View Full Version : Forklift Won't Idle

big rig guy
01-21-2005, 11:15 PM
So my new used forklift decided it won't idle anymore. Unit is a 86 Clark with a 4 cyl propane motor, 2600 hours on it.

Replaced the plugs and wires, distributor cap and rotor, points and condensor, change out the propane tank, removed the carb and cleaned out.

If it does idle, only if I set the rpm up around 1100. As soon as I put it in gear stalls. As I run the motor at high speed, power is there no problem.

Gets enough propane for power, something wrong with the low speed circuit in the carb. Has a electric activated solenoid on the one side of the carb to aid in starting, and I have figured out what this does is simply open a jet inside the carb to flow more propane. Phoned around for a carb today, curious, anyhow about 900.00. don't think it is a carb problem but a fuel delivery problem.

I know the safety system, operates off the motor to flow the propane, if unit stalls, the flow is shut off. Did notice a relay system under the seat tied in with a ballast resistor much like the old chrylers.

Anyhow here is a pic of said carb, maybe someone has an idea ??? On the right side of the carb is the soleniod that activates a plunger to open a passageway inside the carb to allow more fuel to flow, used for cold weather starting, to replace a choke ??

I am assuming that the flow out of the regulator should be around 12 to 25 psi, I did check voltage at the electric shut off and it is good.

01-21-2005, 11:53 PM
Is this happening when the machine has warmed up?
Propane machines don't like to idle when they are cold cause tha vaporizer isn't really working yet.
You probably ain't much warmer than I am right now.

Crithpy Critter
01-22-2005, 12:01 AM
sounds to me like the (a) gasket is leaking and the mixture is too lean.....

of course, I'm nowhere near the thing so that qualifies me as an expert.....

big rig guy
01-22-2005, 12:11 AM
Yup I thought I had a vacuum leak too, resulting in lean mixture at idle, checked the gasket from carb to intake, looks good, went and sprayed either all around the area, no idle change, it will high idle but once put into gear, stalls like not enough fuel to maintain that extra little bit of load, yup she is warm Franz, burn my digits on the exhaust manifold can't count how many times now.

I pulled out the idle set screw as it is a little loose, plugged the hole and same thing, it should have run no problem as definetely no leakage vacuum and idle circuit running full tilt.

I am going to rig up some gauges to measure the pressure out of the evaportor section to see if there is a pressure drop at idle when motor goes into gear, long shot at best.

big rig guy
01-22-2005, 01:00 AM
Well I think I got it, I went to put on the pressure gauge onto the outlet of the evaporator side, I let loose the line, propane excape. so I turned over the motor with the tank on, just to get a feel for how pressure was coming out of there, then proceeded to do the hookup with the gauge installed, fire it up and works like a charm.

So I am thinking there was maybe a little speck of dirt inside the diaphram area that was hanging up and causing a problem at idle, could be from changing the tank and getting a little dirt in the fitting. Real pain in the butt.

Thanks for the help guys.

big rig guy
01-24-2005, 10:26 PM
This damn forklift is acting up again, had problems with it again over the weekend, tore everything out, took it all apart and inspected reassemble and then tore it all down again.

Sent the carb and evaporator and shut off valve and choke assembly out to a forklift repair center, they sent me back a new evaporator and advised that I should update the whole intake assembly. So hoping that the new part was going to solve my problems, I installed all the items again, still not running, so ordered the full intake package and even having them come out to install it. Frustrating, I can't believe this propane 4 cylinder 20 year thing got the best of me. I have to have a qualified forklift service tech repair this thing, cause I don't know ****. lol.

01-25-2005, 06:15 AM
Cheer up big maybe the forklift dude will a have problems to :D

01-25-2005, 10:28 PM
I can relate to your troubles Big Rig, I too had problems a few years back and learned to have the fork lift repair tech come every 6 months for oil change and whatever.

Crithpy Critter
01-25-2005, 11:16 PM
the last thing I can think of is liquid vapor lock somewhere...which, at low flow, can starve a carb.

big rig guy
01-25-2005, 11:40 PM
Well I still have yet to see the parts or the repair man, we have bad weather up here right now so don't expect him for a couple of days now. Anyhow, my buddy who has a forklift, and had it in storage at his buddy's house, well anyhow, something happened and he needed to move the forklift. I sent the flatbed this morning to pick it up, here is a shot of it as it sits in the shop right now. I needed a forklift today, so was all excited to get one, got it here, 200.00 for delivery, roll it off the flatbed, and it's running on three cylinders, well screw with this and screw with that, you know, pull plugs, comp test, check point gap check wires etc, well it all boiled down to a distributor cap. Sent my mobile guy to the store and they even had one.

Installed the cap and the motor came to life, I checked all the fluid levels, gave it the once over and took it outside and got it stuck in the snow.

I like this unit as it has the 18 foot high mast, can almost reach the cieling in the shop, and side shift, but only a 3000 pound lift, barely can pick up the rear of a tractor.

Plus it has these little steps to aid getting in and off the thing, I get a little cramped on the other forklift. More room in the cab area, which to most is not a big deal, but I am 250 plus and approaching 6 foot 4 inches I need alittle room to get around ha.
It's a Allis Chalmers make which I have absolutely no experience with any of thier equipment, maybe someone here can advised if their stuff is good bad or indifferent. Right now, to me, this is the best forklift going, cause it starts and runs. I am thinking this unit was a good machine in its day likely around the late 70"s ?????????????

big rig guy
01-25-2005, 11:43 PM
And here is a shot of the forks way up in the air, I mean this thing has reach, this is real handy for me too, string the kid up there when he does'nt brush his teeth lol. Thats my ten year old on the forklift at 1130 at night, no school tomorrow due to bad weather.

01-31-2005, 07:37 PM
I also learned from my clark forklift technican $275.00 that the forklift's when running on propane need to warm up.......... We were being to cheap on the propane just shut it off when not useing it........ However propane has cosmoline in it that will jell up and plug up the miser tube.......... Result is no mixing will run a short time then crap out and not restart...................

Clean that tube, check the diaphrame, and you should be ready to go.......also as an after thought you have 2 vacume chambers internally both have as I recall a hand prime on them......... Check both...........

As I recall.....................Rock..... :cool:

big rig guy
01-31-2005, 08:05 PM
I ended up doing the work myself due to the forklift guys being too busy to make it out to my shop, I went into the city last saturday morning and picked up the parts and a new seat too.

Installed the vaporizer and lock off, new carb, and now it runs pretty much like a new machine now. Total cost just under 600. So I figure that is not too bad.

Lots of life still left in this machine so I figured it was worth going the distance for this unit.