Another Yammy question

[Mindi]

Its one of those months ..but the tilt tube is good....!

My 60 4 stroke is cutting out under full load near WOT but will idle along up to 1500rpm OK... squeezing the bulb seemed to temporarily fix it...

It doesnt happen until it is warmed up...ran 3-4km at near WOT this morning before it started doing it...but maybe it is just that the problem is worsening and it will do it all the time now. Without another test I cant be sure of that.

Happens same on portatank so not the main Raco bowl filter starving it

The small motor mounted filter clean...no dirt or water

Does not happen when you use the idle lever at rest to go up to 3500-3800 rpm..didnt want to go higher

My guess is the fuel pump failing under max fuel demand..?...but really dont know.. guess it could be electrical..?

[Geoff-]

squeezing the bulb does make it sound fuel related, is the breather on your tank open or is it sucking a vacuum? when cutting out does it die completely, stumble or just sound like it's dropped a cylinder?

[Rhinoc]

Perhaps it's getting hot and the sensors are cutting engine speed to protect it from damage from overheating.

Rhino...

[Mindi]

Perhaps it's getting hot and the sensors are cutting engine speed to protect it from damage from overheating.

Rhino...

That would fit sort of...but the telltale is strong..? and no indications of overheating

[Mindi]

squeezing the bulb does make it sound fuel related, is the breather on your tank open or is it sucking a vacuum? when cutting out does it die completely, stumble or just sound like it's dropped a cylinder?

well i cant be certainj othger than to say i immediately put it into neutral and it continues at idle....if I left it in FWD I am not sure whether it would actually stop or not... but it is not rough running...it is effectively shutting down

[Spaniard_King]

Mindi,

There is a filter on the inlet to the high pressure pump which when it starts to clogg up will cause high speed missfire/surging. Unfortunately the high pressure pump is located within the vapor seperator which is located behind the inlet manifold assembly.

The only true way to confirm the diagnosis is to have a fuel pressure gauge installed on the fuel rail whilst replicating the problem.

The vapor seperator will need to be removed and either clean or replace the filter. Last one I did took about 2hrs + parts.

[Rhinoc]

That would fit sort of...but the telltale is strong..? and no indications of overheating

Hmmm - that's about as much as I have to offer. Although, what if the relevant sensor is faulty? It may be tricking the computer into crawl mode.

You would think a fuel related issue would cause it to run rough prior to the cut out.

Rhino...

[Mindi]

Mindi,

There is a filter on the inlet to the high pressure pump which when it starts to clogg up will cause high speed missfire/surging. Unfortunately the high pressure pump is located within the vapor seperator which is located behind the inlet manifold assembly.

The only true way to confirm the diagnosis is to have a fuel pressure gauge installed on the fuel rail whilst replicating the problem.

The vapor seperator will need to be removed and either clean or replace the filter. Last one I did took about 2hrs + parts.


mmmmmm....thanks Garry

[dreemon]

Sounds like you've narrowed it down on your own with the fuel pump being a possibility because it happens at WOT, does the prime bulb go flat or weak? that would sugest the vent as said above and will basically stop your engine or if there is crud in the tank , but you ran a remote and same thing,

Is yours carbed? I had some Idle issues with mine just a week ago, found small amounts of water in the bowls, (yam 902st) cleaned them but before I tried running it I also fit new plugs so not totaly sure what fixed it, I did have anouther engine that had a pin hole in the fuel pump diafram, every few years there meant to be replaced, let us know the how it goes, Cheers

[Spaniard_King]

Mindi,

The client who had this issue drove it for months.. untill he couldn't drive it over 4000rpm. Initially the problem only existed at full throttle but it got worst.. The engine is not suffering any damage driving it to test.. he would just drop a few 100 rpm to where the problem was not occurring and drove like that.

He lived at couran cove , this was his daily transport to work :smiley:

Also the filter wasnt highly obvious it was dirty being a very fine mesh strainer.

[ozscott]

Mindi,


He lived at couran cove , this was his daily transport to work :smiley:




...I dont like him

[larfin]

A friend had a problem like that turned out to be a kink in the fuel line.
cheers
greg

[Mindi]

Mindi,

The client who had this issue drove it for months.. untill he couldn't drive it over 4000rpm. Initially the problem only existed at full throttle but it got worst.. The engine is not suffering any damage driving it to test.. he would just drop a few 100 rpm to where the problem was not occurring and drove like that.

He lived at couran cove , this was his daily transport to work :smiley:

Also the filter wasnt highly obvious it was dirty being a very fine mesh strainer.

Garry

I havent done enough tests to be confident but what you are saying fits with what I remember....having got this advice I would now look for the exact behaviour. I am very confident about it not being water or hose kinks or breathers...all in good shape. I have to get the major service done so will roll it into that but the feeling you get is that after a short time at high revs it is quite suddenly deprived of fuel......? will report outcome and thanks for the help everyone.

[psychobob]

I had a similar problem with my johnson 115. eventually found the problem to be small leaks on fuel lines letting air into the system and causing the motor to struggle.leaks were very small and difficult to find.

[ShaneJ]

I had the exact same problem with my Yammy 60 4stroke EFI. The motor kept dying/spluttering at WOT.
Squeezing the primer bulb fixed the problem for a minute or two. I also found pulling the fuel hose off the outlet of the mechanical fuel pump and squeezing the primer bulb resulted in badly airrated fuel coming out. After getting all the airrated fuel out the motor ran as normal for a while again.
After seeing this I suspected the problem was air getting in the full somehow.

I took it to Jeffers Motorsport explaining the problem(probably not clearly enough though). They looked at the filters which were perfectly clean. They serviced the mechanical pre pump suspecting this was the cause. This didn't fix the problem :(
I took it back explaining the airrated fuel problem more clearly. Turns out all the air in the fuel is normal and there is a electronic valve on the top of the engine that lets the air out. They suspected the valve may have been faulty but the computer diagnosis and manual testing proved otherwise. They ended up stripping down the whole fuel system and cleaning it out. No obvious problems during this process however I never had any problems after these. Shes been running fine since. The full service cost me $150.

[Jarrah Jack]

I think motor could be just sulking and is trying to tell you that it wants to be back on the Daly. Its sorry that there was no luck on the troll and wants to give it another try.....A year is just too long to wait.:smiley:

Cheers

[Mindi]

I think motor could be just sulking and is trying to tell you that it wants to be back on the Daly. Its sorry that there was no luck on the troll and wants to give it another try.....A year is just too long to wait.:smiley:

Cheers

Ha ha....good one. You wouldn't believe after fishing for 10 days down as far as 26km from Woolianna it first coughed and died about 300m short of the pontoon
coming home to pack up on the last afternoon... so it was good from that point of view...dropped my wife off to bring the car to ramp and just limped back to the ramp.....so the timing was good anyway.