86 or 92 Mercury 9.9 Cold Start Problems

[seed_81]

I've fished from a Kayak for the past 3-4 years and recently purchased my first older flat bottom to take my son out. I have very limited experience or knowledge of older outboards which is why I'm here.
The guy I bought it from said he would put a squirt of starter fluid in the carb to get it running. I know, I know... don't use starter fluid.
I should have walked at that point but didn't know any better.

I pulled some pre-mixed fuel from the tank and can get it running with a squirt or two of that into the carb.
Once I have it running it will idle just fine and start on first crank if I kill it. It also doesn't die when I put it in gear and give it a little gas.

I'm sure I'll have a ton of questions but first is this: Is it normal to have an air bubble in the fuel line going into the carb? We've checked every connection by spraying starter fluid on each connection and the engine will not rev up. If an air bubble is not normal how could it be getting in there and could that be my problem?

 

[nccatfisher]

Spraying starter fluid on a fitting won't find a leak first off. Then you need to find out of the choke/primer is working depending on what that particular motor has. If it has a primer I suspect that is where you are seeing the bubbles in the line and if it isn't seated correctly or if the primer is faulty it will allow air in the line causing a hard start when cold situation.

 

[Pappy]

Curious as to why you would think an air bubble has anything to do with this??

First off.
Do you have a choke on the engine or a primer system? This has to be answered. An owner manual should tell you this or you may find it in a parts diagram. Makes a difference in starting technique but we will cover both.
Common to both.....
You need to pump the primer bulb until it gets tight or firm. This assures the fuel bowl in the carburetor is full and the primer system has pressurized fuel. Same exact thing a fuel pump does while the engine is running. The carburetor will do everything from there once the engine is running.

Primer systems - There has to be a bit of fuel pressure for a primer system to work hence the statement above. The primer is a simple on/off valve with pressurized fuel on the inlet side and one or more ports on the outlet side. When the primer is activated it will allow pressurized fuel from the inlet side, through the primer and to the back side of the carburetor either at the front of the intake manifold or the rear of the carburetor usually.

Manual Primer - simply remove the outlet side hose either from the primer or where it attaches to the engine and pump it to verify fuel flow.

Electric primer - Also needs pressure from the primer bulb to operate. Pull the same output line and activate it and verify fuel flow.
If you have verified fuel flow through the primer and still have a difficult start issue then verify the nipple that the hose fits onto at the engine or carb is open. Very often these are tiny orifices and will plug and not allow primer fuel to flow.

Manual or electric choke - Both of these systems are very effective as long as the choke blades close COMPLETELY....not just pretty close to closed.
Any air leak around a choke blade will kill the suction needed to pull fuel up through the high speed nozzle and supply fuel for starting. Makes for a very hard to start when cold engine!
Engine angle - If you are trying to start this engine while trimmed high or tilted and have either one of these systems listed above the engine will be very difficult to start.

Notice in here that nowhere did I mention an air bubble anywhere.......

 

[seed_81]

Curious as to why you would think an air bubble has anything to do with this??

First off.
Do you have a choke on the engine or a primer system? This has to be answered. An owner manual should tell you this or you may find it in a parts diagram. Makes a difference in starting technique but we will cover both.
Common to both.....
You need to pump the primer bulb until it gets tight or firm. This assures the fuel bowl in the carburetor is full and the primer system has pressurized fuel. Same exact thing a fuel pump does while the engine is running. The carburetor will do everything from there once the engine is running.

Primer systems - There has to be a bit of fuel pressure for a primer system to work hence the statement above. The primer is a simple on/off valve with pressurized fuel on the inlet side and one or more ports on the outlet side. When the primer is activated it will allow pressurized fuel from the inlet side, through the primer and to the back side of the carburetor either at the front of the intake manifold or the rear of the carburetor usually.

Manual Primer - simply remove the outlet side hose either from the primer or where it attaches to the engine and pump it to verify fuel flow.

Electric primer - Also needs pressure from the primer bulb to operate. Pull the same output line and activate it and verify fuel flow.
If you have verified fuel flow through the primer and still have a difficult start issue then verify the nipple that the hose fits onto at the engine or carb is open. Very often these are tiny orifices and will plug and not allow primer fuel to flow.

Manual or electric choke - Both of these systems are very effective as long as the choke blades close COMPLETELY....not just pretty close to closed.
Any air leak around a choke blade will kill the suction needed to pull fuel up through the high speed nozzle and supply fuel for starting. Makes for a very hard to start when cold engine!
Engine angle - If you are trying to start this engine while trimmed high or tilted and have either one of these systems listed above the engine will be very difficult to start.

Notice in here that nowhere did I mention an air bubble anywhere.......

First of all thank you very much. There's a lot of valuable info there.

My theory on the bubble was that it didn't have sufficient pressure to feed fuel to the engine to start it.Once started the engine would create the needed suction to pull fuel in.

As for the choke vs primer. I'm showing showing my ignorance here but I was originally going to say choke b/c I have a knob that says "Pull to Choke". After reading through the manual a bit I'll say primer b/c the manual shows a "Primer System" which is attached to the fuel bowl and "Primer Diaphragm". This is the blue button that gets pushed when I "Pull to Choke".

It's the same carburetor as in this video
https://www.youtube.com/watch?v=rpcrTt5WMUE&list=WL&index=24&t=0s

At the moment I followed the same steps as in the video and have the carburetor off. I didn't do anything other than remove parts and look for gunk. Everything seemed pretty clean. He said something about blowing out some holes but I don't have any carburetor spray to do that.
The primer button does seem to go up and down a little easier now though. Maybe that will help.

The bulb on the fuel line from the gas tank is tight when trying to start. We also checked the fuel filter which looks good and clean.

Thank you for the info about the engine needing to be level. At home it's level and usually starts fairly easily with a couple squirts. The other day I took it to the lake and it was harder to start. REALLY frustrating. Looking back it's probably b/c the engine wasn't level on the boat ramp.

Thanks again... REALLY appreciate it.

 

[seed_81]

UPDATE!!! --- IT'S ALIVE!!!
Thanks nccatfisher and Pappy for the response and information.

After I put the carburetor back on it fired up first pull. COLD!! I couldn't be happier at the moment. Can't wait to put it in the water to see what it does when I put some throttle to it.

It is sneezing a bit though. Is that bad? What causes it and how do I fix it?

 

[Pappy]

Richen the idle mixture until it quits sneezing.

 

[seed_81]

Thanks for the input Pappy I think I've got it idling like it should now.

One more question. I've been told to remove the fuel line and let it idle until it dies before taking it off the water. Apparently this is to burn all fuel in the engine to prevent from sitting in the carburetor, fuel lines, etc and gumming up everything.

I'm using ethanol free fuel but wanted to get your thoughts on doing this.
When I do this sneezes a bit as it runs out of fuel. I assume this is b/c it's sucking more air as it idles down.
Is this hard on the engine?

 

[Pappy]

Not hard on the engine to do this. The engine leans out as the fuel level in the fuel bowl drops.

 

[MrGiggles]

Thanks for the input Pappy I think I've got it idling like it should now.

One more question. I've been told to remove the fuel line and let it idle until it dies before taking it off the water. Apparently this is to burn all fuel in the engine to prevent from sitting in the carburetor, fuel lines, etc and gumming up everything.

I'm using ethanol free fuel but wanted to get your thoughts on doing this.
When I do this sneezes a bit as it runs out of fuel. I assume this is b/c it's sucking more air as it idles down.
Is this hard on the engine?

Really the only time you should do that is before you put it away in the winter, if you do.

Premixed fuel lasts quite a while longer than straight gas, probably 3 months or so depending on storage and environmental factors. Good TCW3 oils should contain fuel stabilizers.

 

[seed_81]

One thing I found mentioned in the manual while researching something else is to remove the fuel line at the tank and shut the motor down when it starts to run rough but before it shuts down. This leaves some oil in the engine to protect everything. Probably not recommended for putting away for the winter though...

Now back to my motor... Apparently it's a bit bipolar. It was starting fine after cleaning the carburetor. I've never not been able to get it to start until yesterday. It would not start on the water. Tried spraying fuel into the carb... nothing. I removed the carb when I got home and can get it started now with a little toying around.

Tonight I figured it was related to the spark plugs so I replaced those.. Unfortunately i didn't bring the desired results. Nothing changed.
I went back to the manual and found this motor is rated for a BP8HS-15 plug. The plugs I replaced are BR8HS-10. Are those two plugs that far apart to cause starting issues?

One more thing. The manual talks about an idle speed screw. My motor doesn't look like the one in the manual but is this simple to open the choke plate ever so slightly? Mine looks different but I understand how it works if this is the purpose.

My next step will be to dump this gas and start with fresh fuel.

Once again... thank you all for the valuable feedback.

 

[seed_81]

Something else I just noticed in the manual is that the engine must be in forward gear to properly adjust the carb.
Maybe that’s part of my problem?

 

[CedarRiverScooter]

I would check for a consistent strong spark. It may be intermittent.

 

[Pappy]

It has been mentioned in this forum a myriad of times that the best way to adjust your carburetor is with the engine on the boat and in the water. This sets up the correct (running) back pressure on the exhaust and the engine should be adjusted this way. Any other type of adjustment should be considered an initial adjustment to get the engine running and get you on the water for final tuning.
"In gear" adjustment takes this one step further in that you are placing a bit of a load on the engine which will require a bit more fuel. That is a good way to adjust your engine but in no way will be the cause of a no-start situation if that was not the way it was initially adjusted.
Spark plugs? You can check your plugs with an ohmeter. Check them against each other before just buying new. An Ohmeter will tell you if you have a shorted or open plug.
Get a spark checker and see of you have spark. If no spark start checking things like your safety (kill) switch continuity and go from there.

 

[seed_81]

I guess I misunderstood what on the boat and in the water meant. I've been tuning messing with it in a tub of water. The water line sits just barely over the fins (If that's what they're called.. over the prop)
Are you saying it needs to actually be on the water so the water level is higher on the shaft?

I also saw another video last night where they mentioned the reeds behind the carb could not be opening/closing properly. He mentioned it was a common problem for engines that are hard to start but run fine once started which is exactly what I'm seeing
Thoughts?

I'll check the spark plugs this evening.

 

[ckwllms65707]

I had a similar engine as the one you have. Mine started giving me the same symptoms as you are describing. There should be a primer bulb inside an aluminum housing( just to the side of the little blue button). This primer is made of mesh with a rubber sort of coating. After several years the coating will wear off and allow the engine to pull air through the primer mesh. When this happens those small mercs are hard to start and won't run smooth at all. I ordered a carb kit that included a new primer and didn't have any issues after that.

Sent from my SM-S727VL using Tapatalk

 

[ckwllms65707]

The video showed the primer under the blue button on the 8hp but it's the same primer. If it's worn or deteriorated they are a bugger to start.

Sent from my SM-S727VL using Tapatalk

 

[seed_81]

Update: I pulled the Reed Block Assembly and can see light through 2 of the reeds on the left side. Not much but I can see light.

 

[seed_81]

The video showed the primer under the blue button on the 8hp but it's the same primer. If it's worn or deteriorated they are a bugger to start.

Sent from my SM-S727VL using Tapatalk

That part appears to be in good shape. Actually the last time I took it off I pushed that blue button and a stream of fuel shot out the back of the carb and i'm like "OHHHH, so that's how it works"...

 

[seed_81]

Before Pappy comes back and politely tells me I'm a chasing the wrong rabbit I'll mention I found a previous post from 2015 and don't feel the reed is my problem. The light I see is VERY slight and Pappy previously pointed out the pressure created by the internals of the crank case is more than likely enough to force the vents closed if the gap is that slight.

 

[Pappy]

Before Pappy comes back and politely tells me I'm a chasing the wrong rabbit I'll mention I found a previous post from 2015 and don't feel the reed is my problem. The light I see is VERY slight and Pappy previously pointed out the pressure created by the internals of the crank case is more than likely enough to force the vents closed if the gap is that slight.

Love it! You made my day with that research and comment! Actually laughed out loud. Kudos to you for doing your homework before somebody here directed you to get way into your engine for a probable non-issue!