Walbro had-79a fuel pump diarpham

[stilh036prohog]

Working on the shindaiwa 488. Which one to use? 1,2 or 3? #4 is what found in it.

 

[stilh036prohog]

Hda

 

[HarleyT]

Use the one that is just like it.

Take out that metering needle and clean the passage through to the screen

 

[pioneerguy600]

Working on the shindaiwa 488. Which one to use? 1,2 or 3? #4 is what found in it.

#2 for ethanol laced gasoline.
#3 is for non ethanol type fuels but it is not the correct diaphragm for that carb, it is open over the impulse driven pump area. (edited)

 

[stilh036prohog]

Use the one that is just like it.

Take out that metering needle and clean the passage through to the screen

I did. So what was in it right then. Is what the symptoms of a bad check valve?

 

[HarleyT]

#2 for ethanol laced gasoline.
#3 is for non ethanol type fuels but it is not the correct diaphragm for that carb, it is open over the impulse driven pump area. (edited)

Look at #1 again.......

 

[HarleyT]

Your main problem is likely all of that scum and varnish in it!!

 

[HarleyT]

Was this a "before" pic?

 

[HarleyT]

What does the other side look like?

 

[pioneerguy600]

Look at #1 again.......

Do they make these new kits so that a combination of diaphragms are used, like #1 along with #3. I have encountered AM kits where none of the gaskets and diaphragms were correct. I only use OEM or Stens kits so these AM kits are baffeling.

 

[HarleyT]

Do they make these new kits so that a combination of diaphragms are used, like #1 along with #3. I have encountered AM kits where none of the gaskets and diaphragms were correct. I only use OEM or Stens kits so these AM kits are baffeling.

I have seen kits with doaphrams with the flappers cut out like that, I believe they were layed atop the one with flappers. I cannot remember ever installing one like it, I always picked what was in the carb, shape wise, and put
that back in the carb.

 

[HarleyT]

Here is a d20-wat kit with the extra non-flapper ones...

 

[pioneerguy600]

I have seen kits with doaphrams with the flappers cut out like that, I believe they were layed atop the one with flappers. I cannot remember ever installing one like it, I always picked what was in the carb, shape wise, and put
that back in the carb.

I am thinking that they must be designed for a piggyback installation, the one with flaps to be put on the machined surface first, the one with the pump diaphragm installed on top of the first to seal the impulse over the pump side. I have had a few carbs sent to me that had the wrong diaphragms installed from these new AM kits, the saws would flood out immediately.

 

[HarleyT]

Yeah, I was guessing that they were there to "stiffen" or reinforce the pump membrane somehow.

 

[pioneerguy600]

I find that the black rubber type diaphragms worked the best, they were more pliable but they can`t stand up to the ethanol in todays gasoline. The diaphragms that can withstand the ethanol are less responsive but will still allow the carb to keep the engine supplied, throttle response is a little slower, doesn`t matter to the masses.

 

[HarleyT]

I find that the black rubber type diaphragms worked the best, they were more pliable but they can`t stand up to the ethanol in todays gasoline. The diaphragms that can withstand the ethanol are less responsive but will still allow the carb to keep the engine supplied, throttle response is a little slower, doesn`t matter to the masses.

Black rubber..........

OOOoooo baby..........

 

[pioneerguy600]

Black rubber..........

OOOoooo baby..........

Dreamer!

 

[stilh036prohog]

#2 for ethanol laced gasoline.
#3 if you are sure you will not be using any gas with ethanol in it.

Good to know.

Was this a "before" pic?

 

[stilh036prohog]

That was after isprayed it with carb cleaner. I wonder why the one's without the flaps were in the kits.

 

[HarleyT]

You need to go over to the other side, and remove the needle, and hold the carb up to a light, and look through the passage under the needle, and look through to the screen. You will see how choked up it is with gunk.
Replace the screen after cleaning out the passage.