What are some possible cuases?

Question

I have a mid 80's 4 cyl Mariner engine, the lower two cylinders are not firing, after running awhile, those heads are cool and the upper two are warm.

It has spark to all four plugs, I removed and disassemebled both carbs and everythign was clean, nothing plugged up or dirty.

I'm running out of ideas.

Is there somewhere in these engines that the fuel/air supply could be blocked between the carbs and intake ports?

Answer 1

Could be the reed valves under the carb base. Have you checked compression? The lower two may be low.

Answer 2

Still sound like carbs or did you cross the plug wires on the bottom 2 cyc??? Spray carb cleaner in bottom 2 cyc while running and see if it picks up any>

Answer 3

I don't know sweetie.

But I'd hug you if I could.

Answer 4

I have no effin clue, Jim.....I just wanted to say hi!!!!

Love ya..xx~~~

LOL...

Answer 5

The big question is compression first. The next thing to check would be your carbs idle ports. They are very small. Should be 2-3 of these located on the bottom front of the inside of the carb. The best way to check if it is a fuel problem is to shoot a little mixed gas in that carb and see if those two cylinders fire. Do not run your motor to long if you are not getting any fuel in those two  cylinders!!!!!!! You will not be getting any lube into those two cylinders!!!!! If the gas trick works you will need to rebuild the carbs. You will have to run a small piece of wire through the idle ports to clean them out.