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Floating VW
Samba Member
Joined: April 28, 2015
Posts: 1596
Location: The South Zone
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 Posted: Fri Apr 07, 2017 7:36 pm Post subject: Re: fuel pump |
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A little bit too high will just cause the air/fuel ratio to go rich, leading to excessive fuel consumption and the problems normally associated with that. But a lot too high will overpower the float valve in the carburetor and dump raw fuel down the manifold and into the cylinders, washing the oil off the cylinder walls and chewing up the piston rings.
Most ACVW carburetors like around 2-3 psi of fuel pressure. I use a Holley fuel pressure regulator to keep my Dells at about 2.5 psi. In my experience, they start to run rich at around 5 psi, and nasty things start to happen north of 7 psi. Some of the cheaper aftermarket fuel pumps have been known to put out as much as 10 psi. Effin' scary, man!
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wcfvw69 
Samba Purist
Joined: June 10, 2004
Posts: 13389
Location: Arizona
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| Posted: Fri Apr 07, 2017 9:23 pm Post subject: Re: fuel pump |
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| sammywells wrote: |
| But what will it do if the fuel pressure is high |
Send that pump back to CIP-1 and buy this-
Shameless plug. 
https://www.thesamba.com/vw/classifieds/detail.php?id=2032158
On a serious note, these Pierburg square top fuel pumps were the best made for generator powered bugs. They simply work and last for decades if they are used on a daily driver. I've rebuilt ton's of these Pierburg pumps with NOS rebuild kits. They need no additional shims or grinding of push rods. Bolt it on and enjoy 3psi of fuel pressure. I run restored Pierburg pumps with NOS fuel rebuild kits on all my VW's.
If your fuel pressure is too high, it will overcome your fuel shut off valve inside the carb causing all kinds of havoc.
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Decades of VW and VW parts restoration experience.
The Samba member since 2004.
**Now rebuilding throttle bodies for VW's and Porsche's**
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Frodge
Samba Member
Joined: October 04, 2006
Posts: 1991
Location: Dump
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| Posted: Sat Apr 08, 2017 4:22 am Post subject: Re: fuel pump |
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| wcfvw69 wrote: |
| sammywells wrote: |
| But what will it do if the fuel pressure is high |
Send that pump back to CIP-1 and buy this-
Shameless plug.
https://www.thesamba.com/vw/classifieds/detail.php?id=2032158
On a serious note, these Pierburg square top fuel pumps were the best made for generator powered bugs. They simply work and last for decades if they are used on a daily driver. I've rebuilt ton's of these Pierburg pumps with NOS rebuild kits. They need no additional shims or grinding of push rods. Bolt it on and enjoy 3psi of fuel pressure. I run restored Pierburg pumps with NOS fuel rebuild kits on all my VW's.
If your fuel pressure is too high, it will overcome your fuel shut off valve inside the carb causing all kinds of havoc. |
I have two OEM kits on hand. I also have the pretension tool that is set to 13.5mm. A nice guy from Germany was able to get the parts and build the tool for me. Is it necessary to remove the check valve? Is that still available? Is it fragile or should I just leave it alone? Do you check the inlets and how? Thanks. |
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Cusser
Samba Member
Joined: October 02, 2006
Posts: 31352
Location: Hot Arizona
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| Posted: Sat Apr 08, 2017 7:39 am Post subject: Re: fuel pump |
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| Frodge wrote: |
| Is it necessary to remove the check valve? Is that still available? Is it fragile or should I just leave it alone? |
I can't answer the above questions. But I can say that the fuel pump rebuild kit I bought a few months ago DID include the check valve, and I did install it on mine. Note that this rebuild kit had too-strong of spring so my fuel pressure was too high, until Bill (wcfvw69) provided a used spring for me to use.
When I rebuilt my fuel pump, I didn't know that the spring from the old pump diaphragm should be swapped over, and I just discarded that as the diaphragm was rock hard. Now I know.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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sammywells
Samba Member
Joined: June 17, 2013
Posts: 244
Location: southern ohio
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| Posted: Sat Apr 08, 2017 12:18 pm Post subject: Re: fuel pump |
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| So i can just swap out the spring from the old pump. Would it be best to just use a tee and a gauge to check my pressure to see it there is a problem first before tearing into a new pump. |
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calvinater
Samba Member
Joined: September 06, 2014
Posts: 3327
Location: 802 The Pointless Forrest
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| Posted: Sat Apr 08, 2017 1:14 pm Post subject: Re: fuel pump |
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Yes
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Cusser
Samba Member
Joined: October 02, 2006
Posts: 31352
Location: Hot Arizona
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sammywells
Samba Member
Joined: June 17, 2013
Posts: 244
Location: southern ohio
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| Posted: Sat Apr 08, 2017 5:11 pm Post subject: Re: fuel pump |
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| Thanks for the info. |
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sammywells
Samba Member
Joined: June 17, 2013
Posts: 244
Location: southern ohio
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| Posted: Tue May 23, 2017 3:40 pm Post subject: Re: fuel pump |
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| Ok, when you say swap out the spring, you are talking about the big one that goes up against the diaphragm. |
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