Vacuum Leak

[packman35]

I am still trying to get my 93 115 running after a carb rebuild. It won't idle unless I shoot fuel in with the primer solenoid and is lean at full throttle. I assume I have a vacuum leak somewhere. I have replaced all the hoses, etc. so I am left with the gaskets.

My carbs have the plastic bowls. When I first assembled the carbs, fuel leaked from the bowl gasket when I pumped it up with the primer bulb. I tightened the screws and now there is no fuel leaking out.

But I am not certain that there is no air leaking in.

Is there any trick to making sure I get a good seal on the bowl and idle air chamber gaskets? I used new gaskets on both and installed them dry per the OEM manual - no gasket sealer.

Any ideas are appreciated.

 

[packman35]

Re: Vacuum Leak

Anyone?

 

[robert graham]

Re: Vacuum Leak

Are your carb floats set right? the level in the float chamber and the operation of the float needle valves is important.

 

[packman35]

Re: Vacuum Leak

As far as I can tell they are. I have the drop set per the manual. I don't have the OMC gauge they show in the manual but the float looks like it is set correctly in the "floated" position (parallel to the bowl).

 

[fch2cxr]

Re: Vacuum Leak

Did u had this problem before the re built??? If in the water if you accelerate will the motor stay running??? if the answer to this two question is NO you might be looking at the our fuel pump itself...try pumping the bulb and see if stays running then if so...it is your fuel pump, other wise there is an issue with your idle circuit? did you made sure your idle orifice was clean w/o obstructions??? need to make sure the idle air passages are unobstructed as well..good way to do this is by pushing carb cleaner fluid thru it...

 

[packman35]

Re: Vacuum Leak

Yes and no. The engine would start and idle but it started getting harder to start and would stall at idle occassionally as time went on. It would run find at mid to full throttle (but I suspect it was running lean). That's why I rebuilt the carbs. I figured they were getting dirty and needed a cleaning. I cleaned all jets, orifices, etc. mechanically (with a wire) and with carb cleaner.

 

[psteurer]

Re: Vacuum Leak

It sounds like there is still some crude in the idle circuit. I am not familiar with your carburetor but they all have core plugs. You should have gotten them in your carburetor rebuild kit and they are silver disks about 1/2 inch in diameter.. Locate the plug on your carburetors that are closest to the idle orifice or idle needle valve. Pry it out with an ice pick (do not go too deep) and take a look inside the hole. If you have crude in there, clean it out and that could solve your problem.

 

[packman35]

Re: Vacuum Leak

I removed the core plugs during the 3rd time I rebuilt it. They were clean. I really don't think I have any crud in there. I am fairly sure it is an air leak somewhere. Where should I be looking for vacuum leaks?

Bowls/gaskets?
Idle Air plate/gasket?
Carb to Manifold?
Fuel lines - all replaced
Oil line to VRO - not yet replaced

Am I missing anything? Would a small perforation in the fuel pump diaphram act like this?