1990 Johnson V6 VRO Outboard - Intermittant loss of propulsion

[Bluelab]

Can someone help me? I launched my boat yesterday. Put in the throttle to go forward...I could not go past 1000 rpm. Went in the reverse for ten seconds and the problem went away. No horn during the episode. Yesterday I started the boat in my driveway before I left...no problem...water indicator good. I had this problem in the Sacramento Delta a few weeks ago...after in hyacinths, I put the engine in reverse several times and the problem went away. Last week I had the boat the out..no problem. When I launched yesterday the water was clear. Several years ago I had this problem. The mechanic said that a part needed to be replaced...it was showed to me somewhere in the engine...but I can't remember what it looks like. I thought yesterday perhaps I had the throttle advanced forward but disengaged the prop...but the boat did go forward. After the incident yesterday, I had no problem the rest of the day. I am kind of beside myself...a little disconcerted about motor confidence. Most appreciate of any input. Thank you.

 

[emdsapmgr]

I've gone through weeds with my pontoon. Once they clog up the prop, it won't come up to speed and the prop will ventilate badly at about 3000 rpm's. Have to stop, put the engine in reverse and rev it up. This procedure is enough to clear the weeds from the prop. After that, it the engine will run normally when shifted back into forward.

 

[Bluelab]

I found what the problem is but I don't know why. The dilemma is that the issue was intermittent...to the extent the engine would start in neutral and when I would advance the trust in forward gear, intermittently it would want to stall at 3000 rpm...but not all the time. At first I thought it was a clogged prop so I would would advance the throttle in reverse for about 20 feet...then I would put it in forward gear and the engine would not stall. While on the water, I discovered that if I stop, turn the engine off, restart the engine...there was no problem. I discovered after the engine sits in the water for an hour or so with the engine off, I would then restart the engine and the problem would come back. I discovered if I start the engine in neutral with the throttle advanced forward at a 45 degree angle from the horizontal neutral position, when I run the engine is this position for about 5 seconds, return the throttle to neutral and then advance the thrust, the engine would not stall. Is this a cold motor issue? I don't understand the fix. I never had this problem on a hot day on the lake. This only has happened in the cold water of the Sacramento River. Quite an enigma. Input would be most appreciated. Thank you.

 

[racerone]

Check / chang the gear oil.----If that is OK then install another prop.----Also test with motor mounted lower on the boat.

 

[emdsapmgr]

At this point, you might consider doing some testing of the powerhead's operating temperature. That powerhead will run maybe 140-150 degrees when at idle for a while. That's normal. Once you start to move the boat through the water, the pressure relief valves in the thermostat open and flood the powerhead with additional cooling water. When at speed the head temps could drop 20 or 30 degrees, depending on the lake water temps. This is also normal. Since you have two operating heat ranges and two thermostats, I'd borrow/rent a laser temp gun and do some temp testing under a couple of scenarios: long term idle, and then when at speed on both heads. See what you get. If everything reads normal, then look elsewhere for the problem. As a point of clarification, weak ignition components tend to fail once the engine heats up to normal operating temps. (140/150)

 

[fhhuber]

Check your VRO/Fuel pump for cracks... could be drawing air.

Similar issues on my 1989. I couldn't find a thing till I had the engine cover off and squeezed the primer... the fuel pump leaked.

The VRO pumps are expensive... there's a way to replace that with a pair of fuel only pumps and go to 50:1 pre-mix. It saves you about $300.

I asked which pump to order for this a few weeks ago. I've been running with VRO disabled (very easy to do) on the VRO/fuel pump for a couple of years.

 

[Bluelab]

Is it possible, at idle, the temperature relief valve is opening too soon? This could make the power head too cold and thus when I advance the throttle the engine stalls. It seems the solution is to run up the rpm in neutral for a few seconds...this would heat up the power head...warming it to accommodate the cooler water. I would then put the engine in neutral...engage the gear...advancing the throttle...and then the problem goes away. No stalling. What is weird is that is that the engine won't try to stall if I go, stop, turn the engine off, restart and go. It only happens when the engine sits in the water for about an hour. Gee...what an enigma?

 

[racerone]

No model # posted so I have to ask.----Is there a shift interrupt switch that is sticky ?

 

[Bluelab]

Model No. 1990 150STLESB . I just spent $1500 on a new control panel (shift throttle), cable and gear drive module...for nothing...the shop wasted my money. So frustrating. :-(

 

[racerone]

More input on your part is required.---What are the compression values ?---Does spark jump a gap of 7/16" on all six leads , yes or no ?---Has the fuel system been inspected from the pick-up screen inside of tank to the fuel pump ?----Have you tried running on a seperate fuel tank with a known to be good hose ?-----$ 1500 for a new control box ?---Did they decide that or did you ask to have that done ?