30 Shutting off
 

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

Re: 30 Shutting off
 

If the carb fuel bowl is emptying then you DON'T have good fuel flow..............
Paul in CT

Re: 30 Shutting off
 

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.

Re: 30 Shutting off
 

I assume you cleaned the plugs.

Re: 30 Shutting off
 

Have you checked the carb filter and float valve?

Re: 30 Shutting off
 

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.

Re: 30 Shutting off
 

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

Re: 30 Shutting off
 

I also suggested to make sure you have the standup filter on the shutoff

Re: 30 Shutting off
 

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

Re: 30 Shutting off
 

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.

Re: 30 Shutting off
 

Thanks Mitch and yep got a pencil filter.

Re: 30 Shutting off
 

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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Re: 30 Shutting off
 

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.

Re: 30 Shutting off
 

Update - I quit the Model A has won! :confused:

Re: 30 Shutting off
 

How much u want for it
I'll tow it away for free

Re: 30 Shutting off
 

Have you made any progress?

Re: 30 Shutting off
 

walk away from it for a few days

Re: 30 Shutting off
 

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

Re: 30 Shutting off
 

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.

Re: 30 Shutting off
 

When it dies or briefly running it is without fanfare, no backfire, missing, coughing, just a sigh.