2003 Tohatsu 9.8B 2 Stroke ran good now wont start

[Sea Rider]

Gee, seems this off topic will go endlessly. I'm not a big fan recommendinjg to buy a Service Manual, but you definitely need a Tohatsu Service Manual, all the information is written there, and NO timing light is needed, that's going back to the wagon era.....It's a simple mechanical synchronization between timing plate rod and end throttle cable + healthy CD/IC pack.

Happy Boating

 

[panamakid]

I have a Tohatsu service manual but it is a 1&2 CYLINDER MODELS
SERVICE MANUAL. Not specific to the M9.8B. Is this how they come or can I get a service manual for my model?

 

[Sea Rider]

There's a 2 stroke 1-2 cylinder Service Manual, assume there are individual HP Service Manuals too, Paul will gladly help you on that one. What about if you bought a Service Manual and found your timing and carb are well synchronized ? What's your next move ? You could have a slight desynchronized engine, that will overheat or run poor but fuel should be ignited on combustion chamber.

I would invest on 2 new spark plug caps, if already leaking, are caput, drainning too much electricity to ground, seems those two are the culprit of the whole long throubleshooting with no avail. Were plug cables loosing electricity as plug caps too ? quite visible at a dark room, just to be 101% sure. On standard IC units you can change both end caps along wire cables, are screwable type on both sides. Don't know about a 9.8 CD/IC pack ?

Happy Boating

 

[panamakid]

Sorry this is getting long. I do appreciate everyones effort.

I just ordered new plug caps, spark plugs, and a analog multi meter (not sure why my $45 digital wont work).

Once I get the meter I can try and confirm that the cdi/ignition components are 100%.

 

[Sea Rider]

I just ordered new plug caps, spark plugs, and a analog multi meter (not sure why my $45 digital wont work).

Once I get the meter I can try and confirm that the cdi/ignition components are 100%.

To confirm all electrical components are on their specified range while cold is relative, all could be ok, but once engine runs and components starts to overheats/shorts whatever, it's another toy story. Those intermitent engine failures are the thrickiest to troubleshoot, unless you have electrical parts to swap and bingo on first try.

Happy Boating

 

[panamakid]

No Title

So I ended up selling the engine as I do not have a garage or indoor work space. The new owner found a hole in the bottom of the head in what looks like a freeze plug.

does this look like an insert? He said he can fix it...

 

[pvanv]

I have a Tohatsu service manual but it is a 1&2 CYLINDER MODELS
SERVICE MANUAL. Not specific to the M9.8B. Is this how they come or can I get a service manual for my model?

The individual manuals for the obsolete 2-sctrokes were condensed into just two manuals (one for 1- and 2-cylinder motors, another for the 3- and 4-cylinder motors). All of the relevant info is in there from the original manual verbatim.

 

[pvanv]

Sorry this is getting long. I do appreciate everyones effort.

I just ordered new plug caps, spark plugs, and a analog multi meter (not sure why my $45 digital wont work).

Once I get the meter I can try and confirm that the cdi/ignition components are 100%.

Digital ohm meters can have 2 problems for this application:
First, if the ohm circuit battery is above 3v, it can fry components by testing them.
Second, they don't deliver enough drive to the circuit under test to get reliable numbers.

 

[pvanv]

So I ended up selling the engine as I do not have a garage or indoor work space. The new owner found a hole in the bottom of the head in what looks like a freeze plug.

does this look like an insert? He said he can fix it...

There is a soft plug at both the top and bottom of the cooling gallery of that head. On severely corroded motors, they are among the first things to rot away. There is not any factory replacement, but they are a standard metric size, so one might be able to source a replacement. I have also seen the plugs repaired with various epoxy putties, with mixed results. But if those plugs are shot, the motor has suffered a lot of corrosion and may well have other issues.

 

[Sea Rider]

That corroded lower head cap is not a badly engine taken care issue, This cap is extremely thin, worst with salt water use. Have had same problem on relatively new engines which were well cared and flushed after use. A thick epoxy coat over cap solved the issue. Down issue must remove complete powerhead to work on it and probably need a new base gasket, as the old one will surely be kaput.

Anyway, this failure won't be the culprit for engine not to run well, there's something more to it. A bad lower cap will flood the entire pan and in extreme cases engine could overheat as huge amount of water that cools head is derived onto pan. Tohatsu should provide spares on parts manual for all their engines that uses these caps. Find cracy to got to a car shop and match a car cap for an OB.

Happy Boating

 

[Bosunsmate]

Digital ohm meters can have 2 problems for this application:
First, if the ohm circuit battery is above 3v, it can fry components by testing them.
Second, they don't deliver enough drive to the circuit under test to get reliable numbers.

wow i had no idea you could do damage by taking a reading with the two probes

 

[pvanv]

wow i had no idea you could do damage by taking a reading with the two probes

Now you know. Depending on the technology of the internal components under test, some testers (running at 9v for instance) can damage some circuits under test.

 

[Bosunsmate]

yes and i wont forget that, i have a 9v