Cranks but won’t start.

[B-Reeder]

I have a Nissan 18 hp four stroke. I think it’s a 2004 model. The model number is NSF18B2, the serial number is 032264XD. It’s set up for a number of years and now I’m trying to get it up and going again. It will spin over all day long but will not start. I have removed the carburetor and disassembled it and have it soaking in order to rebuild it. However even when I spray starter fluid in the intake and spin it over I still don’t get any detonation. Where should I start?

 

[GA_Boater]

Welcome aboard.

Check spark and compression after you put the carb back together. No putts with starting fluid should have told you it's not a fuel problem.

Also if there is a Man Overboard lanyard, make sure it's connected.

 

[B-Reeder]

Thank you. I will check all of that, the only reason I was thinking it may be electrical is because I know that the wiring harness and all electrical components have been removed at one time. I was thinking it may be the pick up Coil possibly not gapped correctly

 

[B-Reeder]

Ok. Got home and checked for spark. Got nothing between the coil and the plugs. Also no warning buzzer when key is on. Thinking maybe bad oil pressure sending unit, man overboard switch or neutral safety switch. Anything I may be missing?

 

[GA_Boater]

Check for blown fuse(s). If it cranks in neutral, it isn't the neutral switch.

What makes you think it could be the oil pressure sender?

Has this thing ever run for you?

 

[B-Reeder]

It has run before. I bought it new in 2003. The fuses are good. The only reason I was thinking oil pressure sending unit is because i remember the buzzer coming on until it built up oil pressure.

 

[pvanv]

It has an alternator and a pulser coil. Whip out your Factory service manual and dx the electrics.

 

[B-Reeder]

Trying to find it right now. I read somewhere were a person can use a regular old analog ohm meter to diagnose most of the electronics

 

[pvanv]

Correct. Analog is important. Full info in the Factory service manual. Non aftermarket manuals.

 

[B-Reeder]

All I have is a SELOC Manuel. Is that acceptable?

 

[B-Reeder]

Ok. So I checked both kill switches and there good and the oil pressure switch test good. I tested the alternator and according to my manual it’s supposed to ohm out somewhere between 12.5 and 18.8. It has no continuity. Tested between the black/red wire and the blue wire. However I also found a switch in the remote controls the has a loose contact in it. Is there any way this switch can be causing no fire.

 

[pvanv]

Seloc is too general to be of much help. The old 9/9/15 is the manual that also covers the 18B2. Only difference between the 15 and 18 is the more aggressive cam and larger carburetor. What is "no continuity? Is that an open or a short? Are you using an analog meter? Which switch in the RC box has a loose wire?

 

[B-Reeder]

It was reading 0 ohm’s. I even back probed each wire from the connector end to the base where it attaches to the alternator. It was the blue wire and the black/ red stripe wire. My wiring schematic lists the switch as the neutral switch. And my schematic came from Tohatsu. I will try to upload a picture of the switch. The part number on it is 24Z3R2.

 

[pvanv]

Zero ohms is dead short. That is the definition of continuity. What range is the meter set to? Neutral switch could prevent any starter cranking, but would not kill ignition.

 

[B-Reeder]

Got her up and running. Turned out it was the alternator. Want to thank the gentleman that helped out with the manual. Got some more work to do but now I know it will be worth it.