Ebay carb or rebuild the carb...

[Fdildine]

Ok, so here goes. I recently picked up a 93 Max II with the original 16 hp Vangard motor (date stamp is '93). I've replaced the plugs, coils, new gas, cleaned the carb, compression tested of 150 on the rear cylinder and 140 on the front, but still we're not smiling. The Max idles pretty good but as soon as I start to give it the gas, it blows gas out of the carb and back fires and has no power. I believe it is a fuel problem and I see I have two choices, rebuild it the carb for $75 or get an Ebay carb complete for $50. Do y'all think I've trouble shot correctly in that my problem is the carb and should I go cheap on Ebay or rebuild? Thanks in advance. Fred, sitting broken hearted in my Max in the garage...

[Fdildine]

Oh yeah, I put on a new fuel pump too.

[dirtdobber]

I'm leaning toward a carb problem. It could be flooding itself thus causing the backfiring and poor running condition. When you do run it, and if it is flooding itself, the plugs should be black. Your post says you cleaned the carb. Did you actually disassemble it, remove the jets, soak it in a cleaner, run a wire through ports, etc?

Also, did you properly gap the plugs and coils?

[Fdildine]

I properly gapped the plugs and coils. I pulled the carb apart, spayed most of a can of carb cleaner on and through the jets and bowl. I used a small wire and I ran it through the jets. On the plugs, the front one is white or looks normal and the back one is black and wet. It looks like gas fouling

[dirtdobber]

pull the back plug and make sure its firing - through the plug, not just through the wire. You could have gotten a bad plug or coil. If the carb was dumping fuel into the engine it should show up on both plugs.

Does the coil mount in only one position (I think so but its worth asking)? If not, is it mounted wrong and thus the ignition timing is off on that cylinder?

[Fdildine]

I'll give those ideas a shot later today. Thank you!

[Fdildine]

Ok so here is the latest. I pulled the back plug and checked it is sparking. I checked the coils, they are not installed backwards and are gapped correctly, yes I really did check, we're all human. I checked the valve clearance and adjusted all 4 valves. I put it all back together amd it fired right up. It idles better and ran at about 80% which is a lot better than 10% power like it was. After about 5 minutes it started missing and was getting worse. It is blowing oil out of the PCV so much so, it was dripping out of the air cleaner and made the Max smoke like crazy. This thing is making me learn, so thanks for the advice and keep it coming.

[ARGOJIM]

What do the plugs look like now?

[Fdildine]

I'll let you know.

[racerone3]

my guess is that you are losing spark on the rear cylinder. you could try removing the small black wire that connects the 2 coils. if it runs fine without that wire you need to replace that. that wire has a diode in it that can cause problems. note that the engine will not shut off with the key when that wire is removed unless you have a functioning antibackfire solenoid. you will need to use the choke to kill it.