johnson 90hp VRO V4

M

misfits

Recruit
Joined
May 13, 2009
Messages
5
hi there im a total novice at boats and engines so any advice would help.
i recently bought a speed boat with the above engine on it its been running fine but last time i used it whilst running at full throttle the revs kept dropping off so i had no drive but as soon as i moved the throttle back it kicked back in and was fine. its happened a few time intermitantly.
Does anyone have ideas or suggestions?
 
AEROCOOK

AEROCOOK

Master Chief Petty Officer
Joined
Jul 28, 2004
Messages
872
Re: johnson 90hp VRO V4

Is the vent open on the fuel tank?
Also, its a really good idea to provide the engine model number when posting in the forum.
 
hoeser

hoeser

Petty Officer 1st Class
Joined
Jun 18, 2006
Messages
253
Re: johnson 90hp VRO V4

The year of the engine is important, but sounds like fuel delivery.

I'm going to also agree with Tank vent being the most likely cause, and bonus for you it costs nothing to fix! If that doesn't work, check the fuel path. Prime the bulb when it happens, does the engine pick up? If so, fuel pump could be going... In your case (if the VRO is still connected) the VRO pump. Bad/consumed water separator cartridges can sometimes cause this, if you don't know how old it is (assuming you have a water separator) replace the cartridge or temporarily bypass the system.
 
C

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,148
Re: johnson 90hp VRO V4

In addition to what the others recommended, check the antisiphon valve in the fuel tank pickup line. They clog
 
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