Carb Issues?

I am the proud new owner of a 1971 CJ5 with a 258 and Carter carb. Runs and drives fine for the most part. However, starting when hot can be difficult, taking a bit of cranking the engine followed by a puff of black smoke and sputtering before she smooths out. Noticed the oil has a fuel smell and some fuel soaked into the air filter today, as well. My assumption is this is all carb related. I have no experience with Carters and have very limited free time, so hoping you guys could help speed up my diagnosis. Thanks!

 

Yes, if the VIN starts with "J2" it's a '72 regardless of the year of manufacture.

Is the choke flap open when the engine is at operating temperature?

 

Your running Rich . Make sure you've got a fully operating choke & a new fuel and air filter. You may also need a carb rebuild. Varnish in the float or metering valves ?

 

Haven't opened up the carb yet, so can't tell you about the state of the float or valves. Not sure about the choke flap either. I'll get it warmed up and get back to you. It does have new fuel and filter.

 

Choke valve is fully open when warmed up. VIN does start with J2, as well. Good to know.

 

Quick update. I did open up the carb, no varnish and everything looked good. Didn't end up messing with anything since since the hard warm starts are just a mild inconvenience and she purrs on the highway. Figured I'd rebuild the carb and go over everything when I had the time. Anyways, I just took her on a 400+ mile road trip this weekend. Did great on the highway, but when I slowed down offroad it started to vaporlock, sputter and die. Looked like fuel was boiling in the bowl and then overflowing onto the intake. I do not have a working temp gauge, but it did not seem like the engine was overheating terrible bad. Once I was back on the highway the problem went away and I drove her 200 problem free miles home. My first guess is this a float and/or needle valve issue combined with a bit of overheating with the slow offroad speed. But before I start chasing gremlins I figured I'd ask the experts. Thanks!

 

Oh yeah..........have you ever done a major tuneup to your Rig ? Changing your fuel pump may be part of this , if you don't have the time to check that its providing the necessary volume output . Then make sure any fuel return lines & vent lines are in good shape . Get your temp gauge working & check the timing . Believe me , I also have seen a can of Quality fuel cleaner & a new gas cap do wonders..

 

Troy ,

If the thing is stumbling on startup when hot only, it could be the heat riser in the exhaust manifold is stuck in the 'carb heat' mode all the time. If that's the case then when it's shut off hot, the fuel can boil in the carb and flood the manifold with, as well as giving you a low float level. Just a thought.

Where in Az are you? I'm south of Phx in the Casa Grande area if you need someone to help tinker on it! I'm an old guy who used to work on vehicles back when these things were new and the world a little younger!

 

A little Seafoam sometimes works wonders.