Jason Just got back from the boat. Disconnected the pulse…

Jason

Yes it is.

Btw the engine is a 2002 75 ELPTO # *****

Yes, the timing light is picking up spark on each cylinder. The rod was still attached.

Jason

The engine was running fine and when used, it started normally as it usually did. It was on the water and seemed to lose power and began smoking. It still continued to run however, although low on power and rough. The gas is non ethanol and the boat is often used. The current owner has had the boat (2 years) since buying it from the original owners who used it infrequently (1 or 2 weeks a year) but had it serviced before and after each 2 week period of use. The original factory setting marks are still applied to the engine settings as far as idle and timing.

Does it have to be you tube? I can take a video with my phone if I can down load it directly. I don't have a you tube acct and have never loaded a video to it at any rate.

Ok, it will take some time to both get the video and figure out how to upload it but Ill give it a shot.

Jason

Got the video and put it on You Tube. "Mercury 75 HP" Posted by marineworks.

Not real good video but shows the smoking issue and running problems.

It is blue smoke, especially at higher rpm. Its a friend's boat. There is a sheen on the water after running that appears to be oil and droplets of fuel as well, (they disappear quickly).

Jason, I don't think there was motor oil placed in the tank by accident but don't know. Ill try running on a premix and by-passing the pump. Ill let you know.

No I don't.

Jason

Used a shop tank with 50 to 1 premix 93 Octane non ethanol fuel (fresh today). Using it, rather than the oil injection (having it run back into the tank, it made no difference what so ever. Engine still smokes blue smoke. It misfires and a cloud comes out of it. Often the misfire will kill the engine at idle.

#1. The oil in the shop tank was Quicksilver. #2 The engine does not seem to be heating up or over heating. #3 It will not run steady at any rpm. Removing spark plug wires doesn't seem to have any effect on the smoke. It continues to smoke especially after it misfires, a large belch of smoke will come out then.

Ok, Ill try that next. Im just wondering why this would start suddenly rather than gradually however.

Ill check that too

Jason

Just back from the boat. All three carbs have about the same amount of suction and the engine begins to die out when each is blocked off. The light from each spark plug wire on the timing light is steady and the same intensity. I checked the static timing with a screw driver in the plug hole and TDC is as indicated on the flywheel and the indicator on the flywheel cover.

I did note two things after the engine had been running for about 10-15 minutes.

The cooling water coming from the engine was not much warmer than the river water itself. The river is 66F and the cooling water was 71F. Outside temp was about 75F. I repeated this check using the temp. sensor leads from my multi meter and it appeared accurate.

The other thing I noted was the tach reads very slow at idle and indicates 100 rpm ( it is not idling that slowly either) but does not increase until the engine is far from idle and then it indicates 5000 rpm. It is not running anywhere near 5000 rpm at that time. Can the tach be partially shorting out the ignition off idle causing the smoke?

Or is the thermostat apparently not closing and allowing the engine to come to an operating temp causing the over rich condition and the smoke? That would account for the blue smoke and the seemingly loaded up engine wouldn't it?

Jason

Just an update and still with no real solution or fix.

Replaced the thermostat and poppet valve. Engine still not heating up to a normal operating temp. It is currently showing exit water as being only in the upper 70's F after 20-30 minutes of fast idle.

Performed another compression check, all between @125-130.

The tach still reads inaccurately as well.

Cleaned the carbs again, this time using carb cleaner and blowing out all the jets prior to ultra sonically cleaning them once again. No change.

Smoking heavily and misfires significantly still.

Charles

Checked the trigger and found it is moving. Engine still running poorly and smoking badly. I also looked at and checked the oil evacuation lines and found them to not be clogged or pinched. Turned all mixture screws to 1 1/2, no change. Engine is running worse now than it was when I started but smoking the same. Timing at idle is right. Spark plugs look sooty and oily. Carbs have been cleaned twice, float levels were ok. Fuel pump diaphram was replaced. Fuel filters replaced, run with premix (non ethanol and quicksilver 2 stroke oil) on shop tank, no change, still smoking. Two of three CDMs (with spark plug leads) were replaced. Spark on all cylinders appears strong. Equal suction on all carbs. Engine can be stalled by choking carb with hand.

Initial complaint was smoking at higher rpms. gradually becoming harder to start. The only problem this engine ever had apparently was a leaky oil cap which was replaced. Engine has low hrs no significant or apparent damage and has been well maintained.

Charles I will try this tomorrow and let you know. It makes the most sense to me so far. I do know the oil evacuation lines are clear and the check valves are functioning as they are supposed too.

Charles

Replaced the check valve with no change. Still over oiling it appears, rainbow on the water is made by spitting fuel and oil. Not sure what to do next.

Charles

Tried to trace the lines as you suggested but they feed under the powerhead somewhere. I did check and rese the float height with no change by the way. Still misfires and belches smoke when it does. The plugs are wet black and sooty. I ran "Powertune" through it and didn't see any change other than even more smoke came out as it cleaned. I visually checked the reed valves and didn't see anything out of place, torn or broken. I did not remove them however. I checked the timing on all cylinders and make a "white out" mark for each cylinder on the flywheel. Each cylinder is sparking at TDC and no where else in the rotation.

I disconnected the tach wire (gray) at the motor and found it didn't make a difference so it is not shorting through the tach. Reran it on a shop tank and precisely used the 50:1 ratio for premix with Quicksilver 2 stroke oil and non ethanol fuel, even bypassing the oil injection (ran into a shop container) the engine still smoked when it misfired.

Doesn't seem to be a fuel or ignition issue so it has to be mechanical and with good compression, that doesn't leave much. Blown head gasket?