3D RFI - low power but high fuel consumption

[afrancva]

Hi guys,
I recently bought a used 2005 3d rfi with low hours on it and in a good overall condition. it starts great and revs up without problems.

But unfortunately I'm facing some problems:
- I think that the power is lower than it should be with 110 hp. for sure the comparison is not valid, but I tested a hydrospace s04, a yamaha superjet and a seadoo rxp ('00) and all of them have dramatically higher acceleration and top speed. I can use it at full throttle all the time and the power is by far not too much, neither in sharp turns.
- the fuel consumption is extremely high. around 40 liters for 1,5h. I already cleaned the flame arrestor.
- during steering the power is decreasing. (the revs are decreasing although keeping the throttle fully open)
- when operating some time on idle, the engine does not rev up at all. the engine stops and cannot get started until the spark plugs were cleaned. the spark plugs are black and oily.

Do anybody have ideas which parts might cause these problem? Maybe some electrical sensors, the RAVE solenoid?

 

[griz400]

check compression first, then check fuel pressure with engine running on the water, sounds to me fuel issue on turns, always check the basics first

 

[afrancva]

Thanks griz for your answer. I already checked compression ratio and it is 9:1. so quite fine referring to shop manual (even too high?, shop manual reads "corrected compression ratio 6:1")

How can I measure fuel pressure? When I pull off the hose from the rail and the ignition is on some petrol comes out. Do I need some specific instruments for measuring the fuel pressure/flow rate?

 

[chucked]

Lol, no you need to check the compression of your cylinders using a compression gauge.

 

[afrancva]

:thumbsup: Maybe you missunderstood my question. For sure I checked the compression with a compression gauge, the fancy thing which you screw inside the cylinder head instead of the spark plug.

My question belongs to the second hint; how to measure the fuel pressure on water during driving?

Lol, no you need to check the compression of your cylinders using a compression gauge.

 

[chucked]

You must find the actual psi that is built in the cylinder when you're cranking it with the choke off and throttle wide open.

 

[afrancva]

I unplugged both plug leads. Then I removed the spark plugs and screwed the hose of the compression gauge inside one of the holes where the spark plug has been before and started the engine. I checked both cylinders consecutively. The gauge said ~9bars = 130 psi for both cylinders. I did not open the throttle during the starting procedure.

If this makes any difference I will try so, but I could hardly understand the impact of the open throttle even though the plug leads are disconnected so the engine could not rev up anyway?

 

[afrancva]

Yesterday I checked compression again, with fully open throttle. Compression is fine with ~130psi. I also removed the fuel pump and checked both filters (in- and outside of the aluminium body of the pump. They seem to be clogged. So I removed them and tried a short ride without the filters. No changes.

Then I removed the injectors and I could not believe my eyes due to their visual appearance:

What do you think about the injectors? For sure, a proper functionality does not correlate with the visual appearance, but anyway. Could they be the reason for the behaviour of the 3d? Fuel comes out when the ignition is on, but I could hardly measure if the amount of fuel is correct.

 

[griz400]

there is a bosh part number on top of fuel injector, give it to http://www.fiveomotorsport.com/

also 130 psi is on the way out -- needs to be 150 psi

 

[wrench2ride]

the outside of your injectors are corroded but as long as the terminal connections inside the injector are clean they should work i would think, with the injectors out of the cylinders and still connected to the fuel rail and wire harness you can crank the engine over and check the spray pattern, it should be a reasonably fine mist, no large droplets of fuel. (be sure to ground your spark plug leads to the grounding posts and make sure you are in a well ventilated area!!) also you can verify the injectors for proper operation by taking them to an shop that works on injection pumps and injectors, shop near me works on diesel injections pumps and turbos also services injectors, not all compression testers test the same, i have two compression gauges that read 15psi different from each other, when you say 40 litres of fuel in 1.5hrs how are you riding it? if you are riding full throttle it would burn that much fuel no problem, to test fuel pressure you will need to disconnect the hose on the end of the fuel rail and hook the pressure gauge in series with the rail and the hose from the pump and route the gauge out from under the engine cover and take it for a ride and when it starts to act up look at the gauge to see what it is reading, top speed on a rfi 3d is about 50mph (80km/h) on gps depending on water conditions and trim adjustment.