951 DI rebuild woes

[DirtyDan5150]

I’ve just did a full rebuild on my 2002 951 DI LRV.
New OEM fuel pump
New crank
New pistons
New air compressor
Fuel pressure is ok. (25 psi with lanyard, 100 when it does fire for a couple seconds)
I think my gauge reads a tad low.
Compression is 130 in both holes.
Both the fuel injectors and air injectors have been OHM tested and cycled with 12 volts to check functionality.
Ski will occasionally start and run but very rough.
I’m not getting any maintenance light.
But the strange thing is that my fuel pressure bleeds off when the raves cycle after a failed start.
I think this might have something to do with a connection that is misrouted somewhere.
Why would the raves cycling bleed off my fuel pressure?????
Is this normal?
I think the fuel pressure should hold around 107 for a little while even after the engine is turned off.
Anyone offer any advice????
It would be much appreciated!!!!
Thanks in advance……

 

[etemplet]

A friend asked me to look at his DI because it wouldn't run. Ended up being the rave line came unpluged. Yes I'm just finishing up an a 2002 GTX DI and I remember spending a lot of time on the hoses on a 2003 I did last year. I have a few pictures and can take more of the ski I'm breaking in now.



Pay no attention to my circle and the arrow but that was a connecting I had to get straight in my mine. I believe that one comes from the breather line for the balance shaft reservior. The other line comes from the other side if the ski I believe..

 

[DirtyDan5150]

Thanks for the pics……
It appears that I’ve got everything hooked up correctly.
I’m thinking I’ve got a sensor problem or something.
I guess I’ve got to start digging deeper…….

 

[etemplet]

If you are losing air pressure it's not a sensor. Check the orings on the fuel rail. Sometimes it is that simple. Not for me but some people. Ha ha.

Nothing wrong with checking the sensors but that won't address an air leak. That pressure has to maintain. Does it drop more when you advance the throttle?


Good luck and post up if you have questions.

 

[DirtyDan5150]

If you are losing air pressure it's not a sensor. Check the orings on the fuel rail. Sometimes it is that simple. Not for me but some people. Ha ha.

Nothing wrong with checking the sensors but that won't address an air leak. That pressure has to maintain. Does it drop more when you advance the throttle?


Good luck and post up if you have questions.

The orings are all new on the fuel rail including the injectors and all the lines.
The engine will start for only a couple seconds and then die.
According to the repair manual this symptom could be low air pressure.
I’m rigging up something tomorrow at work to test the air compressor output.
I haven’t had it running long enough to see if the fuel pressure advances with the throttle.
I’ll reply with the results.
Thanks for the reply!

 

[etemplet]

Oh Ok. I thought you had checked that and yes that is a great place to start. I bought an adapter from this guy last year. Actually (2) one for the fuel side and one for the air side (price around $50 for both). They are GREAT !! Sure made troubleshooting the DI a lot easier.

His name is Tony - ajp25564@gmail.com

 

[Grayson]

If you are losing air pressure I would also check out the gasket between the compressor head and valve body. Spray some soapy water while cranking to find out. Mine leaked after the rebuild so I bought a new gasket and spread a thin layer of Yamabond sealant on both sides. No more leaks

 

[WaarrEagle]

One way to rule out the air compressor as the problem is to hook shop air to the air line. That is where the fitting @etemplet mentioned can be used or you can hack it together (what I did my first time).

 

[etemplet]

If you are losing air pressure I would also check out the gasket between the compressor head and valve body. Spray some soapy water while cranking to find out. Mine leaked after the rebuild so I bought a new gasket and spread a thin layer of Yamabond sealant on both sides. No more leaks

Good move.

 

[DirtyDan5150]

Alrighty then……. I think I may have fingered it all out.
The guy I bought the ski from included the complete gasket kit. (He was in the process of rebuilding the engine when he bought a house and moved on from the project)
It looks like the gasket kit was for a carb model 951 and NOT the DI model.
How much difference is there between the carb and DI models as far as the gaskets are concerned????
Are the ports in the cylinder and head different???
I’m pretty the engine was assembled with the wrong gaskets…….

 

[etemplet]

Alrighty then……. I think I may have fingered it all out.
The guy I bought the ski from included the complete gasket kit. (He was in the process of rebuilding the engine when he bought a house and moved on from the project)
It looks like the gasket kit was for a carb model 951 and NOT the DI model.
How much difference is there between the carb and DI models as far as the gaskets are concerned????
Are the ports in the cylinder and head different???
I’m pretty the engine was assembled with the wrong gaskets…….

The head gasket is the same, engine is the same with a couple of add-ons like the air pump and parts needed for that. If you have an air leak look at the compressor and the system. That is where you will find your problem. Keep at it !!

 

[DirtyDan5150]

Ok……. I’m gonna see if my compression tester will work for the air compressor.
I think with the rubber “push” tip it should work.

 

[DirtyDan5150]

I tested the air pressure from the compressor.
It builds to well over 100 psi within a few rotations with a compression gauge pushed on top of the compressor.
So air and fuel is being supplied properly to the fuel rail.
Even though the fuel and air injectors have been tested ok with both 12v and ohm specs, I wonder if they could still be malfunctioning and/or clogged????
I’m stumped at this point.

 

[DirtyDan5150]

I also retested compression on the holes.
I’m getting a steady 140 psi on each.

 

[DirtyDan5150]

My fuel pressure bleeds off really fast as the rave valves cycle twice after a failed start.
Is this normal?????
I’ve tried to post of video of this but apparently it will only let me post pictures.

 

[DirtyDan5150]

Success!!!!!!
It was just the the fuel injector and air injector connectors swapped around the opposite way.
Switched them around and she fired up and purrs like a kitty……..
Water test tomorrow.
It’s always a pain in the ass to buy something that’s in boxes that you didn’t disassemble.

 

[Crappiedoo]

Do you mean the air and fuel had the leads on the wrong ones?

 

[DirtyDan5150]

Do you mean the air and fuel had the leads on the wrong ones?

Yes……. The PTO fuel and air injector plugs were connected to the MAG injectors and vise versa.

 

[thejuice48]

My fuel pressure bleeds off really fast as the rave valves cycle twice after a failed start.
Is this normal?????
I’ve tried to post of video of this but apparently it will only let me post pictures.

I recently had the same issue with posting a video. I had to add media, link to my Youtube, and upload to Youtube. PIA

 

[POPPS]

I did that with an RFI once, plugs looked the same lol….way to solve your issues.