Carter YS 637S Caruretor

52_M38 · Post by **52_M38** » Sun Jan 21, 2007 9:42 am

I just installed a repro/rebuilt Carter YS 637S on my Jeep, and when I turn the Jeep over, liquid gas is forced out of the reservoir through the gasket between the carb's top plate and lower body. There's no kick from the previously running motor so I'm guessing no atomized gas is getting into the veturis at all.

Does anyone know wat could cause this? Do these guys put something in there to hold fast the float during shipping.

If anyone has any thoughts I would appreciate them.

Jacques · Post by **Jacques** » Sun Jan 21, 2007 8:35 pm

Fuel pump pressure?

Jacques

Post by **wesk** » Sun Jan 21, 2007 11:49 pm

If you installed a new mechanical fuel pump or an electrical pump we could suspect a fuel pressure issue. But since you didn't say you changed or added any pumps and you did say it was running before the crab swap then stay with the carb as the problem. The float may be stuck down or the needle may have some trash on it's seat. They do not fix the float fast for shipping.

52_M38 · Post by **52_M38** » Mon Jan 22, 2007 7:20 pm

I talked to the vendor and he clued me into the fact that you can't cap off the vent hole in the top of the carb that goes over to the xover tube. Currently, all the fording business is gone on my jeep, so I just capped that off (didn't know any better). That seems to have helped.

As far as I can tell now, the fuel is coming out of the large brass inlet that screws into the carb body. I didn't think I would need to teflon tape that, but that is what I am going to try next. I torqued on that thing perty good, and it was still leaking - it does not appear to be leaking from the the line coming from the fuel pump (I had already taped both ends of that fitting).

Thanks for tolerating the rookie questions!

Post by **wesk** » Tue Jan 23, 2007 11:09 pm

This would be a good time to post a photo depicting exactly where the gas is leaking from.

We did not mean your pump line may be leaking. We meant your pump pressure may be too high causing the fuel bowl to overfill. This can be caused by installing a mechanical pump without it's spacer or by installing an electric pump without a pressure regulator.

This overfilling is what we gathered was happening from your first post. Now you are saying it is leaking from a screw hole.

There has been several threads that were caused by the bowl vent being plugged or inadvertantly pressurized.

52_M38 · Post by **52_M38** » Wed Jan 24, 2007 6:22 am

The work continues, but the leak is gone - I went nuts with the teflon tape and no more leak. Might have been the only problem all along - I dunno. Hooked up the manual choke and throttle, and viola she's running.

Interesting to note though, at low idle it'll stall or at a slightly higher idle, "cycle" - i.e. run well, bog, run well, bog, in a cyclic fashion. If I keep the idle up (using the manual throttle), it'll run steady, but it seems like too high of an idle for normal operation (something is still not quite right). I don't have any way of tach-ing her right now to give you an idea of the RPM numbers which are obviously important here.

I stll have a tune-up to finish and the air intake isn't complete (take off air cleaner is on the way and hose from air cleaner to xover will be ordered today). I'm hoping between finishing up the air intake and the tune up (timing) she'll come around.

Progress is good, though.

Post by **wesk** » Wed Jan 24, 2007 9:11 am

None of the hardware threaded holes on that carb should need any sealant to keep fuel in. If they do then there is a crack near them. These cracks may also be causing the cycling symptons. I would seriously consider an immediate warranty settlement before the seller declines warranty because of things you may have done to the carb. The cyling symptons are also caused by induction leaks usually found at the carb to manifold gasket and at the manifold to block gaskets.

52_M38 · Post by **52_M38** » Wed Jan 24, 2007 5:09 pm

Wes, I hear you that the threads should not need taping. I've heard this from other folks as well.

But for the moment suppose the carb's housing is cracked (and was responsible for the leakage prior to taping). Why would taping the inlet threads have caused the (supposed) crack in the housing to stop leaking?

I'm not sure I understand this. It is bone dry now.

I will check the carb and manifold gaskets for leaks that could be responsible for the cycling.

usma41 · Post by **usma41** » Wed Jan 24, 2007 6:00 pm

Just had the same prob. The reason for this is you may have the wrong gasket installed between the manifold throat and the mid stage throat. You must remember there are two different throats for this carb. Wes can tell you more.

usma41 · Post by **usma41** » Wed Jan 24, 2007 6:04 pm

If the gasket is wrong (Orifice to large), then it will dump fuel into the manifold.

usma41 · Post by **usma41** » Wed Jan 24, 2007 6:09 pm

Someone had pictures of the two differant throats on here befor wes, who had them? You? The gaskets have to be the correct ones for each or it won't work.

OKCM38CDN · Post by **OKCM38CDN** » Wed Jan 24, 2007 9:52 pm

All fittings for the fuel lines to the carb need to be inverted flare, not regular flare.

If this is not done that may cause fuel leaks at the fittings also...

It did for me when I did my carb long ago... Taught me how to do inverted flares...

Hope this helps...

Post by **wesk** » Thu Jan 25, 2007 12:08 am

This is why I said post a carb photo with the exact area of the fuel leakage so we can be sure. Your description is not adequate for me to clearly and precisely determin where you were getting fuel leaking from.

I have many photos on my photo site of the differences in the carbs 3 main bodies and their porting.