane contenital Y112 did about the same thing.
I replaced everything except the Dist. cap. Turns out the center carbon pin in the
cap had a crust on it. When I scraped it off the spark got a lot hotter.
I mean it starts at least now....
But it also still will run on 2 or 3 for the first 30-60 seconds, then all 4 chime in eventually.

The slant 6 in my Yale runs kinda rough when cold as well.
And that does now have a 'hi-perf' coil on it.

Best guess:
I'd try replacing the module and put an aftermarket 'hot rod' coil on it to get
as good a spark as possible.

Always wondered if an MSD unit would make any difference.......gap the plugs about .080 and give it hell....
 
I agree with dkmc; I have a clark warehouse tug we're using to move aircraft around, Ford pinto engine on propane, very hard to start, and once lit, won't accept throttle until you "milk" it along for awhile..... Finally talked to someone knowledgeable, and he stated "propane is hard to burn". who would have thought that? He suggested a hot battery, but like the OP, it didn't seem to matter. Ended up cleaning & burnishing all connectors to the ignition module, key switch, two new battery cables, all grounds cleaned, most anything in the area was shot gunned. It helped, but while it ran "better" after start, it was still cantankerous to light off. What I did, was get one of those gee-whiz "Battery Tenders", (a sort of super trickle charger) and if the tug isn't moving, it's hooked up to it. This fixed it.
 
Simply cold natured. Let it warm up before use. My old 1974 Hobart welder with a Ford 200 six is the same way on gasoline. It will not take throttle for the first five minutes or so of running. You just start it and let it idle while you get everything together, then have at it. Some engines just don't run worth a crap cold.
 
Just as a data point for your error search:
I have a propane Nissan forklift and so does a friend. We both had issues with bad starting and running.
In both cases the Nissan dealer proved completely incompetent (but pricey) to correctly replaced the evaporator (I had to have it fixed in my absense). In my case he replaced the whole unit and it would not run at all any more until I re-adjusted everything. Runs great now. The repair cost me 900 Euro, when I could have done it myself for 150 and 15 min work.
In my friends case they just installed an evaporator gasket kit, which made it worse. It turned out that the gasket kit does not include the springs (duh!), but they tend to go bad too. Now its fixed.
Eventhough you replaced the evaporator, it would still be a suspect in my experience. Also for the fact that the evaporator is hooked up to the coolant cycle.

Good luck and tell us the solution.
 
Your plugs look good. The ignition module is most likely NOT the problem. They usually either work or don't. Heat usually makes them quit working, so if it gets better when warm, it would not be suspect imo. With the good condition of the plugs, I would also say the coil is not the issue. I suspect it is just cold natured, and ambient temp really has little to do with it. A compression test wouldn't hurt, but a leakdown test would be more telling. Depending on hours on the machine, it could be a valve that is hanging a little, and corrects with a bit of heat.

I have 2 suggestions that might help, first, an oil change, and replace 1 quart of oil with a quart of Marvel Mystery oil. It will help clean the inside of moving parts of the engine. If the cold nature is really a problem, try a block heater. There are many options for a block heater, you can get one that replaces one of the freeze out plugs, not fond of these, but they do work well. There is also a unit that would plumb in to the heater hose of a car, might need to do a bit of creative plumbing to make this work, but there are fittings that would allow you to add the necessary connections right into the radiator hoses, if heater connections are not available. There are also "electric dipsticks", I have no experience with these at all, so its use would be a learning experiment. They also have heaters that are used by the racing community. It can be in the form a heating "pad" that cradles the oil pan, or they have one that I have heard of that is like a large magnet, and it is attatched to the oil pan, and heats the pan, which in turn, heats the oil. I have not used either of these, but comfortable with the fact that the racing community uses them. When I get to work, I will look through the books, and see what is available on the racing end. I have used the one that plumbs into the heater hoses, and I like it the most, it actually heats and circulates the coolant, which heats the combustion area of the engine, and I think it works the best.

I just went to our company website, JEGS Performance Auto Parts - Holley - Billet Specialties - Edelbrock - MSD - Moroso - Mr Gasket and typed block heater into the search function, and there were several that popped up, they are the ones that replace the freeze out plug...While I didn't speak highly of them, they were the industry standard for years, so still might be a good option...
 
My suggestion would be to try and isolate the problem cylinder or cylinders. You might remove the spark plugs individually and determine which cylinder is causing the problem. If each cylinder gives a random problem, I would suspect fuel or electrical. If only one cylinder is the problem, try switching the plug wires.
One thing I have discovered, over the years, is never eliminate a part because it is new!! I have replaced many parts only to discover I have a bad replacement part.
This is especially true now that virtually everything is foreign made!
 
OK, I put a 6A charger on the battery, it took 5 min or less to click off. Battery showed 12.8V, didn't check it beforehand. Motor fired on the 3rd piston over and purred like nothing was ever wrong. This doesn't yet prove that this solved the problem, because it would on occasion do the same thing without the charger, but it looks promising. I'll test this for a week or so.

It's encouraging to know that this is not extraordinary for propane engines. I thought something was failing and it was going to leave me stranded at a critical time. Now I know it's just a PITA. Don't know why no one local could tell me that. Connecting a charger every day is really more of a PITA than dealing with the short term missing so I'd still like to return it to it's former good natured condition.

I still don't understand what has changed. When I bought this lift it was in pretty neglected condition. The alternator didn't work, and the battery was weak, the plugs and the rest of the motor were decrepit, etc., but it still started and ran fine until the battery ran down so far it wouldn't operate the starter. The rough starting started while it was stored in an unheated building in cold weather and has continued ever since, in spite of a good charging system, new (good) battery, tune up, hot weather, etc. Perhaps the ballast resistor has developed a problem, I could connect a test wire to the coil side and see what readings I get with a voltmeter, but I don't know what the voltage should be there.

Always wondered if an MSD unit would make any difference.......gap the plugs about .080 and give it hell....

I do have an MSD 6A and coil on hand, I wonder it the Clark ign. module would trigger it? There's no fix like an overkill fix. :)
 
Just one question, what gap are you setting the plugs at? Make sure that you set them at .018, many folks install plugs thinking that the factory setting is proper but the factory doesn't know what fuel it will be firing. Remember that propane is a dry gas like natural gas. There are no droplets as in gasoline and as such it is much harder to ionize the gap. I can't tell you how many service calls that I have been on for poor running and starting conditions only to find an improper gaped set of plugs installed (many by the dealer mechanics). Also don't go by the "look" of the plug when judging when to replace them. As the center electrode ages it has a formation much like a used welding rod that you have to tap against a hard surface to get going again. This makes it even more difficult to get the gap ionized.
Also make sure to use the proper plug designed for that engine, not just one that fits
 
I put a 6A charger on the battery, it took 5 min or less to click off. Battery showed 12.8V, didn't check it beforehand. Motor fired on the 3rd piston over and purred like nothing was ever wrong.

Again, the higher the battery voltage (primary) the higher the secondary coil voltage (hotter spark) in theory anyway.....

If the MSD would work with that module, it would be interesting to hear the results!

Also isn't there some theory that you temporarily hold the coil wire 'off' the coil a ways (hold it so there's a gap the spark jumps between the coil center terminal and the coil wire) to increase the voltage to the plugs?
You could try that at cold start to see if it smooths out when you do it (using plastic coated pliers or good rubber gloves of course)!
 
I had a Caterpillar GP30K which has a similar Mitsubishi engine in it. This sounds very much like the propane converter, or whatever it is called. They get gummed up and start failing. There are 2 pieces to it, one is a round type banjo with some hoses going into it. The other piece that I believe it goes into has a diaphragm that needs replacing.

I don't have a manual anymore, I gave it away with the lift when I sold it. But there is a second problem with these engines that involves the solenoid, which pushes a pin into the fuel line to control fuel. When that solenoid is not functioning it doesn't pull the pin out. If this is the problem, you can pull the solenoid off and remove the pin so it is always open.

The symptom you describe is classic for the propane system. You can also see that it won't start after it warms up, aside from the running rough when it is cold.

Can you take a picture of the engine with the cover open ? On the Cat GP30K the engine is under the seat and the entire seat and cover pivot back. Is your Clark similar?

On the propane systems, the coolant from the radiator goes through those propane components to keep it from freezing.

When mine was doing as you describe I believe it was the solenoid not functioning correctly. I will caution you though, since there are various components in the system, it makes it a bit more difficult to troubleshoot.

Those Mitsubishi propane engines are nice, when they are running correctly...:rolleyes5:

I'm looking at the pic of your lift, it looks similar to the cat, your seat/cover must tilt forward with the radiator in the front, under the seat ??? Would like to see some pics of the engine, seeing it might bring back some memory on the components. Also, it's cheaper to buy an entire propane unit, but you might want to use the older piece that attaches the hose to the banjo component. At least there are different connectors for the electrical or mounting bracket, one or the other. Sorry I can't be more specific, I got rid of the lift and now have a Caterpillar R-80 which is Perkins 4 cyl. diesel. Your mast looks very similar to the Cat. I had a single/double on mine also (4th lever) which opens and closes the forks up to 7' wide. That was sure useful...

EDIT: check that solenoid cause I ended up replacing a lot of the other parts and it ended up being that. It is possible to dis-assemble and remove the pin so that it is always open, that might help it when it is running rough. If that is the problem, that will at least tell you that you need a new solenoid. Eventually it will quit running though, DAMHIKT...
 
That was Thursday. Tried it again Friday, charger on, 12.8V, started and missed just like before. Turns out someone had used it Thursday to unload a truck before I got in. Even though the engine was cold to the touch, once it's been fired up once, it's good for the rest of the day even if cold so that one good start meant nothing, back to square one. Sat. I filed the center electrodes square and sharp and gapped them at .015(makes it easier for the electrons to jump). It fired and missed but only for 5 seconds. Today(Monday) it did the same. So it seems to be spark related, maybe a weak coil. Since there are no Sun machines around any more I don't know where to get a coil tested, guess I'll just have to replace it and see. Almost seems like there's an invisible coating forming on the plug electrodes that needs to be burned off in the morning, doesn't it?
 








 
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