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View Full Version : Vac leak @ primary throttle leak; how much is too much?


catamount
06-08-2013, 03:56 PM
I've been trying to get my '87 PS 190 to idle below 750 rpm reliably. In spraying carb cleaner searching for vac leaks, I found that I could easily stall the engine by spraying at either side of the primary throttle shaft ends (RPM drops instantly).

Is this "normal"? Or is it a fairly serious leak if I can stall it with a shot of carb cleaner?

Should I just pick up a new throttle plate?

Cloaked
06-08-2013, 04:20 PM
I've been trying to get my '87 PS 190 to idle below 750 rpm reliably. In spraying carb cleaner searching for vac leaks, I found that I could easily stall the engine by spraying at either side of the primary throttle shaft ends (RPM drops instantly).

Is this "normal"? Or is it a fairly serious leak if I can stall it with a shot of carb cleaner?

Should I just pick up a new throttle plate?New gaskets?? I'd not want one bit of leak...period.... not about the severity of a leak......

Did I mention new gaskets? (I hope I am understanding your location of the leak)....

.

catamount
06-08-2013, 04:24 PM
Hi Cloaked. I rebuilt my carb a couple of weeks ago and put the fresh "thick" (skidim) gaskets on both sides of the spacer. I do not believe the gaskets are leaking, the directed shot of carb cleaner I've aimed at the primary throttle shaft ends affects the motor instantly (probably sealing the leak momentarily).

I am fairly certain the primary throttle shaft bushings are worn. Does anyone know where I could get a replacement throttle plate?

roush611
06-08-2013, 04:47 PM
Hi Cloaked. I rebuilt my carb a couple of weeks ago and put the fresh "thick" (skidim) gaskets on both sides of the spacer. I do not believe the gaskets are leaking, the directed shot of carb cleaner I've aimed at the primary throttle shaft ends affects the motor instantly (probably sealing the leak momentarily).

I am fairly certain the primary throttle shaft bushings are worn. Does anyone know where I could get a replacement throttle plate?

Do you have any idea how much vacuum you are getting?

Cloaked
06-08-2013, 04:51 PM
Hi Cloaked. I rebuilt my carb a couple of weeks ago and put the fresh "thick" (skidim) gaskets on both sides of the spacer. I do not believe the gaskets are leaking, the directed shot of carb cleaner I've aimed at the primary throttle shaft ends affects the motor instantly (probably sealing the leak momentarily).

I am fairly certain the primary throttle shaft bushings are worn. Does anyone know where I could get a replacement throttle plate?
I'm with you now.....

You're doing good..... patience.... :D

I do not know of a parts place for the throttle. I'll look around....and hopefully someone here may have a scrapped out 4160....

.

catamount
06-08-2013, 04:56 PM
roush, I don't have a vacuum gauge at the moment. I am curious why the carb cleaner is slowing the rpms, instead of raising them.

I suppose I need to bite the bullet and pull the entire assembly off again in order to get a part number for the throttle. This stinks, I had just performed the "power valve backfire protection fix" to this throttle plate during my carb rebuild.

roush611
06-08-2013, 05:06 PM
I was wondering the same thing about the carb cleaner. My only GUESS would be its getting too much fuel when that is sprayed.

catamount
06-08-2013, 06:07 PM
I'm wondering that myself; maybe it's too rich at idle now and when I hit it with more fuel (through the shaft) it's choking out. I guess I need to drop the floats and see if that makes any difference. Either way, I'm not excited about about causing an RPM change by spraying the throttle shaft ends.