Vacuum Petcock Manual Conversion
Mar 3, 2017 18:24:57 GMT -5
90GTVert, humanshield, and 3 more like this
Post by dachurchpcguy on Mar 3, 2017 18:24:57 GMT -5
I have had problems with a couple bad tank mounted petcocks and cold starting issues, this mod helps with both problems, plus it eliminates the WOT fuel starvation problem with some vacuum petcocks.
There's a Youtube video on the mod, but the music is annoying and it's a really simple mod, no need to watch a video.
This mod is for tank mounted petcocks since you can simply bypass the external units. You will need tools to remove the tank, a power drill, a 0.111 inch drill bit (#34) or something close like 7/64ths or 2.5mm. (I have a HF drill set so I just picked a bit a little larger than the existing fuel supply outlet.) You'll also need a small bolt to plug the vacuum line on the manifold, unless you have another use for it. Lastly, you'll need a manual fuel shutoff, I bought a bunch of snow blower shutoffs on Amazon.
1) Remove your fuel tank and drain
2) Detach the petcock from the fuel tank and hoses
3) Carefully drill through the fuel supply pipe until you can see the drill bit in the center. The video says to simply drill through the membrane, but that doesn't always work well. I started with a smaller bit and worked my way up since my bits aren't that sharp and the center section is tough to drill with the larger bit.
Note the position of the fuel supply connection
The drill bit is visible from the top
4) Blow out the chips and debris, very important!
5) Install your fuel line back onto the petcock along with the manual shutoff.
6) Cut two short lengths of the old vacuum line and plug them with a bolt that fits tightly.
7) Install one of these short hoses onto the open port of your intake manifold.
8) Install the other onto the vacuum inlet of the petcock. The finished assembly should look like this:
Reinstall the tank and enjoy a trouble free fuel supply!.
There's a Youtube video on the mod, but the music is annoying and it's a really simple mod, no need to watch a video.
This mod is for tank mounted petcocks since you can simply bypass the external units. You will need tools to remove the tank, a power drill, a 0.111 inch drill bit (#34) or something close like 7/64ths or 2.5mm. (I have a HF drill set so I just picked a bit a little larger than the existing fuel supply outlet.) You'll also need a small bolt to plug the vacuum line on the manifold, unless you have another use for it. Lastly, you'll need a manual fuel shutoff, I bought a bunch of snow blower shutoffs on Amazon.
1) Remove your fuel tank and drain
2) Detach the petcock from the fuel tank and hoses
3) Carefully drill through the fuel supply pipe until you can see the drill bit in the center. The video says to simply drill through the membrane, but that doesn't always work well. I started with a smaller bit and worked my way up since my bits aren't that sharp and the center section is tough to drill with the larger bit.
The drill bit is visible from the top
4) Blow out the chips and debris, very important!
5) Install your fuel line back onto the petcock along with the manual shutoff.
6) Cut two short lengths of the old vacuum line and plug them with a bolt that fits tightly.
7) Install one of these short hoses onto the open port of your intake manifold.
8) Install the other onto the vacuum inlet of the petcock. The finished assembly should look like this:
Reinstall the tank and enjoy a trouble free fuel supply!.