Mity Vac problems

[david newbie]

I am working on a 394 and discovered fuel is gushing out of the top of the walbro carb as soon as I put fuel in the tank. Thought I would pressure test the carb, but my mity vac is acting weird. It will build up vacuum but not pressure. I tested it several times(the tool) by blocking off the end of the tube/. Do these vacs require any lubrication? Tool is not all that old and has not seen much use

 

[Mad Professor]

Carb most likely has a problem with the metering side. Needle/seat/lever.

Can't help with the Mity vac

 

[Chevboy0167]

Which model of vac/pump do you have?

I see there are service kits....




https://www.skf.com/mityvac/products/hand-vacuum-pressure-pumps

 

[david newbie]

Which model of vac/pump do you have?

I see there are service kits....

View attachment 1227834


https://www.skf.com/mityvac/products/hand-vacuum-pressure-pumps

I’ll have to look for a number. Thanks

 

[dwaugh]

I do remember on my old Mighty-vac there were some parts that I needed to occasionally clean and lubricate. I think I remember some O-rings and sealing surfaces that I put silicone faucet type grease on. Check the mechanism that makes it go from pressure to vac. That was the cheap all plastic one, I have a new metal one that I have not used yet.

 

[guym3]

Look on youtube at vintage engine repairs where Tom has done an excellent video on stripping down and servicing a mityvac.

 

[Vintage Engine Repairs]

Look on youtube at vintage engine repairs where Tom has done an excellent video on stripping down and servicing a mityvac.

Thanks for the shoutout!

 

[guym3]

That's ok. I hadn't realised until I serviced mine, how knackered it was. Works much better now.

 

[david newbie]

Look on youtube at vintage engine repairs where Tom has done an excellent video on stripping down and servicing a mityvac.

Very helpful! Thank you!

 

[david newbie]

guess I better get a service kit.

 

[atpchas]

Look on youtube at vintage engine repairs where Tom has done an excellent video on stripping down and servicing a mityvac.

Thanks for the shoutout!

Yes, a very helpful video. Tom, do you have a link to the service/repair kit? I couldn't find one.

 

[Vintage Engine Repairs]

Yes, a very helpful video. Tom, do you have a link to the service/repair kit? I couldn't find one.

Thanks i got this one I believe

https://mityvac.com.au/product/mityvac-pump-rebuild-kit-mv5810-pump/

 

[atpchas]

Thanks i got this one I believe

https://mityvac.com.au/product/mityvac-pump-rebuild-kit-mv5810-pump/

Thanks! Do you know if the MV8500 uses the same kit?

 

[Vintage Engine Repairs]

Thanks! Do you know if the MV8500 uses the same kit?

Yes I believe the 8500 is the kit which includes the 8510 hand pump lol. At least it seems that way out here in Australia. I remember having the same question when ordering the kit lol

 

[guym3]

Before you splash out on a service kit, just strip it down and rebuild with silicon grease. Mine is good as new without any parts and you will only have wasted a few minutes if you need to buy the kit.

 

[Sidecarflip]

Before you splash out on a service kit, just strip it down and rebuild with silicon grease. Mine is good as new without any parts and you will only have wasted a few minutes if you need to buy the kit.

Exactly correct. Really nothing to wear out inside. As an aside, Harbor Freight sells a copy, pretty cheap as well.

 

[david newbie]

Before you splash out on a service kit, just strip it down and rebuild with silicon grease. Mine is good as new without any parts and you will only have wasted a few minutes if you need to buy the kit.

I like the way you’re thinking!

 

[Okie]

Before you splash out on a service kit, just strip it down and rebuild with silicon grease. Mine is good as new without any parts and you will only have wasted a few minutes if you need to buy the kit.

That is what I did when my mityvac pressure/vac failed.
I just used toothpicks and Q-tips and cleaned under the check the flapper type check valves leaving the valves in place. I now use a small Briggs red fuel filter in the external vac hose to keep bits of trash from being sucked into the tool when doing vac tests. When cleaning mine I noticed what appeared to be small bits of hard carbon inside the tool.
I did not have to use any spray silcon lube when cleaning mine even though I had a can on the shelf.
Some of the mityvac kits now days are around $20 and may not even be needed.

You can review IPL's and cleaning procedures on-line if needed.