1978 115hp rude. losing about 1000 rpm

[anderso8623]

My rude has had the carbs cleaned by myself once and a shop twice in the past two weeks. When I opened them up, they where surprisingly clean for a motor that had been sitting for 25 years as the PO stated. I cleaned them anyway. Sent it in for high rpm on the hose. They stated it needed a few things and ended up completely rebuilding the carbs. They found a large seed under the Welch cap...I think that's how you spell it... Dropped the boat the next day and it took off like a bat out of hell, I slowed down to idle and then throttled it back up and I could not get it over 10 mph and no rpm at the time. Took it back in that day and they made some trotted adjustments with no luck. Dropped it off again today and the tore the carbs down again and found what looked to be like a piece that was stuck on and broke free after I have it on the water. Took it out again and same thing, took off great but after I idled down I could not go fast again. This time I had a tach and remember seeing 5000 on the first hole shot but could barley break 4000 after. I maxed out at about 23 mph and 4000 rpm after using the choke a few times while WOT to convince it to get that high. Any suggestions?

 

[emdsapmgr]

Once the engine warms up and you experience the rpm drop, check all 4 spark plug wires for spark. You may be dropping spark to one cyl, or it may be intermittent at best. Weak ignition components tend to fail once the engine warms up to normal operating temps....Just to make sure it's not a fuel delivery issue, have a buddy constantly prime the fuel hose bulb when the engine slows. That will force extra fuel into the carb bowls. If it runs normally, as long as you constantly prime the fuel hose bulb, it may be a fuel delivery problem. (pump, hose, tank, etc.)

 

[Bob_VT]

These tests best done on muffs in your driveway so you do not get severely injured by the flywheel.

If you have a timing light with a simple clip on the spark plug wire end then check the motor at a high idle for spark. Look at the light and see it it seems the same on all 4 cylinders.

If you find a problem such as no spark or erratic spark.......then swap the ignition coil with another cylinder and test again. If the problem follows the swap then it is the coil............ if the problem stays with the same cylinder then it could be the power pack


Yup have been there and done that myself many times and it is either a coil or the powerpack if all else is correct. I would be 1000-1500 rpms low and the V-4 will still run but not with the proper power. Since you are in the maintenance mode - remember the impeller too to keep the motor healthy

 

[anderso8623]

Thanks, I will try all above. I did just replace the power pack because two cylinders were not firing originally.

 

[anderso8623]

For time saving purposes, if I need a coil or 4, what part number am I looking for?

 

[anderso8623]

Spark advancement linkage! Took it out and was running slow cold. Tried pumping fuel, nothing. Opened the cowling and it was hanging. started pulling plugs one at a time. Three of the 4 cylinders had less affect on the performance but did drop it. One had a great affect on the performance almost stalling the motor out. I'll start looking into that later. The strong one was the top cylender on the starboard side. But when I put the plugs back on the spark was jumping about an eighth of an inch from the cable to the tip of the plug itself. Took it back out after connecting the spark advancement lino age and it took off again. Hit about 4500 RPM before the linkage came off again. The presume clip that holds it in finally gave free and cracked. I am happy because it's about a $4 part.

 

[Bob_VT]

iboats sells a nice selection of ignition parts for your motor http://www.iboats.com/Evinrude-Outb...6639786--session_id.984306039--view_id.268670

 

[racerone]

Has the compression been checked ?

 

[anderso8623]

iboats sells a nice selection of ignition parts for your motor http://www.iboats.com/Evinrude-Outb...6639786--**********.984306039--view_id.268670

This is true but they do not sell the linkage components to my motor. I need the ball and socket connector for the spark advancement. As for the compression, we are running 125 ish on all 4

 

[emdsapmgr]

125 compression is what it should have been when the engine was factory new!

 

[anderso8623]

125 compression is what it should have been when the engine was factory new!

This is a good thing then! I attempted to insert the socket portion of the linkage, NOT the ball, but had a lot of difficulty. The original was a complete ring with teeth sticking up. The new one is a ring with no teeth and a diagonal cut in it to compress the ring. I broke this socket ring trying to put it in, any suggestions out there as to getting the socket it?

 

[emdsapmgr]

I've wrassled with a number of these over the years. Your current part is different from the original one which is more familiar to me. Can't remember which trick worked. 1. put the socket in the timer base first, then force the ball in, or 2. put the socket on the ball, then force the socket into the timer base. I do recall liberally applying some (white lithium) grease for lubrication first. Fortunately, your part is not a lot of $. Maybe one of the experts can chime in on this...