Carb question

Dragnet · Post by **Dragnet** » Wed May 23, 2007 7:14 pm

Hi guys,

If I had water damage though out the fuel system could that have messed up my carb beyond a rebuilt kit? Because after I got the jeep I found out about the entire fuel system was corrupt with water. I had a local mechanic rebuild the carb with a kit bought from one of the online jeep stores (and I replaced the rest of the fuel system) but she just idles badly. It seems OK when I put a load on it but the idle is 30 secs of smooth...12 secs of sputter...back to smooth and so on. Could some of the parts been damaged that the rebuilt kit didn't fix? If so should I just get a new one? I brought her to another mechanic today so I should hear something tomorrow but in case it the old "I can't fix it" I want to be ready to order so I can get it on before my first parade ever on Monday. Thanks

Post by **wesk** » Wed May 23, 2007 8:22 pm

You didn't tell us what jeep model and what carb model.

There is only one true good quality complete rebuild kit for the military YS carbs with all the correct parts for a COMPLETE OVERHAUL. It's sold by John at Midwest Military and George at Army Jeeps Parts.

Now-a-days "kitting a carb" usually only means new gaskets, rubber parts and a jet or two.

A real carb overhaul includes the removal of ALL closeout plugs and a VERY THOROUGH boiling out of the carb and ALL of it's passageways.

Dragnet · Post by **Dragnet** » Wed May 23, 2007 9:48 pm

I don't know what carb model it is but it's on my 1952 M38 A1 Willys. As far as I know it's the same one that came on it but I don't know the history of the jeep at all. Also I think I got the kit though Rapco last year. I knew nothing about any of this (army jeeps) at the time or I would have checked here first, like now.

So does it sound like the carb has damage that can't be fixed with a cheap rebuild kit? If so where do you recommend I get a replacement carb.? Thanks.

Post by **wesk** » Wed May 23, 2007 11:05 pm

You need to know what model carb to order the correct kit.

This is the correct YS950S carb

This is the same carb inplace on the engine.

This is a civilian YF series carb.

If you want to just order a correct freshly overhauled carb call John at Midwest Military http://www.midwestmil.com/

Dragnet · Post by **Dragnet** » Thu May 24, 2007 5:16 am

It's the YS950S carb. I will call John today to get a price. Thanks Wesk.

Dragnet · Post by **Dragnet** » Thu May 24, 2007 3:26 pm

OK got her back from the mechanic today and he did all he could do (which is not enough). I called John and he is going to be sending me a new carb overnight so I can be in my first parade on Monday. One last question, should that be good to go right out of the box? Thanks and everyone have a great weekend and salute to all of our veterans. Thank you ALL!

Post by **wesk** » Thu May 24, 2007 6:30 pm

Yes and no. Sometimes you get lucky but usually you will have to tweak the idle mixture and idle speed. The YS950S adjustment specs are:

Start with idle mixture screw screwed all the way in and then back it out 1 1/2 turns. Start it up and set idle speed at 700 RPM while maintaining a smooth idle with the mixture adjustment.

This will get you through your parade. A tach and vacuum gage is very helpful when doing this so first chance after your parade try to get her to the mechanic for a finer adjustment.

Dragnet · Post by **Dragnet** » Thu May 24, 2007 7:36 pm

Fantastic... Thanks again wesk. I can't wait to get the new one on.

Dragnet · Post by **Dragnet** » Fri May 25, 2007 10:41 pm

Well UPS dropped it off today (Friday) at 2pm and what a beautiful new carb it is. I got her all done tonight about midnight (got a late start) so because it is late I will be firing her up tomorrow after my fresh eyes give everything the once over again. Fingers crossed....I'll let you know.

Dragnet · Post by **Dragnet** » Sun May 27, 2007 7:24 am

After I had to throw a new choke cable on she fired up fine. I didn't get a chance to test drive her yet because it's been raining but she sure does idle smooth for a change and that was right out of the box. Weather is suppose to clear later today so I can test drive her then.

One other thing, I seem to get a lot of air in my fuel line. I have checked and rechecked all the fittings and I put new gaskets on the breather and pickup on the gas tank last year. What else can I do or check?

Post by **wesk** » Sun May 27, 2007 7:56 am

If you have the early fording vent system still installed make sure the tank to air cleaner vent is open (not plugged up). If you have the two position fording gas cap make sure it is in the vented position. If neither of these is a problem then any pin hole or slightly loose fitting will allow air to be sucked in by the fuel pump but will not show much evidence of leaking gas when not running. You would have to disconnect the feed line at the pump and tank and pressure or vacuum test it alone. If that checks good you'll have to open the tank at the pickup strainer and check the pickup line and fittings inside the tank. A rust hole in a pickup line inside the tank will allow air to get sucked in by the pump anytime the fuel level is lower than the rust hole even though the pump is still able to pull fuel from the tank.

usma41 · Post by **usma41** » Mon Jun 04, 2007 12:23 pm

I'm glad you have it running again. But it sounds like and old problem with your old carb. Wrong gasket on the base section of the carb. Been there done that. You have two different carbs for this vehicle and if you have the wrong gasket on the base section they you have the problem you described. Because all your doing is dumping fuel directly into the manifold.

keats · Post by **keats** » Mon Jun 04, 2007 5:34 pm

in your post on the carb question you mention two different carbs for the M38. I have pondered this question for some time with no information as to why there are two versions and for only a short production period. I have pictures of two versions in my photo gallery. Can you shed an light into why two carbs were produced. Advantages of either? Which can first, though I figure the one missing the side chamber was later? It may be just a step forward as they developed the M38A1 and made design changes, but whould like to see some factual data on all this.

Thanks, Gary Keating

Post by **wesk** » Mon Jun 04, 2007 8:06 pm

I would guess since there's only one part number and model number carb for the M38 (YS637S) (7372509) (2910-737-2509) (G740-7372509) found in all the pubs that what you see is merely a subtle product improvement or someone has used the bowl or base from another model Carter during a rebuild.

keats · Post by **keats** » Mon Jun 04, 2007 9:34 pm

I have seen many carbs in both variations on M38s, and on ebay for sale so definitely not a one shot deal of using a different carb section off another carb. As I did state it probably was a step up to the M38A1 carb that doesn't have the extra section cast in it. Why it was done and what difference in performance are my questions. Subtle or not the pictures are proof they exist. Regardless of part numbers the fact remains there were two carb castings for the M38. Seems odd to me with all the other subtle M38 mysteries that are out there and continually tossed about that this one remains basically untouched and an answer not found. I have tried several avenues of research but all have led to nothing.

If there is any factual info out there (not guesses) I would just like to know as a little pet interest of mine.