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Recent Service, now engine is very spluttery

#1

andybtsn

andybtsn

Hi all,
I’m not sure how to explain the sound so I uploaded a video, hopefully this helps.

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At the end of last summer the mower was increasingly getting harder to start, so thought it was worth servicing.
I topped up the oil, changed the spark, fitted a brand new carburettor, replaced the gaskets, replaced the filter and swapped out the air intake manifold that had cracked. Cleaned everything, drained the fuel and cleaned the fuel tank.

Any ideas?


#2

ILENGINE

ILENGINE

The carb surface were it mounts to the fuel tank has warped allowing the diaphragm to get sucked under the end and you are pulling fuel around the edge of the diaphragm causing rich running. At a minimum will need to pull the tank/carb assembly and replace the diaphragm between the two parts, or replace the carb with a new diaphragm


#3

andybtsn

andybtsn

ILENGINE said:
The carb surface were it mounts to the fuel tank has warped allowing the diaphragm to get sucked under the end and you are pulling fuel around the edge of the diaphragm causing rich running. At a minimum will need to pull the tank/carb assembly and replace the diaphragm between the two parts, or replace the carb with a new diaphragm
Click to expand...
Hi, the carb came with replacement diaphragm which I have put in. Not sure this can be the problem? Shall I take some pics?4BB59821-5F90-43B9-8123-FAA5749326D3.jpeg


#4

ILENGINE

ILENGINE

Did you install the diaphragm next to the tank and then the gasket and then carb. That sputter is very familiar which is the reason that I suggested the diaphragm


#5

andybtsn

andybtsn

ILENGINE said:
Did you install the diaphragm next to the tank and then the gasket and then carb. That sputter is very familiar which is the reason that I suggested the diaphragm
Click to expand...
I’m starting to wonder if I just installed one, they both looked very similar. So in theory do the gasket and diaphragm sit on top of each other?


#6

B

bertsmobile1

Yes
I always do those carbs upside down
So holding the carb in my left palm I sip 2 screws in on opposite side which I keep in place with little finger & thumb
Then
1) place spring in carb
2) place gasket on carb
3) place diaphragm on gasket
4) place tank over carb making sure the screws engage with their holes
5) Push the firmly together then invert & do up the screws lightly, replace the remainder the tignten as you would do a head in a criss cross mannar

By doing this way the gasket & diaphragm are always properly aligned & the spring never falls out .


#7

andybtsn

andybtsn

bertsmobile1 said:
Yes
I always do those carbs upside down
So holding the carb in my left palm I sip 2 screws in on opposite side which I keep in place with little finger & thumb
Then
1) place spring in carb
2) place gasket on carb
3) place diaphragm on gasket
4) place tank over carb making sure the screws engage with their holes
5) Push the firmly together then invert & do up the screws lightly, replace the remainder the tignten as you would do a head in a criss cross mannar

By doing this way the gasket & diaphragm are always properly aligned & the spring never falls out .
Click to expand...

That’s worked. Thanks a lot!!


#8

andybtsn

andybtsn

ILENGINE said:
Did you install the diaphragm next to the tank and then the gasket and then carb. That sputter is very familiar which is the reason that I suggested the diaphragm
Click to expand...
Thank you for your help :)


#9

andybtsn

andybtsn

A slight thread revival but it’s relevant to why I serviced the mower in the first place.

Again, at the end of the summer the only way I could get it started was when the fuel tank was full. If it was half full I could never start it at all, the same thing occurred today, the usual prime occurred but on half a tank it just wouldn’t start. Topped the fuel up and hey presto it started. Any idea why this would be?


#10

B

bertsmobile1

If you are talking about the old carb then apart from the diaphragm being work out so not strong enough to suck the fuel from the bottom you also get cracks in the pick up tube or plain blocked filters .


#11

andybtsn

andybtsn

bertsmobile1 said:
If you are talking about the old carb then apart from the diaphragm being work out so not strong enough to suck the fuel from the bottom you also get cracks in the pick up tube or plain blocked filters .
Click to expand...
No this happened on the old and new carb, can it be anything else? Thanks


#12

B

bertsmobile1

Was the carb bought from a mower shop or genuine on line pars retailer or a $10 ebay/ amazon lucky dip ?


#13

andybtsn

andybtsn

bertsmobile1 said:
Was the carb bought from a mower shop or genuine on line pars retailer or a $10 ebay/ amazon lucky dip ?
Click to expand...
genuine one. Like the one it replaced


#14

B

bertsmobile1

The fact that the problem is the same with both carbs & responds to variations in the height of fuel in the tank points to a pump failure of some sort.
The most usual tank failures arise from the tank warping or from corrosion around the diaphragm.
Once I have seen the threads pulled up on an alloy tank but to this day can not work out how the owner managed that .
So slip it back off and run a strait edge across the mating surface .


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