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Getting it as close to the carb as possible means that the circulating fuel is carrying away the heat radiating from the side of the engine.
I'm not sure what you are trying to say about pressure with the engine off.
The tank rollover valves are plumbed to the charcoal canister.
The tank should not have any way to pressurize the fuel system with the engine off (pumps not running)
Good point - I was thinking about today's wiring where the pump can run when the key is on. But, when I redo this I'm going back stock with an oil pressure switch and fuel pump relay, so pressure off is not an issue. Thanks for clarifying that.
Gary, I think the orifice in the vapor separator is going to return fuel pretty much the same whether the carb is using some fuel, or not.
The volume on the in tank pumps is WAY more than ...... /toying with numbers in my head/.... one gallon in ten minutes. Given ten mpg at 60 mph.
Iirc the pump should deliver "more than a pint in 20 seconds". (So a gallon in two minutes fourty seconds)
Maybe your shop manual gives that spec.
The 1985 factory shop manual, supplied by Vernon, says this on Page 24-35-4:
The fuel pump is a low pressure pump capable of supplying 95 liters (25 gallons) of fuel per hour at a pressure of 30 kPa (4.3 psi). The fuel pressure is controlled by a vapor separator on the engine working together with the carburetor float valve. The vapor separator has an internal orifice which returns fuel to the fuel tank through a return line. The separator limits the maximum system pressure and helps keep the fuel cool. The fuel pump is mounted as part of the fuel sender assembly.
If that were true of all pumps then a regulator wouldn't be needed. But, since I have a regulator I'd like to make sure. On the other hand, if I set it to 5.5 psi and it doesn't get over 4.3 will there be any return?
Was just going through the stash of parts and found something I'd forgotten. So, the first question is, wonder if this will fits Dad's truck? (Sorry, Vernon.) Second, if not, forget upgrading Big Blue to a later model system.
No, and no - in that order. But, I have a Saginaw I rebuilt, so may be able to change out the rear of it for the one with the extra fittings. Or, find another with them. However, I do have the bracket for the Saginaw.
So, a different pedal is needed? Tell me more.......
My 1978 Oldsmobile and 1980 Bonneville both had HydroBoost units, they were plumbed, pump to booster then to steering with return hoses from each to the back of the pump. Look for a pump can for a GM 5.7L diesel it will have the dual return nipples. You might also want to check the pump specs for HydroBoost, I seem to recall it was higher than regular PS spec.
