1999 GP1200's

[2FST4U]

I'm not touching the carbs......

The dealer winterized them last Fall.
The Ski's are under wraps in the garage
and were\are running great. The dealer
stated that I shouldn't have any of the
problems I had last year, as long as they
do the winterizing. I'm not rebuilding the
carbs. They were rebuilt when the motors were
rebuilt last year when they failed.

Are you saying I should dismantle the carbs
now ?

[Bryan Glynn]

You didn't mention the carbs were just rebuilt. No, there should be no need to do so now. Unfortunately for you, you didn't get to see the carbs yourself, so until you do, you'll never know if you have the fuel pump body problem, or just had clogged filters. I would just go ride them at this point!

[97GP1200]

Yes, it's most unfortunate that the DEALER did not advise you of the cause because there had to be evidence of something. Two 99 GP1200 blowing the # 3 cylinder owned by the same person at near the same hours is a very weird happening.

Tell us please, just for the sake of this thread, did both skis die on the same gas? That is to say, did you take them out of storage, top them both up at the same gas place and then they both seized within those same tanks of fuel? If that's the case, then I would say Bryan's thoughts on this are most likely what occurred.

Still, I can't believe the dealer didn't advise you of their findings when you payed that much money. I assume they gave you a year warranty so that is why you allowed them to "winterize" this past winter?

My only suggestion after something as horrible as you experience is to add a Fram automotive style 6mm fuel filter just after the Yamaha fuel/water seperator. The one I use is a clear plastic unit that is about 3 inches long including the 6mm fittings. Costs 2 bucks and replace every 2 months. It has a paper element and will catch much more crap than the OEM unit. Just can't leave it in long.

[Bryan Glynn]

Bad advice on the filter, but good intent.

NEVER use an automotive filter in your ski.

Automotive filters use MUCH denser filter elements, designed for the 50+ psi of fuel pressure put out by automotive electric fuel pumps. They can on high-volume skis, restrict fuel flow and cause lean seizures.

Stick to the proper marine filters only.

[97GP1200]

Bryan, I was just coming back to say thanks for posting the pic of the valve. I know of a few folks that will like to see that new part. You wouldn't happen to have a old version to show as well?

As for the filter, I talking about a low pressure unit. Fram came out with these for sleds. Wish I had a digital camera.

The part number is FRAM G1000 "made in Israel" (weird). Another number on it says 9703. Check it out. Looks like a small version of a fuel filter one would find on a 78 Dodge Super Six (the famous slant six). Very clear plastic, not opaque. Unfortunately, does not fix Rotax 8mm fuel lines.

[Bryan Glynn]

That's cool - I'll have to look for it. I wouldn't call it automotive if it's indeed low-pressure...a good cheap alternative to the $18 marine filters!

Also, on this ski, the water separator is on a separate vent line, not the main fuel line.

The old body design just doesn't have the three straight parts.

[ February 28, 2002, 09:48 PM: Message edited by: Bryan Glynn ]

[97GP1200]

Bryan, I get the picture on the body valve. Thanks for that. I'm getting into my carbs this April.

Internet's tuff to explain one self clearly, but personally I refer to the stock Yamaha OEM "fuel filter" more as a "water seperator" than a fuel filter because I cut an old one in half and I didn't think it had that much filtering power, but it will trap water/moisture in the very bottom.

I'm very much older than you so I live in the past a wee bit. Still have 3 vehicles kicking around with carbs. If you have ever seen the old fuel filters that GM used to use right at the entrance to the carb (early 80's stuff), then I would say these FRAM are about twice the length and about the same diameter.

I meant for this Fram to be used just after the OEM unit. That was my suggestion.

[2FST4U]

97GP1200,

The fuel was toped off in the fall and then
stabalizer was ran thru the system. In the
spring, the same fuel was used. Once the Ski's
were rebuilt, the same fuel was used. I'm sure
they added extra oil in the fuel after the
rebuild, but I don't think it was bad gas. It
could be that the carbs gummed up over the two
previous seasons. Never had to rebuild the carbs
on my VMAX, and it's 6 years old. The frustration
comes from the reliability factor.

Has any one heard of preinjecting before
starting ? I read on another post where they
were spraying fuel down the screw holes above
the arrestor to avoid long starts.

I know of low preasure fuel filters for pre
1976 engines which run at 5 to 7 PSI. Did you
dump your OEM external fuel filter ? Do you
have to break the carbs down to get to the
internal filter ?

As for the dealer......they were not much
help. From the very begining, it had to be
something I did or didn't do. Even after the
one Ski was rebuilt 4 times, and they blamed
me for each time, they never apologized. The
only explanation they would offer was that
they were not winterized properly which caused
the carbs to fail and number 3 to lean out.
I told them what I did to winterize them and
they couldn't find any fault in it. I talked
to alot of different GP12 owners and they
all took there Ski's to the dealer to get them
winterized. They are under waranty until June 1
2002. Because of whats happened, I'm not
comfortable taking the chance doing it myself.
It has been a bad experience and my wife wants
me to sell them while there still running good.
Can't afford to replace the motors again.

Thanks for everyones input. I know where to
go with my technical issues in the future.

[Bryan Glynn]

Your VMAX may be 6 years old, but it's also a 4-stoke, and not prone to the critical lean conditions 2-strokes are, from clogged carbs. Do you let it sit for 8 months with the same old gas in the tank?

Yes, using a primer is highly recommended for almost all skis, as it greatly aid in cold starting. The GP1200 starting problem, however, is most easily fixed by lowering the pop-off from stock 35-40 psi levels to 20. Installing a primer would be much easier for you though.

Yes you must open and rebuild the carbs to check/replace the internal filters. Checkout the Mikuni SBN rebuild guide in the Tech section on this site for a full walk-through.

Wife shmife... [img]smile.gif[/img]

[2FST4U]

Bryan,

Up early this morning aren't we......

If you were to read the GP12's owner's manual,
under the winterizing section, it clearly
states to top off the fuel and add stabalizer.
Never had to rebuild the carbs on a YZ250 I
had for 4 years, and it was a two stroke.
Are you sure you don't work for Yamaha...

What did you mean by installing a primer ?
And whats o pop-off ?

[Bryan Glynn]

Early? We (SBT) are East Coast, man - Florida. No, I don't work for Yamaha.

Yes the manual says to add stabilizer, and so did I.

I don't know what to tell you, man. If you want to believe that you can run your toys without proper maint. and have them last forever, so be it, I'm not going to change anyones mind. The fact is, carbs get clogged, gas oxyidizes, and motors fail. Does it happen right away? No, not always. The fact is, the evidence of your failure has already been erased. All I'm saying is that for the best chance of proper operation from a personal watercraft engine, in our experience (which is vast), carbs left for 8 months with questionable winterization are more than likely in need of a rebuild. If Sta-bil was mixed in external containers, added to the last full tank of gas the ski ran on, then I would feel comfortable that they would be clean, but I know that you didn't do that. Most likely you added it right to the tank, with fuel in it, probably added fuel on top of it, and hoped it mixed (which it doesn't very evenly).

A primer is a pump that replaces the choke system. It squirts gas right down the carbs for easy starting in secnds.

Watercraft carbs have a flow passageway called a Needle & Seat. The needle is rubber tipped and sits down in the seat to block flow. There is a lever arm on a pivot, with a spring under one end, and the arm attached to the top of the needle at the other. The spring forces the needle down.

As fuel is used by the engine, the amount of fuel in the regulator chamber is reduced, and the atmosphereic diaphragm gets sucked down, contacting the needle arm, and eventually raising the other end, pulling the needle up to allow more fuel to enter the chamber. The fuel then enters the chamber, the diaphragm raises and lowers the needle shutting off flow. This is how the fuel is regulated to the chamber.

The pop-off pressure is how much force is needed to lift the needle, and is adjusted by the size of the seat openeing, and the strength of the spring. It's measured with a pop-off gauge, and must be done when rebuilding the carbs.

If your pop-off is set too high, it takes too much vacuum to pop the needle off the seat (get it?) and you have hard starts and poor low-mid throttle response. If pop-off is too low, you have a flooded chamber without regulation, and very sluggish bottom-end performance, along with the possiblity of the case flooding with gas. If the pop-off is really low, on a hot day, if you leave the fuel valve on, the expansion pressure of the tank will force fuel to fill the engine! That's why they have a fuel valve in the first place.

[ March 01, 2002, 11:01 AM: Message edited by: Bryan Glynn ]

[2FST4U]

Bryan,

Didn't mean to piss you off.....

Questionable Winterization....?
I am machanicaly inclined. I have 1/4 mile
car I rebuild every couple years, and I rebuild
the carbs too. I can work on stuff......
But have no experience on PWC's engines.
Not questioning your advise, just looking
for more information.

I winterized them by the book. But you are
correct on the adding the stabalizer in the
tank and not pre-mixing externaly. I guess
all this comes with experience because it sure
isn't in the manual.

What do you recomend for winterizing ? I read
you FAQ on the issue, but that's what I did the
first two years, minus the external mixing.

Is there a write-up on the primer issue ?

[Bryan Glynn]

The external mixing makes all the differnce in the world.

Adding a primer is very simple. Most all the kits you can buy will come with a diagram, but I have seen some that are wrong. Here is the right way to install one:

For most skis, you will be removing the choke system entirely from the ski. This means you will remove the choke knob, the choke lines, and all the choke butterfly valves from the carbs. Some exceptions are late-model Mikuni I body and Kehin CV carbs, which need the choke plates for proper signal.

After removing the choke knob, you need to drill out the hull where it mounts, I use a wood boring bit, I believe a 3/4", but it's been a while. Anyway, the primer pump slips in the hole and a nut on the back secures it to the hull. The kit will have primer line and some line T's in it. You splice a T fitting into the reserve line between the tank and the fuel knob. This run to the inlet on the pump. You then run the outlet line to the carbs.



This gives equal pressure to all three carbs.

When you remove the choke butterflies, there will be two holes on each carb where the shaft was. The kits come with fittings for these holes. One side gets a plug, the other gets a fitting for the primer line. This is where the fuel gets squirted into the carb. That's it.

[ March 01, 2002, 12:02 PM: Message edited by: Bryan Glynn ]

[2FST4U]

Where can I find these kits and how much
should i exspect to pay ?

Thanks

[Bryan Glynn]

http://www.parkeryamaha.com/primerkits.htm