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 21 - 40 of 55 results.
by closing off the air intake hose your equalizing the air/fuel mixture which tells me that it is not getting enough fuel if that makes it run better.
by pressing the primer button your adding fuel to the mix so all this tells me the regulator is not delivering enough fuel.
take a look on the origional regulator and see that the W.P rating is on it, then look on the new one you installed and see what it is.
The W.P rating is the working pressure rating, some are different than others. But all in all since this regulator is so old i'd be willing to bet it is either the wrong pressure rating OR what others have said, it may have a bad diaphram or something. Also make sure the fuel filter isnt clogged up, we'll assume it is not since you already removed the fuel inlet line and got good squirt of raw gas from the line when you cracked the valve on the tank.
DMV, you aught to by your self a repair kit for this unit, it's a straight forward job to install the diaphragms and any springs you get with the kit, this unit did not come of another truck 25years ago did it. The thought being this will come in useful one day, I'm sure we have all done it at sometime or another.if that's the case then you may find that heavy ends have solidified in the honeycomb tracking as I call it, it's easy enough to clean out.
Regards Titus
What doo I look for??
How will I know a defective diaphragm?
Is it obvious?
Yes, a pin hole or a small tear could certainly explain the drop off after an initial good rev up.
Going to be interesting to hear about that diaphragm inspection.
Take the cover off the side with the push button and it's right there.
Well, the carb is new.....bought last week.
The reg. is unused, but 25 years old.
So I guess it would be the Reg.
Now my guess is the diaphram in the regulautor or carburetor leaks.
Mr fixit is definately on the right track here it sounds more and more like a blocked fuel filter, if there is a fuel stop solenoid at the base of the carb which is subject to vacuum activation then if there is a gasket or manifold leak then this may should down as the vacuum falls thus stalling the engine. It may not have a fuel stop solenoid if not set the power mixture valve to the half way mark,
Screw the idle mixture screw up fully and then back of four turns and see if the engine will idle as this should give the engine a reasonably rich mixture if it still stalls out you will have to look for an air leak or a blocked filter.
Regards Titus
Well......I spent an hour with it in a more relaxed and paicient
state of mind instead of trying to find a "pit stop" solution.
As a test I managed to install a piece of 5/8 ID hose in place of the 1/2" OD copper tube between the reg and "carb".
No difference in symtoms.....still goes lean after 20-30 seconds.
Here's the progress part:
I do now KNOW for certain it is going lean as I was able to help it by choking down the air inlet -carefully- and more precisely with my hand and actually keep it running.
The possible culprit:
In this process I have also found I can "play" with the primer button on the Model J and advert stalling altogether!
Matter of fact, after a short learning curve (lol) I found if I play the primer button in sync with the throttle, I can go from idle to wide open with no lean out.
And it seems if I just hold the primer button in with little force from my finger, the whole program seems to improve over the entire no load speed range.
Whe I leave the button alone, again, it will idle for 20-or-so seconds and then 'go lean'.
This Model J regulator has sat in a drawer for aprox. 25 years and was never used.
Is it possible time and age has damaged the internal rubber parts? There were no plugs in the ports, they did look clean, but I suppose it may have dust in it.......
I guess the next step is to do the pressure test and probably disassemble it for inspection.
Oh.......also had a timming light hooked up to the coil wire all the while, and it did seemed to be a steady output with no misses or shut offs.
sorry dk,
musta overlooked that part
was basing my response on your origional post only
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.
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