Yamaha Two Stroke Primestart

[boscoe99]

Wish we could make a sticky from this. This subject comes up time and time again.

https://www.youtube.com/watch?v=x35uqVMu2r0

[robert graham]

Since it's a diaphragm fuel pump similar to the main pump on my 1999 C90 wonder if that diaphragm should be replaced now and then? Never any problems so far....draggin' the boat to Florida this Friday so hope no trouble with Primestart!

[panasonic]

We all roll the dice on stuff like that..until it fails
then we curse ourselves for not doing some preventive maintenance. 20 years for a fuel pump diaphragm not bad. Probably $20.00 to replace it and have a little bit more peace of mind.

[rodbolt17]

whuuuuut?????
maint??????
are you kidding?

[boscoe99]

Drive it until it drops. Then blame Yamaha for a crappy product.

Maintenance? We don't need no stinkin' maintenance.

[robert graham]

Is there a recommended replacement time for the Primestart pump diaphragm?

[boscoe99]

Is there a recommended replacement time for the Primestart pump diaphragm?

Not from Yamaha.

Yamaha has to be careful about their maintenance recommendations. Other company's (one in particular) say their motors need no maintenance at all and will denigrate the manufacturers that do. They say that their motors needing no maintenance clearly shows superiority over other brands of motors that do need maintenance.

Funny but that company has about the least amount of sales amongst all brands.

Meanwhile, back at the ranch, my life's experience has been that the more maintenance I do (within reason) results in my having purchased a higher quality product. If I don't do any maintenance then the product is crap when it breaks from a lack of maintenance.

[robert graham]

Maybe the Primestart diaphragm doesn't run so much as the regular pulse pump diaphragm?....or does it run all the time??? Guess putting a new Primestart diaphragm would be fairl cheap and easy?

[boscoe99]

The diaphragm is being flexed any time the motor is running. Positive and negative pressures from the crank case. About 4000 of them a minute when the motor is being run at cruise. Makes me wonder how the diaphragm lasts as long as it does.

[robert graham]

Have you ever known of anyone changing the diaphragm just as preventive maintenance?...

[boscoe99]

Have you ever known of anyone changing the diaphragm just as preventive maintenance?...

Nope.

In fact I don't know of anyone changing the diaphragm even if they are having a Primestart issue. They generally just spend their time bitching about the motor not having a choke.

[dray0151]

Who was it that said not long ago don't know why they changed from a choke when it worked so well????????

[pstephens46]

Nope.

In fact I don't know of anyone changing the diaphragm even if they are having a Primestart issue. They generally just spend their time bitching about the motor not having a choke.

Do I get any credit at all for changing my fuel pump diaphragms before any sort of failure?
Any at all? Wife just shrugged.

I tell her I do these things for her safety.

[99yam40]

Yamaha put a red lever on the system so you can turn it on manually and to the off position if it has a problem.
I would not worry about it.

[boscoe99]

What we need is someone with a two stroke that has a working Primestart to measure the pressure pulses so we can know more or less what they be.