1990 120hp evinrude VRO

[Brandon A]

My evinrude was running fine today and then all of a sudden, i could not get full power, the motor sounded very strange and was making a slight knocking noise. It was also running real rough. Kind of like it wasn't firing on half of the cylinders. Just would not run right so I limped back to the ramp just running it at idle speed. If i stopped and put it in neutral it would eventually sputter out afte 10-15 seconds of idling.

The motor has had some lower unit issues (bad seals) but I dont think that is the problem here. The head is brand new (rebuild it last year). And the VRO pump has been removed and I mix my own fuel and the aftermarket fuel pump was put in.

I have my own ideas of what all to check, but I thought I would ask yall first.

I'm new on this forum and appreciate any advise.

p.s. this is on a freshwater only boat.

 

[ctriverhouse]

Re: 1990 120hp evinrude VRO

Got a fuel water seperator? Sounds like you might have bad gas. (water). Did you have the carbs rebuilt with the rebuild? I would check for spark first. (4). You could pull the heads for a quick look. Easy to do on this motor. If the motor is running in N and shifting in and out of gear I don't think its your lower unit. My 1990 120 needed a new powerpack(quick skipping) and then a volt. reg.(tack jumping).

 

[Brandon A]

Re: 1990 120hp evinrude VRO

Got a fuel water seperator? Sounds like you might have bad gas. (water). Did you have the carbs rebuilt with the rebuild? I would check for spark first. (4). You could pull the heads for a quick look. Easy to do on this motor. If the motor is running in N and shifting in and out of gear I don't think its your lower unit. My 1990 120 needed a new powerpack(quick skipping) and then a volt. reg.(tack jumping).

Thanks for the suggestion. How would you suggest the best way to determine if it is bad gass?? Go get gas I know is clean and disconnect the hose from the boat tank and put it in the portable tank and see how she runs??


Where do I get a fuel water seperator and what do I do to install it? Is it just an inline thing?

 

[ctriverhouse]

Re: 1990 120hp evinrude VRO

How old is the gas? Old gas smells like varnish. Inline between tank and motor. I-boats sells them. Should come with install directions.

 

[daselbee]

Re: 1990 120hp evinrude VRO

I would do a compression check first. From your description, it sounds as if the powerhead blew again. Running lean, possibly.
Compression should be about 100 or so, and within 10% on all cylinders.

Do that first.

 

[ctriverhouse]

Re: 1990 120hp evinrude VRO

Yeah good call daselbee.

 

[Brandon A]

Re: 1990 120hp evinrude VRO

Well, after testing all of the coils and all of the plugs and wires... I thought it would be the power pack because I had one cylinder that wouldnt change how the engine ran when I disconnected the spark plug wire from it....


Went and bought a compression guage before I spent the money on a power pack... and sure enough, low compression on cylinder number one, about 30# with 130 on the other three.


I'll be tearing the engine apart now. This head is brand new, just put it in a little over a year ago. Hopefully the piston wall will be okay, and I can just replace the piston, we will see.

 

[daselbee]

Re: 1990 120hp evinrude VRO

Well, I hope it doesn't look like this:



My first meltdown caused by lean running #1 carb.

 

[Brandon A]

Re: 1990 120hp evinrude VRO

Well, I hope it doesn't look like this:

View attachment 136938

My first meltdown caused by lean running #1 carb.

looks about like that.... it is ruined, now to see if I will need to do an entire rebuild.

Here is the thing, I replaced the entire power head and block a year and a half ago. I'm pretty sure I had failure in the same cylinder... can anyone explain why this might be happening, and how to fix it for next time?

 

[Brandon A]

Re: 1990 120hp evinrude VRO

I should also mention that I dont see any noticable scoring on the cylinder wall. Is there a chance that I could get by with a new head, new piston and rings?

 

[daselbee]

Re: 1990 120hp evinrude VRO

Yes, sure you can do just the one cylinder.

On the engine in the pic I posted, I had aluminum and oil mixed all through the engine. It got everywhere.
There was no way to fix it without a complete teardown and cleaning. It was all the way down on #6 crankcase.

I do have a "trick" for fixing that one cylinder. You can actually do it without splitting the crankcase, but before I get absolutely KILLED on this board for suggesting it, I will warn you that it is VERY VERY risky.

PM me if you want the details.

This is the oily aluminum I was speaking of:

 

[boobie]

Re: 1990 120hp evinrude VRO

Dasel, I know what trick you did as a fellow tech of mine also did it some yrs ago. But I don't " kiss and tell". And you're right, you'd get KILLED on this board.

 

[daselbee]

Re: 1990 120hp evinrude VRO

Dasel, I know what trick you did as a fellow tech of mine also did it some yrs ago. But I don't " kiss and tell". And you're right, you'd get KILLED on this board.

 

[noelm]

Re: 1990 120hp evinrude VRO

If you have some sort of failure, if you do not find out WHY it failed, and just do a rebuild, then you are just tossing money away, another rebuild is on the way (as you have found out).

 

[archcycle]

Re: 1990 120hp evinrude VRO

swap port/starboard carbs and see if the problem follows?

 

[Faztbullet]

Re: 1990 120hp evinrude VRO

Could be a bad pack or timer base problem also.....