Engine will not idle

[DBank57]

2005 90 TLRD will not idle. Engine will start, initially revs to approx 1200 rpm, comes back down to around 750 +/- rpm, idles about 10 seconds and dies.

Engine has set for several months with only occasional start up and run for approx 15 min each month. I put Marine Stabil (storage dose) in the fuel system and ran the engine to make sure it was throughout the system.

Engine will start and run at idle with the emergency fuel enrichment valve set to the open position. Neither my owner's manual nor my Yamaha service manual give any sort of explanation of the function of the switch. The owner's manual gives a brief description of when and how to use the switch. What is the function of the emergency fuel enrichment switch? When I close the switch after the engine is running (as per owner's manual instruction) the engine dies. If I return the switch to the normal position and attempt start, the engine will start but not run past initial start as described above.

Would someone please explain the function and purpose of the emergency fuel enrichment switch.

Does anyone have constructive advice on what possibilities may be causing the engine to not run in normal operating mode?

I got 3 gals of fresh gasoline in an auxiliary tank, flushed the internal fuel system, drained the filter bowl, drained the carb bowls to ensure I did not have bad fuel in the system. Fuel in filter bowl was clean, no water nor particulate matter. Fuel in carb bowls was a little dark but no particulate matter nor water.

I also put new Yamaha NGK spark plugs in.

Thank you in advance for your help.

[njparker18]

Sounds like the carbs need a good cleaning.
Could have some crud in the idle circuit.


Scott

[mn808gade]

idle jets(pilot jet holes less than .020" dia) because there so small, get plugged very easy by old gas& u mite find more to clean when the fuel bowls come off.hard to start/slow to accel.some times drain/fill with seafoam for coupla days will clean-I like to make sure whats in there-th

[rodbolt17]

by setting the switch to "open" you are bypassing the thermal enrichment valve and forcing the system full rich bypassing the normal idle circuits.
means your carbs need disassembly and cleaning.

[boscoe99]

by setting the switch to "open" you are bypassing the thermal enrichment valve and forcing the system full rich bypassing the normal idle circuits.
means your carbs need disassembly and cleaning.

That sounds like too much time and money. My friend said he fixed his problem with Seafoam. I want you to Seafoam my motor. Here is the can and ten dollars. If you do not get my motor to work properly I want you to get it fixed. I don't have any more money. Since you did not fix it the first time you must not charge me any more money. You have to do all that is needed to fix my motor at your expense because you did not do it right when I paid you.

I need it this afternoon. All my family is coming today for our annual boat trip. We start tonight. If it is not ready I will report you to the BBB and I will tell all my friends that you cannot be trusted.

[rodbolt17]

yep
that's sometimes how it goes.
my neighbor got me last night.
wants to know if I can get his 98 F50 ready by Monday.
I asked when was the last time it ran.
last august or so.
I asked what did you do to store it.
nothing.
good luck with this.

typically if you try to seafoam clean it it will pop a piston long before the carb heals itself.