Rough running Evinrude V90

[Green Lantern]

Hello, i am fairly new to the boating scene. I have n 1985 Evinrude V90. The previous owner replaced the power head with a factory rebuilt unit in 2015. He ran it for the break in period and then didn't use it after that. He said he fired it up once in a while. Anyways when I got it home and went to run it for its first test run in the driveway it ran real rough. So I have literally gone through everything on the motor and now am stumped. I have rebuilt both carbs, replaced all fuel lines, adjusted to carb linkage, new fuel tank and primer bulb, new spark plugs, compression is 115 to 120 all around.
It always starts up right away with ease. When it runs it looks like it's missing and sneezing. It will Rev but it seems to miss as well like it's starving for fuel. I can play with the timing while it's idling but it doesnt stop the missfire and sneezing. It is a VRO motor. I have had the fuel pump apart and have tested it somewhat. I am leaning towards a bad fuel pump and have order a fuel pump kit. When I tested the pump there was some air leakage around the check valve on the oil pump side. But it was such a small amount I have a hard time believing it was causing the motor to missfire like that. But on the other hand it looks like a lean condition. One other thing I noticed when I had the flywheel off was that the stator had green coloring on the magnets. Could this be corosion and could it be causing the signal to jump from one magnet to another while it's running causing a misfire?

Tom

 

[Green Lantern]

Anyone?

 

[racerone]

You rebuilt the carbs.------That is common for folks to start with I do not know why.-----Tell us did you find anything wrong in the carburetors , any dirt / varnish ?----Did you take the high speed jets out of the bowls to confirm they were clean and the right size ?-----It is called lean sneezing.-----Are both throttle plates CLOSED at idle, yes or no ?---Does spark jump a gap of 7/16" on each lead on a test device ?----A simple fuel pump can be mounted directly over the pulse port on the intake manifold.----Yes the spot is there in front of the starter.-----Cheaper / better than VRO repair kit. ----Green color on magnets would be of no concern to me.-----Run with a timing light ( one cylinder at a time ) to see if you can spot an ignition issue.

 

[ryan 98]

Hello, i am fairly new to the boating scene. I have n 1985 Evinrude V90. The previous owner replaced the power head with a factory rebuilt unit in 2015. He ran it for the break in period and then didn't use it after that. He said he fired it up once in a while. Anyways when I got it home and went to run it for its first test run in the driveway it ran real rough. So I have literally gone through everything on the motor and now am stumped. I have rebuilt both carbs, replaced all fuel lines, adjusted to carb linkage, new fuel tank and primer bulb, new spark plugs, compression is 115 to 120 all around.
It always starts up right away with ease. When it runs it looks like it's missing and sneezing. It will Rev but it seems to miss as well like it's starving for fuel. I can play with the timing while it's idling but it doesnt stop the missfire and sneezing. It is a VRO motor. I have had the fuel pump apart and have tested it somewhat. I am leaning towards a bad fuel pump and have order a fuel pump kit. When I tested the pump there was some air leakage around the check valve on the oil pump side. But it was such a small amount I have a hard time believing it was causing the motor to missfire like that. But on the other hand it looks like a lean condition. One other thing I noticed when I had the flywheel off was that the stator had green coloring on the magnets. Could this be corosion and could it be causing the signal to jump from one magnet to another while it's running causing a misfire?

Tom

As far as a green coating on the stator goes. Most rebuilds I've gotten, I think Sierra? Have a green shellac on the core to seal them. Now it should be pretty obvious if it's meant to be there or not. Green fuzzy corrosion is bad but can be cleaned off. Don't quote me but most of that coil is a charging coil only. Theres one small section that looks different and that's the trigger coil for the cdi. Run it with a cheap inline spark tester if you suspect an issue there. Check all 4 cylinders. But any air leak in the fuel system is a bigger issue. These guys really don't like being lean, well actually it's the death of them. There's a lot of opinions on it, but it's not hard to delete the vro and run pre mix. There's tonnes of forms on the process and fuel pump you need. Not a bad time to do it while your in there. A guy I get parts off of rebuilds about 15 of these motors a year. He says about 50% of the blowen ones he gets are vro system failures. And new powerhead probably means a new block with all the bits and vro pump slapped on it off the original blowen up one. Sounds kinda fishy to me. Who spends the money on a new power head, breaks it in and has a great running motor then doesn't use it even once? Sounds to me like he slapped a power head on it, never got it to run right and let it sit. Now it's up to you to find out where he went wrong. Good news is those compression numbers are healthy. So I'd start at fuel system, and I mean everything tank up. New pluggs don't hurt, they do fail internally sometimes. Check spark, maybe throw a timing light on it. I'd basically attack it from the perspective of a motor that was assembled and never ran right vs a motor that developed an issue sitting. So don't rule out a line going to the wrong place or a grossly bad adjustment on the timing linkage. Stuff like that.

 

[Green Lantern]

Carburetors looked ok. There was some varnish in the float bowls. I did not remove the Jets as I assumed, being that they are the factory carburetors that the Jets are correct. I did squirt carb cleaner through each oriface to make sure they were clear. No problems there. Needle and seat seemed to be working. I do suspect the fuel pump may be an issue. When I have the fuel line disconnected at the fitting on the motor the bulb will get hard. When I connect it to the motor it does not get hard when I squeeze. I have disconnected the oil line and capped it and running pre mixed fuel. Haven't checked with my timing light yet.

 

[racerone]

The bulb MUST get hard.-----This means that you have a leak somewhere.----It would be easy for me to find these problems.----But I can't see, hear or feel your motor !!----Up to you to act on advice here.

 

[Green Lantern]

Right. I am suspecting a leak in the fuel pump. Going to inspect the diaphragms more thoroughly this evening.

 

[racerone]

The simple fuel pump that mounts on the intake manifold can be repaired quickly with a new diaphragm.----About $10 or less.-----No need for $600 fuel pumps for me on that motor.

 

[Green Lantern]

The simple fuel pump that mounts on the intake manifold can be repaired quickly with a new diaphragm.----About $10 or less.-----No need for $600 fuel pumps for me on that motor.

I have ordered a kit and a whole new pump as well. I will do the kit first and if it fixes it I will return the pump. Going to inspect the pump a bit better this evening.

 

[Green Lantern]

The bulb MUST get hard.-----This means that you have a leak somewhere.----It would be easy for me to find these problems.----But I can't see, hear or feel your motor !!----Up to you to act on advice here.

Man I have gone through everything. Only thing I haven't done is replace or kit the fuel pump. I am going to inspect it heavily this evening.

 

[racerone]

The bulb must go hard.

 

[Green Lantern]

Went through the fuel pump. It seems to be right in every way with no defects in the diaphragms. I can pump pressure in the bulb with the outlet to the carbs capped off. When I connect the carbs I can't get it to pressurize. At least that's what I have found this far this evening. There is a little fuel dripping ever so slightly from the bowl drains on the linkage side. My plan next is to pull the carbs and make sure there are no leaks and that the needle and seat valve are working correctly though I feel like they are as there isn't fuel spraying in the carb when I squeeze the bulb.

 

[Green Lantern]

Ok, went through the carbs. They are mint. Went through art fuel lines. Synced throttle linkage. She still runs rough and misses. Sounds like it's getting good fuel. The bulb now gets hard and stays hard. This leads me to ignition, correct me if I'm wrong. It looks to me like the timing is too advanced. Is there actually an adjustment for that? I know there is one at idle and one at WOT but what if the whole thing is off by a couple of degrees. One thing I haven't tried is running it in the dark to see if any ignition wires are spark jumping. Here is a video of it running for reference.

 

[racerone]

Is the red lever on the electric primer valve in the right ( run ) position ?

 

[Green Lantern]

I believe it is

 

[racerone]

Checked the flywheel key ?

 

[Green Lantern]

I did. It is in its place. Pulled the flywheel just to make sure. There is no adjustment there is there?

 

[oldboat1]

Put it in the lake or a test barrel (with water about half way up the leg.

 

[Green Lantern]

I have been using a hose attachment. Is it different when it goes in the lake? Also if it is running lean I don't want to hurt the engine by running it like that.

 

[racerone]

Maximum timing advance is set at the factory.-----Set for the life of the engine.----Idle timing looks after itself.-----Idle timing in your manual is the point where throttle plates open.----Work carefully if you decide to make adjustments.