30 Shutting off

William Kelchner

William Kelchner

Senior Member
My 30 was running fine a few weeks ago, then it started acting up missing and coughing through the carb. Here is what I have done up until today. Checked voltages and spark - all good. Battery was on its last legs installed new 6V. Started it up on the main tank and it runs for a few minutes then dies like fuel starvation.

Borrowed a small auxiliary fuel tank, put fresh gas in it and checked the fuel flow (good) fired it up and does the same thing.

Since I eliminated the main tank and the gas I would guess, in my limited knowledge, that this blasted Zenith carb may be the culprit. Seems like it empties the carb fuel bowl and then shuts off. It will restart once or twice and then finally just crank away. Checked the carb fuel filter which was clean.

Any suggestions are welcome. Bill K
 
Remove the carb bottom and hold a small pail under the carb. Turn on the gas and watch the flow. If it's good, then you must have blocked passages or jets.
 
Thanks for all the replies. Replaced the float valve a couple of months ago, checked the carb filter which is clean. I too wondered about fuel flow and thought by completely bypassing the main tank with a separate tank would eliminate the main tank and shutoff valve as a possible source of the problem. The fuel flow from the main tank and the separate tank/fuel line look about the same.

I'll tinker with this a bit more today and see what happens.
 
William, I am going through this with my "new" coupe. I've had it a little over two years and for the most part, it's run well. But all of a sudden it seems a flood of rust has been shaken loose from the walls of the tank.Two days ago,I took the carb (Mod.B) off and took about a tablespoon of rust grit from the bowl. I cleaned every passage and jet. I put it back on a started it and it ran for about a minute then it quit , again! Mitch has suggested using a Wix 33039 or a NAPA 3039 that fits in the glass filter bowl. I'm going to put one in the system.
Terry



William Kelchner said:
My 30 was running fine a few weeks ago, then it started acting up missing and coughing through the carb. Here is what I have done up until today. Checked voltages and spark - all good. Battery was on its last legs installed new 6V. Started it up on the main tank and it runs for a few minutes then dies like fuel starvation.

Borrowed a small auxiliary fuel tank, put fresh gas in it and checked the fuel flow (good) fired it up and does the same thing.

Since I eliminated the main tank and the gas I would guess, in my limited knowledge, that this blasted Zenith carb may be the culprit. Seems like it empties the carb fuel bowl and then shuts off. It will restart once or twice and then finally just crank away. Checked the carb fuel filter which was clean.

Any suggestions are welcome. Bill K
Click to expand...
 
Terry said:
William, I am going through this with my "new" coupe. I've had it a little over two years and for the most part, it's run well. But all of a sudden it seems a flood of rust has been shaken loose from the walls of the tank.Two days ago,I took the carb (Mod.B) off and took about a tablespoon of rust grit from the bowl. I cleaned every passage and jet. I put it back on a started it and it ran for about a minute then it quit , again! Mitch has suggested using a Wix 33039 or a NAPA 3039 that fits in the glass filter bowl. I'm going to put one in the system.
Terry
Click to expand...

I also suggested to make sure you have the standup filter on the shutoff
 
Thanks. Going to replace my carb with a known working carb today - one of the forum members coming over today or tomorrow with it. Let us pray :p

Bill K
 
Sometimes a fuel issue turns out to be an electrical issue. I know you state that you checked for spark. However it may be worth your time to do a quick check on point gap. Over time the point block wears and then the points don't open enough. Will run but hard starting and missing coughing is what happens.
 
eagle said:
Sometimes a fuel issue turns out to be an electrical issue. I know you state that you checked for spark. However it may be worth your time to do a quick check on point gap. Over time the point block wears and then the points don't open enough. Will run but hard starting and missing coughing is what happens.
Click to expand...


Boy am I aware of most carb problems are electrical :) Would you believe today and the car put on its performance I again checked the points - I have spark 40 percent of the time :confused: I'll check that tomorrow, poor Zenith gets blamed for everything.

Bill K
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New ignition points need to be re-adjusted several times after installing them.

One thing to remember about ignition points is that the rubbing block wears rapidly for the first 200 to 400 miles then it "work hardens" and wears less from then on.

How fast this happens has a lot to do about how smooth the dist cam rubbing surface is.

So it is necessary to check the gap several times right after they are installed to be sure that the gap has not closed up.
 
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I just tried out my rebuilt, flow tested, engine tested Zenith from one of our major suppliers and same scenario. Good gas flow, spark, points, voltage everywhere, starts nice, timing is good. Runs good for several minutes. I hung a wreath on the radiator and said a few words over it. :mad:

Bill K
 
William,
Pull your distributor and check the flexible wire under the top plate. It may be your trouble.
If it is going bad it will cause lack of power, coughing and back fire.
 
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