Hi, I just got my brand new (to me) 1950 pickup to fire. It has a 1955 2nd series 235 in it. Next I need fuel. I turned it over quite a bit and got it to sputter but fuel never hit the clear fuel line filter. As a source for fuel I placed a gas tank next to the fuel pump and put the fuel line in the tank to bypass everything beyond that.
My question: can I just get an inexpensive electric fuel pump to try to get this engine to run? I will rebuild the fuel pump later but want to get the engine running now.
Also, can I connect the fuel pump on the gas tank side of the existing fuel pump and leave the existing pump in place?
Hi Mike, For over 20 years I've used an electric fuel pump on mine and I've never been happier. The old type pumps lose their diaphragms with ethanol laced gas. You can get resistant diaphragms, but the benefit to the electric pump is you don't have to crank the motor over to make it work. Here is the one I've used: https://www.amazon.com/gp/product/B00496RE82/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1 The one I have produces 2.5 psi of fuel pressure and that's perfect for the 235. Important note: electric pumps are made to push and not to pull. Mount the pump as close to your gas tank as possible for best results.
Good luck and hope you enjoy the truck.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Should i run the electric pump through the mechanical pump or just bypass. If i bypass, should i just plug both ends of the mechanical fuel pump and leave in place?
I'd bypass it but I don't know if you need to plug the ends, Mike. Occasionally when the diaphragm goes bad mechanical pumps will start sucking oil in (from the inside of the engine), but if you don't see any coming out when you unhook it and run the engine, all the pump will do is suck air in and out. I ran oil filter lines through the opening where my mechanical pump used to be...
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
If you want an "original-appearing" system, just gut out an old mechanical pump and install a sheet metal baffle where the diaphragm used to be. Then run the line from the electric pump through the check valves in the fake pump housing. The biggest risk of running electric pump output through an unmodified mechanical pump is the possibility of gas leakage into the crankcase from a ruptured diaphragm. Wire the electric pump circuit through an oil pressure sensing safety switch. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
i think there was a bunch of discussion on various threads about it i vaguely recall numbers like 2psi is enough, 6 psi is probably a lot, more than that you probably will have a problem. i think some folks mentioned that some new rebuild pumps deliver too much pressure the diaphragm spring in the pump sets the pressure, you could tweek that spring in a new pump to reduce the pressure
fuel is about 3/4 the density of water the fuel pump is about 2 ft lower than the carb to lift the static head pressure the pump needs to generate a bit less than 0.4 PSI per foot of vertical lift about two ft for gasoline is still under 1 PSI conclusion 2 PSI should work in all situation 3 PSI on a new pump would probably be just right, give lots of margin for wear and various real world conditions while not being too much pressure for the carb float valve. -s
What pressure should the fuel pressure sensing switch be rated at for a 1955 235 series 2 engine?
If you mean "oil pressure sensing switch", most of the combination fuel pump and idiot light switches operate at 7 PSI of OIL PRESSURE. That prevents the pump from continuing to run if the engine stalls, or in case of a rollover. Fuel pump pressure on a carbureted engine needs to be 5 PSI or less, sometimes a lot less if you're using some sort of Mickey Mouse aftermarket carb like one of the Weber types. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
When I removed the mech. fuel pump from my IHC 345 because the electric pump made it leak on the ground, I found a pressure reducer accessory, set it at 3psi, stopped flooding the carb., didn't measure the pressures.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires. '47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle. '54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed. '55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
I'm using an electric pump with 2.5 psi. I already gave you a link to it via Amazon. 2.5 is just fine and definitely won't stress your needle/seat (which is what will cause flooding). 3 psi would be ok also. Jerry is right. In my opinion with any carb you'll be using on the 235, 2.5 or 3 psi is more than plenty.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
I hope you ordered a switch like Jerry mentioned or a controller. What Jerry mentioned about the crankcase filling with gas is very real. It happened to me years ago in a VW Camper. Very dangerous!
Here is a link to a controller that gives good information as to why one is needed. Fuel Pump Controller I know nothing about this product, but it does appear to be a viable option.
I would never go electric again without some type of safety mechanism.
Phillip
Cruisin' in the Passing Lane Former owner of a 1954 3100 w/Hydra-Matic "To know what you know and what you do not know, that is true knowledge." - Confucius
