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1990 43 Rough Idle and Stalling after warming

G

glenn_w

Member
"Wow, I feel like I found the

"Wow, I feel like I found the promised land. Can't seem to find a good marine mechanic locally.
My problem is that my boat starts very well but idles rough, not really bad but worse than it should. Secondly, after running long enough to warm the engine it will immediately stall if you bring it back to idle, it is then hard to start but does start with the throtle moved to above idle. If you run it slightly above idle long enough to cool the engine it does not stall. I had it tuned up and the timing set and replaced the fuel filter/water separator. I even cleaned the carb but didn't replace any thing. This issue hasn't left me stranded YET, but it is really frustrating and hard to dock a boat without the engine running.

Thanks in advance for any and all help with this."
 
"Sounds like you have a clogge

"Sounds like you have a clogged idle circuit in the carbuerator. If it's been a long time since the carbuerator has been overhauled, it might be a good time to have it rebuilt."
 
"Thanks for the reply, that wa

"Thanks for the reply, that was my next move but I just wanted to make sure there wasn't something else that was obvious to someone. I just hate chasing problem with cash if I can avoid it. The carb is the holley 2bbl, is there any advantage between the holley and the rochester? Thanks again, Glenn"
 
"I use the Carter, and removed

"I use the Carter, and removed it to spray inside to get the check-ball free, as mine had gummed up, and was loading the motor when trolling at idle. After that it ran fine. BTW...your never chasing problems with money when dealing with a Carb, in my opinion."
 
Are you sure the problem is wi

Are you sure the problem is with the fuel system and not the electrical system? I spent half a season chasing a fuel problem only to find out I was losing voltage after it warmed up.

Rob
 
"Actually, I'm not sure. T

"Actually, I'm not sure. Thanks for the post. What ended up being your problem? This is really frustrating considering I can't really fix anything for 5 months or so because the boat is in storage for the winter but I want to hit the water running in the spring."
 
"You could check and clean all

"You could check and clean all battery connections, including the spot where the ground cable contacts the engine block. Corrosion at any of the connections might give you odd problems."
 
The main fuse at the instrumen

The main fuse at the instrument panel does seem to run hotter that I like. It has never blown but does get pretty warm. Would that indicate the kind of problem that you're talking about? I probably will rebuild the carb either way just as maintenance. Thanks again for the help.
 
"Corrosion in and on the cable

"Corrosion in and on the cables can shut the engine down completely or and/or cause bizarre, hard to figure problems. Are the cables marine grade? It will be printed on the cable. Is the boat subject to salt water? Corrosion on a cable will grow underneath the insulation of the cable. I've seen an old boat with corrosion that worked it's way 8 & 1/2 feet along a 10 foot solid copper cable. I had to peel back the insulation off the old cable to see it. All cable connections should be checked and cleaned at least every year."
 
"a voltmeter at the ignition c

"a voltmeter at the ignition coil + will tell you if you are losing voltage. Of course the one on the dash is also good to look at, but going right to the coil better.
Vacuum leak at the manifold worth checking for.
Points and condenser- general tune up with cap, plugs, wires....
Could also check the anti-siphon valve at the fuel tank. Lots of basics to check."
 
"There is no obvious corosion

"There is no obvious corosion that I saw when removing the batteries, but I wasn't really looking for it, I will try to check that this week. The general tune up was supposed to be done this past summer, but I'm wondering. Prior to taking the boat in for service and carb rebuild I changed the plugs and accidentally broke one of the boots. When I took it in I forgot to mention it. Upon completion and paying the $400 bill, they told me that the compression was down on #3 but didn't mention the broken boot and didn't replace the wires. I checked the compression myself and had all reading above 140# so I wondering how much they actually did. Thanks to all of you for helping. Will probably rebuild the carb just as a matter of maintenance and check all of the ignition again and electrical for corrosion. The main fuse at the instrument panel seems to run fairly warm, would that indicate any specific problem?"
 
"Stop messing with electrical

"Stop messing with electrical components and rebuild the carb! Hey, if it starts and runs okay except at idle, then obviously it's not the ignition system! The opposite would be the case if that was it.

Jeff"
 
"Thank you everybody! I will r

"Thank you everybody! I will rebuild the carb, check the fuel pump, check the voltage at the coil and check all wires for corrosion. I will post when I have the answer, probably won't be till spring though. Thanks again!"
 
"Glenn and Fastjeff,

I was

"Glenn and Fastjeff,

I was only suggesting another angle. My boat started fine and ran rough at idle and would power up cold. Once the engine was warm I sarted losing voltage during accel. If the engine is in N it would run but roughly. This sounded like the same problem you were having. I rebuilt both carbs, changed all filters, tested the pumps, blew out the fuel lines/vents and changed the fuel in the tank all to no avail. Then I found the low voltage problem and chased that for awhile which led to finding several problems there. I still have a low voltage problem with the Port engine when running off the upper station ignition. I guess I'll have to wait till spring for that. Again, I was not trying to question anyone but to offer my own experience with a problem. I thank all who helped.

Rob"
 
"Spring is finally here and th

"Spring is finally here and the boat is out of storage. The first thing I did was replace plugs and wires, that immediately smoothed some of the problem. Checked the voltage at the coil got around 10 on the + side and around 7 on the side to the distributor. Seems to drop when when warmed up though. I'm going to try a new coil. Will also be doing a rebuild on the carb just for maintenance, and possibly the fuel pump. Thanks everyone for your help."
 
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