I have an '06 Rubicon with only 23 hours on it. It has never started all that well, and I routinely needed to use the primer, even in warmer weather.

A few weeks ago, it wouldn't fire, so I had to use the primer again as usual. It would only run for a couple seconds after hitting the primer, and choked and sputtered for a few more seconds if I hammered on the accelerator. the choke doesn't make a whole lot of difference. After a long time, I finally coaxed it to run by revving it up, but it just stopped dead after driving it around for about 5 minutes. Loaded it on a trailer, took it to the shop, and of course it started right up for them. They did the first maintenance on it, including checking the carb for crud. They started it many times over a couple weeks, but could not duplicate the problem.

I took it off the trailer yesterday, started right up. When I went to start it again, it needed the primer, but did run. Ran it several times during the day, put a few miles on it, and re-loaded on the trailer. Went to start it back at home again, and it wouldn't start. It will run for a few seconds after hitting the primer, but then quits. If I hit the primer then hammer the accelerator, it makes a feeble attempt to run, but still kills after a few seconds.

It sounds to me like I am not getting gas to the carb, except for the primer and some from the accelerator pump (does it have one?). If it is not crud in the lines, what else could be stopping the fuel flow intermittently like this? A sensor? The shop did not find anything... Help???

 

Wow, sorry for the trouble. But I would start by following your fuel line from the tank to the carb. Make sure it isn't getting pinched. And yes it could have some trash in the carb jets. It depends how long it sat with fuel in it. I assume you have added gas to it? You might want to drain and refill with new gas. Maybe water in it? Also I know this is pretty far off, but make sure your plug wire is seated on the plug. It can make a problem like this also.

 

There is not an accelerator pump on the Rubicon carb.

How did the shop check for crud? Did they just remove the float bowl? A complete carb clean will eliminate any possibility of the carb causing the problem. From you description it sounds like fuel, however, if it's intermittent there's a possibility it could be electrical.

Where in Wisconsin are you from???

 

You should check the valve clearances, this should be done as part of the first maintence ; and you should add some seafoam to the fuel tank when you clean the carb ! Seafoam is a fuel cleaner/stabilizer that will clean the fuel system and the combustion chamber , you can get the seafoam at O'Reallys , Auto Zone and Advance Auto Parts Stores ! I got mine at O'Reallys for $4.99 + tax , it may vary according to your local ! ..............williebee

 

Thanks for the advice (I am near Monroe). This problem is very intermittent, so I don't think it is something constant like a pinched fuel line. Fire doesn't seem to be the problem, since it almost always runs on the primer fuel. Everything leads me to a fuel problem.

My first guess was a bad needle valve or float in the carb, which could allow the bowl to run dry - if this was the case, it would run on primer fuel but then starve out, which it does. However, if this was the problem, then it should normally kill while it was running, not on startup. If it was running fine on shutdown, then the bowl should still have plenty of gas to get it started again. So that leads me to something like a sensor or switch that shuts off the fuel flow. My problem is that I just don't know these machines well enough...

I read somewhere that there is a screw and hose somewhere on the carb to drain the carb bowl. If I can get it to screw up again, I could try draining the carb, to see if there is any fuel in it. That would tell me if it is the float or needle valve. Any other suggestions for switches or sensors that would shut off the gas?