Plug fouling on Johnson 70hp vro

S

Smasher2005

Cadet
Joined
May 28, 2012
Messages
10
Hello all

I picked up a boat with a Johnson 70hp vro on it. Owner said he was premixing at 50:1 and wasnt using the vro. I did the same and put new champion plugs in, but right away when running it I fouled the plugs and had to limp back. Not sure on the vro, it looked like it was all still hooked up, just wondering if maybe it is still working plus I am adding premix if that would be enough to foul a plug right away? To be honest, I did not check plug gap out of the package as well.

Thanks for your thoughts
 
D

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: Plug fouling on Johnson 70hp vro

I would start by pulling the plugs and make sure they are gapped properly. If you are running premix plus the VRO I would think you would be seeing a lot of smoke.
Since the engine is new to you, I would do a spark and compression test to see the basic health of your engine.
You could also have a carb problem causing that cylinder to run rich.
 
S

Smasher2005

Cadet
Joined
May 28, 2012
Messages
10
Re: Plug fouling on Johnson 70hp vro

Daviet said:
I would start by pulling the plugs and make sure they are gapped properly. If you are running premix plus the VRO I would think you would be seeing a lot of smoke.
Since the engine is new to you, I would do a spark and compression test to see the basic health of your engine.
You could also have a carb problem causing that cylinder to run rich.
Click to expand...

Ok, thanks for the information. I had a Merc mechanic check the compression and ignition when I purchased and he gave the thumbs up to both. I should have checked the gap, I believe they should be set at .030? Also, do you know if I can unplug the vro to disable and make sure this is not still injecting oil. or will I get a fault alarm?

Thanks again
 
K

Kingbee13

Cadet
Joined
Jun 2, 2003
Messages
8
Re: Plug fouling on Johnson 70hp vro

Disconnect the electric plug going into the top of the vro pump. The electric part is only for the oil, the fuel pump is just a mechanical pulse pump, then seal off the oil line going into the pump. I sealed mine off with a large bolt, been working great for years now.
 
B

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: Plug fouling on Johnson 70hp vro

Also disconnect the wires coming from the oil tank. And don't forget the 50:1 premix.
 
S

Smasher2005

Cadet
Joined
May 28, 2012
Messages
10
Re: Plug fouling on Johnson 70hp vro

I did find that the pump appeared to still be functioning, oil in system, I pulled the line and ran the motor and it seemed to be dripping oil out. Disconnected the pump and plugged the line with the bolt idea, worked great. New Champion plugs, gap set, pumped tank out and started with fresh premium 50:1, hope to get it in the water soon to test out and will let you know.
 
S

Smasher2005

Cadet
Joined
May 28, 2012
Messages
10
Re: Plug fouling on Johnson 70hp vro

Well, I had the boat out this weekend and it ran great, so happy to report taking the pump out of the system did the trick.

Thanks for everyone's input!
 
You must log in or register to reply here.
Top