RTX 260 Engine Running Really Ruogh and will not reach full boost nor go above 4K RPM

[lukasava]

I have a 2012 RTX 260 with like 60 hours on it and it was running fine when I winterized it. After the winter it would crank and was not firing. After playing around with the main fuse box it fired and was running really ruugh and seemed like it was only running on one cylinder. When you gun the throttle the response is very intermitment and the majority of the time if does not reach full boost nor go over 4k rpms. I have changed the plugs and coil packs. Drained and replaced all the fuel, added a fuel injection cleaner to the fuel. removed the fuel injection rail and all injectors appear to be spraying the same patten. Removed and inspected the throttle body and that appears to be ok. Took it to marine mechanic and he did a compression test, tested the fuel, did a spark test, inspected the jet drive pump and tested the fuel injectors and cannot determine what is wrong. At idle it is running really ruough and does not appear to change if I disconnect the coil packs on cylinder 1 or 3. Every now and then when on my lift when I gun the throttle I will get full boost and max rpms but this has never happeded when I put it in the water and run it. Ski does 20mph and th at is it.

Does anybody have any idea what the problem could be?

Appreciate any help.

 

[Digdog]

When you inspected the throttle body was there any water in it or the hose going to it? What do the plugs look like? wet or dry? dark or light? rusty?

 

[AircraftDoc]

How did you do a spark plug test? Do you have a plug tester that pressurized the plug with 140 psi air a then put a charge through it?

 

[lightman02]

Remove the hose from the throttle body. Run the ski on a trailer with a water supply into the flush port. If you see water drops spraying out of the intake hose then you have a bad intercooler that is leaking water causing it to get sucked into the engine. If you don't see any water then I would start checking compression on each cylinder.

 

[lukasava]

When you inspected the throttle body was there any water in it or the hose going to it? What do the plugs look like? wet or dry? dark or light? rusty?

No water the inter cooler The intercooler was replaced last season. Plugs were dry and light. The marine mechanic at my boat yard also confirmed the spark is good and that the compression was fine.

Thanks
Pete

 

[lukasava]

How did you do a spark plug test? Do you have a plug tester that pressurized the plug with 140 psi air a then put a charge through it?

I used a spark tester I had no pressure involved Not sure how the Maine mechanic did it but they sell chaparral jet boats so I assume they know what to do. Also the plugs and coil packs are brand new.

Thanks
Pete

 

[AircraftDoc]

How did you do a spark plug test? Do you have a plug tester that pressurized the plug with 140 psi air a then put a charge through it?

I used a spark tester I had no pressure involved Not sure how the Maine mechanic did it but they sell chaparral jet boats so I assume they know what to do. Also the plugs and coil packs are brand new.

Thanks
Pete

Then, replace the spark plugs. SC engines eat plugs. Also, new plugs don't guaranty the plugs are good. Stock boy could have drop them. This is a cheap fix.
The only way to test a spark plugs is under load-pressure.

 

[Digdog]

Try moving the coils to a different cylinder and see if the misfire moves with it, try it with the plugs also. I'm not sure how the plugs in 1 and 3 could be dry if you unplugged the coils and the engine didn't change, but dry usually means it's firing or it's getting no fuel or the intake valve is not opening. If this continues on 1 and 3 then I would do a compression test, there are also separate fuses for each cylinder (10amp) in the fuse box but i'm not sure if they are for the coils or the injectors or maybe both.

 

[Sportster-2001-951C-Stock]

When you pulled the #1 and #3 plug wires while running, did you get zapped? I have a plastic tong for that and often (I will not charge for this free tip I rarely share) just holding the wire a few mm away from the plug end is enough to get a fouled plug (contaminated insulator bleeds off coil voltage) to fire.

FWIW, I find that fogging during winterization tends to foul plugs. Anyway, the advice to change plugs is good, and always the first place to start, I've had numerous instances myself where I've had to change them more than once due to excessive oil and stale fuel. I guess the insulators were glazed by the burning muck.

Running out of things to check but let;s recap:

You've changed the coil packs, presumably troubleshooting this issue? That's how I read the above to mean.

So to cover the basics all engines follow the same rules of squirt, squeeze, bang, fart, all four of these things must occur in symphony. Thus you've confirmed the latter three but how about the squirt part?

Injector test

You should be able to remove the injector rail and lay it on top while cranking to confirm all three are squirting fuel onto a rag,, just be sure not to start a gasoline fire thus no sparks in the vicinity. You can short the plug wires to ground using a set of alligator clip leads or probably disconnect the coils.

Fuel pressure test - You need a pressure test gauge and associated fittings as discussed in the shop manual and on this board in many threads.

 

[Digdog]

When you pulled the #1 and #3 plug wires while running, did you get zapped? I have a plastic tong for that and often (I will not charge for this free tip I rarely share) just holding the wire a few mm away from the plug end is enough to get a fouled plug (contaminated insulator bleeds off coil voltage) to fire.

FWIW, I find that fogging during winterization tends to foul plugs. Anyway, the advice to change plugs is good, and always the first place to start, I've had numerous instances myself where I've had to change them more than once due to excessive oil and stale fuel. I guess the insulators were glazed by the burning muck.

Running out of things to check but let;s recap:

You've changed the coil packs, presumably troubleshooting this issue? That's how I read the above to mean.

So to cover the basics all engines follow the same rules of squirt, squeeze, bang, fart, all four of these things must occur in symphony. Thus you've confirmed the latter three but how about the squirt part?

Injector test

You should be able to remove the injector rail and lay it on top while cranking to confirm all three are squirting fuel onto a rag,, just be sure not to start a gasoline fire thus no sparks in the vicinity. You can short the plug wires to ground using a set of alligator clip leads or probably disconnect the coils.

Fuel pressure test - You need a pressure test gauge and associated fittings as discussed in the shop manual and on this board in many threads.

You don't pull out the whole coil, just unplug it, fuel pressure test is also a great idea.