Posted: Sun Mar 07, 2021 6:40 pm Post subject: Carter YS 950S, no check ball or weight
Rebuilding a Carter YS 950S. There was no check ball or weight when disassembled. It did not fall out, I was looking for them. What would the carb symptoms be without these?
With the engine running the manifold suction would draw extra gas thru the open discharge port all the time. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
It would be rich during start and very possibly lean at low manifold pressure/Higher RPM. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Oct 02, 2014 Posts: 2005 Location: South Carolina, Dorchester County
Posted: Mon Mar 08, 2021 6:10 pm Post subject:
Maybe it's just me JeepDaddy, but do you suppose anybody ever removed those pieces out of a carb just to see how it might act? I could be wrong (often am) but doubt it this time. Bottom line --- obviously the carb ain't right.
I surely understand why you ask, and why you want to know if replacing those pieces might fix your hard starting problem --- but maybe it's time to just get on with it and see for yourself? My bet is a properly rebuilt carb will certainly help. And it sure can't hurt (except your wallet). Got to be done one way or another anyway, right?
Don't expect that rebuilding the carb will fix the low compression on #3 and 4 though.....
Reading your two posts about missing pieces, I had to laugh (no offense), thinking it might be easier for you to start listing the parts it does have rather than the parts that are missing? The list might be shorter.
Good luck! _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
Update for those that have followed my adventure.
The Carter YS950S carb has been disassembled, cleaned and rebuilt using TM 9-1826A..
During disassembly I discovered it was missing parts - the check ball and weight and the metering rod diaphragm spring. The accelerator pump and metering rod diaphragms were old, no longer pliable and in rough shape.
I used a rebuild kit was from Midwest Military (same as AJP) - a very complete kit for a comprehensive rebuild.
It runs.
Starting requires full choke and a little throttle.
Mixture screw has been adjusted.
It does require choke for awhile, maybe a vacuum leak?
Or is this the nature of the YS950S?
It does require choke for awhile, maybe a vacuum leak?
Or is this the nature of the YS950S?
All YS carbs require choking on initial start. Remember the engine is not idling yet and that accelerator pump diaphragm requires a good deal of vacuum to operate. In your case you are already at a loss for adequate vacuum because of your two low compression cylinders which cannot keep up. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
I noted the 1952 TM 9-804A M38A1 starting procedures p. 24, par. 40 c) "pull the throttle control out approximately three-quarters to one inch"
The revised 1955 TM 9-8014 eliminated mention of pulling out the throttle control as part of the starting procedures.
Interesting change, I wonder why?
Wouldn't the vacuum operated accelerator pump benefit from an open throttle and closed choke to maximize vacuum in the carb bore, thereby getting your best shot of gas while cranking?
Joined: May 14, 2013 Posts: 201 Location: Between Crosslake and Emily, Minnesota
Posted: Sun Mar 14, 2021 12:56 pm Post subject:
Several years ago I also rebuilt the YS950 carb on my F134. Like you, there was no check ball or weight. My rebuild kit was also purchased from MM. When I rebuilt the carb, I used the weight and check ball from the rebuild kit. Just so you know, I am not sure that I needed to rebuild the carb, I was having no issues, but did it anyhow.
What differences did I notice before and after the rebuild (ie, before and after having the check ball and weight installed in the carb)?
Not much difference. I would say, however, at a cold start, it seems to be easier to flood the engine now compared to before. I have always cold started with the choke pulled all the way out. Now, I have to be very quick to push the choke in after the first fire. _________________ Steve Stark - 1955 M38A1 MD #85388
Member - MVPA #35153
Member - Red Bull Historic Military Vehicle Association
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