runs then dies, the runs??

Hi i have a 1980 sachs seville, it starts and runs fine for about a half an hour, then dies. it wont start again till i spray a little carb cleaner in the carb. then it runs for a half an hour then dies again. I have replaced the fuel filter, i have cleaned the carb and replaced the gasket. Any ideas??

Re: runs then dies, the runs??

Odd. 1/2 hour, you say?

Is the pinhole vent on the gas tank clear? If it's become clogged, the tank can develop a vacuum as gas is used, and fuel flow will slow down. It might be equalizing pressure during the time you're fooling around with carb cleaner.

Have you checked the fuel line and its inline filter, if it has one? Drained fuel through the petcock into a glass jar and observed whether the fuel flow is even?

Re: runs then dies, the runs??

yeah, i checked the fuel it comes out nice and even.

Re: runs then dies, the runs??

i cleaned the muffler today and it still made no differnece, when it runs it runs great, could it be something like points, compression, or a seal that isn't easilt noticeable?? Thanks!!

Re: runs then dies, the runs??

half an hour is a long time.. it's well past the point where a dirty carb or fuel delivery problem will make itself evident.. and it's way past the point where the engine has reached it's normal operating temperature and all parts have expanded to their max from heat..

This assumes that there's nothing special or different about the last part of the ride (like a long uphill climb or something).

I doubt that it has trouble at exactly every half hour.. If the problem happens at variable times, it could be electrical. Check for loose wires and connectors.. Check for worn insulation.. bare wires that are able to touch something on the frame. Look everywhere, including under plastic ties that gather wires together and secure them.

Why spraying carb cleaner on the carb would have any effect doesn't make a lot of sense, unless some mechanical thing on the carb was sticking. (or are you moving some wires or something to get to the carb in order to spray it? )

It might help track it down if the next time it happens, carefully get off the bike without disturbing anything.. take a close look at it and you may spot something thats out of order..

Re: runs then dies, the runs??

Well,a weak condensor can appear to mess up pretty regularly. I believe if you do a search, you'll see that Ron Brown's MBK condensor seemed to fail regularly around the 20 minute mark. Also we had a coil on a riding mower that would give you 10 or 15 minutes and quit every time.

Also, depending upon the level and amount of fuel in the tank, it CAN wait easily a half-hour because of a plugged gas cap vent. 45 minutes into my ride one day going to work, my fuel stops flowing. Thereafter about 20 minute intervals and usually when I was going at least 30mph, it stopped flowing again.

If you have little fuel in the tank it's gonna take longer than if you have a full tank.

Fill the tank,tighten the cap,and take the float bowl loose with the fuel turned on and see if it flows well thru the needle valve. See if it slows down after about a pint runs thru it........(yeah....that's a lot)! You did clean the banjo filter where the brass screen is on the carb,right?


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