Sea-Doo 3D Di... tried everything...

[Shane0306]

Alright here's the thing, ski was running perfect, so much fun!

Then all of a sudden I went to start it, and nothing.


Things I have investigated....
• 80+ PSI at air compressor... yes (whilst cranking)
•27+ PSI at fuel rail... yes (whilst cranking)
•Spark... yes (looks fine)
•Cylinder pressure... yes (150lbs exactly in both cylinders)
•Battery Voltage... yes, have a fully charged battery and jump pack connected just to eliminate voltage drop whilst cranking.
•no maintenance light on dash
•reed valves look immaculate
•I have completely drained the fuel tank and replaced with brand new premium fuel and flushed fuel system
• cleaned direct injectors
• cleaned rave valves


I am completely out of ideas!!
What's next?

 

[jamiepdavies]

Following[emoji848]

 

[Shane0306]

Righto, just pulled apart the fuel rail to ensure its throughly clean.

Pulled apart the top MFI Injectors on the top of the rail to inspect... all looks good gave them a clean, popped them back in, cranked the ski to ensure they are working

I dumped some fuel injector cleaner in the fuel just to be sure.

Still nothing, I just don't understand what's happening.

I checked to make sure the ignition coil connectors are around the right way, servicing the cylinder, same with all 4 injector connectors (top 2 and bottom 2)
Even though the ski was running perfect before all this, I still thought I'd check anyways as I am running out of ideas

Basically I have a perfect engine, it just doesn't run.

 

[Shane0306]

Oh and yeah I forgot to mention when I say I get nothing when I try to start it... I mean it cranks over perfectly but it doesn't fire.

Only sputs here and there at times (not very often)

There is no water in the engine or anything like that also the exhaust system is good, I checked for holes/leaks or anything out of the norm... looks fine.

 

[racerxxx]

Put some pre-mix gas right down the spark plug holes and then try and start it. That will eliminate any fuel delivery issues.

 

[68ragtop]

Alright here's the thing, ski was running perfect, so much fun!

Then all of a sudden I went to start it, and nothing.


Things I have investigated....
• 80+ PSI at air compressor... yes (whilst cranking)
•27+ PSI at fuel rail... yes (whilst cranking)
•Spark... yes (looks fine)
•Cylinder pressure... yes (150lbs exactly in both cylinders)
•Battery Voltage... yes, have a fully charged battery and jump pack connected just to eliminate voltage drop whilst cranking.
•no maintenance light on dash
•reed valves look immaculate
•I have completely drained the fuel tank and replaced with brand new premium fuel and flushed fuel system
• cleaned direct injectors
• cleaned rave valves


I am completely out of ideas!!
What's next?

You should be able to get full pressure while cranking, 100psi+
27psi with the key on, before cranking would be correct however.

 

[lloyd54123]

Spray some starter fuel in!

 

[Shane0306]

Sorry for the long reply, stripped down every part of the engine that I was suspicious about (inspected o-rings ect.)
Wiring, connectors and dielectric grease.

All came back good.
After putting her back together I did spray some fuel in the cylinder and voila! It ran for half a second.

Changed the spark plugs just cause I had them here anyways
Brought a new battery

Pulled the fuel rail off the head and had a mate holding the air injectors on the fuel rail whilst I cranked it, fuel sprays out nicely.


The only thing I can put it down to is there is too little air pressure to inject the fuel into the cylinders and the pressure in the cylinders is quite high.

Perhaps the air compressor has worn out enough so that it cannot keep up any longer.

If the fuel is injected at or around TDC it in theory would require more than 150psi to force its way into the cylinder??

Maybe the air compressor isn't getting it there.

Does any body know the pressure of a freshly rebuilt compressor?

 

[Coastiejoe]

Sorry for the long reply, stripped down every part of the engine that I was suspicious about (inspected o-rings ect.)
Wiring, connectors and dielectric grease.

All came back good.
After putting her back together I did spray some fuel in the cylinder and voila! It ran for half a second.

Changed the spark plugs just cause I had them here anyways
Brought a new battery

Pulled the fuel rail off the head and had a mate holding the air injectors on the fuel rail whilst I cranked it, fuel sprays out nicely.


The only thing I can put it down to is there is too little air pressure to inject the fuel into the cylinders and the pressure in the cylinders is quite high.

Perhaps the air compressor has worn out enough so that it cannot keep up any longer.

If the fuel is injected at or around TDC it in theory would require more than 150psi to force its way into the cylinder??

Maybe the air compressor isn't getting it there.

Does any body know the pressure of a freshly rebuilt compressor?

Do an inline fuel pressure test. As noted above it should be 127 at idle. If you don't have that, then you KNOW it is the FP and or Air Pump.

I believe it is 100 of air and 27 of fuel.

 

[Shane0306]

I can do an inline test but I can't get it to idle, best I can get is whilst cranking.

I get just over 80 PSI of air when I'm cranking

And pretty much bang on 27psi fuel

 

[Coastiejoe]

I can do an inline test but I can't get it to idle, best I can get is whilst cranking.

I get just over 80 PSI of air when I'm cranking

And pretty much bang on 27psi fuel

Sounds like the air pump is low based on what you know.

I read where someone hooked up an air hose to artificially raise the air PSI to test things.

 

[Shane0306]

That's a good idea, I'll test that next, stay posted

 

[Shane0306]

Hey guys just an update.

I think I've found the problem.

So I did another compressor test and I get well over 110 psi of air pressure, I don't know why I though it was just over 80, it was a while a go I tested it.

But for good measure I connected the air compressor to the fuel rail anyways.


I set the regulator to...
45 psi - engine started very very rough idle
50 psi - very rough idle
55 psi - quite rough idle
60 psi - rough idle
65 psi - lumpy
70 psi - smoother but not 100%
75 psi - perfect idle
80 psi - will not start
85 psi - will not start
Anything higher, will not start

If you put the key on the post you can hear the fuel being pumped into the fuel rail, once the air pressure is over 75 psi the air pressure pushes the fuel back, you can hear a bubbling noise in the tank after you prime with the key on the post, and attempt to start.

So if I have 110psi at the onboard compressor, this is obviously way too much pressure for the fuel pump to fight when cranking/running

I have put it down to the two regulators on the top of the fuel rail.
Does any one know if there is supposed to be a non-return valve on the fuel line somewhere or in the fuel rail? Perhaps that function is built into the regulator and it's faulty.

And also the air regulator may or may not be doing its job.

The reason I am more inclined to think the problem lies with the fuel regulator/or something that acts as a non-return valve is that whilst I had the rail connected to my air compressor and I set the regulator to 80psi or over, there was a hissing noise which can only be the air regulator opening.

So to me the air regulator SEEMS to be operating.

Anyone have any ideas?
I might swap the fuel reg and see where that gets me.

 

[Shane0306]

I have swapped out both regulators, fuel and air.

Now it really wants to run!
I can hear/see air escaping from the air reg so that problem is solved I guess.

Although every time it goes to start, the thing runs for 0.5 - 1.0 second then shuts down, dash goes blank and then after around 4 seconds it starts beeping again telling me I have left the key in.

Anyone got any ideas??

 

[garygarnett]

In the shop manual for any 947di it gives you a flow diagram on how to test the fuel system and air compressor system at the same time
It gives you what pressures you should have at different settings e.g. Eng static Dess contacted and engine starter engaged
Best follow that religiously and you should come up with the faulty component
The fuel pressure is regulated 27Psi higher than air pressure and a good fuel pump is critical