1987 150hp vro runs slow - part ii

[Don Dickinson]

i decided to start a new thread on this because the nature of the problem is a little different.

my 150 is dogging. it runs from between 2500rpm to 3000rpms. it won't push my back-heavy bass-boat up onto plane.

i suspected it was running on 3 cylinders (bad powerpack,etc), but upon removing the spark plugs i found them saturated with oil. the oil isn't up onto the ceramic, but the threads and pin are covered with oil and i can see oil saturating the plug receptacle. i have a feeling the previous owner put some oil in an empty tank and put the gas on top of it (vro disconnected so it runs on mix) and after i ran it for a bit, a concentration of oil got sucked up into the engine.

here are my two questions:
1. what is the best way to clear the oil thats saturated the plugs and cylinder? i have a suggestion from a friend to run 6 or so gallons of fuel mixed 75:1 (from a remote tank) and replace the plugs.

2. if i have good spark on all 6 cylinders, does that indicate that my powerpacks are good? or might 1/2 the cylinders stop working at higher speed because of a bad pack. i have a new pack on order and will have an extra anyway.

tia,
don

 

[bgbass.1]

Re: 1987 150hp vro runs slow - part ii

the best thing to do is keep running 50:1 pre mix it will clean out then put new plugs in and add seafoam to tank to clean it up

 

[Dhadley]

Re: 1987 150hp vro runs slow - part ii

If you're concerned about a heavy oil mix (it'd have to be almost all oil) drain the carb bowls. If it's as you suspect it'll be mostly oil. If it is, get a small pump, disconnect the line from the motor, put the pump in line and run a line back into the tank. Let the pump run. After you circulate the gas / oil it should mix.

Now, how clean are the carbs? It seems like you just bought this rig. If so, cleaning the carbs is a standard "before you run it" practice.

Also, what spark plugs are you running?

 

[Don Dickinson]

Re: 1987 150hp vro runs slow - part ii

PLUGS
i just bought new spark plugs (champion marine QL77JC4 with a .030 gap) and will be replacing the old. the old plugs are exactly the same kind, and, according to the previous owner, were bought new last year.

CARBS
the previous owner claims to have had the carbs rebuilt last year - said it cost him $500 or so. i guess i should take a look at them i'll pull them apart per your advice and get them cleaned up.

GAS
per the gas that's in the tank ... my plan is to siphon it all off into spare tanks and run it that in my mower, etc. if it looks ok, i might mix some back into the boat in small doses, not sure yet. i don't have confidence in the gas that came with the boat (probably 5g of gas and lord only knows how much oil). i'll run it on a remote tank until things settle.

A QUESTION (sorry)
do you think i should run smaller than .030 gap (maybe .025) for a while. that will cause it to run a little hotter and perhaps burn off some more oil? i'm not an expert on this, just an idea someone else told me about.

thanks again,
don

 

[emdsapmgr]

Re: 1987 150hp vro runs slow - part ii

You didn't mention that you had done a compression test. Probably the first thing on any 2-stroke, so that you know where you are starting from. If the fuel is old, or you don't know it's age-throw it out. Take a friend and a timing light to the lake next time. When you hammer down, check each plug wire with the cowl off. Make sure you have strong, constant flashes on each wire. If you have an ignition problem it should show in this test. Sometimes the plug wires will ground on the cowl latches... An extra power pack is an expensive, but good maint. plan. When testing them, you can move them side to side to compare.. Your engine may have the SLOW feature, which limits rpm's to 2500. You'll need to check to make sure this is not active.

 

[Don Dickinson]

Re: 1987 150hp vro runs slow - part ii

hi, the previous owner "said" that the compression was fine last year.
the reason i don't suspect is it is the the engine ran fine for the first 15 minutes or so i had it out. 12 of those were in slow-no-wake and 3 min between 30 and 60mph. i traveled back to the dock after that. just wanted to be sure it worked the first time out.

the problems began after that. per SLOW, the engine now runs between 2k and 3.5k rpms at wot, so i don't think SLOW is on. we'll see i know that the plugs are fouled with oil and i'm going to be cleaning the carbs tonight. i haven't looked inside the carbs yet. my theory is that there was a bunch of oil at the bottom of the gas tank and after running it for 10-15 min, that very oil-rich mixture got sucked up into the engine, fouled the plugs, etc and now its mis-firing a lot.

thanks for all advice so far,
don