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View Full Version : Need Help With Carb. Problem


skilew
05-18-2006, 01:55 AM
I have an older boat that has the 4160 Holley Carb. I just got the carb. back from being completely rebuilt and engine tested. I put the carb on but it will not run unless I hold the Butterfly valve about 3/4 closed.

Any thoughts to the problem? I called the rebuild shop and they assured me that they engine tested it and it ran fine.

erkoehler
05-18-2006, 02:13 AM
JimN or EngineNut will be along to help you out shortly...please hold! :)

T Scott
05-18-2006, 08:48 AM
My guess is a vacuum leak. Since you have to hold the butterfly partially closed, you are limiting the amount of air that goes into the carb. It is likely getting air from somewhere else so I would check the base gasket around the carb.

Workin' 4 Toys
05-18-2006, 10:27 AM
This is not going to help your immediate problem. But the last few times we have had carbs done, we have the guy take the boat out for a test drive, if there are issues, he fixs them on the spot.
:twocents:

ted shred
05-18-2006, 01:12 PM
Is the motor at opperating temperature? If it happens with the motor cold it most likely a choke adjustment problem. Also possibly an air leak at the base gasket. If boat has not been run in a while don't over look the possibility of contaminated fuel. The gas now of days is junk and degrades much quicker than it used to.

jayderwin1
05-18-2006, 01:18 PM
try tweaking you airfuel mix thats what i had to do when i got mine rebuilt last summer

skilew
05-18-2006, 09:57 PM
Is the motor at opperating temperature? If it happens with the motor cold it most likely a choke adjustment problem. Also possibly an air leak at the base gasket. If boat has not been run in a while don't over look the possibility of contaminated fuel. The gas now of days is junk and degrades much quicker than it used to.

It happens when the engine is at operating temperature. I have tried to find a vacuum leak by spraying carb/choke cleaner around the base gasket to see if I could detect any change in the engine idle, no luck but I was trying to do this with one hand holding the choke butterfly partially closed and using the other hand to spray around the carb. not the most controlled test.

redmike
05-18-2006, 10:35 PM
ok with that, are you sure all of the vacuum ports have a plug/hose atatched? From what you have described, it sure sounds like a vacuum leak......

88Tristar190
05-19-2006, 12:32 AM
Check your fuel pump pressure. When I bought my boat, it loped real bad in the high idle position and would not idle at all with the handle in the middle. I changed plugs, rebuilt the carb and still could only make it idle by turning the idle screw (on the linkage) way in. I ordered a new pump from MC (fast shipping!) and put it on, started the boat and it was idling at 2400 :eek: .
So I turned the idle screw back out and adjusted the mixture screws, now it purrs like a kitten.

Good luck.
:toast:

rasmithaz
05-19-2006, 01:26 AM
Let me guess.....cracked base!

skilew
05-19-2006, 03:40 AM
Let me guess.....cracked base!


I just noticed a small crack on my carb base. But not sure this is having any effect on it running. I purposely sprayed that small cracked area with the choke cleaner and did not see it make a difference. And I only have one vacuum line which goes to the PVC line and it appears to be ok.

Plan to replace the carb. base gasket tomorrow and then check again for vacuum leak.

I will also inspect the cracked area tomorrow while carb is off to see how bad it really is.

rasmithaz
05-19-2006, 03:36 PM
Now is the perfect time to ditch that carb for an edelbrock or different model Holley. Many contributers to this sight have had numerous problems with that carb. Good Luck. Pitot in mail.

east tx skier
05-19-2006, 03:51 PM
I've often spoken of problems with a holley carb, but it was a 4010, not a 4160. In the last couple of years that I've had a 4160 on my boat, I've found it to be extremely reliable. If a rebuild doesn't do the trick, and a new carb is in order, if it's a Holley, I think the 4160 is the best bang for the buck. The newer indmar carb boats run a 4150, but to get one with vacuum secondaries, you are going to spend some bucks.

skilew
05-23-2006, 07:22 PM
try tweaking you airfuel mix thats what i had to do when i got mine rebuilt last summer





You are dead on it with adjusting the airfuel mix. Adjusted out 2 turns from the seat and now it runs with the butterfly open but it needs a little fine tuning.

Now how do you adjust the airfuel mix assuming I do not have a vacuum gauge.

Thanks to everyone for the helpful advice.