1985 70 hp evinrude VRO 3 cylinder chokes and or dies when accelerating

Hello,

This is my first boat bought used from neighbor who believed it to be in good running order.

Here is the problem... when I accelerate at about wake speed or a little faster the boat does 1 of 2 things. 1. It will either all of sudden engage and take of like it was starved for gas and then all of sudden got a shot of it or 2. it will bog down and the motor will die. The problem seems to be worse when the load on the engine is more and I say that because it will not have this issue if the boat was still moving from slowing down or if I trim the motor up when accelerating. If the motor catches it runs fine for as long as you want.

Here is what has been done so far:

1. Compression test 125, 120, 120.
2. Leak down test passed.
3. Carbs completely rebuilt.
4. New spark plugs gapped and heat rated for motor.
5. New fuel pump, line and gas tank
6. Timing checked

The mechanic has told me that there is a possibility the cylinders have an egg shape at exhaust port and this will cause motor to choke under big load, but several people have suggested that it would not have had good compression and would fail a leak down test if this was the case.

My next plan is to lower the pitch on prop and get another year or two from motor.

Any suggestions or ideas would be greatly appreciated.

:joyous:Thanks

Re: 1985 70 hp evinrude VRO 3 cylinder chokes and or dies when accelerating

The mechanic has told me that there is a possibility the cylinders have an egg shape at where the exhaust port is and
it will cause motor to choke under big load

ha hah ha ha ha ha ha

do these people actually manage to get people to have them do their work ?
idefinitely wouldn't call him a mechanic

phill

Re: 1985 70 hp evinrude VRO 3 cylinder chokes and or dies when accelerating

Is there anybody out there with any ideas? I would really like to figure this out.

A neighbor (retired GM mechanic) thought it might be the coil (stator) not shooting enough voltage for the engine at mid range rpm's with a large load on the engine. Does this make any sense? The stator is currently sending voltage to battery.

Re: 1985 70 hp evinrude VRO 3 cylinder chokes and or dies when accelerating

YOU HAVE FUEL PROBLEM

the carbs need to be cleaned again, somewhere you have dirt in them or it would sometime be ok and sometimes not.
or you have bad electrical connection and getting a short somewhere !!!

ok now there is a big difference between a coil and a stator.!!!!!!!!!!
could be bad stator connections rattling around and not giving good connections, or a stator just worn out.

coils could be breaking down when warmed up !!!!!!!

you say battery is getting voltage back to it so the rectifier is ok .

have you checked the open air spark gap is jumping a full 7/16ths of and inch ? do this very thing first of all.

what plugs are you using ? ....... exact brand and numbers ?
just because marine shop told you they are the right ones means nothing.

how exactly did you clean the carbs ? have you done a lync and sync since messing with the carbs ?
what is your timing set at on idle and max spark etc.
what is your idle revs ?


phill

Re: 1985 70 hp evinrude VRO 3 cylinder chokes and or dies when accelerating

Plugs champion QL77JC4 plugs gapped at 40th. Idled better at this gap than recommended 30th, however have tried at both and not made a difference for this problem. I have not checked open air spark gap is jumping a full 7/16ths of an inch, don't know if either mechanic did it.

As for the carbs they were rebuilt by 1st mechanic who has been in business for 30 years and tons of recommendations. He said that he cleaned them completely adjusted one of the floats and did a sync and link. Being skeptical after problem persisted and believing it to be a fuel problem initially I took to another mechanic and watch him take them apart and check. He said the job was done well, he made of some minor adjustments but made no difference for problem. This was when i replaced tank, fuel line and fuel pump with no change.

Not sure about timing at idle never seemed to matter in past before problem timing at wot is 26. Could not tell you idle revs because i have no tachometer (i know it's ridiculous) but boat will idle all day.

When second mechanic connected to dyno machine at shop the motor performed within specs over the course of about 25-30 mins. The problem almost always occurs after boat has been at been at a low speed for long period of time but only when in the water.

I'm leaning more toward electrical problem. What exactly is the difference between the coil and stator and is there a way to check them?

Thanks

Re: 1985 70 hp evinrude VRO 3 cylinder chokes and or dies when accelerating

I had a very similar problem with my 1985 50 hp. Kept assuming it was the carbs. Finally got a mechanic on the water with it. It ended up being the spark advance linkage was worn out.

Re: 1985 70 hp evinrude VRO 3 cylinder chokes and or dies when accelerating

what the hell are these people doing with your engine ???????????
Setting timing at 26 degree's is wrong, and by a very long way out.

Now I don't care how long someone has been getting paid for bodging up outboards, it don't mean a thing if he aint any good.
now you have had 2 idiots tamper with your engine and none of them have got it working correctly (proves they are incompetent fools).

now the plugs need to be correctly gapped at 30 and the timing needs to be set up according to the proper book, not 26degree's.
try 19 and you might be a bit nearer.
you need to know what the idle timing is as well now,as if the advance is way out then you can bet the idle is as well.
the lync and sync has nbot been done or it couldn't possibly be 26 degree's !!!!! so again idiot who calls himself mechanic.

you need to now get a correct list of the settings from omc and start to put this right.
first of all get some carb cleaner and carb kits to get the carbs upto scratch properly.

then once these have been done correctly, you can re-fit them and then do the idle timing and a lync and synce with
max advance etc.
until this is done you have no chance of getting it tuned up correctly.

Being as 2 fools have played about with it youl be needing a plenty of proper advice and a genuine (not seloc or Clymer) service manual for your particular motor, there is plenty of these cheap on the fleabay , so easy to get one.

youl soon have your engine up and running and back to normal,

you have come to the right place to help you get it running good again that's for sure.
plenty of the real mechanics on here im sure will help you and advise you, they have helped me out big time with my engine.


phill