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Engine surging at idle

freightguy

freightguy

Active member
I am looking for help on this one. Maybe this happened to someone else. I put my boat in the water for the week at the marina here. I used one day and all was good. 2 days later I went to use it again and went to get it warmed up before putting my gear in and taking off. When I started it up the loq oil alarm came on. I shut it down and restarted it and it did it again. I shut it down and went back to grab some tools. When I came back I started it again and the alarm did not sound. However I notice a pretty good sized smoke cloud from after the initial start up. So, not thinking much of we went out for the day and everything was great. 2 days later I go to use the boat again and now it is surging at idle and/or wont stay running at idle. Made it real hard to get the boat on to the trailer. Wondering if anyone has knowledge on this. I made a 30 second video so you could here it. Sorry it's sideways, but its more about the sound I think, but there is a good amount of smoke as well.
http://www.youtube.com/watch?v=M8YfwUsj5N4

You may have to turn your volume up to hear the surging.
Thanks,
Aaron
 
In doing some research online I am finding that people had problems with bleed valves getting clogged along with a check valve. I have been told to look for a "flow chart" and bleed valve diagram. Anyone know where I could find that?
 
atc250r said:
Have you looked around on Scream and Fly? Tons of info over there.
Click to expand...

Yeah I have been in and out of there all day. Info overload on that site. No complaints though. I just ran a tank of fuel through it with an ethanol treatment. I found a post from someone with the same problem that turned out to be clogged bleeder valves/lines. Remedy was simply to spray seafoam in the carbs to clean them. I think I will do that next time I get back to my boat in a month or so and run so seafoam in the fuel. We'll see what happens. Thanks for the response.
 
UPDATE on this post. Got back to River Ranch last week and was able to drain the carb bowls and thoroughly spray them out with carb cleaner and the carbs in general. I would sprayed the carbs clean on the outside and also the inside with the motor running. I sprayed them enough to kill the engine several times and let it sit a few minutes, then repeat. I also have Seafoam in the tank. I then let the boat sit a full day and then fired it up again. Now it holds idle and only surges once in a while.
Next day I put it in the water and it fires right up and starting giving me the warning buzzer for the oil injection. I just had the cowling off and I know the reservoir on the engine is full so I run the 50 feet to the dock. I start checking and I want to look in the main oil tank to make sure even though it looks 70% full, I unscrew the lid and a loud pop happened. Seem to me the tank had a large amount of vacuum in it. I put the cap back on and the alarm never came on again. check valve maybe?
We ran the boat for a couple hours at mid throttle and low speed and all was good. Can back into the marina and as soon as I reached the docks it starting stalling. Bummer. got it tied up and went for my Jeep. Came back to the boat and it did not really want to stay running but it did, enough to get me off the docks. Then by the time I got to the trailer it was running very good.
Could I be experiencing idling issues due to engine temp? Could it still be varnish in the carbs?
 
Hey Aaron, I don't have a solution, but your syptoms are awfully similar to one of my motorcycles with CV carbs when they sit too long.
Seafoam usually clears it up, but not all the time.....sometimes I do get that little surge when hot also....but thats just tuning i guess.
How does your clear filter look, if there is any junk in there could be junk in the idle valve, especially if it runs good at mid trottle and wide open.
That could clear up and get clogged anytime if the filters dirty....or a bad case of varnish.
Did you check if there is still vacum in the oil tank, if the breather hole is clogged that can cause reduced oil flow....
I may be wrong, these are just suggestions from my motorcycle experiences.
Do you use Stabil? Gas should be varnish free?
Good Luck.
 
To me is sounds like there could be some back pressure in the lines. Or a check valve on the top of the oil res. If the oil reservoir is not allowing pressure through then it does all of a sudden, you could get this surging.

Take the cap off and soak it in gas. A solvent may damage the plastic.

Also check the oil lines. If they are from 88 they are most likely gummed up inside. Run some fuel through them as well.

I am just thinking out loud here.

Good luck.
 
I had an issue that sounds a little like what you're describing and it was the power pack on one bank of cylinders starting to go - I have a Merc XR4.

The weird thing was I had an intermittent loss of power, but the alarm would also sound as well, when I asked my pal at the marina about it, he said that's somewhat typical of a powerpack on it's way out, as a lot of the systems are interconnected.

Kind of a longshot, but I thought I'd throw that possibility out there.

-Chris
 
Thanks for all the input guys. I think everyone has a viable thought going on. I am a full time motor homer, so I travel quite a bit. I store the boat at River Ranch in Florida, but I am not by it all the time to try things and run it often. Hence the reason for the delay in my update. I am the 3rd owner to my knowledge and it ran great when I got it. Then I put it in storage for 3 months while I went away and this problem came right after. Also when I took it out of storage I was nervous about running fuel with ethanol in it so I got some stabil ethanol treatment. I was wondering if the treatment loosened up some crud that then traveled to the carbs. My plan now is to run a few tanks of gas with the seafoam in it and see whats up. Meanwhile I will check out the filters and try to clean out the vent/cap on the oil. I will have to do some homework on the powerpack as I dont know anything about what that is.
 
Chris said:
I had an issue that sounds a little like what you're describing and it was the power pack on one bank of cylinders starting to go - I have a Merc XR4.

The weird thing was I had an intermittent loss of power, but the alarm would also sound as well, when I asked my pal at the marina about it, he said that's somewhat typical of a powerpack on it's way out, as a lot of the systems are interconnected.

Kind of a longshot, but I thought I'd throw that possibility out there.

-Chris
Click to expand...

Well it may seem that you are right Chris. I was able to use the boat fine all year and recently it got worse. I had a tech come out and he found I was only getting spark to two cylinders while under 1500 RPM's. He told me there are two side to the stator. Low and high side. My low side is gone as well as the power packs. I got them ordered as well as a trigger. I will report again when they are installed and I have a result.
 
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