40HP evinrude stalling at high speed when hot-won't restart

tad0912 · #1 June 1st, 2004, 03:33 PM

Can anyone lend a hand?

I have a 1976 40HP Evinrude (model # 40655A)that is giving me some trouble. I have owned the motor for 2 years without any problems, but this year, after replacing the spark plugs with the correct plug type (after finding out we purchased with the wrong type), the motor is intermittently stalling at high rpm (not sputtering out, just plain stopping). It appears to be only after a running/soaking/running cycle when it is hot. Also, sometimes it will be hard to start just prior to the high rpm stall. When hot, I let it sit overnight, the motor will sometime start again after cranking, but is sometimes sporadic. The plugs are gapped at .030Â”, and look okay (not fouled or blackened/sooty). IÂ’ve tried to check for spark when it doesnÂ’t run, and I donÂ’t get a positive signal, however, IÂ’m not certain I am getting a good ground on the plugs either with the tester I am using. I am leaning towards a condenser/coil issue, but wanted to make sure there wasnÂ’t anything else I should be checking. I have also ruled out the overspeed switch, as it has both run when this was connected/disconnected, and not runÂ—no link.

Any help would be appreciated.

OBJ · #2 June 1st, 2004, 06:21 PM

Hello Tad....welcome to iboats forums.

Lets' do a couple questions here.

When was the last tune up, points, condensers, water pump impeller, compression readings, carb over haul...etc. etc. etc.

Are we sure the engine is not over heating?

Did you check the spark right after the stalling? Usually when an engine just stops, it's ignition related. Have you lately check under the "hood", flywheel, to see what shape the coil and points/condensers are in? Could be time for replacement.

Most important question, do ya' have a manual? Losts of nifty stuff in them including troubleshooting guides.

Mull the above over and let us know what ya' done.........Thanks!

tad0912 · #3 June 1st, 2004, 07:02 PM

Based on fact that I don't have much history on the motor, I bought a manual and started going through it last week . I also ordered a tune up kit (not in stock at that time) as a means of taking those components out of the equation for the $20-30---and also some peace of mind for the future. I don't believe the problem is temp related (doesn't seem to be too hot, appears like I have good flow, and it wouldn't start a couple of times even after sitting a couple of days), but if you have any advice to help me confirm that, I'd be willing to chech. Mostly, I'm just trying to make sure I'm not overlooking something else really obivious (like the overspeed switch, which doesn't appear to be the problem, but I didn't know about). Thanks for your help. I'll do the tune up this weekend, see what it looks like, and let you know what I find.

OBJ · #4 June 1st, 2004, 07:18 PM

Real good start Tad....and check the coils under the flywheel. Make sure none of them are cracked. If they are, would be a good ID to replace them.

Let us know what ya' find and how she runs.

tad0912 · #5 June 8th, 2004, 04:13 PM

OBJ,

Popped of the drive plate off this weekend. Condensor/points looked relatively new, but since I had a set already procurred in case, went ahead a swapped them out and re-set points. (I don't think I had to re-set any timing did I??) Tried out boat over the weekend with them and it ran fine with no issue during limited use. However, stopped running for my aunt after used for about 45-50 min. After 4-5 hrs. of sitting I was able to re-start it quite easily. Don't consider the ignition time a waste, but should I go after the impeller or a carburetor rebuild next?? It seems like I'm getting enough water flow when I look at idle, but are there any rules of thumb? Also, another issue I noticed is that the priming bulb never gets really completely hard when pumping up the system. Visual inspection of the gas line doesn't indicate a leak, but could there be anything going on there. (if you think its worth it,I could try and replace with some clear tubing to identify anything else--only thing is, it does this both when it runs, and doesn't). Thanks for any advice you can give.

TAD0912

Solittle · #6 June 8th, 2004, 06:00 PM

Have you done the carbs & t-stats since you bought it? If not - - - -

OBJ · #7 June 9th, 2004, 01:23 PM

That's good news Tad.....Couple things. Check the engine temp after running for a while. There is a flat place on top of the block just forward of the head. With the engine running, you should be able to lay your fingers on there for several seconds before having to remove them. If after running a while and the area feels relativily cold, either you need a t-stat or the one in there is stuck open. The engine needs to run at a certain temp to get the best performance outta it.

Look at the carb. Where the bowl and body meet, theres a gasket. If it's black, I would suggest a carb over haul. The black gaskets have a habit of drying out and breaking off with the newer gas. Of the gasket is a reddish brown, the carb has been rebuilt at some point in time.

Water pump impeller....this is always a good thing to replace if your not sure when the last time it was replaced. Even if the engine is running good and no overheat indicated. These things have a habit of just going out.

That otta keep you busy for a while. What we are trying to do is keep you outta trouble and have a good boating experience. What we've suggested above should do that.

Keep us posted Tad....thanks.

OBJ · #8 June 10th, 2004, 04:35 PM