Servicing info on 3.0lt 135 merc

Actually the original post quoted "The motor also ran on after the key was removed" as one of the problems mentioned in the post. I suppose that is the reason the suggestions to cure that problem have been mentioned.
 
Thanks, Biff. I read through that a few times....:smt101 Just kidding! It was a good read.

Totally agree about the pre-detonation and high-compression engine vs lower octane.

I'm picking up what 'yer putting down about formula differentiation between companies. In fact, we might actually be speaking the same language, but just differing in the delivery. I have definitely experienced adding higher octane to nix run-on. However, this run-on will typically only occur in the early fall - when gas companies change their formulation. So, what you are saying is more technically correct than what I am saying - and I don't disagree with what you are saying. But, even though I may be using the same gas company, simply increasing the octane has helped. So, it seems the higher octane is making up for the "winter" gas. Now, I don't know the difference between "summer" and "winter" gas - maybe octane is part of this? :huh:

By the way, this is not just limited to my personal experience. This goes for customers who call and ask why their engine is having run-on issues all of a sudden. These calls won't start until early fall.

Just to be clear, I agree that octane is not a "cure-all". Reading what you wrote helps to clear some things up for me. Thanks!

This also may not be Mark's problem, but it's easy enough to add some octane boost to try - since we are in the fall, anyway. Plus, doesn't gas lose it's octane (goes down) over time? Maybe just fresh gas would help, depending on how long it's been sitting in Mark's tank.

MARK - are you still hangin' on, here? Have you fixed your problem? How many gallons was your "fill-up" of 95 octane? Was this the first time you had the boat out? In re-reading your original post, I think you're saying the boat ran fine before the 95, you just weren't satisfied with the power? In that case, Biff was more than likely correct on his first response about getting rid of the 95.

Thanks again, Biff - I appreciate the time you're taking to explain things.
 
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Hi Dennis and Biff

Thanks for all the information. I have been away on business ( Great Barrier Reef Australia) Tough gig but someone has to do it:)!!

I picked up the boat from the mechanic yesterday and they found nothing wrong. The engen is fine and so is the timing ect. I am partly happy that it is in great shape, and partly sad that there was no more power available.

I had previously filled up with 95 octane, which is lower than the 98 octane available in premium, but higher than the 91 octane "normal " fuel. I filled the tank to the top from empty, 80 liters.

The mechanic played with the timing, air fuel mix, and props. The final outcome is that the engine was fine. We had a 4blade 18 pitch prop, running 60kmh at 4600rpm wot. Changing to a 15 pitch 3 blade stainless gave a brilliant hole shot (as expected) and still topped out at 60 kmh but at 5300rpm. I am going to purchase a 4 blade 16 pitch stainless prop to dropp the revs a bit and still improve the hole shot.

the running on has stopped mainly because I idle a little longer and the idle speed is a little lower. This causes the motor to stall when cold but a small price to pay.

Again thanks for the help and the education!!

Mark
 
Mark RSA2AU said:
We had a 4blade 18 pitch prop, running 60kmh at 4600rpm wot. Changing to a 15 pitch 3 blade stainless gave a brilliant hole shot (as expected) and still topped out at 60 kmh but at 5300rpm. I am going to purchase a 4 blade 16 pitch stainless prop to dropp the revs a bit and still improve the hole shot.
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Anyone know the approx MPH conversion of that? and if the austrailian pitch is equivilant to ours here in the US? I'm running a 17 pitch and is by far the lowest of anyone I've talked to on this set up. With some small carb issues I'm planning in under 2.5 seconds maybe even under 2... that 15 would really have to be something...
 
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Hi User Error

This converts to 37.5 mph @ 4600rpm using my old 4 blade 18 pitch prop. (pitch measurement is universal 1 inch per rotation) Changing to a 15 pitch 3 blade stainless prop gave me the same top end 37mph but lifted the rpm to 5300, which is too high.
By comparison to the 18 pitch the hole shot with the 15 was great, but by my standerds it is still poor.

I took the prop to a professional prop shop to check and they have adjusted the pitch to 17.5 with a 1mm cup on the trailing edge. The computerised measurement of the prop showed each blade was about 0.25 of an inch out. Not much but enough to make a difference on an underpowered boat. I will be testing it this weekend and will let you know.
 
Mark RSA2AU said:
Hi User Error

This converts to 37.5 mph @ 4600rpm using my old 4 blade 18 pitch prop. (pitch measurement is universal 1 inch per rotation) Changing to a 15 pitch 3 blade stainless prop gave me the same top end 37mph but lifted the rpm to 5300, which is too high.
By comparison to the 18 pitch the hole shot with the 15 was great, but by my standerds it is still poor.

I took the prop to a professional prop shop to check and they have adjusted the pitch to 17.5 with a 1mm cup on the trailing edge. The computerised measurement of the prop showed each blade was about 0.25 of an inch out. Not much but enough to make a difference on an underpowered boat. I will be testing it this weekend and will let you know.
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Mark, maybe you should shoe-horn a V-8 in there? :smt001

I guess nobody is going to convince you that the boat is not under-powered. But, for the boat's designed/intended purpose it is actually one of the best boats out there - especially at it's price point.
 
Lazy Daze said:
Mark, maybe you should shoe-horn a V-8 in there? :smt001

I guess nobody is going to convince you that the boat is not under-powered. But, for the boat's designed/intended purpose it is actually one of the best boats out there - especially at it's price point.
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Yeah I agree, my 2000 180 meets my needs for a first boat I bought the smaller motor so we could enjoy the boat and not break my pocket in fuel to play all weekend. It's just a lil 4 cyl it's not gonna be a speed demon. Do I wish I could get a bit more top end out of it sure.. but even at a top end of 32mph @ 4200 which is where I am right now I find it fun... It's more of a relax thing to me. If I want to go fast I've got a GSXR 1000 in the garage that i've had up to 186 mph on the speedo, 174 on GPS. So speed wise nothing other than a bike is really going to make me pucker. But thats not why I bought the boat. I do look forward to your openion of the repitched prop the SS Quicksilver 17 I've currently got installed has a small ding or two so I'm wondering if I should have it looked at. I put my alum 21 on the other day for 10 minutes and hated it. 15+ seconds to plane out 25-27mph top end at like 3400 rpm WOT trimmed out. It might of had a bit more if I let it run out for a few more miles but it was so nonresponcive I made two passes and back to the trailer pulled it out the water swapped back to my 17 Stainless and redunked.
 
User Error said:
Yeah I agree, my 2000 180 meets my needs for a first boat I bought the smaller motor so we could enjoy the boat and not break my pocket in fuel to play all weekend. It's just a lil 4 cyl it's not gonna be a speed demon. Do I wish I could get a bit more top end out of it sure.. but even at a top end of 32mph @ 4200 which is where I am right now I find it fun... It's more of a relax thing to me. If I want to go fast I've got a GSXR 1000 in the garage that i've had up to 186 mph on the speedo, 174 on GPS. So speed wise nothing other than a bike is really going to make me pucker. But thats not why I bought the boat. I do look forward to your openion of the repitched prop the SS Quicksilver 17 I've currently got installed has a small ding or two so I'm wondering if I should have it looked at. I put my alum 21 on the other day for 10 minutes and hated it. 15+ seconds to plane out 25-27mph top end at like 3400 rpm WOT trimmed out. It might of had a bit more if I let it run out for a few more miles but it was so nonresponcive I made two passes and back to the trailer pulled it out the water swapped back to my 17 Stainless and redunked.
Click to expand...

PM sent.
 
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