pulse nipples job.....???

bob johnson

Rear Admiral
Joined
Feb 25, 2009
Messages
4,306
35hgymf.jpg


here is a picture of my 60 degree looper crank case from a 1997 v4. as you can see one of the drain nipples is rusted through. also in the picture is the pulse nipple. I can blow through this nippled as well as such air through it....is it supposed to be a two way?

I would think it is supposed to block flow one way and allow flow the other way...otherwise why do you need a fancy nipple?

getting ready to reassemble. and need to attend to a few things....

thanks

bob
 

CatTwentyTwo

Chief Petty Officer
Joined
Jan 11, 2005
Messages
425
Re: pulse nipples job.....???

Bob, my manual says that the fitting has an integral, non serviceable check valve. It says that you can backflush it though by removing it from the block and spraying carburetor cleaner into the hose end of the fitting.
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: pulse nipples job.....???

The check valve only closes if # 4 cyl backfires. It protects the vro pump.
 

multimech

Petty Officer 1st Class
Joined
Apr 26, 2012
Messages
386
Re: pulse nipples job.....???

It is a pulse fitting which protects the fuel pump from possibly catching on fire if there is a backfire in the cylinder. I have seen thousands of them and have never found one that is bad. However, their cost is not much and it is a regular service item to change when the fuel pump is serviced or replaced.
 

bob johnson

Rear Admiral
Joined
Feb 25, 2009
Messages
4,306
Re: pulse nipples job.....???

Bob, my manual says that the fitting has an integral, non serviceable check valve. It says that you can backflush it though by removing it from the block and spraying carburetor cleaner into the hose end of the fitting.

I just read that yesterday, I couldnt find it previously in my manuals. and i found there is a spring in the valve, and that it actually is working and seems clean....I guess i didnt provide enough vacum to pull the valve closed....I assume that a back fire would have more force from the inside than my light suction on the outer end.

thanks guys

bob
 
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