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ZR409 lack of power |
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rockdog 
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Joined: November-03-2013 Location: Vic. Australia Status: Offline Points: 31 |
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 Topic: ZR409 lack of powerPosted: October-22-2023 at 7:09pm |
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Hi all, I've recently bought a 2012 SN200 with closed loop ZR409 and 370hrs off a fellow club member as he has barely used it the last two seasons. It had a miss in it which we knew about and put it down to the old fuel and reasoned it will be ok with new fuel, injector cleaner etc. This has mostly proven to be correct as I've run a tank of 91 through it and the miss has all but cleared up. The problem is that out of the hole it is has a distinct lack of power and takes a bit longer than it should to get up to 34mph. The crew I ski with pointed it straight away and I've since raced it directly against our club boat which has exactly the same setup. That boat has immediate pickup and seems much stronger. Two other crew members have exact same boat/setup. So mine seemingly having less horsepower than three others is not something we've imagined. Importantly the props are the same 668 so rules out that as an issue. I'm unsure what to do about this, can anyone advise steps to source the problem here? What I've done so far: - replaced spark plugs - cleaned flame arrestor - replaced FCC filter and fuel/water seperator - just drained tank and refilled with 98 (not run yet) - inspected throttle linkages and cable movement Once the boat is up to speed it seems fine, no noticeable miss in the engine or anything else I can pick up. Appreciate any help. |
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MrMcD
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Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3749 |
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Posted: October-23-2023 at 2:25am |
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Because you mentioned old gas I will share, I repaired a Fuel Injected 502 engine that had been sitting. To get the injectors all working I had to remove them, flush each one with Carb Cleaner till I had a good spray pattern from each and then I actually sprayed some ATF fluid in to lubricate and help clean each injector as a last step before re installing them in the engine. The engine fired right up with full power after the cleaning and is still running great two years later. Before the repair it did not have enough power to get the boat up on plane but it would run. Also had to drain the fuel tank and the fuel rails to dispose of the old fuel.
With your ZR409 can't you plug into the computer and read what the injectors are doing? Maybe the marine version is locked and does not allow that? Old gas can plug the injectors with a goo that does not clean up easily.
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MrMcD
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Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3749 |
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Posted: October-23-2023 at 2:50pm |
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Running an engine on bad gasoline causes internal issues also. If gasoline is one year old or more it can be dangerous to run. I have seen Pistons with the piston heads looking like they were varnished, a sticky coating forms on the piston head, the same varnish like substance can stick to the valves making them stick in the valve guides. If valves are stuck the only way I know to free them is to remove the heads and have them taken apart and cleaned. If the engine has this type damage the old gas puts off a smell that is quite strong when run in an engine till it fails and your engine parts will stink. Not like a skunk but still a strong unique smell that any machinist will recognize right away as bad gas in an engine. I have been in machine shops where they were tearing down an engine after it failed from bad gas. The tear down room is in the back of the shop but I could smell it when coming in the front door of the shop 100 feet away.
A compression test would tell you right away if any of your valves are not closing properly just to rule this out. The common story is an owner takes his engine out as part of a classic car rebuild. Over a year later they install a brand new engine in this old classic and fire it up on the gas that was in the gas tank all that time while the car was apart. Then they bring the new failed engine in for warranty work and can't believe it failed due to old gasoline. Sad but it happens fairly often. I hope you are chasing a much less complicated repair.
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Fl Inboards
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Joined: January-20-2008 Location: United States Status: Offline Points: 2119 |
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Posted: October-23-2023 at 5:54pm |
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Did ya fuel pressure check it under load? Did ya check all grounds (earth) for tightness? Did ya check your power requirements with a multi meter? Anti syphon valve clean and clear? Did Ya have a scan performed and cylinder isolation test? what did you gap your plugs to?
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Hobby Boats can be expensive when the hobbyist is limited on their own skill and expertise.
1993 Shamrock "fat" 20. 2008 Nautique 196 5.0 |
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rockdog
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Joined: November-03-2013 Location: Vic. Australia Status: Offline Points: 31 |
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Posted: October-23-2023 at 6:28pm |
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Thanks MrMcD for the info. Yes I think Diacom can be plugged in and get the detail on the injectors amongst other things as you say so maybe that's next thing to do.
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rockdog
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Posted: October-23-2023 at 8:19pm |
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Thanks for the response Jody. I have not done any of those things you've listed, I've done the first basic things (in the manual) I'm capable of doing myself before I move on to next options. I'll check anti syphon valve tonight and make sure ground is tight also. Plugs are .040 gap per manual. I think I'll try to organise fuel pressure check before I get scanned.
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MrMcD
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Posted: October-24-2023 at 1:22am |
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If you have a fuel pressure gauge it is good to test it while operating on the water. Probably need to leave the engine cover open and be very careful as there are moving parts but if pressure falls under load you learn more than seeing good pressure while on the trailer. Jodi gave you several good tips to follow.
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 11112 |
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Posted: October-24-2023 at 7:12am |
If you really want to rule out the prop, I'd swap props with the other boat just to be sure, since it's right there and readily available
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rockdog
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Posted: October-24-2023 at 8:44am |
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Checked anti syphon valve and all clear. Ground connections all seem to be ok. I've got a fuel pressure tester now and a compression tester so I'll do both on the weekend and see what happens.
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rockdog wrote: