21. Precautions when starting up an engine that has been sitting idle

Assuming that the previous owner followed the simple procedure of “fogging” the engine with Marvel Mystery Oil when it was last shut down, and/or that the engine still turns freely, there are only a few things that you need to be concerned about.

1) During early attempts to start, we recommend keeping the raw water thru hull valve closed until the engine actually starts, to insure that you won't flood the exhaust system (and engine) with water. As soon as the engine does start however, be sure that you open the valve immediately.

2) Remove the spark plugs and turn the engine over a few times on the starter to check for compression. The compression should be enough so as to make it practically impossible to hold your thumb over the each of the spark plug holes while the engine is turning over. If one of two cylinders are weak, it might be that one of the valves is slightly hanging up. This condition will probably clear up as soon as the engine starts. A few squirts of Marvel Mystery Oil in the weak cylinders would be helpful.

3) Check all fuel filters, and inspect the fuel supply by removing one of the plugs in the bottom of the carburetor (preferably the “main passage plug”). Then pump some fuel through the carburetor and into a small glass container, by either working the manual priming lever on the mechanical fuel pump, or by powering the electrical fuel pump.

If the fuel appears clean and free of water, reprime the carburetor, and inspect the choke valve to insure that it fully closes when you pull the choke control in the cockpit. You should then be ready to start, fuel-wise.

NOTE: There is frequently a lot of concern over old fuel. If later, the engine won't start and you think that it is due to old fuel (like if it smells funny and has a strange color), I would suggest that you pump off enough to try it in a lawn mower or other small engine prior to going through the rigors of draining and replacing all the fuel. Not that you may not want to do a lot of heavy maintenance on the fuel supply at some point, but you can probably pick a better time when you're dealing with a lot of other start-up issues. In most cases, the concern over old fuel is overstated.

4) Clean the points by rotating the engine until they are closed, and then run a piece of cardboard between them. Then, with the ignition switch on, flick the points open and closed a few times while holding the main coil lead from the top of the coil about a quarter of an inch from the head, while observing for a good spark. If the spark is healthy (a half inch or better), the engine should be ready to start, ignition-wise.

5) Check for good oil in the crankcase, charge the batteries, and start the engine. - Updated: November 4, 2003