Fuel Pump Bypass

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Topic author
skiplane
Posts: 4
Joined: Sun Jan 06, 2019 2:37 pm
First Name: Skip
Last Name: Lane
* REQUIRED* Type and Year of Model Ts owned: 13 Tour, 16 Rdstr, 16 Spdstr, 21 Coupe, 23 Can Exp
Location: Melbourne, FL

Fuel Pump Bypass

Post by skiplane » Sun Sep 01, 2019 12:24 pm

Have a 1921 coupe -- gas tank is in trunk. Was having trouble on steep hills with gas starvation, even with almost full tank. Installed an Airtex electric pump with switch to give boost. when needed Car runs fine with pump on. But, pump is supposed to allow gas to flow through when not running. If I switch pump ''off'' engine will run for a few minutes, then run out of gas. Apparently, gravity pressure from tank is not enough to push through "free-flow" pump. Would like to be able to run without pump unless needed on big hill. So, question is, would a bypass line around pump allow more gas to flow when pump not running AND still let pump work when 'on' to assist gas flow on hills?


Scott_Conger
Posts: 6523
Joined: Sun Jan 06, 2019 11:18 am
First Name: Scott
Last Name: Conger
* REQUIRED* Type and Year of Model Ts owned: 1919
Location: not near anywhere, WY
Board Member Since: 2005

Re: Fuel Pump Bypass

Post by Scott_Conger » Sun Sep 01, 2019 12:34 pm

Skip

my dad had a depot hack in TN and was surrounded by very steep hills. He would always run very hot by the top of the hill and sometimes sputter and die on the hill...having to wait a minute or two before he could restart.

I suspect your problem is the same as his, and that is a constriction at the float valve. Modern replacements simply have too small of a through-put. I designed a valve with the proper flow Cv and installed in his very heavy hack. He now has no trouble keeping up with other drivers on hills now and does not sputter or run hot at the end of a long hard pull.

In keeping with forum rules, this is as far as I will go publicly with this info, so Feel free to contact me via email for more info, or not.
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves™
Obsolete carburetor parts manufactured

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