# Ford 850 Rough under load



## spkepler (Apr 20, 2012)

I have a 1956 Ford 850. It starts like a champ and runs well for the most part. I use with a finish mower for cutting my lawn. After mowing for about a hour, the tractor will suddenly start running very rough. If I push in the clutch, it runs a bit smoother. Then after 20 seconds or so, starts to run well again. I can continue mowing, but the problem randomly reappears. If I shut down the tractor when it is running rough and wait 5 minutes, it starts right up and runs well ... for a while until the problem starts a gain.

It has new gas and a 12 v electronic ignition.


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## pogobill (Jan 31, 2012)

How are your plug wires?


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## Big_T (Dec 1, 2011)

Intermittents can be difficult to locate. It's either a lack of spark or fuel. Here's what I would do:

1. Take one spark plug wire off a plug and position it so that you have about a 1/4" gap and can see (blue/white) spark jump across the gap. Leave it this way. When it starts acting up, have a look at the gap to determine if your spark remains strong or if it has degenerated to a weaker orangish spark. If it stops running, crank the engine quickly to see if you have spark across the gap. 

2. If you have good strong spark, pull the drain plug out of the carburetor to see if you have an adequate fuel supply. Another thing to check is if your gas tank cap vent is plugged. Or if the fuel screen (attached to the shut-off valve) inside the tank is plugging - is there debris in the bottom of the tank that plugs the screen and then drops off the screen when the engine is switched off??

Good luck, and let us know what you find out.


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