3.5 HP Difficult Starting

[fenderbassfan]

Every B&S Engine I've ever had starts easy, needs almost zero maintenance, and can sit for years and still work fine so I don't know why this one that I bought new and is hooked up to a small compressor, and only has like 10 hrs. on it is still hard to start even after taken in to have a tune-up and the carb cleaned. Also, once started it needs to have the choke and throttle messed with for a while before it stays running well. So then it runs ok but the RPM surges high and low no matter if idling or higher Rpm. I haven't disconnected it from the compressor and ran it, but the belt seems properly adjusted.

 

[skidoo50]

Sounds like its bouncing on the governor.

 

[Clayon]

Yes, like skidoo50 said, it could be the governor, but how is the carb adjusted? while it is running try turning the needle out/in until you find where it runs best. :shrug: I just rebuilt 4 3hp Briggs and that's what I did and it smoothed it out and they start first or second pull.

 

[jim210]

Do you have a idle mixture screw or is it a fixed pilot jet? (betting pilot jet) Did you put fresh gas in it when you got it back from the shop? The newer syle 3.5s come pretty lean and can take awhile to warm up even if everything is perfect. They have a governed idle which will cause it to really surge if something is wrong.

First I would make sure the pickup tube isn't bottomed out on the bottom of the tank. Try to slide a bent hanger under the pickup. If it doesn't go under it, you should atleast be able to move it. If you can't even move the pickup with the rod you have a problem. Then I would check the pilot jet. If the jet is clean I would try blowing compressed air into the idle circuit. I have had some luck with this when in a hurry. But make sure the engine is cold and remove the airfilter so it doesnt get soaked with gas. (Be careful not to get gas In your eyes) If you still can't get it to run right I would remove the carb and rebuild it concentrating on the idle circuit. Making sure to check the transitional holes behind the welch plug. Stepping the pilot jet up would help with the cold starting and warm up period once you corrected your problem