550 back fires

[Plumbroke200]

Battery went dead on my 550 and it sat for a couple months. Finally got around to it and put in battery - during that time carb float must have stuck and tank drained dry. Filled it up and it starts but runs rough and backfiring a lot. I can"t think of any reason the battery would cause this so I assume problem is in fuel system. Rebuild carb? Tank filter? I already know now to shut off fuel.

 

[rrlund]

Cracked distributor cap?

 

[Plumbroke200]

Ran fine before being parked for a couple months so I don't see how it would have cracked but I will look at it this weekend.
Thanks

 

[rrlund]

Any moisture in it with cold temperatures like we've had could have cracked it.

 

[Plumbroke200]

It has been cold

 

[rrlund]

Another thought too,it could have just drawn moisture on the inside of the cap which has turned to frost and the spark could be jumping to the frost. Wouldn't necessarily need to be cracked to make it miss.

 

[Bob M]

A couple things to check:

1 - If the old battery went dead because the ignition switch got left on, check for burned points. (Could also possibly cause a ruined coil from overheating - however this is unlikely)

2 - If the tank ran dry by the gas draining out through the carburetor, could well be the engine ran very rich the first couple minutes until the old gas pooled in the carb air inlet got burned off. This will cause carbon fouling of the plugs thus backfiring and missing.

Recommendation: Clean and reset the breaker point gap and install a fresh set of plugs. Also make sure the distributor cap is clean and dry inside and out.

Good luck!

 

[60 Fan]

I believe what rrlund is referring to is not necessarily distributor cap cracked in the sense of a window being cracked. More along the lines of carbon and/or moisture tracks short circuiting the spark as it is supposed to be distributed systematically around the inside of cap. Very hard to see and very prevalent in temperature/moisture changes. So the suggestions as to new points, condenser, cap and rotor would be right on in this case. My two cents worth.

 

[Don-Wi]

I'm with rr- replace the points, condensor,rotor, and the cap.

Donovan from Wisconsin

 

[Plumbroke200]

Ordered a tune up kit point cap ect. figure its due since I started it two years ago after sitting for a couple years and didn"t do anything but replace the battery and repace the sediment bowl the previous owner had taken off.

thanks

 

[Plumbroke200]

Thanks all, changed cap, plugs, points and rotor. As bad top of rotor was I am suprised it ran at all.