M38 Cdn Carb Help

[Mike K]

I guess this is a original Carter ?

There is a guy on the G503 forum (scoutpilot)) who runs a business, he rebuilds these , he knows more than any of us will ever know. He will freely offer advice.

Is the throttle shaft worn ? A slight slop in the shaft and air will be sucked in. This air leak upsets the idle citcuits.

Also, a inlet manifold air leak ?

Have you seen this https://oldjeepcarbs.com/

Edit. Looks like a YS Carter was fitted. The old gaskets from a NOS kit will have shrunk , might not be sealing ?

[rob love]

A common problem I run into on the Jeep carbs is that, with todays ethanol poisoned fuel, those two little diaphragms on the front and rear of the carb will crack or puncture and you will not get a good running engine. Usually though, that is more of a flooding situation. I have had better luck with the ethanol resistant kits from places like midwest military, but even better is to stay away from the ethanol fuel as much as possible.

Note there are also conflicting illustrations in the manual on which side the little spring goes on one of those diaphragms. I also go 5/16 on the float level by using a long shanked bolt.

There is some good carb info here: http://www.willysmjeeps.com/v2/modul...wtopic&t=11341

[Peter Phillips]

Originally Posted by rob love

A common problem I run into on the Jeep carbs is that, with todays ethanol poisoned fuel, those two little diaphragms on the front and rear of the carb will crack or puncture and you will not get a good running engine. Usually though, that is more of a flooding situation. I have had better luck with the ethanol resistant kits from places like midwest military, but even better is to stay away from the ethanol fuel as much as possible.

Note there are also conflicting illustrations in the manual on which side the little spring goes on one of those diaphragms. I also go 5/16 on the float level by using a long shanked bolt.

There is some good carb info here: http://www.willysmjeeps.com/v2/modul...wtopic&t=11341

Hi Rob,
I thought about the ethanol attacking old components but figured in the short term this thing should go for the summer at least until I get a newer one ordered....could be wrong here, lol. I'm thinking a newer kit is in the making and I'll definitely try the new float height at 5/16".
I'll look into the WillysM Jeep link, thanks!

As an added conundrum, I took another YS carb and gave it a thorough cleaning and adjusted the float and the jeep runs the same way which I found ironic. Could a fuel pump ever be able to overpressure past a needle and seat?
BTW, great to bump into you again at the Calgary Gun Show

[rob love]

A fuel pump is way more likely to produce less to no pressure than too much. They regulate by the spring under the diaphragm. Springs get weaker, not stronger.
A common problem, even in service, was the very fine particles of rust from the tank would make it through the course in tank filter, and either unsent the checkvalves in the pump or lodge in the float valve, causing flooding. The solution is to install an online filter, either before the pump or at the carb. The telltale sign this is the problem will be a very fine reddish sediment in the bottom of the float bowl.

If you used an original gasket kit, and the rubber was not happy with the ethanol, the bad results can occur quickly. Overall, they are a simple carb with little that can go wrong aside from those two diaphragm.

The calgary show is a great place to meet the guys from out that way. Only problem is there are way too many buyers vying for my time which cuts into the visitation time.

[Peter Phillips]

Morning Rob

Well I've had some success finally. I'm hoping this will get me moveable for the short term as I just ordered a new kit from Midwest Military.

Going through the TM was absolutely helpful in understanding the different circuit flows and cleaning (again and again) along the flow paths a few more times. I still can't definitively say I did anything different or a visible piece of gunk was dislodged....I'll take the win anyways. One thing I found funny in measuring the 3 metering rods I have (original, new kit and parts carb) and all 3 measure differently at 1.346, 1.319 and 1.356 respectively. Idle is good but it stumbles if I give it too much gas. I have the 1.356 rod in it now and may try the others.
I'm getting mixed opinions on the laminated base gasket...is it supposed to be solid or have 4 slots cut out, or have the V-shaped diffuser below? I'm using the solid one that came with the kit.

Update: Took her out for a test run and after only a few miles it really started to run/idle great. Too many ice creams will go down range now that the Mrs and me can go cruising again

I'll install a filter as suggested.

[Peter Phillips]

Originally Posted by Mike Kelly

I guess this is a original Carter ?

There is a guy on the G503 forum (scoutpilot)) who runs a business, he rebuilds these , he knows more than any of us will ever know. He will freely offer advice.

Is the throttle shaft worn ? A slight slop in the shaft and air will be sucked in. This air leak upsets the idle citcuits.

Also, a inlet manifold air leak ?

Have you seen this https://oldjeepcarbs.com/

Edit. Looks like a YS Carter was fitted. The old gaskets from a NOS kit will have shrunk , might not be sealing ?

Hi Mike,
Original YS carb
Throttle shaft is tight...in fact while I had it running I sprayed carb cleaner around every gasket mating surface and the shaft to hear a change in engine rpm, nothing I could tell.

The new base gasket was definitely garbage and leaked. I used the old thicker gasket with success.

I will look into those references you mentioned, thanks!