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pulse limiter

J

john j

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I have a 99 johnson 70 hp i would like to know how to test the pulse limiter ? and do they give much trouble if so what would the symtoms ?
 
There really is no test for them and the newer "blue" ones seem to give no probs. You can remove it and see if it has any carbon build up in it. If it does clean it up with some de-carb.
 
I have never seen a bad pulse limiter. If the engine is not backfiring and runs without having to pump the primer bulb, the limiter is working. If you are still unsure, just buy a new one, they are cheap. Why are you concerned about it? Does the engine run normally?
 
Unfortunately only one way to test.
Lean out the engine until you start getting crank case combustion.
If that blows your pulse membrane to pieces, change the limiter!!
Another way to check is to look for carbon on the crank case side of the pump membrane.
If carbon deposits, change!
 
Now why would anybody want to lean out the mtr to check the pulse limiter or pop a vro pump. Any ?? about it, just replace it. Cheaper than vro's. Haffiman, have you ever checked what it says in the OEM service manual for pulse limiter servicing???
 
I have never found a 'defective' pulse limiter, however numerous 'blown' pump membranes.
A general rule:
If engine starts 'sneezing', fix it before other and perhaps more expensive parts blows up.
 
Initially, a pulse limiter was not used. The result was (in a few engines) that the flames that may occurr within the crankcase would melt anything on the other side of the crankcase pressure/vacuum hose.

If your fuel pump (any kind) operates as it should, has not melted or exploded lately, consider the pulse limiter to be functional. :)
 
VRO pumps are quite large.----A pressure spike can do damage to the plastic housings on the air motor of the VRO.--------The pulse limiter is designed / calibrated to close should there be too much air flow to the air motor.--Thus it prevents damage to the pump.
 
racerone said:
VRO pumps are quite large.----A pressure spike can do damage to the plastic housings on the air motor of the VRO.--------The pulse limiter is designed / calibrated to close should there be too much air flow to the air motor.--Thus it prevents damage to the pump.
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Thanks, I didn't know whether it was a one way valve or what it did.
Many parts in these engine are not explained in any detail now I know what it's for, to keep crankcase pressure from blowing out the diaphragm in the pump.
 
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