doctorcad

I'm thinking of converting my 350 TBI motor to a returnless fuel system. My plan is to remove the stock regulator and plug the return line port. Also, replace the electric fuel pump with a mechanical piston pump and deadhead regulator from www.racepump.com. Maybe a schraeder valve fitting where the return line used to be would allow you to 'bleed' the system to purge air etc?

Some people have suggested that vapor lock may be a problem with this setup. What do you folks think?

BMmonteSS

Your going to spend an awful lot of money for very little benefit. What do you hope to achieve with this setup? If you want to be able to have better (wider) control of your fuel pressure you can do like you suggested only use a return type regulator on the frame, then run the pressure line to the TBI unit from your regulator. It gets hard to find springs that will let you get much higher than 20 psi with the stock regulator. This takes care of that. A walbro 190 will support any amount of power that TBI will be able to support.

doctorcad

I like the idea of the mechanical pump. What can I say?

Right now I have a Walbro pump on the frame rail, but since it is installed on a Jeep the pump isnt located below the pickup. It seems to have trouble priming when the truck has been sitting for a while... I was going to install an in-tank pump from a later model jeep but I hate the idea of trying to drop the tank in the bush when the fuel pump craps out.

I know the race pump is spendy but that aside, what do you think of dead heading the TBI pod?

RBob

iTrader: (1)

I have run a standard SBC mech pump on a TBI as a returnless system. The MY '67-'69 pump didn't have a vapor return line, just an inlet and an outlet. Pressure was in the 8-9 psi range. If I did it again I would run a return line and use something such as the 14 psi Edelbrock race mech pump.

I did have an issue with vapor lock. The cause was cold weather fuel in a warm (hot) weather environment. No problems all Summer. Then Fall came, a month of cold weather, a tank of cold weather fuel, and the temperature went into the low 80's.

Of course it would only flash the fuel while sitting in traffic. Got used to pushing the car off the read

So, I tie-wrapped a rag over the fuel pump and carried water with me. Even wrapped the fuel line going to the pump. Then soaked them down before heading anywhere. Shortly thereafter a return line went in. Followed by an electric pump some time afterward.

RBob.

dimented24x7

iTrader: (2)

RBob, where the pulsations from the pump ever an issue? It seems like one would need a pulsation damper when using a mech. fuel pump with fuel injectors.

doctorcad

Hey Everyone,

Thanks for your replies, I appreciate it

Rbob,

Do you think a return line from the pump (or from a deadhead regulator inline before the TBI in my case) would be good enough, or would the return have to come from the TBI as it did from the factory?

RBob

iTrader: (1)

The engine ran smoother with the return line then without. This could have been from vapors or the pulsations. Even without the return line the engine ran rather well. Had to set the BPC a tad high. . . but I'd still take it over a carb any day of the week.

RBob.
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Only thing you can do is to try it. From my experience I would use a return line off of the TBI unit. And if the pump isn't too large (too much volume) the stock TBI regulator can be used.

RBob.