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Why did I have loss of speed.
https://www.smwebhead.com/phpBB3/viewtopic.php?f=6&t=14940		 Page 1 of 2
Author:  LVChris [ Mon Jun 20, 2016 12:25 pm ]
Post subject:  Why did I have loss of speed.
Didn't really know how to word this. This is what happened...

Great day at the lake and cruising back at my normal 35 rpm about 27 mph, not full throttle. Been cruising for about 25 minutes when the boat starts to slow down. I look at the gauges, everything is normal oil pressure, temp, everything. I hit the throttle all the way down and the speedometer keeps falling. I pull back thinking somethings goin to break and idle for a few seconds. I gradually start to throttle back up and she gets right back up on plan and I cruise for another 5 minutes to the dock at 3500 rpm and 27mph.

Can't for the life of me figure out what this could have been. It happened once last summer also.

any ideas?

TIA
Author:  Boydzz [ Mon Jun 20, 2016 12:36 pm ]
Post subject:  Re: Why did I have loss of speed.
Dirty/clogged spark arrestor???

Just a guess.
Author:  babbot1 [ Mon Jun 20, 2016 12:58 pm ]
Post subject:  Re: Why did I have loss of speed.
another wild guess, sucked in some water in the fuel? Maybe you reached the limit on your fuel filter and now pulling in water with the gas.
When you increased throttle and it wasn't responding did it sound like it was bogging down?
Author:  TheDanceII [ Mon Jun 20, 2016 2:01 pm ]
Post subject:  Re: Why did I have loss of speed.
Was actual speed and RPMs slowing down or was just the speedo dropping?
Not real clear the way you worded things.

If speedo, then you picked up a piece of trash in front of the pickup. Once you slowed down/stopped, it drifted off and speedo worked again.

If actual boat speed and RPMs dropped, what did the engine sound like? Bogging? Missing? etc...
Author:  rpengr [ Mon Jun 20, 2016 2:11 pm ]
Post subject:  Re: Why did I have loss of speed.
LVChris wrote:
Didn't really know how to word this. This is what happened...

Great day at the lake and cruising back at my normal 35 rpm about 27 mph, not full throttle. Been cruising for about 25 minutes when the boat starts to slow down. I look at the gauges, everything is normal oil pressure, temp, everything. I hit the throttle all the way down and the speedometer keeps falling. I pull back thinking somethings goin to break and idle for a few seconds. I gradually start to throttle back up and she gets right back up on plan and I cruise for another 5 minutes to the dock at 3500 rpm and 27mph.

Can't for the life of me figure out what this could have been. It happened once last summer also.

any ideas?

TIA


Check the engine compartment for Gremlins!

Image
Author:  rpengr [ Mon Jun 20, 2016 2:13 pm ]
Post subject:  Re: Why did I have loss of speed.
babbot1 wrote:
another wild guess, sucked in some water in the fuel? Maybe you reached the limit on your fuel filter and now pulling in water with the gas.
When you increased throttle and it wasn't responding did it sound like it was bogging down?

+1

That does match the symptoms of getting a small amount of water through.
Author:  LVChris [ Mon Jun 20, 2016 3:34 pm ]
Post subject:  Re: Why did I have loss of speed.
Thanks for all the responses. My first thought was water in the fuel. The tach was dropping which is why I hit the throttle harder. The boat was slowing, not just the speedo, and we actually fell off plane. There was no missing or sputtering or bogging down it just started slowing down as if I had eased back on the throttle. When I pushed the throttle all the way down it kept slowing down. I just had the fuel filter and impellar replaced and an oil change at the beginning of this season (less than a month ago) filled it with gas two weeks ago and no real rain since then. It was a calm day and no water in my bilge.

Flame arrestor...that might be the culprit.
Author:  Boydzz [ Mon Jun 20, 2016 10:34 pm ]
Post subject:  Re: Why did I have loss of speed.
I'm in the middle of a steering actuator repair on my 1999 Sundowner.. When I removed the engine cover I was shocked at the amount of lint/dust/dirt/fiber-like material that was on the flame arrestor. I'm not sure if it had ever been cleaned (you have to remove quite a bit of interior before you can even remove the engine cover). I wished I had taken a pic prior to cleaning it.

Good luck in your troubleshooting.
Author:  Jdpber [ Tue Jun 21, 2016 8:55 am ]
Post subject:  Re: Why did I have loss of speed.
at the beginning of the seasons when i reverse the winterization i always use the air hose on the compressor to clean the filter and all around int he engine crevices.
Author:  LVChris [ Fri Jun 24, 2016 5:02 pm ]
Post subject:  Re: Why did I have loss of speed.
Finally got to removing the flame arrestor....I'd say it was pretty bad...

Image

Image

Image

and clean

Image

I'll give her a good run this weekend and see if it fixed the problem.

thanks again,
Author:  LouC [ Fri Jun 24, 2016 7:29 pm ]
Post subject:  Re: Why did I have loss of speed.
The black stuff is probably bits of wear from the belts, you get this a lot on boats because the pulleys wear and the belts will throw off tiny bits of rubber.
More info on your engine..FI or carb?
You said the fuel filter was replaced, make sure its tight, because if not air can be sucked in.
A tricky problem I had years ago when I bought this boat was a corroded anti siphon valve, it was restricting fuel flow to the point that the engine would start fine, rev fine in neutral, but then would not plane the boat. I had gone through the fuel system and checked everything I could think of but the anti siphon is not even mentioned in the factory shop manual. Our mechanic found this and fixed it. After that was changed I never had that problem again.
Author:  LVChris [ Fri Jun 24, 2016 8:45 pm ]
Post subject:  Re: Why did I have loss of speed.
LouC wrote:
The black stuff is probably bits of wear from the belts, you get this a lot on boats because the pulleys wear and the belts will throw off tiny bits of rubber.
More info on your engine..FI or carb?
You said the fuel filter was replaced, make sure its tight, because if not air can be sucked in.
A tricky problem I had years ago when I bought this boat was a corroded anti siphon valve, it was restricting fuel flow to the point that the engine would start fine, rev fine in neutral, but then would not plane the boat. I had gone through the fuel system and checked everything I could think of but the anti siphon is not even mentioned in the factory shop manual. Our mechanic found this and fixed it. After that was changed I never had that problem again.

Yes Lou I shredded about 5 alternator belts last year. still trying to clean that mess in my bilge. (Any tips?) The anti-siphon was checked a couple years ago so I am familiar. We'll see how she runs with the clean flame arrestor
Author:  Flyer51 [ Mon Jun 27, 2016 3:53 am ]
Post subject:  Re: Why did I have loss of speed.
LVChris wrote:
Didn't really know how to word this. This is what happened...

Great day at the lake and cruising back at my normal 35 rpm about 27 mph, not full throttle. Been cruising for about 25 minutes when the boat starts to slow down. I look at the gauges, everything is normal oil pressure, temp, everything. I hit the throttle all the way down and the speedometer keeps falling. I pull back thinking somethings goin to break and idle for a few seconds. I gradually start to throttle back up and she gets right back up on plan and I cruise for another 5 minutes to the dock at 3500 rpm and 27mph.
TIA


I just replaced my fuel pump after having similar problems. See the fuel issue thread in the engine section.
Author:  Partner Ship [ Mon Jun 27, 2016 9:34 am ]
Post subject:  Re: Why did I have loss of speed.
Flyer51 wrote:
LVChris wrote:
Didn't really know how to word this. This is what happened...

Great day at the lake and cruising back at my normal 35 rpm about 27 mph, not full throttle. Been cruising for about 25 minutes when the boat starts to slow down. I look at the gauges, everything is normal oil pressure, temp, everything. I hit the throttle all the way down and the speedometer keeps falling. I pull back thinking somethings goin to break and idle for a few seconds. I gradually start to throttle back up and she gets right back up on plan and I cruise for another 5 minutes to the dock at 3500 rpm and 27mph.
TIA


I just replaced my fuel pump after having similar problems. See the fuel issue thread in the engine section.


Similar problem on my 268. Was time for a new fuel pump. Problem solved. Well, except for the $1,000 on my credit card
Author:  LVChris [ Mon Jun 27, 2016 12:32 pm ]
Post subject:  Re: Why did I have loss of speed.
Took her out this weekend...problem got worse...I am thinking bad gas because when my fuel pump went out 4 year ago we replaced it. http://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=10192&start=15 It also acted completely different than this. When the fuel pump went out it sputtered and died at low speed/idle. This was just slowing down. At one point I was at about 3/4 throttle 3500 rpm 27 mph like normal and it just started slowing so I hammered the throttle got her up to about 4200rpm and 32 mph and then pulled back to 3500 rpm again and she ran fine for a while.

But aren't there 2 fuel pumps? Could be the IAC I guess?

Lou last time you mentioned the vent on the fuel tank. I replaced mine last summer..is there anyway to check to see if it is clogged?

TIA,
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