1991 Evinrude 150 XPS

I'm trying to figure out the reasoning here. I bought this motor from the 3rd owner. 3rd owner only owned it for a year and most of that time it was just sitting on a trailer.

When I bought it from him, he said it was fouling plugs like crazy, but otherwise it ran great. The carbs had been gone through, the head gaskets replaced.
He had removed the VRO connections and was mixing the fuel 25:1.

After mounting it on my boat and taking it for several test runs, it was running "okay", but it was going through fuel like crazy. Yes, I know, these are the gas hogs of the outboards, but this was much worse than I expected.

I mix the fuel at 50:1, which is what these motors really call for.

My brother decided to go through the carbs again and clean them all up. He really didn't find much except there was a tube that was busted. I believe it was just a vent tube so it made little difference.

Still running okay, we decided to connect the VRO up and see if it worked and then used straight gas. It ran better, plugs looked perfect after running for several hours, but I went through fuel at about 18 gal/hour. Ouch!

I decided to go back to the carbs and check a few things and this is where my question comes up. The main high speed jets in this thing are 65C. According to the book, stock jets for the 150 HP is 56C. I'm trying to figure out why someone would re-jet it at all, specially going larger, since from the factory they are jetted to sea level.

My guesses are:

1. Removing the VRO and mixing the fuel, they thought they needed to up the jet size.

2. They were dyslexic and bought the wrong jets (65C vs 56C).

3. They thought they could replace the jets and make it a 175 HP (175 HP uses 61C jets)

4. They bought the wrong carb kits when they went through the carbs.

Any other thoughts?

All you can do with this mtr is get the right jets back in it and go from there.

TheBearAK,TRY a decarbonizer on motor,running a 25-1 more than likely fouled up heads and pistons and plugs!!!!

Bit of confusion today with it. Went to see if either of the local dealers would have the jets, one dealer didn't have them, but their parts lookup confirmed that it should have 56C in them. Then at the other dealer, they also didn't have them, but their parts diagram showed that it needs the 65C that I have. Further digging, various models of the 150 HP of that year take 56C, but the E150STLEIE takes the 65C.

We've ran a camera inside the motor and it actually looks extremely clean. Our first thought was that it would be all gummed up.

Being curious, I cracked my books............

Bear is correct pertaining to Model #E150STLEIE requiring the 65C high speed jets whereas the other V-90 model uses the 56C.

I find it strange that the Crankcase of the two V-90 models are the same, the Pistons are the same, and the Reed Plates are the same.

The differences that I found were with the Cylinder Heads and the Carburetor assemblies only.

What am I overlooking?

Probably big bore carbs and higher compression heads.