Rough running Evinrude V90

[oldboat1]

Test run it with a portable tank and a 50:1 ratio. Testing on muffs has limited utility, as there is no back pressure. Further, water pressure from the hose substitutes for action of the water pump, so not a good test of cooling system.

 

[racerone]

Time to pull the cylinder head with the lowest compression.----See if motor was rebuilt.-----Head gasket is cheap in the big picture.

 

[Green Lantern]

Time to pull the cylinder head with the lowest compression.----See if motor was rebuilt.-----Head gasket is cheap in the big picture.

Compression is good all around. It's an Evinrude factory remanufactured unit.

 

[Green Lantern]

Test run it with a portable tank and a 50:1 ratio. Testing on muffs has limited utility, as there is no back pressure. Further, water pressure from the hose substitutes for action of the water pump, so not a good test of cooling system

Time to pull the cylinder head with the lowest compression.----See if motor was rebuilt.-----Head gasket is cheap in the big picture.

Do the reed valves need back pressure being in the water to help them operate correctly?

 

[oldboat1]

no. Don't get into the reed valves yet. Test cylinder compression with a standard tester (reed valves have nothing do do with cylinder compression values.)

 

[racerone]

Reed valves are generally trouble free.----But good luck with this rebuilt motor and your trouble shooting.

 

[Green Lantern]

no. Don't get into the reed valves yet. Test cylinder compression with a standard tester (reed valves have nothing do do with cylinder compression values.)

Checked the compression. All between 115 and. 120.

 

[ryan 98]

It didn't sound all that bad running there. Seemed sluggish on the throttle tho. These motors really do need back pressure on the exhaust to run properly. Even mine that idles dead smooth in the lake sounds all broken up and rough on the water muffs. I'd take it out and see how it behaves. Then you will have a better picture of what it's doing. As long as you don't have a carb situation where one barrel is dead and you keep driving through the issue you shouldn't do any damage. But of course that's my experience with them so take it with a grain of salt. If it's lean popping and showing the signs, don't try and drive through the issue. Also if it's sat for Manny years check that water pump. Should be a nice steady stream at idle and a pretty high pressure jet of water at speed.

 

[Green Lantern]

Does anyone think this is a problem?

 

[Green Lantern]

It didn't sound all that bad running there. Seemed sluggish on the throttle tho. These motors really do need back pressure on the exhaust to run properly. Even mine that idles dead smooth in the lake sounds all broken up and rough on the water muffs. I'd take it out and see how it behaves. Then you will have a better picture of what it's doing. As long as you don't have a carb situation where one barrel is dead and you keep driving through the issue you shouldn't do any damage. But of course that's my experience with them so take it with a grain of salt. If it's lean popping and showing the signs, don't try and drive through the issue. Also if it's sat for Manny years check that water pump. Should be a nice steady stream at idle and a pretty high pressure jet of water at speed.

Ok that's good advice. I think I might try that. I will get all of the throttle linkage set up and try it on the water. Starts up fine every time, and yes when I have the timing lever pushed pretty much all the way back it seem to idle ok.

 

[RBoyd1971]

Does anyone think this is a problem?

That is a coating the manufacture put on there. It's green in color.

 

[RBoyd1971]

Check the connection to the small wire on each coil. If they aren't making a good connection due to corrosion or the wire being almost broken it'll run like that. Mine was acting kind of like that and when I pulled on one of the wires the connector broke off. Fixed that and it ran well. Be sure you hold the lever so the idle stop screw is solid against it's stop when checking idle. I noticed your had the throttle cable disconnected.

 

[RBoyd1971]

That plastic yoke attached to the throttle cam controls timing as the throttle plates open till the timing plate reaches the max advance stop. You didn't mess with that did you? That's the pickup timing and is set for a specific timing just as the roller meets the cam and aligns with the smaller embossed mark. On my 82 model, that is 4 to 6 degrees.

 

[ryan 98]

Does anyone think this is a problem?

Not a problem at all. That's just a shellac or coating they spray on the lamentations so they don't rust. I could be wrong but I'm fairly sure that's a aftermarket or re wound coil. All the original omc stuff I've seen has had an amber colored shellac on it. But I could be wrong. Either way it shouldn't matter

 

[racerone]

Looks factory original to me.----I see nothing wrong there.

 

[Green Lantern]

This evening I was inspecting some of the wiring. The power head is painted black. The ignition module on each side of the motor were grounded to a painted surface on the power head. I cleaned them up and put them back together. It was too late to run it. Would it makes sense that if these were grounded to a painted surface that they could cause the odd misfire? I had an old air cool VW and the distributor but was loose. This was causing an arc between the distributor and the block and was giving similar symptoms to this Evinrude. Thoughts?

 

[RTZ]

That's how mine runs on muffs in the driveway. It runs much better on the lake. If it starts good, it must be a pretty minor issue. Normally if anything is off a bit, they normally do not start very well. At least that's what I have noticed.

 

[Green Lantern]

Starts mint everytime. I feel like it's something super minor that I've been missing. I cleaned the 2 ignition grounds that were on the painted surface last night. Going to fire it up this evening. Fingers crossed. It should run better than it does in the driveway. There is definitely an intermittent ignition miss.

 

[Green Lantern]

Pretty sure I have the fuel set up right. Ses to idle nice now, and it will Rev strong. But there is still an ignition miss and it looks like ignition is intermittent. When I use a timing light on each cylinder it indicates no miss at any time. Soaybe the spark is not strong enough or the signal to the coil is not strong enough. Here is a video of it using a gap tester.

 

[oldboat1]

Try this tester (open air adjustable -- and cheap at an auto parts store). Start at about a half inch or a bit more, and dial back if the spark intensity is uneven: