Cylinder Full of Fuel

[ScoLoc]

I am helping my young nephew try to resurrect a 1976, 70 hp Johnson. The motor has not been started for 10 years or longer. We squirted WD-40 then some TC_W oil into the spark plug holes and let it soak for a week. It turns over without any hitch. Compression is 120, 120, 115. So, we then put in a new water pump impeller, and hooked up the fuel to see what would happen.

What happened is that we managed to fill the lower cylinder so full of fuel that it wouldn’t turn over. Took out the spark plugs and a bunch of fuel just poured out of the bottom spark plug hole. Pretty freaky, but is this just what happens when one or more of the carbs has a stuck float valve and you keep squeezing the bulb anyway? Probably a dumb question to anyone who understands how a carburetor actually works, but what I am wondering is if this just means the carbs are gummed up and need to be cleaned and rebuilt, or whether it’s indicative something more serious.

 

[GA_Boater]

After sitting 10 years, gummed up carbs are almost guaranteed.

A carb rebuild will probably get her going. Have you checked for spark on all 3 cylinders.

 

[ScoLoc]

Thanks GA-Boater. There is spark to #2 and #3, but not #1. That coil has a visible crack, so I assume it is what's bad. But, before ordering a replacement, we will switch the #1 coil with #2 to confirm. My nephew is on the hook for buying parts, and is only working part time at close to minimum wage. So, thats also why I didn't simply have him order the carb rebuild kits before asking here.

 

[GA_Boater]

Understandable about a young 'un with not enough money - Been there. :smile:

To make the kits a little more affordable, search the web for the best price and call iBoats. The store matches prices and as a forum member you can get another 5% knocked off. The discount code is FORUMS5.

 

[Chinewalker]

Bad fuel pump will do that. If diaphragm is shot, priming fuel line will force fuel right into the crankcase through the pump.

 

[ScoLoc]

Thanks Chinewalker. To test, I disconnected what appeared to me to be the line from the crankcase to the pump ( B to 2 in the attached pic) then squeezed the priming bulb.. Fuel entered at 1 and immediately exited at 2. So if I B goes into the crankase as I believe to be the case, then fuel was entering straight into the crankcase instead of through the carb at A. That certainly would explain what happened. I disassembled the pump expecting to see a damged diaphram, but all looked pretty good.

Now I am wondering if the prior owner may have the tubing connected up wrong. Should A actually connect to 2, and B to 3 instead of the way I found it?

 

[havoc_squad]

By cross referencing multiple parts lookup websites, you can find out that item #9 in the fuel pump parts schematic goes to the carb. Without the service manual, I can't say that this is a typo or not, but I would say with reasonable certainty it does.

Unfortunately the iBoats parts lookup does not provide this information on #9, but other competitors do.

iBoats direct reference: https://www.iboats.com/shop/engine-p...ump-Parts.html

This is why it is often useful and sometimes mandatory to use multiple reputable website sources for verifying parts information.

So in short, it does "appear" that the hoses are swapped for the crankcase pulse vacuum and the fuel flow to the carb in that picture.

 

[racerone]

From tank to #1.---squeeze bulb.----If fuel comes out of # 2 then that goes to carburetor.

 

[ScoLoc]

Thanks for the confirmation that the lines appear to have been connected wrong.

My nephew gave a friend's grampa $70 for this outboard. It was hanging from the rafters in a pretty delapadated old shed. The controlls were still connected but the cover had been left off. It was covered with dead vines, leaves, cobwebs etc. But the Grampa said it ran ok when it was last used. Tthe only problem he knew about was there were sparks arcing from one of the coils. (he actually said from one of the "magnitoes.")

So, its a mystery when and how the fuel lines could have been misrouted because it obviously never ran with the fuel bypassing the carb and dumping straight into the crankcase like I found it! I just put them where they belong, and the primer bulb firmed right up. Who knows, it might even start. Unfortunately, the battery is dead, I so will have to wait until the weekend to give it another test. Meanwhile, we did go ahead and order a new coil, fuel pump kit and 3 carb kits. With luck that will do it. I'll post again with results or more questions.

 

[ScoLoc]

I just wanted to close this thread by confirming that rerouting the fuel lines fixed the problem. We set it right, replaced the coil and it started right up with a jumper to the solonoid. The ignition switch isn't working; the throttle linkage is messed up, and the control box won't shift into forward. We also had some oiley discharge mixed in with the water coming out of the exhaust for a bit so, I'm not sure there isn't also a leak into the gearbox somewhere. But, thoise are all issues for another thread. I appreciate all the help sorting this one out.

 

[Chinewalker]

Some oily goo coming out the exhaust is normal with two stroke outboards. Excessive amounts might point to,a cylinder not firing, resulting in its fuel dumping right through unburned.

 

[F_R]

This started off with a cylinder filling up with fuel. So of course there was excessive oil coming out the exhaust upon startup. Some discharge is normal though.

I think it is remarkable that it started and ran after such neglect. Just goes to verify Johnson's reputation for dependability.