# Tractor starts to misfire after running 5 minutes



## Lizer (Sep 12, 2015)

I have a 1974 Oliver 550, 4 cylinder gas. I did a complete ignition tune up because tractor has been low on power....condensor, points, new coil (internal resistor), wires, plugs. Did not replace cap, looked fine but ordered a new one tonight.

The tractor fires RIGHT up (fired up real slow before tune up), initial timing is good (checked it with timing light). Mechanical advance on distributor looks to be in working order. The problem is after the tractor has been running for several minutes and gets warmed up, it starts running pretty rough and sounds like it's missing.

I'm out of ideas as to why it's missing now despite what I've done. 

Would it be worth it to try to adjust timing when the misfire starts after running for a few minutes to see if this smooths it out?


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## BigT (Sep 15, 2014)

Hello Lizer, welcome to the tractor forum.

I recommend that you keep a good set of notes on what you do. 

Temperature sensitive components: coil, condensor, resistor, Ignition switch?, distributor cap/rotor?, etc. 

Fuel supply problem: Plugged fuel screen or filter, plugged vent in gas cap, etc.
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Do you have access to a timing light? Check the timing when it acts up.

Does your carburetor have a drain plug on bottom of bowl? If so, remove the plug and check fuel flow for a five minutes. See if the flow subsides to a trickle... 

Try "hot-wiring" the ignition system to eliminate the ignition switch and wiring to the coil. Connect a wire from the battery hot post directly to the coil input terminal. Don't forget to remove this wire after testing.


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