1990 50 Johnson keeps dying

[atistang]

model number shows it a 1998, careful/don't run at high rpm's in neutral could cause a runaway engine

Like diesel runaway? I always have a hand on the throttle and a hand on the ignition switch when I do.

 

[jakedaawg]

There are two rollers on the linkage. One is the throttle cam follower. I believe yours also has a roller the timing cam follower. Either way, inspect those rollers. There is a black plastic inner layer and a translucent rubber outer layer. If the outer layer has fallen off you'll play hell getting it to run right.

 

[atistang]

There are two rollers on the linkage. One is the throttle cam follower. I believe yours also has a roller the timing cam follower. Either way, inspect those rollers. There is a black plastic inner layer and a translucent rubber outer layer. If the outer layer has fallen off you'll play hell getting it to run right.

Interesting. I did notice there is a tone of slop in one of the rollers, I'll see if I can get that piece.

 

[atistang]

Update.

So I replaced the throttle cam and timing advance rollers.
Rebuilt the carbs.
Replaced all the fuel lines.
Redid the sync and link.

And it still has the exact problem. And when it dies I check the plugs and they are dry.

So my next move is to rebuild the VRO. If that doesn't fix it I may just give up.

 

[atistang]

Latest update. I pulled the VRO. I found a small amount of fuel in the pulse line at the pulse limiter. I would think this is not normal?

Anyway for OMC parts it's going to be about $150 to rebuild it. Now I'm wishing I would have tried to test the fuel pressure before removing the pump, but I was thinking how would I do that when I can't keep the engine running.

 

[Tourtney]

Did you ever check spark? Seems to me it wouldn’t be the fuel pump. I’ve had issues at higher rpm with the fuel pump when the diaphragm was worn out.

 

[ct1762@gmail.com]

why don't you just put a traditional fuel pump in it and skip the OMS/VRO? that motor is set up for the traditional ones... super easy install.

 

[atistang]

why don't you just put a traditional fuel pump in it and skip the OMS/VRO? that motor is set up for the traditional ones... super easy install.

Actually that's what I ended up doing yesterday and sure enough it seems to be fixed.

 

[IDFISHER]

Actually that's what I ended up doing yesterday and sure enough it seems to be fixed.

Glad you solved your problem! Any chance you have a photo of your new fuel pump setup or could give a quick step by step of what you did? I have a '94 60 HP that i'd like to replace the VRO with a standard fuel pump on.

 

[atistang]

Glad you solved your problem! Any chance you have a photo of your new fuel pump setup or could give a quick step by step of what you did? I have a '94 60 HP that i'd like to replace the VRO with a standard fuel pump on.

https://maxrules.com/fixomc-no-oil-vro.php

they have directions and kits with everything you need.

It was simple on mine. Take the VRO out, plug the pulse port in the block.hook up new pump. I would premix your fuel before you start so you don't get excited and forget to do that on the test run.

 

[atistang]

Did you ever check spark? Seems to me it wouldn’t be the fuel pump. I’ve had issues at higher rpm with the fuel pump when the diaphragm was worn out.

I never did. Everything kept pointing to a fueling issue. I launched it last night and it ran great.

 

[IDFISHER]

https://maxrules.com/fixomc-no-oil-vro.php

they have directions and kits with everything you need.

It was simple on mine. Take the VRO out, plug the pulse port in the block.hook up new pump. I would premix your fuel before you start so you don't get excited and forget to do that on the test run.

Awesome, thanks!