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Author Topic:   2 cylinder 90HP?
EddieS posted 09-09-2002 11:58 AM ET (US)   Profile for EddieS   Send Email to EddieS  
I need some help diagnosing a problem I encountered yesterday with my Nissan 90. I took it out the Golden Gate yesterday and after motoring down the channel at 5mph it stuttered when I gassed it to get onto plane. It only sputtered once and then ran fine. I went to duxbury and trolled for about two hours and when I pulled the lines to move to another spot the same thing happened only this time the motor was only running on two cylinders. I decided to call it a day and limp home, after about 13 miles I hit the patato patch outside the Gate and had to slow down, all of a sudden the third cylinder sputtered and came back to life! The motor ran fine the rest of the way back, I was able to do 39 miles an hour going under the Gate, and still not at WOT.

When I got it home I pulled the plugs on the 1998 Nissan and found that the bottom cylinders plug looked slightly oily and the insulation was brown vs the white color of the other two plugs.

My question is could it be the coil for the number 3 cylinder? When coils go bad do they just quit or could they go intermittent? I checked all of the plug wires on the water and they were all firmly connected. All of the electrical connection on this motor are nearly perfect no rust or corrosion. The fuel bulb was hard, filter clean. It also would start easily even when it was running badly on two cylinders. My buddy thought it could also be a magnito, or the computer? Any thoughts or tests that I can run to determine the problem. In a way I wish the thing had not started working right at the end of the trip now I am afraid diagnosis may be more difficult.

Any help would be much appreciated


Bigshot posted 09-09-2002 01:33 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Trolling for 2 hours and you have not replaced the plugs? Try replacing them....not cleaning them. Also run some techron in the tank. lower carb could be a bit gummed. I doubt it is coil or anything else. Next time it acts up, stick your finger or tongue in the plug boot and see if you have spark. Make sure feet are in water....preferably salt water(it conducts electricity better). This will determine if coil or stator, etc is bad. remember that above is strictly a joke. Change the plugs, run some techron.
EddieS posted 09-09-2002 02:23 PM ET (US)     Profile for EddieS  Send Email to EddieS     

The plugs are new, I replaced them about 16 hours ago. I routinely troll for many more hours than two while salmon fishing. It would not be unusual to troll for six or more. None of the plugs were fouled, the lower cylinder plug had a different color on the insulater and also an absence of any carbon. The other two plugs had a little carbon build up on the the ends of the plug threads and the base of the metal piece that the electrode archs the spark (not sure what to call it). I also noticed this morning that there was quite a bit of two stroke oil thrown up around the magnito's. I had to fill the resavoir at sea a couple of runs back and had some spillage (Resevoir is under the cowling). It looks like some oil got onto the starter gear and was thrown into the surrounding area when starting.

I guess I will try the techron, could be a clogged jet, though the carbs look really clean. It just seems odd that after 70hours of running it this season, a jet on the carb would clog then unclog and clog then unclog?


Bigshot posted 09-09-2002 03:51 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
True....but it might be making the cyl run rich and foul the plug. ry switching the plugs around and see if still acts the same. Anything can go wrong, but you must deduct the obvious. Have you done a compression test? If not do one immediately. I doubt that too but don't hurt. A coil usually dies, along with powerpack unless a loose wire. I doubt flung oil but you never know. Could have grounded something to something.
Bigshot posted 09-09-2002 03:52 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
PS you have to be careful with running on 2 cyls. If you are getting fuel, no biggie but if cyl is starved for gas, you can burn up a cyl real easy.....hence is why I suggest a comp test. A float could be sticking. If you had no spark, the plug would be wet.
Salmon Tub posted 09-09-2002 04:34 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
Eddie, do a good check everywhere under the flywheel. Your comment about the oil is interesting. If the starter happened to throw some onto where the little electic contacts are (don't know the exact term for them), you know, the ones that create the spark, then this may have caused the problem. I don't think the oil would short anything, but it won't help conductivity either. I have noticed with my engine that the lower plug is always a bit darker. I write this off as the effects of gravity, since even though we have fuel pumps and oil pumps, it is still easier for the lower cylinder to get fuel and oil than the top one. I don't think that the insulators should be perfectly white though, just the nature of the beast, make sure your oil pump is set to the correct marks.

EddieS posted 09-09-2002 06:57 PM ET (US)     Profile for EddieS  Send Email to EddieS     
Thanks for the info guys. BigShot I will do a compression check and change the plugs out just to eliminate a possible problem. I will also run the techron, I need to look up your post about running it through with a couple of gallons of fuel. I was definetly sweating bullets running the motor with only two cylinders hitting! I kept checking the temp and it did not seem to be overheating at all, when it did fire up toward the end of the return trip it ran great. My guess is it is OK but I think I will follow your advice on the compression check just to be sure.

Salmon Tub,

Where are the marks on the oil pump? I have looked before, and just went down to the garage now, but I cannot see any marks or means of adjusting the pump!


Salmon Tub posted 09-09-2002 08:07 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
Ed, they are there but it might be easier if you e-mail me your fax, I will make a photo-copy from Clymer book and fax to you. I am planning on going out this Saturday, hopefully. Did you get any fish? My e-mail address is in my profile.
EddieS posted 09-11-2002 01:29 AM ET (US)     Profile for EddieS  Send Email to EddieS     
Update on the 90, I found two ground wires one comming off the lower coil going to the ground connection on the motor that had quite a bit of corrosion on the brass ends (no heat shrink tubing used) when I cut and stripped some of the wire back the copper was completly black along the entire length of wire. I replaced this using quallity connectors and adhesive backed heat shrink tubing. I also cleaned the stators with contact cleaner and got the oil off of them, replaced the plugs, cleaned the fuel filter (not much there) used decarb before replacing plugs. I am going to stop and pick up some Techron and run that through with a couple of gallons of gas. I also noticed in the manual that the nissan can use 87 octane however they recommend using 89 or higher. I think I will switch to the middle grade of fuel.


Bigshot posted 09-11-2002 11:55 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
My money is on the wires. Sounds like you found the problem. I would just buy enough techron to run through the tank, she will clean her up.
jimh posted 09-11-2002 12:10 PM ET (US)     Profile for jimh  Send Email to jimh     
I am curious how you cleaned the stators? Aren't they under the flywheel?
EddieS posted 09-11-2002 01:17 PM ET (US)     Profile for EddieS  Send Email to EddieS     

I may have been looking at the magnito's not the stators. I assumed that they were the stators, but there was a lot of oil on the three electrical components just under the fly wheel. On my Nissan you can get to these fairly easily by removing the plastic cowling. It looks like there are more electrical components buried pretty deep under the fly wheel closer to the shaft, but these were protected from the thrown oil.

I have ordered a Clymers manual in the meantime to help out with my lack of knowlege on two strokes.


Salmon Tub posted 09-11-2002 02:15 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
Ed, those books are good but I have found a few Type-O's in them. When you get your book, read up on how the book explaines the fuel intake: there is a chart that shows the flow of fuel and oil through each of their pumps and through the check-valve. When comparing to how it is routed on my engine, it is completely different. Mine has been that way out the box, and I think that this is a mistake in the book.
EddieS posted 09-11-2002 06:53 PM ET (US)     Profile for EddieS  Send Email to EddieS     
Salmon Tub,

Thanks for the information, and thanks for faxing those schematics on the oil pump. It ends up that my pump was set correctly! I appreciate the heads up on the typos.

Are you happy with the way you retuned your carbs?


Salmon Tub posted 09-12-2002 12:16 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
A funny thing happened on my way back in yesterday. I went out and decided to try trolling for a few hours after work. Got out, trolled around Muir beach, got one nice fish right away, 15 lbs, and was debating on if I should call it a day and go home. I am completely satisfied with the way the way the engine idles now while out of gear, and how it runs and accelerates, but not quite as happy about trolling. If I troll at idle, I can hear the engine change pitch and drop RPM's when going up-hill. If I give it a bit of gas to eliminate the noise, it runs too fast, 4.5+ mph, and the engine does not like that position, starts to shake and bounce around. I set mine on what should be the rich side, at 2 turns open. Now, a funny thing happened on the way back in, call it De-Ja-Vue but after I rounded Pt. Bonita and was around Pt. Diablo, the engine started to loose power and a definate vibration started up. It seemed that I too now have a 2-cyl 90. Being in the place that I was, there was only one option, damn the torpedoes and full speed ahead. It ran rough all the way in and seemed to be smooth at idle, though I could tell that the RPM's where lower than they should be, only 600-700 out of gear. I made it back, it ran smooth enough at the flush station, but sounded a bit different. I pulled the plugs this morning and 1 was clean (black tip, black electrode, tan insulator), the middle was same except for darker insulator, and the bottom was all black. Oddly enough, the top plug came out tighter the the others. All plugs had carbon particles, the middle had more carbon build-up around electrode than the other 2, and the bottom was wetter (fuel/oil) than the top two. I am sure that the problem was only in one of the cylinders rather that a fuel problem that effected the whole system. I will be checking the compression to make sure no damage was done, and will remove the jets to make sure they are all clean. Once I have eliminated these two variables, I will proceed with electrical diagnosys. I ended up running in 7 miles with the problem, and hope that it was not caused by a fouled jet, that is my biggest fear. I normally use the boat once a week, but have not for the past three weeks. I did get fuel yesterday, so that could be a possibility, but I doubt it. The engine did not overheat, steam, smoke, or sound as if something was grinding when I returned to the harbor. By the way, what is your timing set at Eddie, the stop screw on mine was set at 3 ATDC out of the box, and the book calls for 5 ATDC. I adjusted mine to the book specs. and it ran much smoother. I am wondering if this is also a type-o?

Bigshot, in response to the advise you will post after reading this, thanks for the advise on the Techron, and the compression check will have probably already been done. Oh, did I jump the gun on your response? Something made me think you might just suggest that stuff, just kidding, I don't use Techron, but I buy only Chevron 91 Octane gas and run Carbon-Free through the tanks every so often.

NEVER SCARED posted 09-12-2002 01:57 PM ET (US)     Profile for NEVER SCARED    
Eddie and Salmon Tub

I was out near Muir last Saturday and couldnt start my main engine. The starter motor would spin but wouldnt engage to crank the engine! I limped in with my 15 and took 3 hrs to touch land! First there was that Orca boat that washed up in the rocks (loss of power), my engine wouldnt start, now I hear of your guys problem. Im wonder if we have a Bermuda Traingle thing going here? My problem turned out to be 1. bad starter solenoid. 2. bad plugs. 3. bad battery connection and corrosion.4. loose nut on the throttle. 5. plugged jet on carbs. 6. and a leak in my oil tank system. I got an unsolicited offer for a tow but had confidence in my new 15 4-stroke kicker. Thanks anyway guys!

Never scared

Tom W Clark posted 09-12-2002 02:05 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

Why didn't you just rope start your motor?

Salmon Tub posted 09-12-2002 02:35 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
Tom, that ain't the point, call Leonard Nemoy, isn't he still doing In Search Of, or that guy on Fox network with the weird stories.
NEVER SCARED posted 09-12-2002 05:16 PM ET (US)     Profile for NEVER SCARED    

I tried to. Using what tools I could find, I removed about 20 bolts that secured the flywheel cover. Then I removed a screw that adjusts the throttle setting (had many tiny grooves for adjusting, hope I got it right). After the cover still didnt come off, I didnt want to remove any more cause I really dont know what I was doing. I put all the screws back in and finally got the engine to crank (in the potato patch) but wouldnt turn over -bad plugs! Was I close to removing the flywheel Tom?

EddieS posted 09-13-2002 01:43 PM ET (US)     Profile for EddieS  Send Email to EddieS     

That is an extremely wierd coincidence! Did you check the ground wires coming off the lower coil? Mine did not have any heat shrink tubing and the connectors were corroded. Your problem sounds exactly like what I encountered. When you put the boat on plane were you just able to make it at full throttle?

I am going to check the timing, though my motor seems to have been running real well before this latest problem. I will be taking it out on Sunday for a test run, tankful of techron loaded super to clean out the fuel system. I will post and let you know how she fairs. Keep me updated if you find anything more out.


EddieS posted 09-13-2002 02:11 PM ET (US)     Profile for EddieS  Send Email to EddieS     
Salmon Tub,

I emailed you my phone number. Give me a call if you get the chance.


grandmufti posted 09-13-2002 10:02 PM ET (US)     Profile for grandmufti  Send Email to grandmufti     
Bigshot;Of the three powerpacks that I have had go bad in my lifetime only one died at once.My experience with them is a slow intermittent death.Sometime it would start with an occasional miss other times an intermittent loss of power.
I wish they would just die all at once as it would make trouble shooting a lot easier.Had one drive me nuts because it would fire at idle while testing it but would cut out at higher rpms.
Bigshot posted 09-16-2002 01:31 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
salmon....electrical problem....obviously. If fuel, carbs would not be wet:)

Powerpacks....everyone I had that quit did so at startup. Cold motor, gop to crank and no spark. NEVER had one go intermittently. Maybe that is because it was always OMC or soemthing.

Salmon Tub posted 09-16-2002 04:06 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
Ran a compression check on Fri., all are fine. Odd thing is that Cyl. #3 is now completely clean. Other than the dirty plug, there was not a hint of carbon inside the Cyl. or on the face of it. I doubt it is from water entry, but rather the same effect from the gasoline as it did not burn but rather just went in compressed and went out. Put in new plugs and have yet to try it. Does anyone know how to check the coil for spark? I have an idea but it is a bit aukward for 1 guy to do.
Bigshot posted 09-16-2002 04:35 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
To check for spark....stick finger or tongue in spark boot and have someone turn over the engine. Having one barefoot in salt water will help conduct electricity even more:)

Actually you will need someone to check or turn key. Just stick new plug in boot and rest against cyl head. Spark should be very evident if plug is touching metal. not try this on electronic engines like new EFI's. A nissan-tohatsu is OK but you may want to ask your dealer.

Salmon Tub posted 09-16-2002 04:57 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
Exactly, I was planning on putting dummy plug into plug hole, and attaching a jumper from plug in plug wire to block, but I am not sure about the CDI unit, I know that if the spark isn't grounded out, you can kill the unit. The less harmfull way would be to use a timing light which would pick up the pulse, but that would not tell me of if it is a strong or weak pulse.
EddieS posted 09-16-2002 05:38 PM ET (US)     Profile for EddieS  Send Email to EddieS     
Latest update on the Nissan. I took it out for a run on Sunday. I did use the Techron and fueled up with premium. Motor started easy as usual and ran fine. I launched in Bodega and ran it for 30 miles. At the end of the run I took her into Spud Point Marina to see if a buddy of mine was there, I could not believe how well it idled and ran at low RPM's! It normally vibrates quite a bit at the low RPM's, I am not sure if it was the decarb, techron, or the electrical wires that did the trick. I was pretty jacked up with the way it ran though.

Thanks for all of the input and help in tracking down this problem.


Salmon Tub posted 09-19-2002 02:03 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
Just did a test run yesterday eve. With the new spark plugs, I first put the muffs on to test. Motor started easy, idled at 700 rpm. Slowly came up to 800-900. Put in water. Idled at 800 out, and 600 in gear. Adjusted idle up a bit to specs: 900 out and got 600-700 in gear. Specs call for 750 in gear. Idled out of 5mph zone and opened up slowly. It ran fine then back to normal. Again, my pilots were set to 1 7/8 open each. Closed the bottom a hair, just above 1 3/4, left other two as they were. ran for a half hour at 3000-4000 rpm, too lumpy (rough) for more throttle. Good acceleration (can feel the pull). After 1/2 hour, I came down to idle and while in gear adjusted idle to steady 700 rpm. out of gear this bumped me to 900 rpm. I have noticed that at this setting, if I run and slow down to troll, I have no problems, I run into problems if I run then stop to drift. Upon re-starting, it will idle higher up to 1000 rpm. This makes the shift rougher. I have a solution, start, warm up, then hit the choke for a second to drop the rpm's momentarily to engage gear, again after a run, the idle stays low enough for smooth shifting. I think what happened was that in my previous settings I had was in effect too rich, with the idle screw set lower (it only controls the butterfly). What would happen was that for the setting the timing is now at (as per spec. 5 atdc while previous was 3 atdc.) When I would troll, I would give a hair of throttle from idle to bring rpm's up to 700. This opened the butterfly to where it is now, but it would also advance me to say 3 atdc while previous would advance me to say 1 atdc. Now I do not advance throttle so the timing remains at 5 atdc. In effect I have retarded it even more if you compare the position of the butterfly at idle to the timing position. Logic seems to dictate that this will make the engine run hotter. It may be that I was running too cool before. Running too cool is a good cause for premature fouling as I have always been told. Also, for what it is worth, I realized that at troll, the engine performs much better trimed up to max, just before you hit tilt. I guess it does not get as much resistance and lugs less when trolling in swells and going uphill. Will be pulling the plugs today to check color. Any input would be appreciated if something doesn't make sense, I still have a hard time trying to get the whole picture in my head.
Bigshot posted 09-19-2002 02:39 PM ET (US)     Profile for Bigshot  Send Email to Bigshot have no trouble putting it on paper!:)
Salmon Tub posted 09-19-2002 04:34 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
I see no paper here, only screen ;)
Bigshot posted 09-20-2002 09:40 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Salmon Tub posted 09-20-2002 01:42 PM ET (US)     Profile for Salmon Tub  Send Email to Salmon Tub     
By the way, I was a little disheartened by this situation in that I too had recently installed the plug that failed (6/27/02), about 20-30 hours ago. This is not good if this is the average life of a plug in my engine. I tested the plugs yesterday, and to my delight, the plug from cyl. 3 seemed defective. plugs 1 and 2 showed continuity between the tip (wire side) and the center post, and no continuity between the same tip and the threads. #3, was the opposite, so it was shorting out directly to the block. Problem found, case closed.
Bigshot posted 09-20-2002 02:03 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I have no idea what it is with plugs in 2 strokes but I have bought more defective plugs than I can shake a stick at. I have had dirtbikes where the plug shoots a sprk, but yet bike won't run. Throw another plug in it and she fires right up.

This is why I always tell people to try new plugs. Most say "but the plugs are new!" and I say rule out the problem for $2 a plug and if I am wrong, they don't go bad now do they?

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