Yale G83P-040
1970
Chrysler slant 6 engine
Velocity Governor question*
Symptoms:
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.
Showing items 31 - 45 of 55 results.
The 1/2" copper is more like 3/8 ID
So your thinking on this is that.......the mixer cannot sufficiently pull enough vacuum signal from the regulator to cause adequate fuel flow......?
That may well be something to look into.
Big difference between3/8 ID and 5/8 ID
I would try it, 5/8 hose is I.D. 1/2 tubeing is O.D. the difference might just do it.I have seen tubeing at the output but its larger than 1/2
So you think the 1/2" copper line is too small?
That does not explain the times it does run ok momentarily for 20-30 seconds.
true,( too many posts ),previously it was suggested a 5/8 dry gas hose between the vaporizer and mixer be installed, it does not mention (or i missed) if one was installed. I dont recall seeing an Impco system useing 1/2in. tubeing in that application.If the engine used to have an Impco vaporizer that ran with this tubeing I would not mention it. It just seems to be the only unusual item in the system as described.
Agree as far as 100 HP output.
It does not take 100HP worth of fuel to make this engine idle or even run up to speed with no load
after a crash course on chrysler slant 6 engines I discovered that the smallest (the 170) STARTED @approx 100hp (75KW) you have a 198 or 225cid, the model J can only deliver up to 75KW engines , you are possibly over the edge of what this Reg. can deliver. something to consider
Try as you guys might you cannot present any challenge that I have not already attempted.
I wish someone would have success !
I'm at a total loss as to where to look or what to try next.
Sadly, I did rotate the 1/4 turn valve on the mixer......tried it both rich and then lean.......no difference.
I called IMPCO and they refereed me to their tech support distributor who specifically told me the Model J and the CM100 is in fact the very components they recommend for this engine.
I had the mod J, and bought the CM100 from them last week.
My mind is per-occupied trying to find some possible clue as to what this may be......
Sometime tomorrow I will try a different coil.
And I may make a spacer to take the place of the velocity governor----just for a test.
Forgot to mention that a worn throttle body can cause a vaccume leak and a lean condition , also (Im no impco guru) but model J vaporizers are mostly mounted in 4 cylinder applications ,you are trying to feed 6 (1970s ) cyls.A vaccume leak ,if bad enough could introduce enough unwanted air into the manifold to lean out a regulator at the edge of its output limits. Ensure your vaporizer is equipped with a blue secondary spring (highest output pressure). If there is no leak at the throttle shaft ,the proper spring is installed,and the previously mentioned fuel adjustment does not work enough, you may need to go to a higher volume reg.
Has not been previously mentioned so here is some thing to consider. Are you aware of the air fuel (power) adjustment hidden below the inlet to the impco mixer (quarter turn valve you can turn with seven sixteenths wrench,you need an inspection mirror to see it) crank towards "R" all the way , see if that makes any diff
I guess the proper way to test is to install a pressure gauge in the primary test port on the regulator, start it, and watch what happens.
Yes, original fuel solenoid from the BEAM system.
Is there something special about the IMPCO VFF-30 vacuum lockoff that the Model J needs it ??
I think Mr fixit is closer to the mark here, not being familiar with this truck model myself I can say I'm am familiar with beam regulators and impco fuel systems. When old beam systems where used they had an inline fuel solenoid and filter combined these would eventually get filled with the heavy ends and clog up. Most impco systems I've come across don't have a fuel lock of solenoid but a vacuum lock off unit and filter that feeds the fuel regulator. Have you left the original fuel solenoid in the line when you changed to the impco units.
Regards Titus
"Could the regulator mixer be defective out of the box?"
Not really that likely. Be careful of your terminology in describing things. Mixer is the part that is sometimes called a carburetor.
Carburetor is incorrect because it is metering a gaseous fuel instead of atomizing a liquid fuel.
If you did the lean out test properly by spraying an alternate fuel into the mixer intake when the stalling began.....and you noticed an improvement in the running while spraying.........then fuel deficiency is the culprit, not ignition.
Not much of a practical way to actually test the regulator/vaporizer for fuel flow volume.
I wonder if 1/2" copper is large enough to operate the J model secondary valve in this application.
If you could substitute a larger diameter vapor hose from the regulator/vaporizer to the mixer that would solve that question.
No hose between the reg and mixer......brand new 1/2" copper line. The prev. Beam setup also used a 1/2" copper line.
I am going to closely go over the ignition system again, maybe swap coils also.
This seems like a very simple fuel system and very simple ignition system.
Very frustrating symptoms that make no sense.
There is nothing else to replace with new parts.
Could the regulator mixer be defective out of the box?
Yes did that this morning first thing....seems like plenty of fuel flow for 4-5 seconds and beyond.
The cap, rotor, points, condenser all have less than 30 minutes run time on them. Will hook timing light to coil and watch that....
Would be handy to have an automotive scope!
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