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Clark engine running rough - LP

Number of messages: 8

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rick_v
Illinois, United States

I have a 1979 Clark forklift C300 /40 serial #356-37-4370 with a Continental F163 engine, running on LP. The engine starts and idles. It also runs at very high rpm. However, when accelerating from idle it is very rough running or when putting a load on it. Driving along at mid rpm it runs very rough, sounds like it is chugging along. Plugs, points and settings seem ok. Can this be the LP regulator? Any cleaning of this needed?

Thanks in advance,
Rick

Modified 14 Oct 2009 01:30 AM
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Forkliftt
Louisiana, United States

Rick,
my first question would be what type of LP system do you have the original system had a regulator that bolted in place of the thermostat housing. They provided pressurized fuel to the carburator. Some were preset and others were adjustable. I THINK that it should be around 5-9 PSI. The most common problem I use to see with this system was that the carburator fuel needed to be set. There should be a short linkage on the side of the carb. Made of aluminum. Hold the center with vice grips and loosen the jam nut on each end a few turns. One end is left handed thread. Start the machine and allow to idle. Shorten or lengthen the rod by turning with your finger and thumb until it "sweetens up". Snug the jam nuts gently and you are finished.
If it is an Impco style fuel system post it to let us know and we can address that style.
Steve

Posted 14 Oct 2009 05:35 AM

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edward_t
North Carolina, United States

I would say that the spark plug wires ay "look ok" but until you put a good tunup on this unit, looks are not all that important.

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webhome = forktechs.com

Posted 14 Oct 2009 08:14 AM

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mrfixit
New York, United States

Sounds like it is not getting enough fuel and running lean.

Posted 14 Oct 2009 10:51 AM

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rick_v
Illinois, United States

Thanks for the replies.

Based on your description it does NOT sound like I have the original regulator setup. There is nothing on the thermostat housing. I will get some more details for you on the regulator and the routing of the fuel lines.

Regarding the lean condition, I tried adjusting that on the carb and it did not really make any difference. I had someone bring the rpm up fairly high while running the forklift and adjusted the high speed jet. I turned it in to the point that it went lean and started to drop rpm. Then increased jet setting and continued to increase 2 to 3 turns more, no real effect on running.

Rick

Modified 15 Oct 2009 02:15 AM
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bigGlittlestar
United States

Doesnt sound like a fuel problem to me. High RPM's require the most fuel and you say once it gets to that range its OK. The problem seems to be in the transition area from low RPM's to high RPM's. If I were working on it and I was certain the simple stuff like plugs, wires, points etc. were OK. I would pull the distributor and clean and lube it, it sounds like the advance is frozen. If it is not advancing under accelleration or load you will have the same stumbling, missing situation at mid range.

Modified 15 Oct 2009 05:39 AM
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rick_v
Illinois, United States

What should the timing be at idle and then once advanced. I can put a light on it and see if the advance is the issue.

Thanks,
Rick

Posted 15 Oct 2009 11:05 PM

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rick_v
Illinois, United States

Update, we replaced the regulator and there was a slight improvement but still had the issue. I checked the advance weights in the distributor and they were ok. Had it running and adjusted timing and it is running much better. Timing must have been off.

Thanks for the ideas,
Rick

Posted 22 Oct 2009 01:42 AM

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