Yale G83P-040:
Propane fuel system problems and Velocity Governor question

Yale G83P-040
Chrysler slant 6 engine

Velocity Governor question*

Propane forklift started running rough and stalling, restarts got harder and longer till
the thing would only just fire a couple times but not start up.

Had an old BEAM regulator and carb.
Since I got the machine 3-4 years ago, I knew the regulator had problems because
when you turn the key 'on' the fuel solenoid clicks, and you could hear propane hissing
into the carb....even before the engine is running.

SO.....got a new IMPCO regulator and carb, installed and mounted.

STILL does the same thing with these new parts, although, it does idle and will
rev up, but starts a lean out trend over 20-30 seconds and then stalls.

Sometimes it seems rich enough and revs up crisply, and idles, then it 'goes lean', runs rough, stumbles and eventually dies after 20-30-60 seconds.

There is a velocity governor under the carb........

* My key question is, HOW DO THEY FAIL ?
Is there a diaphragm inside that can break and let in a giant vacuum leak?

Seems like there is an intermittent lean out condition going on here.
  • Posted 21 Nov 2012 09:35
  • Modified 21 Nov 2012 10:07 by poster
  • Discussion started by dkmc
  • New York, United States
Showing items 1 - 15 of 55 results.
Just wanted to say....I did install a 'small cap' HEI dizzy in the slant six. The distributor is from a mid-1980's chevy V6.....aka
S10 pickup. I did some testing with a standard round oil filled coil
and the HEI 'epoxy filled' square coil.
The round coil will reliably throw a spark about 3/4 inch, and the HEI coil will reliably spark up to about an 1-1/8" wide gap.
It runs really nice now, starts very reliably as well.

The other thing I did was toss the old prestolite alternator that was over charging, and installed a small Denso unit off some Toyota car. Nice little alternator, and the voltage is rock steady at all engine RPM now.

Just got in a new clutch disc...(oil spray setup)..the old one has always stuck to the flywheel, and I intend to fix that annoyance shortly.

  • Posted 17 Jan 2013 01:47
  • Modified 17 Jan 2013 01:49 by poster
  • Reply by dkmc
  • New York, United States
Is the vacuum hose hooked to the Beam regulator? It must sense vacuum to allow the fuel to turn on.
  • Posted 16 Jan 2013 22:03
  • Reply by mrfixit
  • New York, United States
you know, this discussion has sparked some old memories in me from dealing with those old ignition systems years ago. I remember having some of the same issues like this. One of our fixes with points issues etc was to convert the distributor to a breakerless points system. We would get a perlux kit and install it in the distributor and that generally would solve those issues.

Gee i had forgotten all about those good times lol
  • Posted 16 Jan 2013 21:31
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
make sure the coil and it's mounting bracket are well grounded.
  • Posted 16 Jan 2013 21:09
  • Reply by edward_t
  • South Carolina, United States
"it's not rocket surgery"
I have a Yale forklift. Was converted to L.P.. had to replace piston rings. Pulled it apart had to wait on boss to get parts. Took him 4 months. Got it back togeather and it turns over made sure everything engine side was right. Wasn't getting anything to carb. Replaced the beam T-60 regulator. Still not getting fuel from regulator to carb ring. Not sure of the exact part name. But I get fuel to the regulator but nothing coming out of the regulator. Any help greatly appreciate.
Thank you
Sgt B
  • Posted 16 Jan 2013 08:07
  • Reply by sgtbasham
  • Texas, United States
/I think I just saw a ghost./


/1995 Hyster S-50 XL/

1995! Wow!
This past summer I operated a 1988 Komotsu 8000lb pneu. tire.
What a joy to use!
Forklift ergonomics have come a LONG way in 30-40 years.
Even between the 1953 and 1970!
  • Posted 16 Dec 2012 08:36
  • Reply by dkmc
  • New York, United States
1953 Chrysler flat head six!
I think I just saw a ghost. We used to have a 1962 Yale with a Chrysler flat head six in it at our old shop. We ran that thing up until April of 2006 when the company had an opportunity to replace it with a 1995 Hyster S-50 XL with 150" lift capability.
Yes, the old flat head six had a persnickety ignition system.
Seems like we were always having to reset the breaker points gap. We looked into converting it to a Pertronix electronic breakerless set up but we were unable to obtain a conversion kit from Pertronix, so we just kept on with the old girl like she was born until she was replaced with the Hyster.
  • Posted 16 Dec 2012 08:27
  • Reply by L1ftmech
  • Tennessee, United States
I'm sure it will be an over-reaction to the problem, but
here is what I intend to do to address this:

I had a 1953 Yale High Cowl with a Chrysler IND30
flat head six. It's still around, as i sold it to one of the neighboring
businesses here. 20 years ago I had rebuilt that forklift nearly from
bare frame up. Engine was completely rebuilt as well.
It served me well.

That unit always had problems that were ignition related.
Damp conditions, cold, high humidity, etc.
Seemed like it always was running intermittently on less than 6 cylinders, despite being in good tune, with carburetor rebuilt, etc.

One day about 10+ years ago, I had enough.
I went to the auto recyclers and got a GM HEI distributor from
a 90 degree V6 Chevy engine.
I machined the distributor, fit the old gear on the shaft and installed it in the engine with all the junk yard parts still in it (cap, rotor, module, etc). A Saturday afternoon project really....

To this day, that forklift starts and runs well on all 6 cylinders in all weather and temperature conditions. Never has had any further ignition system maintenance done on it.

In the near future, I will do the same for the Slant Six in this 1970 Yale that has been discussed in this thread, and thus will end it's ignition problems as well.

There is nothing wrong with using old equipment in my opinion, as long as it can be made to be reliable and remain low cost to operate.

  • Posted 16 Dec 2012 06:47
  • Modified 16 Dec 2012 06:48 by poster
  • Reply by dkmc
  • New York, United States
dkmc, I tip my hat and give you the nod for finding the true cause of the problem.
I especially like how you employed the induction timing light to evaluate the spark. Good move!
This thread was beginning to take on the persona of a mystery novel.
  • Posted 16 Dec 2012 00:26
  • Reply by L1ftmech
  • Tennessee, United States
yep dkmc
its those little things that get ya
run into this type of thing sometimes and its a lesson learned, be it an expensive lesson but none the less a lesson.

Glad you figured it out
good job :)
  • Posted 15 Dec 2012 21:21
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!

For possible future reference and help in others trouble shooting adventures....

All the new IMPCO parts are installed.

I called the IMPCO tech dept and they said the "Vapor Fuel Hose" that connects between the regulator and mixer should be at least 5/8 ID and preferably 3/4 ID.
Anything smaller could cause the regulator to not work correctly.

The same problem still existed!
An "apparent" lean condition off idle with eventual stalling all together after a period of time, usually 15-20 minutes.

The solution:


Old hot rodders saying:
95% of Carburetor problems are electrical.

After a run of about 20 minutes, it got rough, stumbled and died as usual.
I started to think what else it could -possibly- be.
So I hooked #1 spark plug wire to an external plug.
And I hooked up a timing light to the coil wire.
Started engine at idle and watched.
After 2-3 minutes at idle, the engine began to run rough........I could actually see the spark on the plug hooked to #1 wire get thinner and weaker, and more orange.
30 seconds later, the timing light stopped functioning!
5 seconds after that the plug stopped firing and engine quit.

Crank engine......no spark.

Wait 5 minutes, crank engine, starts back up.

Theory and conclusion:
My guess is the spark was so weak it was just enough to allow the engine to start and run, but with increased throttle, and added fuel, the spark was simply extinguished.
Spark was stronger for first 15-20 minutes of operation.

Coil did not get hot or even warm to touch.

Installed old, use, poor looking coil to test and engine runs
perfectly. Idles smooth as a watch with excellent pick-up and power.

Thanks for all the info and responses.

  • Posted 15 Dec 2012 02:02
  • Reply by dkmc
  • New York, United States
$45.00! WOW! I have bought complete Model J Convertors for slightly over $30.00 in the past.
Well, anyhow......$14.00 is a very good price.
  • Posted 27 Nov 2012 01:29
  • Reply by L1ftmech
  • Tennessee, United States
I called the local Toyoda/Crown/Clark dealer and they had the kit in stock.

$45 !!

So I called Carb & Turbo systems in Shakopee, MN
They also had it in stock and the price was

A few extra days wait, but....
  • Posted 27 Nov 2012 01:15
  • Reply by dkmc
  • New York, United States
Have you checked the propane coupler at the propane tank? The female brass coupler should be about 1/4 inch from large nut on the male half of the coupler. Make sure that there are no gaskets or O-rings inside the female brass coupler. The 2 nipples inside the coupler have to be fully depressed to allow full fuel flow.

Have you checked the fuel lock off? Sometimes (albiet rarely) the solnoid initially opens the lock off, only to have the solnoid fail & the lock off closes. Try by-passing the lock off to see if the symptoms change. Note- even with the fuel line connected directly to the vaporizer & the fuel tank open, there should be no fuel flow out of the vaporizer until the vaporizer senses a draw from the mixer.
  • Posted 25 Nov 2012 11:08
  • Reply by bbforks
  • Pennsylvania, United States
bbforks (at) Hotmail (dot) com
Customers love technology- until they have to pay to fix it!
Actually I never had any doubts..... :-)
  • Posted 25 Nov 2012 03:53
  • Reply by dkmc
  • New York, United States

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