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Wisconsin W4-1770 Won't Start

NorbTenn

Registered
This Wisconsin engine is in a Bobcat 630 which probably puts it at or about 1975 vintage. It's always run good then couple of years ago it started misbehaving. Started missing that was worst at high throttle. I had carb rebuilt but that was not the remedy. I should mention that this got very little use when running good and possible excessive carbon buildup over the years of low use. Last time I got it running it was running on just two cylinders -- Nos 2 and 4. I pulled the coil and had it tested -- they said it was weak...so I've replaced coil, new plug wires and hot Ngk plugs. I'm getting nice blue spark on all plugs. Now when I get it to fire -- most of the time it seems Number 4. After cranking at length pull the plugs they are dry so fuel not getting to plugs. Pull the carb and the float bowl has gas in it so fuel pump seems to be working. After the carb rebuild and when the engine was still not running well I messed with adjusting the float after which the carb rebuild guy told me I should not have messed with that. I've pulled carb again to bring back for him to recalibrate but before doing so anybody have suggestions. BTW the carb is Zenith 11532C.
 

Arlie Levy

Registered
Most Wisconsins that set for some time usually have stuck valves. That is why you did not have gas on the plugs. Sometimes you can pull the plugs and spray into the cylenders with penetrating oil or wd40. Spin it over and see if it will free up. sometimes it will and then it might not. If you have to pull the heads be careful. The head bolts twist off real easy. good luck!

---------- Post added at 12:43:01 PM ---------- Previous post was at 12:41:08 PM ----------

ps take a compression test. that will tell the story.
 

NorbTenn

Registered
Arlie Thank you for the tips. Compression test was going to be my next step. Here's another weird symptom -- After a bit of cranking, gas backing up into the intake hose and dripping from air cleaner. Seems to me the only reason this should be happening is gas not being drawn through intake manifold to the cylinders. I remove air intake hose, cup my hand over the carb intake and can feel suction but that may only be a couple of cylinders. Thanks again!

---------- Post added at 12:27:20 PM ---------- Previous post was at 12:25:27 PM ----------

I'm going to do compression test next next trip to the farm.

---------- Post added at 12:29:45 PM ---------- Previous post was at 12:27:20 PM ----------

Thanks! I'm seeing good spark at the points.
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
Ah, spark at the points means bad condenser and that means weak spark and short lived points. Weak spark will manifest itself most at high throttle when cylinder pressure is highest.
 

NorbTenn

Registered
To confirm what you are saying when the engine was running albeit roughly it was pretty smooth at idle speed but very rough at high throttle. Is sparking at points only way to diagnose a bad condenser?
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
Well, not the only way, but I do know that an ordinary ohmmeter and capacitance tester can miss one that fails under high voltage. Whereas a true condenser tester will subject it to high voltage. But generally speaking there shouldn't really be any significant sparking at the points.

I had one that was running just fine one minute, then terrible the next, then after not too long wouldn't fire at all. I thought crap had gotten into the carburetor. The condenser tested good with an ohmmeter and a capacitance meter, but a new one cured the problem.
 

NorbTenn

Registered
I used Sea Foam to treat all cylinders, checked compression and measuring 90 on all 4 cylinders. Still not starting however. I have not changed points and condenser yet but will do that. Meanwhile I have gas dripping at air filter. Is that caused by float level problem? What should float level be set at on the Zenith carb?
 
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