15hp nissan 2-stroke no run

[MILLSMAN]

Picked up a '98 14 HP Nissan 2-Stroke (NS15D2). Very clean motor. No salt corrosion. Tore the carb apart (it was spotless) and put in new bowl gasket and carb O ring and cleaned it out. Looks like the motor has not been run in years. The bowl gasket was brittle and in pieces. Good spark..................but it will not run. (New plugs) Occasionally will "pop" which sounds like a backfire? but that is all. Checked compression and it was 80 on both cylinders. Sounds a little low, but ?? Injected start fluid into each spark plug and nothing happened?? Need some guidance. Thanks ....................

 

[racerone]

Check the flywheel key.

 

[pvanv]

Or at least connect a timing light and see if it's firing near TDC.

 

[racerone]

On many motors a timing light will not find a sheared flywheel key.

 

[Sea Rider]

If compression tester read accurate, 80 PSI is way low. When that low engines are very difficult to start. A good compression should be at least 120 PSI and up. Have never seen a key gone bad on those models, are sturdy and built to last.

BTW, was carb fully opened when cranking, how many rope pulls were needed to read 80 PSI ? Check timing and carb synch to be sure that both remains adjusted to factory specs..

Having a good spark does not necessarily means is strong enough, check it with a appropriate spark tester to determine that too.

Happy Boating

 

[MILLSMAN]

Thanks for all your input. I did have the flywheel off to check for a rusted flywheel. That would be an easy fix. Will check that later today plus the other items. Checked the spark with a visual spark light. Seemed strong but no numbers available. Pulled the cord about 5 times to obtain readings. Lots of resistance when pulling.

 

[MILLSMAN]

OK, checked Flywheel and it was keyed properly. Took off the carb and found that air was coming OUT of the intake inlet more than going in. Bad Reed Valves????

 

[raczekp1]

maybe spark plugs wires are crossed

 

[Sea Rider]

Took off the carb and found that air was coming OUT of the intake inlet more than going in. Bad Reed Valves????

Was that found when cranking the OB ? 80 PSI is incompatible with strong rope resistance, should check same OB with say 130-140 PSI to hand check the stronger resistance difference while pulling rope.

Are both internal spark plugs caps contacts is a shinny state ?

Happy Boating

 

[MILLSMAN]

Both spark plug terminals are bring and shiny. The air I felt coming out of the card is coming from the hole that feeds the fuel pump. Put oil in the cylinders and now they read 110 - 120 PSI. 3 Rope pulls gets me to 120 PSI. What wire goes to what plug? One has a tag on it. Is this the top plug? Will play with it more tomorrow. I want to bring it back to life!!

 

[pvanv]

maybe spark plugs wires are crossed

NO. They fire at the same time. It has a siamese coil. Duh.

 

[pvanv]

Both spark plug terminals are bring and shiny. The air I felt coming out of the card is coming from the hole that feeds the fuel pump. Put oil in the cylinders and now they read 110 - 120 PSI. 3 Rope pulls gets me to 120 PSI. What wire goes to what plug? One has a tag on it. Is this the top plug? Will play with it more tomorrow. I want to bring it back to life!!

What do you mean "hole that feeds the fuel pump"? If you mean when the carb is off, that pulsing (in/out) is required to operate the fuel pump diaphragm.
If the plugs are bone dry, they are not getting fuel. If they are wet, no spark. After having oil in the cylinders, you will need to clean the plugs off before checking that.
All 2-stroke reeds do spit a bit as they are seating. Tohatsu reeds seldom if ever fail, but a ham-fisted "mechanic" could have damaged the reed block.

 

[MILLSMAN]

There is a small hole next to the intake. See attached pic.

 

[pvanv]

There is a small hole next to the intake. See attached pic.

Yep. Normal. That needs to pulse in and out.

 

[MILLSMAN]

Plugs are dry .......not getting gas. Will review my carb gasket and fuel feed. Got to go away for a few days but should get it running then. Thanks for all your help.

 

[Sea Rider]

Did you opened the tank's air valve, primmed the engine with bulb's arrow pointing upwards till firm, rotated the throttle to start position while pulling rope ?

You posted that squirted starting fluid and nothing happened. If compression would have been much higher than 100 PSI engine would have started much easier assuming that all other electrical, mechanical components are working good.

To squirt oil into the cylinders and achieveing a much higher pressure as stated is a clear symptom that engine is very low on compression, whether has issues with rings or pistons/rings or even cylinder walls. When the oil applied to the cylinders has been completely wiped off, compression will surely drop back to 80 PSI. It's an instant compression increase for testing purposes only while cheating yourself about restoring its lost compression LOL!!

Happy Boating

 

[MILLSMAN]

OK, finally got my Nissan running and it RUNS GREAT! The main problem was the exciter coil that is under the flywheel. Replaced that and it now runs fine. Starts on first pull. Thanks for all your suggestions.

 

[Sea Rider]

OK, finally got my Nissan running and it RUNS GREAT! The main problem was the exciter coil that is under the flywheel. Replaced that and it now runs fine. Starts on first pull. Thanks for all your suggestions.

Was the exiiter just way altered or was open producing 0 Volts ?

Happy Boating

 

[MILLSMAN]

It was producing intermittent volts. Sometimes it would fire OK, other times it would produce spark on the wrong stroke causing a "backfire" ??

 

[Sea Rider]

Was askind due to having had 2 exact same issues with that same coil, but the culprit was not the exciter coil, the cable than exits the timing plate had broken internally under the holding clamp due to too much cable felxing when throttling through the years. Check probably EC is still good and cable is shot.. If so repair it and keep it as a spare..

Happy Boating