1986 Johnson GT150 Won't Start

[scott2000d]

I have a 1987 Ranger 373V with an 1986 Johnson GT150. I was out on the lake yesterday with it all day and it worked great. I beached it and left it for a few hours. When I went to start it again to put it on the trailer it would not start. I tried and tried but it would not go. So I loaded it by hand. Now that I hve it home I have hooked the muffs up to it and it still won't start. It just keeps backfiring over and over again. I took out all the sparkplugs and cleaned them and checked for fire. They are all firing. I removed the airbox cover and it had a lot of gas in it from flooding i think. A friend of mine suggested possibly a crank seal went and I should check the compression, and if all cylinders are low possibly the seal is gone. When I was cranking and afterwards there was some very black oil coming out of the exhaust and around the prop. I checked and the lower unit oil is still green so it isn't that. I mix the oil in the tank since the oil injection isn't hooked up. I mix it 50:1 and haven't had a problem yet. I plan to hook up the oil injection later this summer. I am going to get ahold of a compression tester tonight to check my compression in all cylinders. What should I get for compression in this motor?? Also does anyone have any ideas what could be the cause of this problem??

Thanks, Scott

[ChampioNman]

Flooded. Junk coming out of the LU is unburned gas/oil. Pull the kill switch and with the plugs out and disconnected from the coils crank the motor for a few burst of 10-15 seconds. Take the plugs and put them in a vice with the electrodes facing up. Hit them for a few seconds with a propane/benzene torch and burn off all the fuel. Let them cool and check the gap. Make sure they are Champion QL77JC4 gapped at .030. Put them back in and it should bust right off.

[scott2000d]

Excellent. Thanks for the reply. I just checked my Compression and got:
1: 85 2: 89
3: 89 4: 90
5: 85 6: 89

The plugs in it right now are Champion QUL-77V these are what were in it when I got it. I have already hit them with the torch and wire brush to clean them up and they look like new. However there is no way to gap these ones. I have never seen a plug like this. The little piece that you would bend to gap them isn't even there. the bottom is completely flat. I am thinking that I am going to try all new plugs. Should I stay with what I have or should I go with the QL77JC4 and gap them? Thanks again, Scott

[ChampioNman]

Those are surface gaps, the QL77jc4's are more readily available and not quite so expensive as the QUL's. Comp numbers look pretty good. Make sure you gap the QL77JC4's at .030.

[scott2000d]

Ok. Thanks, I will buy a new set of QL77JC4's and gap them to .030 instead of going with the expensive QUL's. Hopefully it'll fire up with some new plugs. I'll let you know how I make out.

Thanks, Scott

[scott2000d]

OK, so I went out and bought 6 new plugs, checked the gaps on them all, and put them in after cranking many times with no plugs in and fuel turned off. I am still getting the same thing. It cranks for a few seconds, then backfires and the starter disengages. It will even continue to do this for a while with the fuel turned off for a while. Whenever I turn the fuel back on it just goes back to the same old crank until backfire thing. Any Ideas?? I'm running out.

[scott2000d]

So I was out working on the motor again and I realize that I am actually not getting any fuel. I disconnected the line from the VRO pump to the fuel rail, and fuel will come out there if I squeese the primer ball, and also when I crank over the engine. Any Ideas?

[ChampioNman]

That 373 wouldn't happen to have 2 tanks would it? If it does replace BOTH feed lines from the tank to the selector with 3/8" ID BRP fuel line to the selector switch. While you are into the lines remove the barbs from the tanks and dislodge the anti siphon valve or just replace the barb fitting.

[scott2000d]

Alright.. So I now have 6 new spark plugs, 3 spotless carbs, countless hours wasted, and much hair loss. I gave one of my friends at a local ATV repair shop a call and explained my situation. The first words out of his mouth were "timing's off, check your flywheel key." So I pulled off my flywheel and there was the key in 2 pieces. BINGO!!! I went to my local marine mechanic and he gave me one for free and wished me luck. Gotta love that for service!! I put the new one in and it fired right up and runs perfect. Maybe even a little more responsive now with the cleaned carbs. Thanks a lot for all your help!!

[ChampioNman]

Glad you got hooked up.