yamaha 130 loses power

[Tractor-Tug]

bump!


still no luck, and its getting hot and we're finally having some nice weather.


any more ideas? i took the carbs apart last night and the float adjustment was correct and those needlevalves seemed to work fine.


still messed up. fuel pump is working. what the hell is next? i want to avoid my local $tealers because they are all crooks around here.

[Wally]

Since pumping the bulb solves your problwm, it seems to me that there is an air leak in your fuel line between the tank and the bulb or the tank vent is somewhat plugged. Try connecting a small external tank to the bulb and see if that solves the problem. If so, you will know it is the line or the tank vent.

[Tractor-Tug]

i've used an aux tank, same problem either way. as long as i pump with the external or the boats tank, it solves the problem. has to be engine fuel related

[Ken]

tt,
I agree with you that the problem is fuel related.
At this point, we're just trying to eliminate possiblities.
Try bypassing the onboard fuel filter, if you can.
Route the fuel line directly to the fuel pump, just to see if that makes any difference.
Let us know what happens.
Ken K

[jb123]

check pickup tube at tank, then spray gas into each carb throat or use your finger as a choke to enrich mix. listen for the rpm change. this family mechanic, cant figure it out either? i have in the past, had to go thru my carbs up to 3 times to get them cleared out, and id bet those are your problem.

[Tractor-Tug]

i hooked up an old electric fuel pump from some carburated car i had in the past.. 4-7psi. i installed it inline between the tank and water seperator. problem is much better now, but still eventually lose those rpms, although i can get them back if i back off the throttle for a few seconds and give it to it again.

i think at this point i need to replace the water seperator again, as with that pump it should be fine. obviously not a proper and permanent solution, but the weather is beautiful and until i get someone to fix it right in the next two weeks its working. i'm familliar with abyc and i know they would kill me, but it is wired and installed to provide the least dangerous installation...ahah. yeah.

i hooked up a spare bmw fuel injection pump to see if there were any leaks also (not running engine with that pump..35psi) and i did not see any fuel leaking; at that pressure fuel should spray through any opening that air can get through.

we're through with the family guy, he's stood us up one too many times.

[kahoona]

I went through the exact same thing last year and finally got it straightened out with the help of these folks and some advice from a local Yama mechanic. I bought my boat after it sat for a while too.I would be flying along just fine when all of a sudden the power just went away! The carbs had been rebuilt also.On the advice of the Boats.net folks I started at the incoming side of the fuel line and replaced clamps, any older hoses and the big filter. I dosed the tank with a cleaner and replaced the bulb on the hose.I replaced the fuel pump and some of the internal hoses and clamps. Now I was certain that I was OK to the carbs. What I found is that... rebuilt or not they get varnish flakes in them from sitting. The flakes block the passages and sometimes they survive a cleaning and even gas additives. They float around and only block the passages when there is enough flow to stir them around. On the advice of the mechanic I removed the carbs and one at a time dismantled them and cleaned them.These are old school carbs and real simple to work on. After all the parts ore off and set aside to soak in cleaner it is time to clean the passages. I used automotive spray carb cleaner and a can of compressed air and I alternated both on all the smaller passages several times paying special attention to the chambers closest to the inlet tube. Do this area several times. Blow it all out and reassemble. Reinstall. That fixed my problem. The gas evaporates inside the chambers and leaves varnish flakes. Hope this helps. If it sat for any length of time you need it anyway.

[Tractor-Tug]

[Tractor-Tug]

took the carbs apart again today, and cleaned the hell out of them. way easier to take apart and reasemble than i thought. engine HOLDS those revs and runs great, except for one small thing.

basically at around 2500 or so i have a dead spot, but if i give it some more juice it picks right up and gains revs. im assuming i just need to mess with the adjustment as my book probably isnt the best. may someone please give me the accurate/yamaha quoted needle valve adjustment specs, and any other ideas on that dead spot? its a nikki double bowl carb, 91 130.


otherwise thanks for everyones help, i'm a very happy guy now.

[Ken]

t-t,
You really need to get yourself a Yamaha shop manual for your model Yammie - it will pay for itself [img]smile.gif[/img] .
I checked my manual for a 2000 model 130 hp - they list the pilot screw adjustment at 7/8 turn out +- 1/4 turn, if this helps.
But I don't think that would give you a "dead spot" around 2500 rpm. I'm thinking maybe worn out throttle linkage Have someone move the throttle smoothly and slowly and observe the carb linkage and look for a "dead spot".
Good luck [img]smile.gif[/img] ,
Ken K