Tried out boat this past weekend.

msojjo · Oct 18, 2010

Ok, so after i reconnected the vaccuum line to the throttle body again, i was able to get the boat out for the last time to try and get it rite. So i put the boat on the water on saturday morning and i buzz around the lake, and it seems to be running perfect. Gets on plane nice and great top end. Next day on sunday go out again and it runs like absolute crap. Try and get on plane and it's backfiring out the exhaust while i'm trying to get up, i finally get up and going and it runs great. Happend every time i try to get onto plane. Why one day it's perfect, the next runs like crap. It sat in the water at the dock overnight, what's going on. Why would it backfire now. This has never happened to me before in all of the problems that i have had? Please Help.

Bondo · Oct 18, 2010

Re: Tried out boat this past weekend.

Why one day it's perfect, the next runs like crap.

Ayuh,... Something Changed,... Donno what though...

Backfire through the Exhaust might be stray Igntion,....

spdracr39 · Oct 18, 2010

Re: Tried out boat this past weekend.

cracked distributor cap? maybe got a little moisture in there somehow ? does sound like something in the ignition.

Alpheus · Oct 18, 2010

Re: Tried out boat this past weekend.

msojjo said:
it's backfiring out the exhaust while i'm trying to get up.

Are you positive it was backfiring through the exhaust?

If you are hearing loud pops it could be backfiring through the carb.

If that is the case you may have been running it lean...

fat fanny · Oct 18, 2010

Re: Tried out boat this past weekend.

Sounds like you need to trouble shoot your ignition circuit along with the entire electrical harness for a short and or loose connection. My gues would be loose connection somewhere

msojjo · Oct 19, 2010

Re: Tried out boat this past weekend.

Bond-o said:
Ayuh,... Something Changed,... Donno what though...

Backfire through the Exhaust might be stray Igntion,....

The only thing that i can think of that i really changed, is i plugged in the vaccuum line to the throttle body. The other thing is that i was running the boat on the duel battery switch on both, last weekend i was running it on either 1 or 2. Could worn out batteries cause something where it was ok on two batteries then when i changed to 1 it wasn't enough?

msojjo · Oct 19, 2010

Re: Tried out boat this past weekend.

Alpheus said:
Are you positive it was backfiring through the exhaust?

If you are hearing loud pops it could be backfiring through the carb.

If that is the case you may have been running it lean...

I'm fairly sure that it was through the exhaust, but i could be wrong, it was a fairly quiet poping sound, 1 or 2 pops each time i tried to get onto plane. I have switchable exhaust and when i brought it above the water line it seemed a little louder than when i had the exhaust go through the outdrive.

How do i run it either lean or rich, it's all done by computer and no adjustments?

dingdongs · Oct 19, 2010

Re: Tried out boat this past weekend.

might be a dodgy plug breaking down under load.

msojjo · Oct 19, 2010

Re: Tried out boat this past weekend.

i am having the boat winterized at another place and told them about the backfiring, he was able to get the motor to backfire, and he said it could be possible that the thermostat is sticking open, because he noticed when the backfiring occured the temp was reading about 120, and then jumped back up to 165.

ccustomrides · Oct 19, 2010

Re: Tried out boat this past weekend.

Could be the thermostat. Cold temps and cold engine will do that. Also I did have a bad battery switch one time where number one battery position would short out and cause power loss. It would act like that under heavy load and when I used the trim. After switching to battery 2 position I figured it out. For the longest time I thought it was ignition or fuel related.
Also timing being way off will make it backfire.

msojjo · Oct 19, 2010

Re: Tried out boat this past weekend.

ccustomrides said:
Could be the thermostat. Cold temps and cold engine will do that. Also I did have a bad battery switch one time where number one battery position would short out and cause power loss. It would act like that under heavy load and when I used the trim. After switching to battery 2 position I figured it out. For the longest time I thought it was ignition or fuel related.
Also timing being way off will make it backfire.

I'll be trying the new thermostat, and i'll be checking with the battery switch, to see what happens. Timing is set with the computer.

msojjo · Oct 27, 2010

Re: Tried out boat this past weekend.

Just a little update, i winterized and while i was running it was paying attention to the temp gauge and saw that while giving more rpm 1300 to 1400my temp gauge dropped down to 120 for a breif moment and then back up again. Would 45 degrees really give me that big of a problem. I'll be replacing the thermostat in spring, eventhough i have 10 hours on the one now. Also i found the vaccum line from the throttle body to the fuel pressure regulator was not connected at the regulator, so before this problem i just found the line laying on the side of the motor. Went through the whole thing and made sure i didn't have any corroded electrical connections, it all looked good. Also while i was going through the motor i found that almost every single hose clamp on my water lines and exhaust was loose so i tightened them all up. I'm so glad to have this boat out of the shop that put the motor in, talk about half a$#.

msojjo · Oct 29, 2010

Re: Tried out boat this past weekend.

msojjo said:
Also while i was going through the motor i found that almost every single hose clamp on my water lines and exhaust was loose so i tightened them all up.

Could that have been causing my fluctuating temps? Getting air pockets in the system?

spdracr39 · Oct 31, 2010

Re: Tried out boat this past weekend.

Unlikely, water would come out before air would go in because the water pressure should be higher than the outside air pressure. maybe you just saw the thermostat opening and letting the fresh water start flowing.

Don S · Oct 31, 2010

Re: Tried out boat this past weekend.

msojjo said:
Could that have been causing my fluctuating temps? Getting air pockets in the system?

Only on the suction side of the pump could you suck air into the system, and yes, if it was sucking in air, it could cause problems.
The only way to know for sure is to run it on the water and see.

msojjo · Nov 14, 2010

Re: Tried out boat this past weekend.

Thanks Don, I cant wait to try it in spring to see if tightening all of the hoses worked.

msojjo · May 10, 2011

Re: Tried out boat this past weekend.

I think i have all of my problems figured out. This spring took it to a mechanic that i talked to several times over the winter. He told me to just bring it in and he would have it figured out in less than a half hour. He sounded confident, but i like that because everywhere else i took it, including where i had it 10 times after i had the new motor put in, because i still thought someting wasn't right. Any way got a call this morning telling me that the boat was ready to be picked up. What was wrong....................................well, the timing was off "retarted" by 16 degrees. Now he says the boat runs great, but i'll need a new prop, because i'm way under proped now. He had it at the test pond to put it under load, and was reving the motor to 2000 and was pushing the truck up the ramp......great news right...

Tried out boat this past weekend.

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