97 Yamaha wont stay running

[james sullivan]

Have a 97 1800 with original, same yr 115 Yammy, was running fine, but now when started, will not stay running. Made sure gas was fresh and plentiful, even plugged in a spare aux tank, still the same. I'm good with car engines, but a bit clueless on marine OBs. Thinking fuel pump perhaps.? Any help/tips appreciated

 

[tomc585]

Maybe time for a rebuild of the fuel pump, easy job.
When it stalls check for fuel in the carb bowls. The screws are hard to hold onto so don't drop them. Place some rags under the carbs to catch them and the fuel.
You could bypass the fuel pump and gravity feed for testing purposes and check the output of the current fuel pump.

 

[james sullivan]

Update, put in a new fuel pump, now starts, idles fine. took it out into the bay and ran it up to about 3k. It ran up to 3k fine, but kinda flattened out at that point, would not get on plane and was kinda sluggish/plowing. Was thinking of changing the plugs (do these motors go through a lot of plugs.?) and see if that makes a difference. Again, any tips/advice is very much appreciated

 

[Puck-n-Fish]

My only problem ever with my Yam 115 Saltwater Series was a plugged carb jet. Mine was a plugged low speed jet. It would idle but idle rough and ran fine at higher RPMs. At idle and on the muffs, I restricted the air intake, one carb at a time, and narrowed it down to a specific carb. Restricting the air intake changed the RPMs immediately on 3 of the carbs. The 4th carb didn't react to the restricted air so I assumed that was the plugged one. After taking it apart, I found a small piece of varnish in the low speed jet. Cleaned it and it ran like new.
I'm not saying that's your problem, but these carbs have more than one jet and you could have plugged main jet. I hope that's your problem because it's an easy fix.

 

[tomc585]

Plugs should last for years. Sounds like it's starving for fuel.
Clean the carbs, check the fuel supply at the carbs.

 

[james sullivan]

Thx Folks, had an idea it may be dirty carbs, plugged jets (I get this a lot on my 396 Big Block Nova with original Holley carb, idle circuit gets gummed) with jets, can they be accessed/serviced with the carbs still on the engien or do the carbs have to be removed. Figured if that is an easy/quick job, maybe try that first. Thx again

 

[tomc585]

They come off as a triple. If your careful you can reuse the gaskets

 

[Carmeda]

If your Yammy has a VST, vapor separator tank, you may need to change the filter at the bottom of the internal pump. I would also change all the fuel filters and the water separator filters too. We had the same issue on our 2005 Yammy and it corrected the problem. Our unit would die out if we tried to get it above 3500. good luck

 

[tomc585]

If your Yammy has a VST, vapor separator tank, you may need to change the filter at the bottom of the internal pump. I would also change all the fuel filters and the water separator filters too. We had the same issue on our 2005 Yammy and it corrected the problem. Our unit would die out if we tried to get it above 3500. good luck

It's a carb model

 

[Puck-n-Fish]

Mine was a V-4 and the carbs came off as a pair I believe.