</font><font color="blue" class="small">( Could the gas in the carb just be so hot that it boils? )</font>
Scott,
My 422 gets pretty hot in the compartment, too, but I don't think you should start modifying (just yet, anyway /forums/images/graemlins/crazy.gif), till we discover a 'root' cause...mine will run several hours in low 90's ambient temp's (I vaporlock after that) /forums/images/graemlins/grin.gif
1)Changing fuel source (or grade) is a quick start on the path to elimination...
2)Is that electric fan running at the top of the cover(that keeps engine compartment temp's "closer" to ambient...
3)Is the 'pulse' line from crankcase to fuel pump tight?
4)If I recall, the top of that carb comes off pretty quickly...
when it gets to failure mode, try to get the top off the carb to check the bowl/float to see if there is fuel in there or the float is stuck in "fuel off" position (this will be a most difficult task because it's hot! /forums/images/graemlins/shocked.gif)
5)If you check the bowl in the morning on a cool engine,you may dissapointingly find very little fuel in there because of carb design (which is another reason I added a 3rd(out of 4) shutoff just before the carb (and after the fuel pump).
With fuel levels in the tank above the carb, ((and a failure of the float to shutoff the flow(like that's never happened) a possibility of fuel siphoning out and into cylinders exists(very bad).
You might like to try a little experiment to check fuel pump capacity (non scientific)...
1) on a motor just barely warmed up...pull off hose at output of fuel pump(have a couple feet of extra fuel line and a means of clamping off flow on the line you just pulled and the line at input to pump)
2)put extra line on pump and other end into small container(the usual cautions apply to careful handling of fuel around heat and ignition sources)
3)Unplug wire going to fuel shutoff solenoid(check for tightness while you're there). (we don't want engine to run and we don't want plug wires disconnected and arcing).
4)crank for a given amount of time(e.g., 10 sec.) and note the volume pumped...(also note level of fuel tank)...
Yea, you know where I'm going here /forums/images/graemlins/smirk.gif...
...Same thing when it gets to failure mode...If fuel tank is at the same approximate level, pump volume should be pretty close, too....If not, debris in pump(or pulse line leak,or ...)
Of course,if volume is ok, disassemble and clean carb...
All this assumes fan (hydraulic cooler) is running !
Now get busy and stay away from that dealer /forums/images/graemlins/grin.gif
Regards,
Bruce