1990 XP 150 VRO idling rough

[Stratos275Pro]

I purchased a 1990 Stratos 275 Pro a few weeks ago and it has a 1990 XP 150 VRO, E150STLESB. The hull and everything else is in excellent condition for a 26 year old boat.

The issues I am currently having is that is idles rough. I spoke to the dealer that has preformed services on it the past few years says that it is over oiling. Through further inspection of the motor and doing some research of my own. I discovered the possible over oiling issue, fuel line coming off the bottom of the VRO pump was not properly clamped, $4 fix with new clamps. After clamping the fuel line, motor started up and was running fine, holding pressure on the fuel bulb, then all of a sudden started idling rough again and losing bulb pressure.

Prior to fixing the fuel line i put in brand new spark plugs. After shutting it down i checked the plugs to see if any were fowled. The top left plug was fowled and the rest look a little wet but fine.

Am I safe to say that that coil pack is going out or would it be the power pack messing up?

I know i have multiple issues going on but needing some insight before i drag it to the shop to Bust Out Another Thousand (BOAT) LOL. Hope someone can shed some light on what i could do to narrow down the problems and fix them with out it going to the shop.

[Joe Reeves]

Start with the basics to avoid going down the wrong trouble shoot route.

What is the compression psi readings of "all" six (6) cylinders?

With "all" spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it? NOTE, the 7/16" gap is important!

(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4
*******************

If both of the above areas check out as they should, then that leaves a fuel problem, possible engine linkage, BUT at least you know where you stand in the compression and ignition area.

Let us know what you find.

[TheBearAK]

Only has 6 cylinders.

My first instinct would be to go through the carbs. Clean them all up.

I have the same motor and discovered one of the small tubes on the carbs was busted. Replaced it and that cured one of the issues.

However, mine always idled just fine. Just taking off seems to cut out and when cruising at about 4800 RPM, I can see the RPM go up once in a while and I could feel the boat surge slightly. Really couldn't hear anything though.

I need to get a wire diagram for this motor so I can go through and check all the connections. The previous owner had removed the VRO because local dealerships never trusted it. #1 problem with the VRO is pumping the primer bulb on the oil, as there is no float to stop from over-oiling.


My compression is perfect and the piston wash is amazing. So my issue has got to be wiring or coil(s).