97 25hp 2 stroke fuel issue

[Jamesaelliott]

It’s a manual start, single carb. This thing fires up and runs great at idle, as soon as I put it in gear it bogs down under acceleration. Here is the list I’ve done. Cleaned carb about 10 times, replaced fuel line, prime bulb, filter and pump, bypassed the fuel connect at motor. The primer bulb stays tight, Compression is at 120. Checked spark with spark tester. Spector fuel tank is 11 months old. I have noticed that my vent is not working, it’s not pressuring up during the hot days, it’s actually kind of sucking in a little bit. I don’t really see it being the vent causing my issue but I could be wrong. Any other suggestions?

 

[99yam40]

use a timing light to see what the timing is doing.
make sure it is in spec and that it advances as you throttle up

 

[Jamesaelliott]

use a timing light to see what the timing is doing.
make sure it is in spec and that it advances as you throttle up

Is there a good thread on timing? I can’t find much on this specific model motor. I did however watch the linkages while working the the throttle and I didn’t notice anything off. I was running the boat very frequently and then out of no where started doing this.

 

[racerone]

Pull off the top plug wire.-----Try and start the motor.-----Repeat with other cylinder.-----Checked reed valves ?----Checked flywheel key ?

 

[Jamesaelliott]

Pull off the top plug wire.-----Try and start the motor.-----Repeat with other cylinder.-----Checked reed valves ?----Checked flywheel key ?

I’ve done that spark plug test and nothing changes, where and how to check reed valves and fly wheel key?

 

[mike_i]

What do you mean "I have noticed that my vent is not working"?

 

[99yam40]

Is there a good thread on timing? I can’t find much on this specific model motor. I did however watch the linkages while working the the throttle and I didn’t notice anything off. I was running the boat very frequently and then out of no where started doing this.

The motor is bogging down, so you need to see if timing is in spec.
do you know what a timing light is?

 

[Jamesaelliott]

What do you mean "I have noticed that my vent is not working"?

Usually the fuel tank swells up in the hot sun, now it’s kind of sucking in.

 

[Jamesaelliott]

The motor is bogging down, so you need to see if timing is in spec.
do you know what a timing light is?

I know what it is, I’ve never used one. Very mechanically inclined I’ve never messed with timing though. Especially on an outboard, have no clue on it.

 

[99yam40]

hook up timing light to #1 plug wire and start motor, aim light at timing mark on flywheel.

 

[mike_i]

Have you run the motor with the fuel cap removed? Can you confirm there are no restrictions in the vent system?

Usually the fuel tank swells up in the hot sun, now it’s kind of sucking in.

 

[Jamesaelliott]

hook up timing light to #1 plug wire and start motor, aim light at timing mark on flywheel.

Have you run the motor with the fuel cap removed? Can you confirm there are no restrictions in the vent system?

Yes, I’m almost positive it’s my fuel tank. I was reading the bad reviews on them and I saw quite a few say after a year the pick up line starts coming apart, which makes since because when this problem started back in April, I took the carb off to clean it and I had to blow a chunk of trash out of the inlet of the carb. How it passed through the filter and pump beats me.

 

[mike_i]

Do you have access to a portable tank?

 

[Jamesaelliott]

Do you have access to a portable tank?

That’s what I have now, going to buy another one when I leave work today to test it out. You figure as expensive as they are their quality would be way better.

 

[racerone]

The older (1960 / 1970 ) metal tanks are better than the modern plastic ones.

 

[mike_i]

keep us posted.

That’s what I have now, going to buy another one when I leave work today to test it out. You figure as expensive as they are their quality would be way better.

 

[Jamesaelliott]

keep us posted.

New fuel tank made no change. So everything fuel related is brand new. From the tank to carb. There has to be a blockage in the carb I can’t see or get too. Or the timing some how jumped.

 

[racerone]

Checked the flywheel key ?-----Open low speed mixture screw 1/4 turn at a time and test run.----Does spark jump a gap of 3/8" on a test device ??

 

[Jamesaelliott]

TDC Timing marks on flywheel and engine line up to each piston so it’s not the flywheel key. I haven’t messed with screw. I think from lightly seated I have it between 1-1/2 to 1-3/4 out. That’s where I’ve always had it and it ran great before this. Have not tested the spark gap. My tester is only the light bulb kind. And from bad experience I know what good spark feels like. Cylinder 1 has exceptional fire. I thought the spark test was insulated. It definitely is not. Lol

 

[racerone]

A good Yamaha shop in your area ??