Questions from the Darkside Mercury 9.8 1972

[bullie]

Recently the guy that built my house drove by and saw my garage in all its proud disarray and OMC glory. He stopped and chatted as I was tinkering and mentioned he had a couple of motors he would like me to look at to see if they might run again. Well, he dropped one of them off this weekend. I believe, from the serial number that it is a 1972 Model 110 9.8 hp Mercury.

It has really strong compression at 125/130, no spark, and a few cracked fuel lines. The lower unit is turning freely and will engage into both F and R. Now for the questions, are wires and fuel lines available for these motors? It looks like most every wire on this engine is losing insulation. There are quite a few bare sections with the metal exposed. And, I am curious about the fuel lines too. Several of them have, what looks to me, like compressed fittings on them. Sort of a complicated carb too.

Wires and hose available or could be made reasonably easy?

[outbdnut2]

These are known for bad insulation on the wires. I don’t know if wiring harnesses are available, but if they are, they will be expensive. You are $$ ahead running each wire separate. I’ve found that wires going to the points are known for shorting to ground metal where insulation has cracked where they enter and are routed on the breaker plate. If your motor has coils mounted outside the flywheel, the points are "Maker points" they "make" to energize these coils from voltage stored in the rotor, so spark is initiated when the points close instead of open.
For fuel lines inside the motor, go to a good auto parts store and ask for the proper inside diameter in rubber automotive fuel lines – these were common when most all cars had carbs, and still available at better stores – maybe NAPA. If you need a new gas line for the tank, go to Walmart’s marine accessories shelf.
If I remember right, the carb has the fuel filter and fuel pump on board – someone here correct me if I’m wrong – i’m not sure just what year some of this changed.

You can find parts lists and exploded views at http://www.marineengine.com. also a lot of info and parts at http://www.oldmercs.com
Dave

[david-bartlett]

There is a member on Johns Old Mercury site that makes the fuel lines. Great job and reasonably priced.

[20mercman]

There was just a post on Johns about using "Tinned Marine Wire" for replacement wire. Much more reasonable than using OEM harness that can have poor insulation even sitting on a shelf. These are "Phase Maker" point systems, and are really not bad. The issues is often a bad insulator on the lead from the breaker points to the coils. This system uses a high voltage to and a capacitor to charge the primary windings of the ignition coil. The path to ground for the primary circuit is through the kill switch. Make sure that you have a good ground via the kill switch. This is also a weak point in the system. Using the kill switch will cause high voltage looking for a path to ground. This will cause carbon tracking on the insulators I was talking about. Many people urge operators with these systems to avoid using the kill switch and use a combination of choke/low throttle speed. In any case, using the kill switch at high RPM can cause failure of the insulators. I have several motors with this system, and I have no reservations in using them, they start and perform well, just need to know the limits of this system.

Steve

[need2fish]

This may not suit Bullie’s requirement, but it’s useful for small and emergency repairs…. I keep a can of it in my pontoon boat (aging Evinrude V-4).

http://www.starbrite.com/category/liquid-electrical-tape

[bullie]

quote need2fish:

This may not suit Bullie’s requirement, but it’s useful for small and emergency repairs…. I keep a can of it in my pontoon boat (aging Evinrude V-4).

http://www.starbrite.com/category/liquid-electrical-tape

I have actually used liquid tape on a number of these 9.8 Mercury motors. It works well enough if the repair area is small. This one has lots of bare wire.

[seakaye12]

I really like those motors; small and light-weight and mine run very well.

For the fuel lines….if what you have are original equipment they will be custom lengths with crimped brass fittings at the ends. You can buy replacements for those or you can replace with barbed connectors (mine are 1/8" Pipe Thread but there might be other sizes) and then just use the correct generic fuel line from an auto parts store. Much cheaper.

The real issue is the cause of your "no-spark" condition. If you end up having a failed stator it can get pricey.

If you need the test-procedures and electrical specs for testing with a VOM…let me know. I have the manual and can get you what you need.

Good luck….

Chuck

[Author]

Posts