Guys, a couple months ago I purchased a fairly clean 1989 Javelin 366fs with the original Johnson 120 v4 vro motor. I’ve been tracking everything down, trying to rigorously go through its whole system to get it running in tip top shape.
The issue I’m running into is that the motor has trouble getting up on plane. At first, before I replaced any parts on it, it pegged out around 2500-2800 rpm. I thought okay, it’s in slow mode, or it’s not getting enough fuel, let’s go over all of the problems that could occur with throwing the motor into that safe feature. The things I’ve replaced is this
- Carbs cleaned and rebuilt (and sanded down the float chambers as they were warped
- New coil packs
- New spark plugs (gapped correctly, and they are champion omc recommended plugs)
- New looper double fuel pump ( vro deleted)
- Brand new Power Pack
- New thermostats
- New temp Sensors
- New impeller
- Deleted the oil reservoir
- New Stator, Voltage Regulator, and timer base (tach didn’t work and wasn’t charging the battery)
- New ignition switch
- New fuel lines from tank to carbs, (including a new pick up tube, and anti sion valve).
- New Fuel Filter
- New primer bulb
- Fresh gas
I’ve had this thing out on the water about 10 times just diagnosing problems, and I’ve gotten it to open up and run but it’s very inconsistent and spotty. Sometimes she will bog forever and never grab plane. Sometimes she pops up out of the water and takes off wide open doing upwards of 50 mph. I’m at a loss, I’ve replaced all I can think of. Now, could it be possible that the magnets in the flywheel are weak? The battery is charging now but it doesn’t seem like very much of a charge. With a fully charged battery, reading 13 volts, the volts read about 13.25 with the motor running. As I changed the stator and timer base, I inspected the flywheel and the center magnets lookd fine and nothing seemed out of place so I didn’t change it but, do I need to?
Yesterday I had her out on the water. I putted away from the boat ramp and layed into the throttle. She popped out of the water, but at WOT I was only cruising about 30mph with the rpms around 4K. It wouldn’t get over that whatsoever. Once I got to an area on the lake where I figured it was time to throttle back, and give her another go to see what’s up, the boat only ran around 2,800 rpm, and would respond and gradually get up on plane if I was messing with the trim.
The only other thing I could imagine be wrong is just low compression, but I find it hard to think that is the problem because randomly when it does open up it just takes off and it’s very powerful. Another problem that was mentioned is that it the motor could be over propped, and I know these boats were propped for speed and pulling skis and stuff. I just do not think that’s the case either because the motor is all original, with the original prop.
Anyways, if anyone on here has done all that I’ve described and could give me any tips or points on what I’m missing or what I’ve done wrong, please don’t hesitate to say so. It’s been trial and error the whole way with this thing, but it was cheap and I’m trying to conquer these issues and enjoy the boat.
The issue I’m running into is that the motor has trouble getting up on plane. At first, before I replaced any parts on it, it pegged out around 2500-2800 rpm. I thought okay, it’s in slow mode, or it’s not getting enough fuel, let’s go over all of the problems that could occur with throwing the motor into that safe feature. The things I’ve replaced is this
- Carbs cleaned and rebuilt (and sanded down the float chambers as they were warped
- New coil packs
- New spark plugs (gapped correctly, and they are champion omc recommended plugs)
- New looper double fuel pump ( vro deleted)
- Brand new Power Pack
- New thermostats
- New temp Sensors
- New impeller
- Deleted the oil reservoir
- New Stator, Voltage Regulator, and timer base (tach didn’t work and wasn’t charging the battery)
- New ignition switch
- New fuel lines from tank to carbs, (including a new pick up tube, and anti sion valve).
- New Fuel Filter
- New primer bulb
- Fresh gas
I’ve had this thing out on the water about 10 times just diagnosing problems, and I’ve gotten it to open up and run but it’s very inconsistent and spotty. Sometimes she will bog forever and never grab plane. Sometimes she pops up out of the water and takes off wide open doing upwards of 50 mph. I’m at a loss, I’ve replaced all I can think of. Now, could it be possible that the magnets in the flywheel are weak? The battery is charging now but it doesn’t seem like very much of a charge. With a fully charged battery, reading 13 volts, the volts read about 13.25 with the motor running. As I changed the stator and timer base, I inspected the flywheel and the center magnets lookd fine and nothing seemed out of place so I didn’t change it but, do I need to?
Yesterday I had her out on the water. I putted away from the boat ramp and layed into the throttle. She popped out of the water, but at WOT I was only cruising about 30mph with the rpms around 4K. It wouldn’t get over that whatsoever. Once I got to an area on the lake where I figured it was time to throttle back, and give her another go to see what’s up, the boat only ran around 2,800 rpm, and would respond and gradually get up on plane if I was messing with the trim.
The only other thing I could imagine be wrong is just low compression, but I find it hard to think that is the problem because randomly when it does open up it just takes off and it’s very powerful. Another problem that was mentioned is that it the motor could be over propped, and I know these boats were propped for speed and pulling skis and stuff. I just do not think that’s the case either because the motor is all original, with the original prop.
Anyways, if anyone on here has done all that I’ve described and could give me any tips or points on what I’m missing or what I’ve done wrong, please don’t hesitate to say so. It’s been trial and error the whole way with this thing, but it was cheap and I’m trying to conquer these issues and enjoy the boat.