Lean #1 cylinder

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mamm7215

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No matter what I've tried, I still have a lean #1 cylinder on my '81 90hp Johnson. The carbs are fine, cleaned them at least 2-3 times after new kits, pulled jets, cleaned them as well, adjusted floats, I have a factory manual. The only thing I haven't done is pull the recirc hoses. I also have noticed the top crank seal looks kind of warped so I have another, just haven't put it on yet. The choke circuit works. Given clean, proper functioning carbs, could the recirc hoses or top crank seal cause #1 cyl. to lean out?
 
Faztbullet

Faztbullet

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Re: Lean #1 cylinder

could the recirc hoses or top crank seal cause #1 cyl. to lean out?
Click to expand...
The recirc hoses .uhhhhhhhhhhhhhhhhhhhh maybe, the top seal definitely as will a warped transfer plate or blown transfer port gasket.
 
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mamm7215

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Re: Lean #1 cylinder

I don't know where or what the transfer plate or transfer port gaskets are but thanks for the reply, I'll definitely do the top crank seal next.
 
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mamm7215

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Re: Lean #1 cylinder

Sorry, the link just takes my browser to the evinrude page where you select the year of your motor, nothing else...
 
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Haffiman

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Re: Lean #1 cylinder

The reference goes to the covers on the cylinders where the recirculation hoses are attached.
Be sure that those gaskets are 100% DRY and not leaking fuel.
 
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mamm7215

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Re: Lean #1 cylinder

Ok, thanks, that's kinda what I thought they were. They're definitely not leaking. I'm more concerned that the hose isn't blocked or the valve itself blocked.
 
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mamm7215

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Re: Lean #1 cylinder

The spark plug after running is mostly dry while the other 3 are slightly oily. Also when I had the cylinder head off the other day replacing the head gasket I noticed that cylinder 3 was wet/oily while cylinder 1 only had a very slight sheen of oil on it but almost dry. Also the underside of the cylinder head chamber was oily on 3 but almost dry on 1.
 
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jonesg

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Re: Lean #1 cylinder

mamm7215 said:
The spark plug after running is mostly dry while the other 3 are slightly oily. Also when I had the cylinder head off the other day replacing the head gasket I noticed that cylinder 3 was wet/oily while cylinder 1 only had a very slight sheen of oil on it but almost dry. Also the underside of the cylinder head chamber was oily on 3 but almost dry on 1.
Click to expand...

Suspect carb jets, you didn't get them switched around by chance did ya?
Swap carbs if possible.
Stuck reed?
 
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Haffiman

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Re: Lean #1 cylinder

Or:
you have one working and 3 'defect' cylinders.
Check the check-valves.
Flow should go from cylinders to intake.
Another 'possibility' is you have a cooling problem, air-trap on top of cylinderblock making #1 run a bit hotter.
Check engine temp and thermostats.
 
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ezeke

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Re: Lean #1 cylinder

If you still have the overboard indicator running from the exhaust cover to the lower cowl directly, you may want to run a longer hose, routing it to the top of the engine and back down. This will help to keep air out of your cooling circuit.

Also, check your water passage deflectors.

Often the cylinder most affected by lugging on the V4 crossflow will be #1.
 

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mamm7215

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Re: Lean #1 cylinder

Wow, didn't think a too short hose could trap air, my hose does go basically right from the exhaust cover fitting to the lower cowl pee-hole fitting. I'll look into that.
Also, how would I test the check valves, I am suspicious of these as well. I should note that the jets are all proper, carbs are def. clean. I also thought about a damaged reed. This motor has been seriously overheated previously (not by me, I discovered this after I got it), so that adds a bit to the mystery. I have to take the intake cover off to see the reeds, correct?
 
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ezeke

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Re: Lean #1 cylinder

mamm7215 said:
Wow, didn't think a too short hose could trap air, my hose does go basically right from the exhaust cover fitting to the lower cowl pee-hole fitting. I'll look into that.
Also, how would I test the check valves, I am suspicious of these as well. I should note that the jets are all proper, carbs are def. clean. I also thought about a damaged reed. This motor has been seriously overheated previously (not by me, I discovered this after I got it), so that adds a bit to the mystery. I have to take the intake cover off to see the reeds, correct?
Click to expand...

It does not trap air, but allows air to reach the engine as the water drains out. Running the hose high creates a water trap and helps to prevent that from happening.

You have to remove the carburetors to see the reeds, though reeds are not high on the list of probable causes of your problem unless someone has put composite reeds on.

To service the recirculation check valves, you have to remove the carburetors.
 
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petryshyn

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Re: Lean #1 cylinder

Is #1 contributing at idle? Have you tested the temperature of each cylinder individually?

When you did the carbs, did you check the float bowls for warpage?
 
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mamm7215

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Re: Lean #1 cylinder

float bowls are steel, no warpage. Haven't tested each cylinder individually. Once I remove the carbs, how do I service the recirc valves, or does the whole intake then come off?
 
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Haffiman

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Re: Lean #1 cylinder

No need to remove anything for initial testing of the check valves.
Take a syringe and fill it with Isopropanol.
Pull the hoses of on the cylinder side.
When attaching the syringe to the hose, you should be able to push through but not suck.
However they often gets partly blocked on the inside restricting flow. This may only be checked by removing them.
 
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jonesg

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Re: Lean #1 cylinder

Serious overheat and suspected lean running on one cyl, a compression check would rule out a warped leaking cyl head gasket.
And an infra-red thermomter would show if one cyl is running hotter.
 
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mamm7215

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Re: Lean #1 cylinder

Again, I appreciate so much all who voice their troubleshooting skills here. Compression is basically 118-120 across all four cylinders. I'll look into an ir thermo in my area.
 
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