Questions on '78 115 Evinrude

[Searcher 200]

My 115 won't plane the boat. The engine starts easily. Takes a little choking to get it to idle. After it warms up it will idle (maybe a little rough). Compression is 125 to 130 on all cyliders. My fishing buddy says it needs a powerpack. In my troubleshooting so far in the driveway all ignitio wires will jump a blue spark with the tester gap set at .5 inch. That normaly means that the spark has sufficient energy to fire under pressure at least on autos. I need some help on the tach readings. Tach is a sunpro inductive with the selector set to 2 cycle. All cylinders show the same reading except the upper left which shows twice the reading of all others at any rpm. What gives? Accelleration is good but the engine seems to not rev all the way (my tach in the boat doesn't work and I just got the inductive today), almost like it is in limp mode. That wasn't an option on that old an engine was it? I thought maybe fuel pressure but I changed the pump today with no improvement. There is a sensor on the motor directly foward of the circuit board. It has 2 wires (1 red and 1 yellow with blue stripe) running to the circuit board. I can't find this sensor in the wiring diagram. Looks like heat. Can someone tell me what the sensor controls? Also can anyone point me in the right direction to troubleshoot this monster? One last thing, The planeing problem is constant whether the motor is cold or hot. I'm sorry for the extra long post. Thanks for your help.

 

[OBJ]

Re: Questions on '78 115 Evinrude

Welcome aboard Searcher!<br /><br />Compression sounds great....spark sounds like it's OK also.<br /><br />Would these wires (red and yellow with blue stripe) be coming from a thing that looks like a tin can on a triangular base? If so, that is the rectifier and there should be another yellow wire w/gray stripe coming from it also. <br /><br />What kind of tach readings did you read....rpm wise? Knowing this will help.<br /><br />Is this engine new to you or have you had it a while and the problem has just cropped up? If the engine is new to you, do you know anything of the most recent maint. that has been performed on the engine....ie....carb overhaul...impeller change out.....<br /><br />Does the engine run cold or warm?<br /><br />Lot of questions but info and history does help....thanks!

 

[Searcher 200]

Re: Questions on '78 115 Evinrude

Thanks for the reply. The boat is fairly new to me. I've had it in the water two times. It did the same thing both times. The first time I thought maybe bad fuel or a bad line. Brought it back and drained the fuel and replaced the hose. It did not help. According to the manual I didn't like the fuel flow I saw from the pump so I elected to change the pump kit today (even though everyone says that Evinrude doesnt pump fuel til the engine starts). The manual says it should have a steady flow. Maybe it did improve but not much. I bought the boat as is from an estate sale. Price was right and engine seems to be great with the exception of this one problem. Temps seem to be normal to maybe a little on the cool side. I did get a temp horn in the driveway with ears tonight but that took a long idle time and the water was a little low. On the water the engine seems to run perfect except not enough power to plane and low rpm but no cutting or spitting. I thougt that maybe the foam was waterlogged and to heavy to plane but the concensus of several people at the lake was it coudn't be and still sit as high in the water as it does. Everyone at the lake agrees that the prop is right for the boat. Boat is a 17.5 foot RayCraft rated to 140hp. Bad weather or not it goes back to the lake tomorrow so I can check the rpm with the new tach. Also it does have a good stream of water from both outlets and the pee streamer.

 

[Solittle]

Re: Questions on '78 115 Evinrude

Your buddy may be right on the powerpack but don't just go and buy one. Get a shop manual and test it first. I wouldn't be too concerned about the tach for now.

 

[ledgefinder]

Re: Questions on '78 115 Evinrude

Runs good at idle and low throttle? If so, and it sat for a while, could be a clogged main jet. There are 2 mains in each carb, located behind those plugs in the bottoms of the float bowls.<br /><br />Also, on the lake you might try disconnecting one spark lead at a time. If one of the four makes no difference, there's your problem. With the 1/2 inch spark in the driveway, it's probably not ignition, but still worth ruling out. Ground the loose wire to a spare plug or something, so the ignition system's not fighting it's insulation trying to get rid of that charge. <br /><br />That hot horn bothers me. Sounds like the motor & pump weren't getting enough water - could have damaged the impeller or ?. <br /><br />The main causes of death for those old V4s are dirty carbs & failed water pump impellers.

 

[Searcher 200]

Re: Questions on '78 115 Evinrude

I'll watch the water pump close and it's on my list to change the impeller. It's never happened before on the water or in the driveway. I think I simply didn't turn the hose up high enough. I shut it down as soon as the horn went off and waited 30 minutes then turned the water up. Never happened again.

 

[Searcher 200]

Re: Questions on '78 115 Evinrude

Anyone have an idea on why that one cylinder would be showing exactly twice the rpm of the other 3 cylinders? My inductive tach does have a switch setting for 2 cycle.

 

[G DANE]

Re: Questions on '78 115 Evinrude

It coulddoublefire at one cylinder, due to a bad power pack. If it does, that can couse piston failure. If you can borrow a timing light, mark tdc on each cylinder at edge of flywheel with pencil marks, or numbers for each cylnder. If that cylinder lets you see a "ghost" mark besides the real for the actual cylinder, it double fires, and power pack or stator is probably bad. You have to get everything in order before you run it for longer periods or something will be damaged.

 

[R.Johnson]

Re: Questions on '78 115 Evinrude

The pack is double firing, check it with a timing light, with all cylinder's marked on the flywheel. upper left is #2 cylinder, see if they both fire at #1, and #2 as showing up on the timing light. Mark the flywheel at TDC for all cylinders. Left bank 2&4, right bank 1&3.