Loose power

[Robertkelly]

Hi all,

When cold the engine(yamaha 70 1999 autolube) runs fine, refs good. But after about 20 minutes she starts to loose power, like she would go in limbmode. , cleaned petrol tank, checked sparkplugs etc. does anyone have an idea?

Thanks for reading

Robert

[TownsendsFJR1300]

Can you post a FULL MODEL #?

And are any warning lights/buzzers going off or JUST LOSING POWER?

You may want to check the vent, that its clear, in the fuel tank.

[Robertkelly]

Hi, its a 1999 2 stroke autolube 70 hp, coulnd load a photo up? No alarm beep going of, it does beeps when low in oil and goes in limbmode, just tried again : starts and runs perfect for 20 minutes and then loosing power, like its in limbmode. Suspect the.

[boscoe99]

What is limbmode?

limb

noun
an arm or leg of a person or four-legged animal, or a bird's wing.
synonyms: arm, leg, appendage; archaicmember
"his sore limbs"
a large branch of a tree.
synonyms: branch, bough, offshoot, shoot
"the limbs of the tree"
a projecting land form such as a spur of a mountain range, or each of two or more such projections as in a forked peninsula or archipelago.

Still would be nice to have the complete model identity. What types of tachometers is in the boat? Does it have lights and/or icons to indicate if the motor has an oil issue or temperature issue?

What does the oil tank look like when the problem occurs? Does the motor appear overly warm when the problem occurs?

[99yam40]

Need to check spark and timing when the problem shows up to see if those are changing from when it runs well.

test overheat to see if it sounds the alarm when switch pink wire is grounded

Make sure the prime start enrichment system is functioning properly and that the red lever is in the normal position.
Check fuel pump to make sure it is not leaking into the crankcase

[DennisG01]

Like mentioned above, the easiest thing to check is a fuel blockage. Vent, vent line with a dip/low spot, failing gas hose, failing primer bulb, plugged filter. Any of these could allow enough gas to get through (after sitting for a while) to run a little bit, but then slowly the engine starves for fuel.

FYI, "Loose" = not tight. As in "the limbs on the tree were loose and fell off". "Lose" (lost, losing) is what you want.

"Cleaned petrol tank"... is this a portable tank? If permanent, how did you clean it?

[Robertkelly]

Sorry my english isnt great, just want a solution for my engine, stainless steel tank cleaned with new petrol , no leaks, was fine last year,, doesnt get. Hot, , anyway have a specialit coming saterday, dying to know whats wrong, got new rods and fishfinderplotters installed so iam on hot charcole. Thank,.

[DennisG01]

Sorry my english isnt great, just want a solution for my engine, stainless steel tank cleaned with new petrol , no leaks, was fine last year,, doesnt get. Hot, , anyway have a specialit coming saterday, dying to know whats wrong, got new rods and fishfinderplotters installed so iam on hot charcole. Thank,.

No worries about the English - it was just friendly help.

SS tank? Not aluminum? Is it a portable tank?

Are you near the boat and got a chance to check for blockages? Is this something you are willing to do yourself, or are you more comfortable with having a spe******t do it?

EDIT: Not sure why the "grammar police" are ***-out that word. Replace the ******-part of the word with ******.

EDIT #2: Well, crap, did it again. What the heck? Oh... never mind... I figured it out. I ended up spelling a very special drug's name (a "make both of us happy" medicine).

REPLACE the "spe******t" word above with "technician".

[Robertkelly]

Stainless steel 100 ltr tnk, last year never problems with vent or fuell lines

[TownsendsFJR1300]

If your out on the water before your technician shows up, try running the engine (at speed) with the fuel cap NOT snapped down.

It sounds like the cap isn't allowing the tank to breath and then the tank developes a vacuum and won't let fuel flow...

Check around ALL your fuel lines for any leakage as well (not as likely)..

Something has obviously changed since last year...

Please post what the issue was once fixed...

[DennisG01]

last year never problems with vent or fuell lines

Of course not. If you had, then you would have posted about it last year.

It may or may not be the problem, but what we're getting at is... try the EASY things first. A blockage can explain what is happening - it's not the only thing - but it's where you should start.

There's a few other questions above not answered. Most importantly, will you be attempting to fix this, or just relying on the technician? It's totally fine if you rely on him/her, but it may be a little pointless for us to keep guessing.

[Robertkelly]

Will wait till the technician comes, will let you know what the problem is.

robert Kelly

[Robertkelly]

Technician just fixed my yamaha, hope i spell it right. Sprayneedle middle carb. Was Blocked.. Running fine again! Btw tought was model 1999 its a 89. Tagplate number 778099 , happy days ahead' thanks for replys

[DennisG01]

Thanks for posting back! Have fun on the water!