Carb/fuel question

[TCapelle]

So the 67 11A has been out and about the last few weekends.
She starts right up and runs fine for about 20 minutes or until it "warms" up.
When I turn it off it will start again and run for a minute or two but then chug and conk out.

I pulled the fuel line at the carb and there is fuel being pumped.
If I dumb a little gas in the carb it will fire up and run just fine.

So I am guessing it is a carb problem but can't understand why it seems to act up after it has been ran and is warm then shut off and tried to be restarted,

Any thoughts/help?

Thx,
Tim

[kevin-ct]

How's the filter? What type of carb do you have?

[TCapelle]

Need some advice

I think I have a Zenith single barrel carb on my 2.25 five door- I see a 361v stamped on the carb.

Here is the issue-
Starts up fine when cold -can run the truck tarting it , turn off, fires right up again.
After a longer ride when the motor runs "hot" if you shut off the truck and then try to start it again it will die a few moments later and then not start.

I rerouted the fuel line to ensure it is going up hill and kept it away from the valve cover heat as best as I could.

When it dies and doesn't start I tried to manually move the throttle linkage- It doesn't "spray" any gas in the chamber like it does when I do the same thing when it is cold.

I took the fuel hose off the carb and crank the engine- after a few cranks of the engine I get gas to come out of the hose so I am assumming the fuel pump works. If I dump a little gas in the top of the carb it will start even when hot.

If I let it sit and cool it will start up again.

Any insight- Is it the carb? Is it a fuel pump issue? Vapor lock?

[scott]

maybe after sitting with the heat under the bonnet fuel evaporates from the float bowl. maybe there's enough to start but not run and it takes a few minutes for the pump to catch up. try hand pumping it before starting it when it's warm. maybe it's a tired pump and an ill adjusted float

[bmohan55]

I'm guessing vapor lock, sounds like how mine behaved. I think it's the combination of ethenol gas and weak mechanical fuel pump that makes you starve for gas when hot. I solved my problem by installling and electric pump I got at NAPA for $50.

Of course I now am in the process of re-building my engine around that nice pump!

[printjunky]

I would suspect some kind of carb fault (though I've never had vapor lock, so cannot attest).

Could the carb need the Zenith Disease fix? Heating/expanding exacerbating any gap in the two halves? Seems unlikely to cause a total no-start symptom, but maybe.

http://www.lrfaq.org/Series/FAQ.S.carb.zenith.fix.html

I've had a similar problem, except no pumping (spraying) in any temperature, so I did a rebuild and lapped the halves. turned out I was missing a plug in the body of the carb, and had a couple of clogged, or partially-clogged jets. After the rebuild, I definitely can hear a "pumping" sound when I work the throttle. We'll see what it does with fuel in the bowl.

Unfortunately, I can't tell you the result yet (maybe this weekend!) as I got derailed by pulling the dash and some other wiring projects.

But it still adds up to me recommending a rebuild. (trying the Rochester also appealed to me, but I haven't gotten around to finding one yet.)

[109 Pretender]

Sounds like classic vapor lock which is problematic as summer comes on w/old carbed vehicles. Try to make sure you don't run gas laced w/ethanol if you can. Alcohol makes the problem much worse.

There's several things to try - some are more effective than others.

1. Route incoming gas line as far away from manifold as practically possible. (best)

2. Ck that your float level is correct - if it's a bit low the gas will more easily evaporate away - but don't set it too high either because that'll make it run richer. (might make a diff)

3. Ck that the adjusting screws for fuel and air (idle) are appropriately set. (probably won't be a major effect on problem)

4. Construct some sort of metal plate to insulate carb from heat as much as poss. (could help but might not look too good or be orig. if that's an issue)

Good Luck!

Cheers!

[TCapelle]

So I think I have zeroed in on the issue
I went ahead and installed a new fuel pump- It seems to deliver a little more volume and instead of the truck completely stalling out when hot it just starts to run bad and sounds like it is about to die.
At that point I tapped on the base of the carb with a screwdriver handle and it changes how it ran. So my guess is it is the carb.

Took the carb apart and cleaned it-didn't rebuild it- will try to put it back on tonight and see if cleaning solved the issue...

Anyone want to guess what is wrong with the carb if when tapping on the base of it improved running condition and stopped the complete stall?

Thx,
Tim

[bkreutz]

I'd guess the needle valve is sticking closed (or partially closed). I've had this problem on a Carter carb on my CJ2A(). Sometimes I have to tap on the carb to get it to start. I'm thinking the ethanol mixed gas doesn't lubricate things as well as the old stuff. Adding a fuel stabilizer seems to have helped (StaBil for example)

[Tsmith]

Make sure that the vent in the gas cap is clear. If it stalls, open the cap and listen for air rushing in.