F20 startup issue +video

[TownsendsFJR1300]

Yep, it runs too long, too good for it to be the prime start..

It's running itself out of fuel..

[merc200dalarna]

Changed the link, got it....

Location should be mandatory. Often helpful.

What country are you located Merc200?

Sweden, northern europe, we have temps below freezing each night now, that is why I used the IR-sensor in the video. set to fahrenheit for you imperials ; )

Spraying carb cleaner down the holes doesn't mean it is going through the holes. I used compressed air and a blowgun with a rubber tip to blow out the passages. Sometimes a single strand of very small copper wire or such is needed to probe the holes.

If you look carefully in the carb throat, while spraying the carb cleaner down the primestart passage, you should be able to see the carb cleaner come out through a very small hole ahead of the butterfly.

I used compressed air too, but only directly applied it to the jets. The carb housing I held the gun away a bit, never applied it to any passage directly. I used a strand of dishbrush, plastic, to go through the jets. I have pretty thin fishing line, perhaps they are rather harmless to use in passages too? Nylon?

It starts and idles so nice that I would be guessing it to be a fuel pump issue. Pump may not be functioning when cold but does when it gets warmed up a bit.

That is also why I wanted to show it was an absolute cold start, it hadn't run for about 12 hours. When it has fuel it is a one pull motor. It idles absolutely smooth for hours of fishing. No "hickups" what so ever. Even though the other day was the first time ever it kind of hesitated a little at WOT, after like 5 minutes of WOT. It started slowly losing revs and then became very hesitant to stay at top revs. It revved up and then down abit, then up and then down again. So that behaviour made me think not enough fuel from pump.. I will search for videos of fuelpump tonight. I do not have the pressure gauge the workshop handbook test use for the fuel pump, but I will pull it apart gently and have a look.

Yep, it runs too long, too good for it to be the prime start..

It's running itself out of fuel..

I removed the fuel pump. I have never looked at one or pulled one apart, so I will first have to find some videos on it. I go slow to avoid making anything worse.

I ran it again today, and after the stall it did actually have fuel in the bowl, but I let it all drain, and I suspect the bowl wasn't full.

And after that I repumped the bulb and started it, and keeping pumping the bulb did make it run longer, but eventually it couldn't keep it running. Instead of running 45 seconds, it ran about 2 minutes while pumping the bulb. Thanks for all the advice.

[TownsendsFJR1300]

Not sure of your exact model, but if you look up to the right(this page), in RED, is "Purchase Yamaha Parts".

Go there and put in your info. It has all the parts break down including the fuel pump, IE:

2006 and Later F20ELH Yamaha Outboard FUEL 1 Diagram and Parts

The diaphragm, part #17 is what you want to focus on. It also shows what parts go where so your not going in blind... Very helpful in most cases...

The now "revving" issue also points towards the fuel pump(not keeping up), possibly crap in the carb, but if used regularly and it went to WOT for a bit, it's very likely NOT the carb.. WOT operation and cold start(Prime start), are two separate circuits altogether.

The fuel pump affects BOTH of those...

[pstephens46]

Service manual was helpful in removing the plunger and diaphragm for the first time. There is a pin. Pump is similar to the two on my F150. Be sure to check your oil level to make sure the fuel is not getting past diaphragm into the head and crankcase. There is a second diaphragm on the other side of pump. It has a clear membrane. I guess that could leak pressure also. Two check valves in metal body in between the two. All of these parts looked to be pretty robust in my 12 year old motor.

Don't be afraid to use some thin copper strands on those passages in your carb. Fishing line or plastic may not do the job.

[merc200dalarna]

Not sure of your exact model, but if you look up to the right(this page), in RED, is "Purchase Yamaha Parts".

Go there and put in your info. It has all the parts break down including the fuel pump, IE:

2006 and Later F20ELH Yamaha Outboard FUEL 1 Diagram and Parts

The diaphragm, part #17 is what you want to focus on. It also shows what parts go where so your not going in blind... Very helpful in most cases...

The now "revving" issue also points towards the fuel pump(not keeping up), possibly crap in the carb, but if used regularly and it went to WOT for a bit, it's very likely NOT the carb.. WOT operation and cold start(Prime start), are two separate circuits altogether.

The fuel pump affects BOTH of those...

yes, I checked the exploded view first, plus a video on youtube on a similar pump. There is nothing obviously wrong inside the pump. It is hard to determine the state of the rubber, but no obvious tares or elongations. I do not have the skill to try to remove the #17 diaphragm from the pin and spring. Tomorrow I will re-assemble and clean the carb one last time before handing it in to the workshop. My model is 2013 long shaft, tiller, manual start. I use the abbreviation "MLH" when I look for parts on boats.net.

Service manual was helpful in removing the plunger and diaphragm for the first time. There is a pin. Pump is similar to the two on my F150. Be sure to check your oil level to make sure the fuel is not getting past diaphragm into the head and crankcase. There is a second diaphragm on the other side of pump. It has a clear membrane. I guess that could leak pressure also. Two check valves in metal body in between the two. All of these parts looked to be pretty robust in my 12 year old motor.

Don't be afraid to use some thin copper strands on those passages in your carb. Fishing line or plastic may not do the job.

Very interesting about the oil level, I changed the oil 15 running hours ago, and I might have overfilled it a bit????? How would you go about checking if fuel gets into crankcase? This was interesting and my gut tells me I am the cause of my motors problems, I usually am ; )
pics of the disassembled pump:
https://imgur.com/a/fDPqP

[pstephens46]

You will have to repost. Maybe different wording?

The posts that are sent to moderator never make it back......

You can click the back button when this happens to recover the post and modify.

[merc200dalarna]

Not sure of your exact model, but if you look up to the right(this page), in RED, is "Purchase Yamaha Parts".

Go there and put in your info. It has all the parts break down including the fuel pump, IE:

2006 and Later F20ELH Yamaha Outboard FUEL 1 Diagram and Parts

The diaphragm, part #17 is what you want to focus on. It also shows what parts go where so your not going in blind... Very helpful in most cases...

The now "revving" issue also points towards the fuel pump(not keeping up), possibly crap in the carb, but if used regularly and it went to WOT for a bit, it's very likely NOT the carb.. WOT operation and cold start(Prime start), are two separate circuits altogether.

The fuel pump affects BOTH of those...

yes, I checked the exploded view first, plus a video on youtube on a similar pump. There is nothing obviously wrong inside the pump. It is hard to determine the state of the rubber, but no obvious tares or elongations. I do not have the skill to try to remove the #17 diaphragm from the pin and spring. Tomorrow I will re-assemble and clean the carb one last time before handing it in to the workshop. My model is 2013 long shaft, tiller, manual start. I use the abbreviation "MLH" when I look for parts on boats.net.

Service manual was helpful in removing the plunger and diaphragm for the first time. There is a pin. Pump is similar to the two on my F150. Be sure to check your oil level to make sure the fuel is not getting past diaphragm into the head and crankcase. There is a second diaphragm on the other side of pump. It has a clear membrane. I guess that could leak pressure also. Two check valves in metal body in between the two. All of these parts looked to be pretty robust in my 12 year old motor.

Don't be afraid to use some thin copper strands on those passages in your carb. Fishing line or plastic may not do the job.

Very interesting about the oil level, I changed the oil 15 running hours ago, and I might have overfilled it a bit????? How would you go about checking if fuel gets into crankcase? This was interesting and my gut tells me I am the cause of my motors problems, I usually am ; )

[merc200dalarna]

Not sure of your exact model, but if you look up to the right(this page), in RED, is "Purchase Yamaha Parts".

Go there and put in your info. It has all the parts break down including the fuel pump, IE:

2006 and Later F20ELH Yamaha Outboard FUEL 1 Diagram and Parts

The diaphragm, part #17 is what you want to focus on. It also shows what parts go where so your not going in blind... Very helpful in most cases...

The now "revving" issue also points towards the fuel pump(not keeping up), possibly crap in the carb, but if used regularly and it went to WOT for a bit, it's very likely NOT the carb.. WOT operation and cold start(Prime start), are two separate circuits altogether.

The fuel pump affects BOTH of those...

yes, I checked the exploded view first, plus a video on youtube on a similar pump. There is nothing obviously wrong inside the pump. It is hard to determine the state of the rubber, but no obvious tares or elongations. I do not have the skill to try to remove the #17 diaphragm from the pin and spring. Tomorrow I will re-assemble and clean the carb one last time before handing it in to the workshop. My model is 2013 long shaft, tiller, manual start. I use the abbreviation "MLH" when I look for parts on boats.net.

[merc200dalarna]

Service manual was helpful in removing the plunger and diaphragm for the first time. There is a pin. Pump is similar to the two on my F150. Be sure to check your oil level to make sure the fuel is not getting past diaphragm into the head and crankcase. There is a second diaphragm on the other side of pump. It has a clear membrane. I guess that could leak pressure also. Two check valves in metal body in between the two. All of these parts looked to be pretty robust in my 12 year old motor.

Don't be afraid to use some thin copper strands on those passages in your carb. Fishing line or plastic may not do the job.

Very interesting about the oil level, I changed the oil 15 running hours ago, and I might have overfilled it a bit????? How would you go about checking if fuel gets into crankcase? This was interesting and my gut tells me I am the cause of my motors problems, I usually am ; )
pics of the disassembled pump:
https://imgur.com/a/fDPqP

Had to split the replies apart. Thanks stephens for advice on the dissappearing posts.

[pstephens46]

Don't panic........I was simply stating that sometimes the diaphragm will fail and allow fuel past into the engine. I am not saying that is your problem. But it needs to be monitored if you think there is a fuel pump issue.

The oil level will rise in the oil pan as it starts to be diluted by the fuel getting past the diaphragm. The oil level will read abnormally high. Way past the point that you last filled it. Strong smell of gas in the oil.

It would seem strange that the diaphragm would fail in your 4 year old motor.

Have you ever removed the clear plastic bowl on the fuel filter? Dump the gas out of that bowl after the motor is good and warmed up. Put the bowl back on and watch to see if it fills back up. Fairly rapidly, maybe 10 seconds? That would at least show you the fuel pump is indeed pumping. It may not fill to the top of the bowl. As long as it rises to 3/4 it should be fine. Post a video if you wish.

[merc200dalarna]

Don't panic........I was simply stating that sometimes the diaphragm will fail and allow fuel past into the engine. I am not saying that is your problem. But it needs to be monitored if you think there is a fuel pump issue.

The oil level will rise in the oil pan as it starts to be diluted by the fuel getting past the diaphragm. The oil level will read abnormally high. Way past the point that you last filled it. Strong smell of gas in the oil.

It would seem strange that the diaphragm would fail in your 4 year old motor.

Have you ever removed the clear plastic bowl on the fuel filter? Dump the gas out of that bowl after the motor is good and warmed up. Put the bowl back on and watch to see if it fills back up. Fairly rapidly, maybe 10 seconds? That would at least show you the fuel pump is indeed pumping. It may not fill to the top of the bowl. As long as it rises to 3/4 it should be fine. Post a video if you wish.

That seems like a pretty straight forward test.Can I unscrew it without loosening the bolt on top? Empty the gas out of it and screw it back and see how fast it refills!
Awesome advice.

Yes, the motor is very fresh, overall. I have used it 140 hours.

[TownsendsFJR1300]

The cup, part #7: 2006 and Later F20MLH Yamaha Outboard FUEL 1 Diagram and Parts

simply unscrews from the mount. There is a small red ring (floats if water is in there). as well as an O-ring seal at the top. The "unit" inside is your under cowl, fuel filter...

Stick a rag under there just so your not spilling fuel under there....

[merc200dalarna]

The cup, part #7: 2006 and Later F20MLH Yamaha Outboard FUEL 1 Diagram and Parts

simply unscrews from the mount. There is a small red ring (floats if water is in there). as well as an O-ring seal at the top. The "unit" inside is your under cowl, fuel filter...

Stick a rag under there just so your not spilling fuel under there....

I know I took it fully apart last winter, it all looked fresh then. I will be on the lookout for the red ring and o-ring. Should I stop the motor and then restart it with the cup emptied? Or should I do it while running?

[pstephens46]

Yes! Stop the motor. Take bowl off and empty. Put it back on and start motor.
Observe....

[TownsendsFJR1300]

The engine should be turned OFF.

You want the cup emptied, re-install, then start the motor and watch the cup fill. It should stay that level when running.

My FI'ed engine, cup, stays around 2/3's full normally..

Make sure that cup and seal are FULLY SEATED when installed...

Ethanol tends to expand the cup, making installation tight.