1987 Evinrude 70hp, can't hold idle

[Tim Kane]

Get the manual and do a linc and sync make sure everything is is working correctly

I did this last night but have not been able to run it yet. It was too late plus pouring rain. Looking at the three cylinders top to bottom, which is the number 1 cylinder? I want to try the timing check procedure now.

 

[jakedaawg]

Top is #1

 

[fireman57]

100 compression is good for this engine. Is the roller cam resting between the two lines on the flange that rotates when you move the throttle forward? This is really part of the link n sync. Once you adjust your throttle cable to make sure the cam rest there then you can make other adjustments. If you have changed anything with your idle adjust screw then you might have to start over. Do a search for idle screw adjustment on your engine. One last thing, I have a '76 75hp that will not run properly with an inline fuel filter. Try removing it and see what happens. Could be that it is restricting enough to not let you idle. I can't explain why mine won't work with one in but it won't. Just something I had to accept, and yes, I have to clean my carbs at least once every season.

 

[Tim Kane]

100 compression is good for this engine. Is the roller cam resting between the two lines on the flange that rotates when you move the throttle forward? This is really part of the link n sync. Once you adjust your throttle cable to make sure the cam rest there then you can make other adjustments. If you have changed anything with your idle adjust screw then you might have to start over. Do a search for idle screw adjustment on your engine. One last thing, I have a '76 75hp that will not run properly with an inline fuel filter. Try removing it and see what happens. Could be that it is restricting enough to not let you idle. I can't explain why mine won't work with one in but it won't. Just something I had to accept, and yes, I have to clean my carbs at least once every season.

Thanks for the compression values verification. Cam is in the right position. Interesting about the inline filter. I will try bypassing it with a straight connector and see if that plays a role. That would be something if that was it all along.

Thanks jakedaawg for the #1 position info.

 

[Tim Kane]

RE: Inline filter(s). I have a large water removal filter just after the 6 gallon tank and then a small inline particulate filter up beside the engine. I wondered, how important is the water filter if I am using up a tank of gas usually hours after purchasing it? Perhaps this filter is not necessary?

 

[racerone]

???---Just took the motor apart this morning and the cylinder with 110 PSI compression is getting a new piston !!!--I guess everyboy works to a different standard.

 

[Tim Kane]

???---Just took the motor apart this morning and the cylinder with 110 PSI compression is getting a new piston !!!--I guess everyboy works to a different standard.

Different engine?

Regarding water filter use: http://www.boatus.com/magazine/2011/december/ethanol.asp

See Myth #2

 

[racerone]

Different engine you say ???----Parts and pieces that go round and round , up and down in the cylinder are the same between an 87 model and 1990 model 70 hp Johnson / Evinrude.--All the adjusting / fiddling / tuning won't fix a motor that is in bad shape.

 

[Tim Kane]

Different engine you say ???----Parts and pieces that go round and round , up and down in the cylinder are the same between an 87 model and 1990 model 70 hp Johnson / Evinrude.--All the adjusting / fiddling / tuning won't fix a motor that is in bad shape.

No , I did not say, I was asking if you are dealing different engine. It was a question. It sounds like you think my engine is in poor condition due to the compression values I got from testing, is that right?

fireman57: Do you know it to be true that 100 is an ok compression for this motor or does racerone make a valid point?

 

[flyingscott]

your compression is on the low side my 86 70 hp will test at 130+ on all 3 cyl I would get a second compression tester and retest the cylinders because rental gauges get abused so it could be off especially since it tested all 3 the same. if your motor does have 100# of compression you are at the point where your motor may or may not run right

 

[biggjimm]

If I had any questions or concerns about the compression on mine I would just pop the head & take a look-see. Gaskets aren't that much & it is a pretty straight forward procedure (at least on my 90 60hp 3 cyl) & you can learn a lot about your motor. Just my 2 cents. Good luck with it. Jim.

 

[Tim Kane]

If I had any questions or concerns about the compression on mine I would just pop the head & take a look-see. Gaskets aren't that much & it is a pretty straight forward procedure (at least on my 90 60hp 3 cyl) & you can learn a lot about your motor. Just my 2 cents. Good luck with it. Jim.

What would you look for, scores on the cylinder wall?

 

[Tim Kane]

your compression is on the low side my 86 70 hp will test at 130+ on all 3 cyl I would get a second compression tester and retest the cylinders because rental gauges get abused so it could be off especially since it tested all 3 the same. if your motor does have 100# of compression you are at the point where your motor may or may not run right

Thanks. I'll see if there is a second tester there that I can rent. Thinking about this, if the compression is still very low, I just may use it for the remainder of this season and perhaps do the top end over the winter. I found a website, http://maxrules.com/, that offers a rebuild kit for all three cylinders for $587. Includes everything I would need. Sound like a good deal?

 

[Tim Kane]

I checked this web site for a kit but did not see one. That is what I liked about the other web site. I looks like on this site you have to know what you need and order everything one piece at a time. Buying a kit ensures that I don't miss something in my order. Maybe there are kits and I missed them?

 

[durban]

Before you spend any money try this if every thing else failed to get your idling spot on.The intake manifold has got machined slots in it leading to each carb coming from the top right hand corner which lines up with a small hole in the gasket in the top right hand corner, that little hole in turn lines up with a hole in the crank case were the top bearing fits in & that little hole in the crank case viewed from the inside has a slot in it which leads into the crank case . now all these things are there for a reason as you don't have an idling screw on this model what you do have is an orifice which is not adjustable its fixed [ its screwed in and stays there ] the idea of those slots in the manifold is for air to come in from the top end by the manifold through the hole in the

 

[biggjimm]

What would you look for, scores on the cylinder wall?

Anything abnormal Tim. Scores on the cyl wall, head gasket blown or seeping, cracked block or head, warpage- are just a few things that hopefully aren't but could be going on in there that could cause low compression that are usually pretty evident once you pop the head off. What Durban said in #35 is an interesting thought on a poor idle situation that I'll have to remember. Good luck with it Tim. Hope you get it figured out.

 

[Tim Kane]

Before you spend any money try this if every thing else failed to get your idling spot on.The intake manifold has got machined slots in it leading to each carb coming from the top right hand corner which lines up with a small hole in the gasket in the top right hand corner, that little hole in turn lines up with a hole in the crank case were the top bearing fits in & that little hole in the crank case viewed from the inside has a slot in it which leads into the crank case . now all these things are there for a reason as you don't have an idling screw on this model what you do have is an orifice which is not adjustable its fixed [ its screwed in and stays there ] the idea of those slots in the manifold is for air to come in from the top end by the manifold through the hole in the

Not sure what "a hole in the crank case were the top bearing fits in &" means. I think I know what you are saying. If I remove the carbs I will see something on the intake manifold that will match up with your description. I will have to check. Thanks.

 

[durban]

Before you spend any money try this if every thing else failed to get your idling spot on.The intake manifold has got machined slots in it leading to each carb coming from the top right hand corner which lines up with a small hole in the gasket in the top right hand corner, that little hole in turn lines up with a hole in the crank case were the top bearing fits in & that little hole in the crank case viewed from the inside has a slot in it which leads into the crank case . now all these things are there for a reason as you don't have an idling screw on this model what you do have is an orifice which is not adjustable its fixed [ its screwed in and stays there ] the idea of those slots in the manifold is for air to come in from the top end by the manifold through the hole in the

in the casket clean the top hole i drilled the hole in gasket to 3mm i had your problems & this solved mine

 

[durban]

in the casket clean the top hole i drilled the hole in gasket to 3mm i had your problems & this solved mine

clean out the top hole at manifold end with brake spray & nozzel

 

[Tim Kane]

Thanks durban, will give this a try.