4.3 Surging in rough water

[smarks]

1989 4.3 Cobra: 19' Bowrunner
Finally got the lake this holiday weekend to have some fun and for the most part I did. Sort of a sea trial/time with wife and friends thing.

Ran kids around on the tube for awile and boat was running great.

Went for a cruse ride with my wife and my son and his wife when
after running mid throttle for about 10-15 min I got into some rough water.
Bounced around a bit, then motor started "Surging" in the 2-3k rpm range.
Had to feather throttle to keep motor running.

This has happened before to a lesser degree but seems to be getting worse.

After this last episode I reversed coarse and headed back towards launch and by the time I got back symtoms had disappeared. Motor has a fresh tune-up as well as new filters.

Boat is new to me so I don't know how long it's been for a carb rebuild if ever!

I have read several post's on "Surging" but would like to get some fresh ideas from the group. Any thoughts would be great.
Regards
Steve

 

[smarks]

Re: 4.3 Surging in rough water

Guess I'm on my own on this one...

 

[SeanMcl]

Re: 4.3 Surging in rough water

Guess I'm on my own on this one...

Nah, sometimes the post just has to ripen a bit.

I would start by cleaning your fuel float needle/seat and setting the float. If the float is prone to stick open or shut, you would have symptoms like you describe. Rebuilding the carb is at your discretion.

Next I'd look for low fuel pressure or a restricted fuel feed between the tank and the carb. Those things are less likely to be the culprit, but may be a contributing factor and are easily checked with a pressure/vacuum gauge.

 

[rad1026]

Re: 4.3 Surging in rough water

something similar happened to me a while back but it was more cutting out then surging. When I would hit a wake the engine would cut out for a second then kick up again. Turned out to be a lose wire at my ignition key. Purple wire I believe.

 

[smarks]

Re: 4.3 Surging in rough water

Thanks for the replies, this is difinatly fuel related. I had the ignition switch out over the winter and tightned and cleaned all connections. I'm pretty sure it's the carb due to it's age and lack of maintence from previous owner.

To my knowledge its original so 21yrs old.. I've tried to run "Sea Foam" through it but Like I said in my first post it seems to be getting worse.

Thanks again
Steve

 

[smarks]

Re: 4.3 Surging in rough water

Decided to replace carb with a rebuilt one. Removed the old one today, not so east of a job but I got it out.
I thought I would check it out on the inside while waiting for the rebuilt one to show up.
Removed top to expose floats and the like. There was some crap in there that reminded me of wet sawdust. The pump seemed to be operating fine.
So I believe the trash in there is causing my surging problem. I had just changed out all the fuel filters so it makes me wonder if the tank has trash in it as well??
Steve

 

[Bondo]

Re: 4.3 Surging in rough water

So I believe the trash in there is causing my surging problem. I had just changed out all the fuel filters so it makes me wonder if the tank has trash in it as well??

Ayuh,... Probably...

 

[smarks]

Re: 4.3 Surging in rough water

Update: Ok, so I finally have the rebuilt carb in place along with a new fuel/water sep. as well as a new carb filter. Turned the motor over a few times and it fired right up.

I set the idle and it seems to be running fine but it was running fine before on muffs.

When I changed out the fuel/water sep. and dumped the old one it was about half full of water. This filter was brand new and had approx. 14 gal of fuel run through it.

I also pulled the fuel tank filler tube and checked the screen as well as the anti siphon valve. All was well.

So, tommorow my plan is to dip the boat in the lake and run the remainder of the fuel out, at the same time, I'll be stopping and spinning a few fuel/water sep. on. I figure about two or three along with the new one on ther now.

I,m hoping to rid the tank of all water and possibly any other contaminents that may be lurking. Then fill her up and dose with seafoam on the way home.

I'm hoping this will fix her up for the summer

Steve

 

[smarks]

Re: 4.3 Surging in rough water

Update: for anyone interested, me and my son in law took the boat to the lake today and did the filter thing.

The boat ran great, we ran it for about an hour & half with no problems. I was able to extract a few ounces of water like I wanted. I'll continue to do this as long as I'm getting signes of water in the fuel/water sep.

At $10.00 a piece it's starting to add up but it's working and like I said the boat is running great. No more surging and rough idling or stalling. The carb rebuild really made a big differance along with getting rid of the water.

It was a good trip and a good day on the lake.
Steve

 

[Bondo]

Re: 4.3 Surging in rough water

No more surging and rough idling or stalling. The carb rebuild really made a big differance along with getting rid of the water.

Ayuh,... Great News,... Glad it worked out for ya...

 

[CChase86]

Re: 4.3 Surging in rough water

Do you mean to say you were dumping the contents of the water/fuel separator and getting water?

 

[smarks]

Re: 4.3 Surging in rough water

Yep! If you dump it into a clear bottle or pan and leave it settle for a few moments the water will pool at the bottom of a bottle ar look like an underwater oil slick in a pan container.

Now I'm only talking an ounce or so but still over time if you wern't empting and replacing the fuel/water seperator it would add up until the carb has nothing left to suck up but water.

Hope this answers your question.

I seen this procedure on Deadliest Catch, where the Time Bandit was taking on water and contaminating there fuel. They just kept replacing there Fuel/Water sep. filters until they were able to clean up there tank.

Regards

Steve

 

[bruceb58]

Re: 4.3 Surging in rough water

Might just want to remove the fuel sender and pump out the bottom layer(water) out of the tank.

 

[wire2]

Re: 4.3 Surging in rough water

If there's only a bit of water still in the tank, pour a few ounces of gas line anti freeze (methyl hydrate) into the tank. It will mix with the water and allow it to mix with the gas. In that form it will go through the filter, pump & carb with no ill effects.

 

[smarks]

Re: 4.3 Surging in rough water

Thanks for the replies, I'm going to keep both ideas to fall back on if water continues to show up in the next couple of filters changes.

I need to get one of those liquid pumps that pulls a vacumn and holds about 5quarts. Not sure where to get one??

I've heard of them used for sucking oil out from the dip stick. But I could use it to suck the gas tank as well. I'll look around.

Thanks to all. Hope this post has helped someone out there.
Regards
Steve

 

[Rscardina]

Re: 4.3 Surging in rough water

do what wire2 says...its a lot less expensive... and you dont have to keep throwing them filters away...thier designed to seperate the water from the feul..so just dump and put back on ...why going new all the time?

i would seriously invest in a couple bottles of dry gas and let it run through..

another thing i do often is at the end of each season i dump several bottles of dry gas, stabil and then octane boost frist thing in spring (i usually try to drain the tank but if i have a descent amout of feul ill keep it )

PS..water is more dense than feul, so when you run fast the water pools at the pickup of the tank..if you can trim it way up it may speed up the water removal for you...

 

[smarks]

Re: 4.3 Surging in rough water

If there's only a bit of water still in the tank, pour a few ounces of gas line anti freeze (methyl hydrate) into the tank. It will mix with the water and allow it to mix with the gas. In that form it will go through the filter, pump & carb with no ill effects.

I'm going to give this a try as well as, maybe recycle some of the Fuel/water seperators. That will save me a little money.

I just don't want to contaminate the freshly rebuilt carb.. That could get expensive!

We are going to go to Lake Hartwell on the Georgia side for a week in July the week after the 4th. The water there is normally very smooth/calm.

I can't wait to open it up a bit and make sure I have the correct prop on it.

Thanks to all

Steve