85 hp air leak?

[Dman]

It's been forever and a day since I posted on here. I recently acquired a FREE 86 85hp Force. I replaced the lowest cylinder piston and now have about 125 psi across all the cylinders. However, I am having a hard time getting it to start and run. I think there's an air leak somewhere. I can put my hand over the carbs and get it to fire, leading me to believe too much air is getting in. Maybe I missed something on the rebuild. Gas will pour out of the carb when I put my hand over it and get it to fire. I may have to tear it down again to check. Maybe a bad crank seal on top....hopefully.

This was the first outboard project I've done. Not too bad. I've rebuilt about 20 snowmobiles and know all the basics about 2 strokes. Slow going for the first one though.

Spark and all electronics are good. I have run into this one other time on a sled and it was a crank seal. There's not a lot of pressure sucking on your hand when I crank it over.

D

 

[jerryjerry05]

Re: 85 hp air leak?

Carbs been rebuilt? Make sure the main jet is clean.The air screw should be turned all the way in then out 1 to 1 1/8 turn.Ethanol has been really screwing up the fuel systems.Check for junk in the filters.J

 

[Dman]

Re: 85 hp air leak?

Yeah, I did forget to mention the carbs are spotless. Cleaned them the first time I couldn't get it started.
With all my other experience, I have to beleive it's sucking air. The plugs are dry and it will fire if I spray gas into the cylinder. I'll probably taker' apart again.....great.

D

 

[Dman]

Re: 85 hp air leak?

Does this sound like an air leak to anyone else? It previously burned the lowest piston. Maybe it's the seal on the lowest crankshaft bearing? I'm just guessing at this point. Gas is getting to the carbs but not entering the cylinders.

D

 

[pnwboat]

Re: 85 hp air leak?

Before you tear it down, take a close look at the reed assemblies that are mounted inside the block underneath the carburetors. They control the air flow into the motor. Also make sure all gaskets are good on the reed assy.

 

[john from md]

Re: 85 hp air leak?

Take another look at your fuel diaphram. There must have been a bad batch out there as I have seen several with tears this season. Many of them have only been on since the beginning of the season!

John

 

[sho3boater]

Re: 85 hp air leak?

Before you tear it down, take a close look at the reed assemblies that are mounted inside the block underneath the carburetors. They control the air flow into the motor. Also make sure all gaskets are good on the reed assy.

Right if its not sucking air check the reeds, though if you get gas in carbs it must be sucking something. Strange part is it should run on other cylinders if one is messed up.

Crank seals can make for real hard starting that is for sure.

 

[jason32038]

Re: 85 hp air leak?

Does your choke work?

 

[thimsllib]

Re: 85 hp air leak?

I'm having the same problem... I pulled the carbs off but haven't had a chance to take them apart yet. I also pulled the fuel pump and the diaphragm was intact, but i noticed the check valves looked pretty shot. I ordered new ones ($6 each at crowleymarine.com). I should have the carbs and fuel pump done sometime next week. If you take her apart, please post your results, as I'd be interested to see what you find. I'm really hoping mine is due to bad check valves and dirty jets, but you never know. Also, my reed valves were in perfect condition, so I've ruled that out.

 

[sho3boater]

Re: 85 hp air leak?

You can always take a line off the carbs and see if it pumps fuel.

 

[Dman]

Re: 85 hp air leak?

It does pump when I have the fuel line off from the carbs so I think the fuel pump is working fine.

I dismantled again today and checked everything. Took the powerhead off. Still have some stuff left to hook up and I'll try it tomorrow. I'll post the results. I didn't find anything that was alarming. Cross my fingers for tomorrow. Getting good and speedy working on it now....
D

 

[sho3boater]

Re: 85 hp air leak?

Did you check compression? That still does not show a bad seal though. I ran mine hard this weekend, it runs 5200rpm with a modded 19p. I thought that was slow but I see it says 4600-5500 and 5000 is rated hp.