787 RFI Low Speed Issue

[BigTwinLake]

Currently running a 2004 3D with the 787 RFI motor, it was replace with a brand new crate motor and oil pump 2 years ago by previous owner.

Ran great last year, earlier this year started to notice a loss of power on tight turns.

Issue is a little worse now, and picking up a lower speed slight hesitation.

Knowing that the new motor only has approx. 20 hours, I do not believe this to be the motor.

Cleaned the rave valves prior to last ride, they were really clean when I cleaned them and it did not make an improvement.

Any ideas, I'm stumped!

 

[griz400]

i would check compression, just for starters, if good, put some new plugs in it -- only like 2.50 ea. , also check your battery voltage, and with ski running at 3000 rpms, also, take off spark plug boots, take a little like pocket screwdriver, put inbetween wire and boot, loosen it up and screw it off, trim off like 1/4 - 1/2 of inch, screw boot back on and secure it with a tie strap, -- these here are all the basics, and you can do for like 5.00 --- but on tight turs, sounds sorta like a fuel pump module issue, maybe coming loose inside tank -- does it happen on full tank ??? or when like half empty ??? i have a thread here started call rfi spot, there is info on fuel pump and screens -- not real expensive -- discount auto parts has it all -- around 100.00 i believe

 

[BigTwinLake]

Low Speed and Hard Cornering are still issues, ski is also not starting as well as it used to.

I checked the compression, I am at 120 psi on both cylinders.

New Plugs, removed the boot that was under the spark plug boots, boots now "click" when installing.

I am about to take the unit to a dealer and hate the idea of paying them to trouble shoot the machine when I can do it for free.

I really think this is a fuel/delivery issue, does anyone know if there is a fuel filter on these machines? Seadoo web site does not show one.

 

[Coastiejoe]

At 120 PSI you are at the bottom of acceptable.

Not saying you don't have other issues. But you have limited life left in the engine.

Have you trimmed back the spark plugs wire? The ends break down over time.

Anything can help you get through the season but I think your engine will not make it much into next year.

And every ski I have ever seen has a filter. Normally near the tank as well as screen inside the carbs.

 

[griz400]

Low Speed and Hard Cornering are still issues, ski is also not starting as well as it used to.

I checked the compression, I am at 120 psi on both cylinders.

New Plugs, removed the boot that was under the spark plug boots, boots now "click" when installing.

I am about to take the unit to a dealer and hate the idea of paying them to trouble shoot the machine when I can do it for free.

I really think this is a fuel/delivery issue, does anyone know if there is a fuel filter on these machines? Seadoo web site does not show one.

did you read the previous post i made ??? look at this link http://www.seadooforum.com/showthread.php?50814-The-RFI-(Rotax-Fuel-Injection-)-Spot it tells you where the screens are as i posted previously

 

[griz400]

also, no carbs on this ski

 

[BigTwinLake]

Griz, I originally searched for your post and could not find it, just finished reading it (thanks for attaching the link).

Too bad I didn't have it yesterday....
I pulled the "fuel sending unit" out of the tank and cleaned the 2 filters, everything looks really good.
I ended up having to drill out the two rivets at the bottom to re-assemble the fuel pump, but got it back together.
Put it back in the machine, reattached the fuel and electrical connector and the machine started right up (on the trailer).
It ran well, but I noticed a low speed sputterring at first but attributed it to being emptied out, hit the throttle a couple times and the sputtering went away, turned machine off, then I went to restart after 5 minutes, and now when I connect the DESS key, the fuel pump primes,
but I do not get any beeps and it will not turn over. Stumped again!!!

I don't understand how the machine started and ran, but is doesn't do anything now.

One thing I want to mention is the connector under the fuel sending unit, two of the four wires runs to the fuel level sensor and the other two run to what I assume is the fuel pump, but the connector is not "fool proofed", meaning it can be connected forward and backward. I may have connected this the wrong way, but I would not expect the machine to start if I did.

By the way, Great Job on the RFI post, very informative!!! When I get the ski running again I think I am going to replace the filters, pump, and injectors. Originally I was looking at over $500 just for the BRP fuel sending unit.

 

[Minnetonka4me]

If you bring it to a dealer they can check the TPS sensor...if thats off idle will be all over the place and slowly getting into the throttle will make it hesitate.