1990 Evinrude 70hp bogs/dies off when moving into high gear

[stp125]

Hopefully someone can help me with this. Have a 1990 Evinrude that won't hit into top speed. Basically starts great, I can rev the engine in neutral nicely up, but as soon as I put in gear I can get it to around double the idle revs, but any higher causes it to bog down and die out. I did clean the carbs out, was running older gas, but tried with new gas and did the same, I've also changed the spark plugs. I also recently replaced the water pump and its getting good water flow through it. I hear from a friend that he replace the power pack and this solved his problem which was similar, but thinking I should maybe retry the carb cleaning first? Also could the floats need to be adjusted? It does seem to have some gas sitting in the carb bowl. Any other suggestions would be greatly appreciated...annoys me how well I can rev it up in neutral and yet can't get it to go anywhere and summers running out!

 

[Bahummbugg]

I'm having the same problem with my 1958 evinrude 35hp I changed plugs cleaned carb. Rebuilt fuel pump..

 

[stp125]

I might do a compression test, but would think that since i can rev it up that it should be fine, seems like as soon as i move it into gear the fuel/air mixture is being somehow thrown off. i thought maybe a link and sync between the carbs, but all seems fine and i did put it into gear and manually press the throttle at the carb connector and again it stalls out.

 

[racerone]

Even a motor in poor condition will rev up in nuetral !!!---That sort of test means nothing !!---Start with a meaningful compression test.

 

[stp125]

but would poor compression cause it to stall or just not to get any power?

 

[racerone]

Just do a compression test.----If that is all good I can point you to other things to check.---Testing is the path forward !!!----This advice comes to you from someone who has repaired motors since about 1968 , but if you want to proceed your own way that is OK by me.

 

[Bahummbugg]

I've diagnosed my problem to ignition check spark gap on all cylinders.

 

[stp125]

Okay so compression is good. Any other ideas?

 

[durban]

race one is correct you have to start doing the trouble shooting , where i would start is synchronization then advance timing good luck . :happy:

 

[stp125]

Syncd fine, timing is fine, could it be electrical?

 

[durban]

Have you tried advancing the timing in other words increased it a little [ doing this the butter fly's need to be closed at all times ] dew to exhaust pressure when in the water try this first.

 

[racerone]

No compression numbers posted ?-Try seeing if there is spark on all 3 leads.---Does spark jump a gap of 7/16" on all 3 leads , yes or no ?

 

[stp125]

I'll check the spark this week, thanks for the help. Still think it's some really easy issue, like a screw that has come out of adjustment or something..maybe this is wishful thinking.

 

[durban]

raceone is correct about the 3/16 spark jump you mentioned : as soon as I put in gear I can get it to around double the idle revs, but any higher causes it to bog down and die out ;this is a typical example of what happens if you dont have enough spark , for the simple reson is when the trigger advances anticlockwise to release the spark when the piston is lower down in the sleeve on the upcoming stroke you need a strong spark to ignite the fuel after you checked the spark with a spark tester & you satisfied its jumping the gap then start looking towards the carbs , good luck my friend :joyous:

 

[stp125]

Great thank you..if it is a lack of spark. What are some main causes? I'm far,away from any,store so would like to take a many parts as possible with me to try out.

 

[fireman57]

Usually it is a coil that is cracked or just kaput or the power pack. Don't just go replacing parts though. Doing a step by step diagnosis will save you a lot of trouble and money. These guys are trying to get you on the right path so it will become second nature the next time something goes wrong. None of the procedures they have told you to do take much time and they cost absolutely nothing.

 

[durban]

Usually it is a coil that is cracked or just kaput or the power pack. Don't just go replacing parts though. Doing a step by step diagnosis will save you a lot of trouble and money. These guys are trying to get you on the right path so it will become second nature the next time something goes wrong. None of the procedures they have told you to do take much time and they cost absolutely nothing.

Thank you for your reply fireman 57: i hope he replies with results of the problem so that others on this forum can learn from it, beneficial for all .

 

[fireman57]

yep. Everyone looks for a quick easy fix.

 

[stp125]

Not a quick fix, but would like 5-10 common trouble shoot ideas at a time, saying try this, and then i'll give you more wisdom if that's not it is a little tedious..anyways i do appreciative the help...i'm just grumpy....but problem solved!

 

[stp125]

What it ended up being, and this is very good for anyone with this engine is that Evinrudes were equipped with a system called S.L.O.W that kicks in when you have a problem with overheating or low oil to protect the engine it limits the speed. It was easy to check as there are two brown wires that disconnect the low oil and high temperature wires. I disconnected both and in ran perfectly. Reconnected the low oil and it died again. I checked the temperature and it wasn't running hot (used a laser thermometer). It turned out the temp sensor was broke causing it to register running hot and kicking in S.L.O.W mode. Replaced the sensor and all is fixed!