No power under load

[HandyJack]

I've got a 1998 Yamaha outboard that ran great until one day a few days ago I went to plane off and it jumped like a scalded cat for 4 seconds, then it fell off to 2500 rpms. From that time on it takes 45 seconds to plane off. No torque at all.

At first I thought it was a spun hub but I marked the hub and have gone out several times since then and it's fine.

Then I checked compression and all 6 cylinders are around 120psi. (whew!)

Then I changed the fuel lines, bulb, pulled the line into the fuel tank and it was all clean, gas pumps great just using the bulb all the way to the on-engine filter.

I checked the timing, did a full link&sync, and still it has no power.

Now, get this - if I turn the motor off, wait 10 minutes, pump the gas bulb up till it's hard, then fire it up then I get the same 4 seconds of hold-on-to-your-seat power, then it falls off to 2500 rpms again until I get up on plane then it'll hit 4500 rpms but it takes forever to get there.

What does that sound like to you guys? My gas is new, always non-ethanol. All spark plugs are firing. Carbs are rebuilt back in April. No problems until just a few days ago. I'm stumped.

[panasonic]

Fuel pump crapping out? Clogged fuel filter? Sounds like a fuel issue to me...not refilling the carb bowls back up fast enough, engine starving for fuel. Can you get someone to pump the primer bulb constantly as you accelerate? See if that keeps the power up...

The fine fellows here will need full model and serial number off the transom bracket to help you out.

[HandyJack]

Fuel pump crapping out? Clogged fuel filter? Sounds like a fuel issue to me...not refilling the carb bowls back up fast enough, engine starving for fuel. Can you get someone to pump the primer bulb constantly as you accelerate? See if that keeps the power up...

The fine fellows here will need full model and serial number off the transom bracket to help you out.

I can't get anyone to pump the bulb while I hit the gas. All my helpers are under age 10 It's a p175tlrw if that makes a difference.

Fuel filter is great. I took it off and it's spotless. Fuel pumps are a possibility. It's got two of 'em. I'll go that route and see what happens.

[99yam40]

do you have gauges and an alarm system?
have you tested to make sure they work as they should if the motor has a problem?

can you pump the primer bulb to get it to run again with out letting it sit for 10 min?

[HandyJack]

do you have gauges and an alarm system?
have you tested to make sure they work as they should if the motor has a problem?

can you pump the primer bulb to get it to run again with out letting it sit for 10 min?

I don't have pressure gauges if that's what you mean. I've got just about every other tool though.

If I kill the motor and start it back up after a second or two it still has no power.Frankly I was surprised to find the power returned after pumping the bulb and letting the kids get in the water to um....warm it .
(10 minutes)

New fuel pumps are now on the way.

[99yam40]

hard to believe you have no gauges on your boat telling you what the motor is doing, or that you did not try pumping the primer bulb

[HandyJack]

hard to believe you have no gauges on your boat telling you what the motor is doing, or that you did not try pumping the primer bulb

HAHA! I thought you meant TOOL gauges, like to measure the fuel pressure. The gauges on the boat all work. It idles up to 750 rpms, coughs and goes down to 650 or so, then picks back up to 750, and repeats every few seconds. I can pump it when it's idling and it will act normal. Unable to pump it when it's in gear and moving.

[99yam40]

will the gauges tell you if you have an overheat problem or low oil, have you tested them to see if that part of the systems/gauges work or the buzzer?
have you looked at the gauges when this problem shows up?

did you try pumping the bulb and starting the motor right after you shut it off instead of waiting 10 mins.
this cannot be that hard to do

[HandyJack]

will the gauges tell you if you have an overheat problem or low oil, have you tested them to see if that part of the systems/gauges work or the buzzer?
have you looked at the gauges when this problem shows up?

did you try pumping the bulb and starting the motor right after you shut it off instead of waiting 10 mins.
this cannot be that hard to do

The gauges have a buzzer/light for overheat and they both work. Low oil light works as well. Nothing shows up when it's acting up.

I did not try pumping the bulb then starting the motor right after due to being out with the kids and the difficulty of balancing on the end of the boat to pump the bulb in high wind. I've got about an 8" ledge to stand on when I'm pumping the bulb and with the waves etc. it was sure to put me in the drink. I'll give it another shot after I've changed the pumps.

[panasonic]

I think 99yam40 wants you to pull the kill switch lanyard and crank the engine to check and see if you warning buzzer works.

Also what gages do you have installed on the boat...for example a multifunction gage that give warnings for oil pressure, engine temperature..things like that.

If this is not what he is asking...he will let us know...lol

[99yam40]

how do you know they work if you have not tested them?

testing the alarm buzzer may work as he said and that would be good to know, but you have no idea if the over heat or low oil works if you do not test them

also the buzzer is not part of the gauges it is in the con*****er

most people have the bulb where they can reach them easily from inside the boat

[panasonic]

Never mind what I just asked, you answered the questions...

[HandyJack]

how do you know they work if you have not tested them?

I have tested them.

Oil: I busted off the oil tank sensor a few months ago. The buzzer and the oil light threw a fit. It's new.

I regularly get up and have my kill switch attached to my LJ. It kills the motor if it's running, but then when I restart it the buzzer throws a fit.


For the temp sensor, I've done a light-up test while searching for wiring colors and it worked. i have yet to overheat the motor to test the reaction.

[99yam40]

Well it sounds like they work.
after installing the new oil level switch it is always good to test to make sure it works as it should along with the overheat every year.

it is a pain to find out the warning system did not work out on the water in a bad place when it should have, so you could take care of it

[panasonic]

Well I guess if you already have the pumps coming then you will find out if that will solve your problem or not.

Seeing that the engine is 19 years old and if the pumps have not been rebuilt or replaced then that is not a bad thing anyway.

Have you had this engine since new? If not, do you have any service records from the past owners?