Questions about silencer and fuel pump

[22E6441]

So I've just removed the carbs on my '90 50hp Johnson and was wondering about a couple things.

1) What the heck is the silencer for anyway? It's not like there's a filter or anything in there....I just can't see the purpose.

2) Should there be an air filter, or might it be a good idea to remove the silencer and mount filers over each carb? I'm thinking like k&n's on a motorbike sort of.

3) My VRO was disconnected by unplugging the wire and plugging the hose. Works fine, but it's big and unsightly, and since the wire is unplugged from the harness how the heck does it work? I can't see any power going to it anywhere. The only thing that has power is the electric primer thing on the other side of the motor. This is making me nervous.

4) Can I replace my VRO with a standard fuel pump? If so, which one would work with a 50? I saw a post about a brp pump model for a 70, but would it be the same one?

Thanks.

 

[jonesg]

Re: Questions about silencer and fuel pump

It sounds like you're trying to ruin your engine.
Air silencer is needed and important for life of engine, thats all I know.
Why did you disconnect the VRO system?
you're running premix ?

They do sell a fuel only pump, the sierra version is very cheap by comparison.
I'm still using the VRO system, the previous owner instaled a new pump.

 

[tx1961whaler]

Re: Questions about silencer and fuel pump

1. The silencer just reduces the carb intake noise and keeps random crap from getting sucked in the carbs. The old ones just have a screen.
2. No air filter needed. You're on the water. No dirt in the air. Putting one on would restrict the air flow too much.
3. VRO was disconnected because it either quit working or somebody got paranoid about it. It has two sides; the fuel side and the oil side. Both sides run off of engine vacuum, not electricity.
4. You can replace the VRO pump with a standard pump, but why bother if the fuel side of the VRO pump is working.

 

[ezeke]

Re: Questions about silencer and fuel pump

The VRO and OMS systems work off a pulse from one of the cylinders. They are strictly mechanical. As long as the pulse limiter and the connection are in good shape, the VRO and OMS pumps can be used as pre-mix pumps and the gasoline side can be rebuilt.

The electronics on VRO and OMS are for the warning system and are not needed when premixing. The VRO pumps are more powerful than the lift pumps, but it is fairly simple to change to the conventional lift pump.

 

[22E6441]

Re: Questions about silencer and fuel pump

My VRO was disconnected by the previous owner after it failed. It has run perfectly until I just got some gunk in my carb necessitating a carb kit and cleaning. That's what got me thinking of air filters, etc.

So the fuel pump is simply mechanical and driven by the pulse thing. Interesting. I was just thinking of replacing it with a simple fuel pump to save some space...the vro and all the hoses are really crammed in there.

 

[tashasdaddy]

Re: Questions about silencer and fuel pump

why mess with something that is working properly. it is a good way to screw up a motor. i suggest that you get and OEM service manual, make it your best friend for a week. get to know your motor. sounds like you are a tinkerer, if so, best you know what you are tinkering with, before you mess it up good.

 

[5150abf]

Re: Questions about silencer and fuel pump

I always assumed that whoever designed my motor was way smarter than me so if they went to the time and expense to put something on the motor it needs to be there.

A motorcycle engine was designed to run air filters your motor wasn't, if you change anything on the intake you get into rejetting and that can get really tricky.

If you ever change your fuel pump you can see it plugs into a hole that goes into the crank case and it operates off of the intake pulses of the engine but a stated, if the pump you have on it now works why mess with it?

I would install an inline gas filter, that should keep things from getting into your carbs but beyond that I wouldn't mess with engine much.

I have never understood the carb design on those with the main jets at the bottom of the float bowls right where any crap that gets in will go first but they are easy to clean and 99.9% of the time they work great.

Get the carbs cleaned and install a fuel filter and don't fix things that aren't broken, it usually leads to breaking things.

 

[22E6441]

Re: Questions about silencer and fuel pump

Good points. I will resist the urge to tinker for the sake of tinkering. Yeah, I would have to agree that the Johnson engineers probably do know more about motors than I do. Funny how I need to step back and remember that sometimes!