oily grey residue

[samancus]

Hello,
It has been a while, thanks to so few problems. But now I am in a quandery.

My motor, 1991 Evinrude 9.9hp pull start, blew a head gasket last time out.
It continued to run with diminished power. Back home a compression check determined the diagnosis. With the head off I found thermostat had been removed, I installed a new one. Cylinders were perfectly smooth, and now compression is 90 in both. It ran very rough at first and I thought a little Sea Foam would help but it did not. I also noticed oily, grey, gas smelling residue spitting from exhaust relief holes. I figured it was a fuel pump diaphragm leaking excess gas into the cylinders, and ordered a rebuild kit.

I drained lower unit and the drained oil resembled the grey residue. Refilled with new 80/90 synthetic. Cleaned carburetor, again. Replaced plugs which were not fouled but oily and used a spark tester to determine ignition is functioning correctly. I found the cam follower had been epoxied and replaced it, plus checked to be sure it was aligned correctly on the throttle plate. A few months ago I installed a new impeller, and the motor pumps water with vigor. Also, as a note, I have removed the tiller arm and installed throttle cables, shifter cables and steering cables. I built the console, made the connecting parts and the whole thing works pretty well on my home made boat.

Installed the rebuilt fuel pump, got some new gas and oil with a 50:1 ratio and started the motor. It fired up and it raced pretty much out of control for half a minute and then stalled. But it ran great! I got it so it ran at a comfortably high speed but not racing, and it would go like this for up to about two minutes and then die. After ten or so tries like this and a sore arm I bought a new fuel pump and installed it.

Now it starts fine but will not accelerate above idle speed where it runs for a few minutes and dies. Placing the shifter in gear and throttling up causes a very slight increase in speed and it dies after a few seconds. Still getting the oily residue from the relief holes. I removed the new fuel pump, replaced it with the rebuilt one and the motor started and raced like it did before and died like it did before. Removed and replaced with new fuel pump and I am back to slow speed only and for a few minutes at a time. Did I mention that I cleaned the already immaculate carburetor again?

Any idea what is going on and what to do next?

[boats.net]

Check throttle linkage is working properly, throttle plates in carbs are opening when throttle up and timing base under flywheel is advancing when throttle up. The old fuel pump has an air leak causing a lean fuel mixture cause engine to rev up. Check that the fuel supply to new fuel pump does not have a restriction causing it to run out of gas.
May have a air leak in crankcase, top or bottom crank seal leaking or bad intake gaskets.