Evinrude 40 hp problem.

[valkie]

Hi All;

I have read several posts about idling problems with evinrude engines but I need some advice.
My evinrude 40hp is a 1989 model, the manual I have is basically crap with too much information that dont seem to match my engine.

The engine refuses to idle.
I have only had it for a short while and when I first got it it was a very slow idle, rough but it still idled.
Now it will not idle when in the water or in a tank.
Out of the tank it idles at about 500rpm and it idels without fail.
In the tank or water, it just stalls.
If Im quick enough I can get it into gear and be off and it goes all day at any throttle with no problem and plenty of power.

The manual states 750-850rpm at idle, but there is no idle screw to adjust it.
The timing seems ok and advances to the recomended 19 deg at 3500 rpm
If I operate the carby throttle without the advance, it accelerates, but rough (as expected).

I have fiddled with the slow speed mixture screws (taking care to know where it was originally) but nothing changed, so I put it back (about 2 1/2 turns from seated)

The carby control cam follower was about 1/4" away from the cam originally, I adjusted it to touch the cam as detailed in the book and it now accelerates much smoother, top end seems uneffected.

In order to keep it running I have moved the carby follower to touch the cam and hold a higher idle, this is not the way it is noted in the manual, but it seems to work and the motor still performs faultlessly, but dont stall.
i would like to have it correct instead of jury rigging it.

To summerise.
Motor will not idle in water, but will using earmuffs.
Motor performs well at speed, pulls well and smooth.
Compression seems good.
Advance works and hold steady
Sparks good (warning dont touch spark plugs, it hurts)
Plugs are a little oily after idling for a while, but the colour is good so I assume it runs ok at speed.

Any advice would be appreciated.

NOTE
I have managed to up the idle speed by adjusting the cam follower on the carby.
Idles at 750-800 rpm in the water (at 1000 rpm with earmuffs)
Moving the carby cam does not affect the advance, just the carby.
Advance is correct at 3500.
With my adjustment the motor runs fine.

thanks for any help.
with

 

[oldcatamount]

Re: Evinrude 40 hp problem.

2 1/2 turns out on the slow speed needle seems a little to much to me. It sounds like you need to pull the carb, take it apart, and clean it, then install a new carb kit. Also, you may need new Champion spark plugs # UL81C gapped at .030. You may even try gapping a bit wider (0.35)

 

[Silvertip]

Re: Evinrude 40 hp problem.

Don't be so hasty on carb rebuilding. The reason it idles (although still too low) on land is that there is no exhaust back pressure like there is when you put the engine in the water. 500 rpm is right at the ragged edge for idle. Yes -- there is an idle SPEED screw and YES you need to adjust it. Make all adjustments with the throttle cable disconnected and with the engine in the water. Adjustments include idle mixture (first) then idle speed, followed by idle mixture again, followed by idle speed. Then adjust the throttle cable using the trunnion (knurled wheel on the cable).

 

[valkie]

Re: Evinrude 40 hp problem.

2 1/2 turns out on the slow speed needle seems a little to much to me. It sounds like you need to pull the carb, take it apart, and clean it, then install a new carb kit. Also, you may need new Champion spark plugs # UL81C gapped at .030. You may even try gapping a bit wider (0.35)

I have checked the plugs, apart from a little wet after idling, all sems to be ok.
At speed there is no problem, not a miss in sight.
The plugs are set at .030, but I will try 0.035.
I really would prefer not to pull down the carby if I can.

Don't be so hasty on carb rebuilding. The reason it idles (although still too low) on land is that there is no exhaust back pressure like there is when you put the engine in the water. 500 rpm is right at the ragged edge for idle. Yes -- there is an idle SPEED screw and YES you need to adjust it. Make all adjustments with the throttle cable disconnected and with the engine in the water. Adjustments include idle mixture (first) then idle speed, followed by idle mixture again, followed by idle speed. Then adjust the throttle cable using the trunnion (knurled wheel on the cable).

I tried holding my hand over the exaust (to duplicate back pressure) apart from making the exaust a little more quiet, no change, didnt stall.
Im interested in the idle speed screw.
I have been all over the motor, and I cant for the life of me find one.
On earlier engines they show the screw on the port side of the carby, but on mine there is nothing but the end of the shafts for the butterflies.

Please, if Im missing something, or the screw is somewhere else, let me know.
Ill try the mixture adjustment to see if it makes any difference.
Where should I start, 1 1/2 turns out?, 2 turns out?


Thanks for the help.

 

[Silvertip]

Re: Evinrude 40 hp problem.

The idle speed adjustment is not on the carbs. Its on the linkage that controls the ignition advance AND the carb linkage. Have someone move the throttle while you stand on the starboard side of the engine. Watch the big lever. Note the screw postion at idle. Be careful what you mess with. The procedure commonly called Link and Sync and its purpose is to synchronize throttle opening with spark advance. This is a long process and one does not start in the middle. You need a service manual for your specific engine as nobody is about to type the many pages and post the pictures involved.

Lastly -- holding your hand over the prop does not seal the exhaust. It may quiet it down some but the exhaust will simply excape from the gap between the prop and the lower unit housing.

 

[valkie]

Re: Evinrude 40 hp problem.

The idle speed adjustment is not on the carbs. Its on the linkage that controls the ignition advance AND the carb linkage. Have someone move the throttle while you stand on the starboard side of the engine. Watch the big lever. Note the screw postion at idle. Be careful what you mess with. The procedure commonly called Link and Sync and its purpose is to synchronize throttle opening with spark advance. This is a long process and one does not start in the middle. You need a service manual for your specific engine as nobody is about to type the many pages and post the pictures involved.

Lastly -- holding your hand over the prop does not seal the exhaust. It may quiet it down some but the exhaust will simply excape from the gap between the prop and the lower unit housing.

Thanks for that.
Im new to boats, but I have rebuild cars, bikes and aeroplane motors.
This one has me stumped.
I know the big cam you are talking about and whne ith throttle cable is advanced it moves everything. I was worried that any adjustment on this would affet the idle as well as the advance, so I didnt touch it.
Silly me thought that blocking the exaust at the prop duplicated back pressure, obviously I have much to learn.
I have a manual on order, the one that came with the boat was far from instructive it covered every motor from 1962 through to 1989. As my motor is a 1989 Im assuming there may have been additional changes that the book has not caught up with.

Do you know what the timing should be at idle, Mine idles at about 6 btdc?

Thanks again

PS
Ill be travelling over the next three weeks and unable to do anything to the baot, so its not that Ive gone off the boil, its just that Im not at home.

 

[valkie]

Re: Evinrude 40 hp problem.

Just double checked my timing at idle, its actually TDC.
This dont seem right to me, every engine Ive ever worked on had at least a couple of deg BTDC.

If anyone out there has a 40HP 1989 evinrude, please run the motor it idle and let me know what the timing is at that speed.

The book only tells me what it is at 3500 rpm, not at idle, me thinks this could be half my problem.

Any help would be appreciated.

 

[Silvertip]

Re: Evinrude 40 hp problem.

You are working on a two-stroke engine so forget everything you think you know about four stroke auto engines. Ignition timing and carb operation is synchronized for a reason on a two stroke. Slow idle, quick throttle response and safe WOT operation require proper carb and timing sync.

 

[valkie]

Re: Evinrude 40 hp problem.

You are working on a two-stroke engine so forget everything you think you know about four stroke auto engines. Ignition timing and carb operation is synchronized for a reason on a two stroke. Slow idle, quick throttle response and safe WOT operation require proper carb and timing sync.

Damn, I thought it might be too easy a fix.

I contacted the last owner last night.
It appears that he replaced the CD unit as it was faulty, it was running alright after the replacement, but had a slow rough idle.
I bought it about a month ago and the first couple of trips it was ok, rough idle, but ok.
It never got above 4000 rpm.

Then it started to have problems idling, would run ok, but would not idle.
The cam follower on the carbs was not touching the cam (as it said in the book) and when I went to make that adjustment, the screw holding the cam follower was loose, obviously came loose.

Now, the only way I can get it to idle is bu putting some very light force on the cam follower to increase the opening of the butterfly (a very very small amount)
It idles nice, runs well, but I would prefer it to be correct.

When I checked the timing at idle last night, it was TDC or perhaps a little retarded.
Im thinking that this does not make sense.

If someone could tell me what their idle timing is I would feel much better.
I have checked the timing at 3500 and its correct or very close.

The adjustments on the engine allow me to adjust both WOT timing and Idle timing.

Oh, I just found out that the manual I had ordered will not be coming.
Ill have to try another source, any suggestions?
Im in Australia, so everything is just so much harder down here.

 

[Cofe]

Re: Evinrude 40 hp problem.

Here is a ebay link for your manual, and they say they ship world wide. http://cgi.ebay.com/ebaymotors/1989...30498294807QQptZMotorsQ5fManualsQ5fLiterature

 

[valkie]

Re: Evinrude 40 hp problem.

Here is a ebay link for your manual, and they say they ship world wide. http://cgi.ebay.com/ebaymotors/1989-...sQ5fLiterature

Thanks Cofe;

I have asked if they deliver to Australia, the cost and when I can get it.

The looks of things it could be a couple of weeks.

thanks again.

 

[valkie]

Re: Evinrude 40 hp problem.

Thanks Cofe;

I have asked if they deliver to Australia, the cost and when I can get it.

The looks of things it could be a couple of weeks.

thanks again.

Got the manual, didnt help much.
Finally bit the bullet and took it to a workshop.

Turns out there was a compression differential between top and bottom cylinders.
The head gasket was leaking.

Simple fix which I could have fixed had I read the instructions and checked the compression first "this is what the manual first states"

So
Just to let you all know.
Read the manual, if it says to do something first, try it, could save you a lot of trouble.