couple issues with a 236 with a ZR-6

[tisnyler]

Test drove a 236 today and noticed a couple things that didn't see right to me:

1) the exhaust risers never got hot, cold the entire time (30min) Temp gauge was between 165-175 degrees.

2) loaded down the boat wouldnt plane out, wouldnt go above 3K RMP and 10 miles an hour. Not loaded down it would go 29mph full speed but took forever to get there.

Spark plugs were replaced a couple hours ago, as was the fuel filter and the low pressure pump.

[beamons]

I would guess that is not right either, though I have never driven a 236 with the ZR6. It sounds to me that there are engine issues. Could be as simple as a clogged fuel filter or something else. Good luck. I would pass unless the price is great.

[scottb7]

Other people can chime in but IMHO

1) the exhaust risers never got hot ::: that temp gauge reading is fine...so i would not worry about this...

2) loaded down the boat wouldnt plane out:::what propeller?

Spark plugs were replaced a couple hours ago, as was the fuel filter and the low pressure pump.:::how many hours on the boat...i replaced these things on my boat myself so as not to have problems down the road...

I look forward to hearing other peoples thoughts....but none of those things sounded bad

[mpost]

Possible that there are a couple of plug wires on the wrong plugs. This happened to me when I changed my plugs last year. My 98 GT40 would not top 25 MPH. got the wires on right and does over 40.

[Evening Shade]

Test drove a 236 today and noticed a couple things that didn't see right to me:

1) the exhaust risers never got hot, cold the entire time (30min) Temp gauge was between 165-175 degrees.

2) loaded down the boat wouldnt plane out, wouldnt go above 3K RMP and 10 miles an hour. Not loaded down it would go 29mph full speed but took forever to get there.

Spark plugs were replaced a couple hours ago, as was the fuel filter and the low pressure pump.

Describe what you mean by loaded down? Factory ballast or a ton of sacks everywhere?

Depending on the prop, top speed on that boat should be close to 40mph and it should get there fairly quickly. I will also add, that if the top speed is only 29mph because it has a very low pitched prop then it should reach top speed VERY quickly and maybe even hit the rev limiter. This type of prop shouldn't have trouble planing a loaded down boat, unless 95% of the weight is in the very back of the boat.

It sounds like something is possibly wrong to me, but it could be something very simple. I need the answer to my first question to be of more help. It would also help if you could tell us the pitch and diameter of the prop.

[tisnyler]

Prop is a 1235 (Acme) 14.5x14.25.

Factory ballast was full and had an additional sac on each side in the rear and one in the bow under seats.

Total weight of additional sacs is a little under 1400lbs.

Boat has 500 hours.

Wouldn't crossed plug wires cause backfiring?

Before we even filled up the ballast and additional sacs, I accelerated with the boat and looked over and told my buddy "this boat is slow."

Now I am curious about the science, how can any part of the exhaust not be warm/hot. Shouldn't it reflect the engine temperature?

[Evening Shade]

I still think something isn't right. With a 1235 and ZR6 I would think that boat should at least get to 35mph and get there pretty quickly with a 14.25 pitch prop. It won't make it to 40mph with that prop.

Now I'm not sure why the exhaust risers never got warm. Where are you located? How cold was the water you were in? 165-175* is normal operating temp for these engines, but that's thermostatically controlled. The exhaust manifolds/risers are not thermostatically controlled. They see a constant flow of water so I suppose that if the water was 35* it could keep the risers cool.

Does the engine sound healthy/idle smoothly?

[Blamey]

Agree with evening shade shod get close to 40mph and to 35mph very easily unweighted.

Can you tell if the RPM is limited. If it gets to 3k fairly easily weighted and unweighted then I think the engine is in limp mode.

More often than not limp mode is due to a failed sensor. Read the post from earlier in the week my Rockymountain. Similar issue. Spend a lot if time investigating, turned out to be a wire connected to the sensor that shouldn't have been.

Code reader should tell you what sensor is causing the issue, then you can determine if it's a real issue or just a bad sensor.

What did the seller say?

you could use it as a negotiating tactic to get a low price (if I liked the boat I look for anything over 5k off what I'd be willing to pay for the boat without issues). The hope is it's a simple fix but it could also mean you need to rebuild the engine.


It could also be a totally different issue, bad plugs/wire, fuel pressure issue.




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[Indygreen]

I have a 236/230 with a 1235 prop and ZR6. These boats run strong and what your describing doesn't sound right.

[SilentSeven]

Personally, I wouldn't by a ZR6 powered boat without a compression test. The moniker on the engine leads to hoonigan type operation. You may have tuning issues or you may have dead cylinders. Better safe than sorry.

[tisnyler]

Boat was taken to dealer for diagnosis. Said to have 3 fuel injectors not firing/clogged. All three were cleaned and one ended up having to be replaced. Also did a compression test which was good. Took the boat back out for a test drive and it was a night and day difference. Filled up all the ballast and it pulled out of the hole like you would expect it to.

Bought the boat, took it out for the first time yesterday. Put 25 gal fresh fuel in there. went about 16 miles up river (wakeboarding, stoping and starting, talking). No hesitations, had full power and very responsive. Filled up the sacs and it would go above 10MPH again, wouldnt get on a plane. Emptied sacs and then it was fine again, had full power and was responsive. Drove 25-30MPH home, no problem.

I am thinking to attack the fuel filter and then go from there. I believe that maybe the gas/junk that "clogged" the injectors the first time was agitated by me dumping in 25 gallons and maybe went back through the fuel system.

Can the gas tank be removed from these hulls? Thinking to start from zero.

[tisnyler]

*it wouldn't go above 10mph, would not get on a plane.

[d_nodixon]

Change the plug wires also

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