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Evinrude 70HP 1984 3Cyl 2stroke Rev RPM problems

C

Cape Horn

Member
Hi Guys, I most likely have some ignition problem which I'm struggling to identify. I have cool motor, 130PSI+ compression, carbs cleaned, ran strong @ 40mph on 13x19 prop. the other day, RPM fell to 2.200 after 15mins of strong WOT, so temperature could come into play. pressing primer ball did not have any effect, nore did pressing choke solenoid so most likely no fuel or carb issue here. Carbs spent plenty of fuel despite only 2200RPM and motor was nearly about to fully bog down at WOT. Motor has no SLOW temperature sensor, so I'm guessing on stator, timerbase, CDI or ignition coils issue. Idling and neutral RPMs were fine at any time though, no probs. After cooling down a bit, I could ran again at WOT, but after 1 Minute .. see above, story repeated. I'd be so glad to get some troubleshooting support what to do 1st. best regards Joerg
 
Does spark jump a gap of 1 cm or more on all 3 leads , yes or no ?----When was water pump impeller changed last ?----Have you tested the overheat heat warning horn ?----Replaced fuel pump diaphragm ?----Checked for water in fuel ?
 
Racerone, I will check spark jump by gap of 1 cm or more on all 3 leads asap ! I'll report.

Waterpump impeller ->
was checked a month ago since I had crashed my lower unit on swedish lake rock, so I did a complete change of lower unit and replaced it with a used one. Water pee through nipple is plenty, strong and fairly cool, impeller looked new & healthy.

Overheating warning horn ->
I didn't ever hear any alarm by the motor. I have a warning horn in my controlbox. I'll check if it works, I'll look for that tan wire coming out of the cylinderhead, with an insulating sleeve over the wire. I'll then slide the sleeve back to expose the terminal underneath, turn on the key and ground the tan wire to the head. Horn then should blow. Maybe I should use temp gun to crossckeck while in operation. However, there is no SLOW function (1989+) for this motor (1984) in case of overheating, e.g. no automatic Rev decrease, afaIknow.

Fuel (fuel pump / water in fuel) ->
I don't think it's a fuel related issue. It runs 40mph for 10-15 mins, then bogs down to 2200rpm. If I apply starter pilot spray during WOT at 2200rpm to each of the carburetors, there is further bogging down instead of Rev increase. Motor seems to run too fat or has ignition / temperature trouble. Fuel pump was changed last summer by a chinese 10$ bling-bling replica but ran wow since then.

this was to provide my view. I'll come back with the results of the spark gap test. I also will provide Ohms resistance of coils and CDI, if that helps.

best regards !
J oerg
 
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changed Trigger and Stator the other day, I took parts from exchange engine .. ignition problems are now fixed, runs faster then before ! However I dunno whether root cause was Trigger OR Stator. Will roll back piece by piece eventually to figure out.

I wasn't successful in testing my overheating warning horn though. I wiretapped that wire coming out of the cylinderhead and grounded that to the block while motor was running, expected Horn, but Motor shut off.
 
by the way: Motor is now 35years, has 130PSI per Cyl. Anybody out there who would recommend precautionary changing of gaskets (head, Reeds, cooling plate, etc.) HeadGasket looks little crusted. However, motor was not operated in salt water. Would appreciated any opinion... Joerg
 
Head gasket might be a good idea to change out. Excellent compression. You guys run straight petrol or fuel with ethanol? Make sure cowling insulation isn't breaking down.....I've found it trapped in reed valves over the years. Ethanol fuel is mandated in at least 7 states here, one of which is Minnesota, a big corn growing state. I encourage all who care for their motor to never, ever use ethanol.....or any additives containing hydroxylated hydrocarbons. Even our diesel fuels contain the crap now. Gotta burn heating oil in my old equipment, then use an Amsoil suppliment.
 
great recommendation regarding cowling insulation, I'll remove any foam stuff immediately !

Motor Fuel in Europe is currently circa as follows:


  • Super E10 (95ROZ Octane / max 10% Ethanol) currently 5,50$ per Gallon
  • Super (95ROZ Octane / max. 5% Ethanol) currently 5,65$ per Gallon
  • Super+ (98ROZ Octane / max. 5% Ethanol) currently 5,97$ per Gallon
  • Diesel (Gazolinie, max. 7% BioEthanol) currently 4,40$ per Gallon
  • Gas (LPG) currently 2,65$ per Gallon

Since Ethanol has lower energy density you'll loose 1-2% Power on the crankshaft with that E10 10% blend.
you see, our motorboat hobby is something of worth for us.

greetz
 
These prices are "staggering". Octane levels are impressive. I have fuel here at 91 octane and "clear" non oxy. Filled my tanks in May @ $1.75 per gallon. Right now, clear non oxy (ethanol free), selling at retailers for around $2.50 per gallon. Thanks for converting for us. Excellent information. So ethanol free is not available? I have noticed more cowling insulation deterioration on motors using ethanol. Tried soaking some in alcohol and it certainly encourages rapid deterioration.
 
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"staggering" is spot on. right, minimum Ethanol level is 5% so no clear fuel available. some MineralCos do some hocuspocus within that 5% since there is no chemical difference between Ethanol from fossile Carbon compound and bioEthanol from plants. so they try to suppress any Bio image within their premium blends (Super+).
I'll remove that foam today (-:
 
Cape Horn said:
I wasn't successful in testing my overheating warning horn though. I wiretapped that wire coming out of the cylinderhead and grounded that to the block while motor was running, expected Horn, but Motor shut off.
Click to expand...

any ideas ? shutoff indicates imho that temp sensor is connected to shutoff cable of CDI (black yellow). However, I definitely have warning horn in my control box want to connect that. I'm quite sure about that warning horn since I did box renovation last winter, see picture. Is my warning horn not connected anywhere ? how2test ? best regards

IMG_2399.jpg
 
The wire going to the other side of the warning buzzer.....could it possibly be black/yellow? Not yellow /black......but black/yellow. Don't let any power get into that wire. You could find a new power pack on your grocery list.
 
Tim,
1) TempSensor @ motor (tan/blu) -> via Plug -> connected w'th black/yellow @ CDI. If I shorten tanblu wire on motorblock (ground), engine shuts off, no beep, so far, so good ?!?!
2) yellow / black does not exist in my motor nore in Evinrude colourcode table
3) what I'm simply looking for is: how to wake up my buzzer horn in ControlBox ? never heard it except from shortening it.
best regards
Joerg
 
Trouble is I am always nervous with power on one side of buzzer, and the same wire on the other side going to stop your motor via the black/yellow. I cannot say that buzzers all have a diode on that wire to prevent a "backfeed". Other techs might chime in here, but I would prefer to shut the motor down myself after I hear the buzzer. Keep that black/yellow away from the power.
 
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Joerg probably sleeping now...UK fella. Something like five or six hours later than Eastern Time.
 
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thanks guys, sleep was great, German dreams .. currently it's you dreamin
Motor is E70TLCRD 1984 thanks
Should I diassemble the ControlBox to gather colour codes of the wires connecting the horn ?
@racer: you may be right since Tempsensor & wire is overpainted with overall motor paintwork, could also be pure tan or similar colour.
 
Right, should be pure tan. Someone got Evinrude blue on it. You may have to revisit control box. Buzzer has power to one side when key in "run" position, right. When other wire, tan, originating at temp sensor, gains continuity to engine ground.......or everything ground (control box, ignition ground, boat ground)....you know what I mean, then the buzzer sounds. Check all these grounds and it should work. Once again, I would disconnect the black/yellow from this circuit. This shut down is not something I personally recommend for a responsible operator.....but that advice is coming FROM a responsible operator. Thats just me.........a guy who drives a 74 Chev truck.....stupid, right? Maybe.....but why should I drive something that more controls me, than me controlling it?
 
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great, resolved !!

I visited ControlBox and grounded there, Buzzer sounds !
I visited motorside. blue motorpaint on both tan and black/yellow lead to mix-up of cables so when mistakenly connecting black/yellow to engine ground (assumed tan) it shut off. That is, what it was supposed to to.
I now connected tan wire to engine ground at motorside and "beeep".

Finally, it was my mistake to mix up cables due to motorpainting. thanks for your support in resolving & best regards Joerg
 
morning Guys ! as mentioned above, I changed both Trigger & Stator due to Rev problems, it worked out !

Now I have the old faulty Trigger (581949) culprit on my desk for diagnosis purposes.

Trigger plug has four holes A/B/C/D. Measuring with multimeter in Ohms ->

A/D: 11,5 Ohms
B/D: 11,3 Ohms
C/D: zero Ohms (0L) C is purple wire

If I measure ohms and get a result that is a number, then there is, by definition, continuity. If there's no continuity, then resistance is infinity,which most meters show as 0.L. Resistance is the only bench test available for this trigger, right ? any chances to do some repair on this culprit or disposal to bin ?

best regards
Joerg
 
morning

coming back to Timguys recommendation to remove the old insulation due to Ethanol disintegration:
I replaced the former insulation with my Yoga mat which is of 15mm thickness, pls. see pictures.
I only covered areas, where old insulation was placed before. It may also have positive effect on noise.

Does anybody think, it may get too warm inside there ?

best regards & happy Christmas
Joerg

02.jpg01.jpg
 
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Great job, insulation looks good. This will not cause overheating and have little or no effect on operating temps. Sound abatement, certainly, and not a bad idea especially for tiller operation where your right next to the motor. That trigger should be saved.....doesn't take up much room on the shelf....just in case of an emergency...we know it still can run the motor.
Regards and greetings to all in your place too.
 
morning, my Motor had strong start into season. I'll try to replace my stock reeds with Boyesen B133. will one kit do one engine ? any experiences with those valves apart from record. Does it affect revs ? compression ? fuel consumption ? whole shot / top speed ? Is it worth or should I rather do not change running system ? I'd be happy about any opinion. best regards Joerg
 
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