1993 Nissan 70 won't run

[eight]

Last weekend I was running it at full throttle for 15 minutes or so, and then slowed down for some larger waves from a ferry. When I went back to full throttle the engine started missing. I found that it ran fine below 3000 rpm so I ran it like that until I was out of the ferry lane. When I let the engine try to idle it died. I could get the engine to run if I cranked it at half throttle. I had spare spark plugs with me so I changed them and it made no difference. I started it back up and began the 12 mile trip back to the ramp at 8-9 mph. As I was going, the speed at which the engine would run well slowly decreased and eventually got to what seemed like it was running on one cylinder. I was still able to do 4 mph at wide open throttle so I kept going until I hit a wave from a yacht that lugged the engine down and killed it. I haven't been able to get it started since then.

Yesterday I started trouble shooting it. I found that it would not run on starter fluid so fuel is probably not the problem. I checked that I had spark at the plugs and it did on both cylinders. I pulled the plugs and they were wet with fuel so I changed them again and it still wouldn't run. I could occasionally get it to backfire. It seems to me like the timing is way off.

Is there any common problem that would effect timing on this engine? Any other ideas on how to fix the problem?

Thanks,

Ryan

 

[TOHATSU GURU]

Re: 1993 Nissan 70 won't run

This may be a mechanical issue. The crank may have twisted, the flywheel key could have broken(so rare as to not really be the issue) or the trigger coil could be bad. Unless you are well versed in outboard repair you might want to take it into a dealer.

 

[eight]

Re: 1993 Nissan 70 won't run

The problem with taking it to a dealer is that I don't know who I can trust to actually diagnose a problem.

So if you think it's mechanical I'll pull the flywheel, check the key, and take a look at the trigger. I'd like to check the trigger but if it's not too expensive I might just replace it. Is a twisted crank common on these engines? I guess I could figure out if the crank is twisted by checking if top dead center on the flywheel mark and the actual piston position are the same.

If the CDI was bad it wouldn't spark at all, right?

 

[TOHATSU GURU]

Re: 1993 Nissan 70 won't run

Trust is always an issue. For instance, I have no faith in my closest Ford dealer. $800.00 bill from them for a "fuel pump issue"....Same problem. Independent shop, $127.00 and the problem was solved. Depending on the model number of your engine, a trigger or trigger assy can cost a lot. Twisting cranks are very rare outside of racing applications as it requires an over rev of 1500 RPMs to to it...Or a collision with an underwater object that stops the engine dead. CDI's usually fail 100%, but not always. About half of all bad CD's have partial juice going through them. Spark strength is what you are looking for there.

 

[eight]

Re: 1993 Nissan 70 won't run

Is there any online place I can order parts for this thing from? Do I have to go to the dealer?

 

[TOHATSU GURU]

Re: 1993 Nissan 70 won't run

There are around 20 online sources for Tohatsu/Nissan parts in the U.S., all of whom are dealers. Or, any other Nissan/Tohatsu dealer will be able to help you..

 

[eight]

Re: 1993 Nissan 70 won't run

I did some work on this yesterday, didn't get anywhere.

I cleaned the carbs. They were pretty clean anyway. One of the holes in the tube under the main jet on the upper carb was pluged, but the other 13 were clean. I also replaced the primer bulb, fuel filter, and some fuel line. I didn't really expect this to fix it but figured it should be done anyway. I changed the plugs to some new ones. Pulled the flywheel and took a look under it. The key is still as it should be. I went through all the electrical connections to make sure they were clean and tight. The 3 prong plug to the CDI had some corrosion on it so I cleaned it off. One of the connections there was a little loose so I tightened it up. Still didn't help. All I can get it to do is pop real loud in the storage unit.

I would like to check the timing. I found the marks on the plate under the flywheel but don't see any TDC marks on the flywheel. Are they supposed to be on the flywheel or is there something else to look at? Maybe I'm not looking close enough.

 

[TOHATSU GURU]

Re: 1993 Nissan 70 won't run

The timing procedure can be found in a service manual. It's done bymeasuement on the timing link rods....The timing can't change unless someone has changed it manually.

 

[eight]

Re: 1993 Nissan 70 won't run

I was just wondering if the trigger coil or the ESG was bad and causing the timing to be off. I can get a spark at least a 1/2 inch long from the coil.

I found some new information. My boat is a 93, but the motor is a 91 NS70A2.

 

[lexi]

Re: 1993 Nissan 70 won't run

Is there compression on cylinders? Be careful when turning engine with plugs out. Some engines require the kill button to be pressed while doing it to avoid damage to CDI/COILS.
Alex

 

[TOHATSU GURU]

Re: 1993 Nissan 70 won't run

ESG's never go bad so that's pretty much not the problem. You can disconnect yours anyway without any bad things happening. The trigger coil could be bad....And you test that with the values out of the service manual. But, the trigger coils are no longer available.

 

[eight]

Re: 1993 Nissan 70 won't run

Yes it has compression on both cylinders. How much I am not sure. I just pulled one plug and turned it by hand, then reinstalled it and pulled the other plug and turned it by hand. Both times it seemed pretty good. I suppose the next thing will be to actually put a compression gauge on it.

With the way it pops when trying to start, it just seems that timing is way off. I have fuel, have spark, think I have compression. I also know where a pair of 70hp evinrudes are in an outhouse and I think one is good.

 

[lexi]

Re: 1993 Nissan 70 won't run

Could you have a carbon problem somewhere . Maybe blocked up port or the exhaust?

Alex

 

[TOHATSU GURU]

Re: 1993 Nissan 70 won't run

Popping might mean a bad reed.

 

[eight]

Re: 1993 Nissan 70 won't run

I think you may be onto something there. You know if they're still available?

I checked the timing roughly by drawing a mark at TDC on the flywheel and looking where it ended up on the engine. Not sure of actual degrees or anything but its close enough it should run. Also moved the throttle to make sure it advances.

 

[TOHATSU GURU]

Re: 1993 Nissan 70 won't run

They are still available from any Nissan or Tohatsu dealer.

 

[eight]

Re: 1993 Nissan 70 won't run

Reeds looked good.

I finally checked the compression. 150 psi in the top, 148 in the bottom. Seems a little high to me.

I think the timing is 180 degrees off. I put a white mark on the flywheel when the top cylinder was at TDC, and a red mark when the bottom cylinder was at TDC. I put the timing light sensor on the top plug wire and got a red mark. Then found the white mark on the other side of the flywheel. Change the sensor to the lower wire, and I get a white mark.

This is really throwing me off. How could the timing get to be 180 degrees off?

 

[TOHATSU GURU]

Re: 1993 Nissan 70 won't run

The timing is set by static adjustment as shown in your service manual. If you don't have a service manual you are wasting your time.

 

[eight]

Re: 1993 Nissan 70 won't run

I got it running yesterday. I removed the timing linkage and advanced the timing as far as it would go. Still not right, and still no idea how it would get so far off.

 

[eight]

Re: 1993 Nissan 70 won't run

Today I bypassed the Electronic Safety Governor and it fire right up and ran like it should. I hade bypassed it before with no luck. I fired it a couple more times over the next hour or so. So I got to cleaning things up and decided to try to run it again and it was back to it's trouble. Plugged the ESG back in and it ran. Turned it off and it wouldn't start again. Advanced the timing all the way and it ran then started dying so I put the timing back where its supposed to be and it ran fine for a few minutes and died. Advancing the timing all the way got it running again. I put the timing back where its supposed to be and cleaned up my stuff. Just before leaving I hit the key and it started and ran right.

I have checked all the electrical connections many times and have never found one bad. Seems the CDI is working fine, I'm going to replace the trigger.