HI,

I posted this also on the carb page...

I am changing my motor from a mpfi 3.4 v-6 (currently for sale on ebay...what a deal!) to a carbed v-8 (sorry) and was wondering if I can use an aftermarket electric fuel pump to pull gas through the tank pump or if I will have to use a special return-type regulator with the in-tank pump.
Thanks.

 

I'm doing the same thing & people keep saying to use the mallory 3port w/bypass. $75 for it but seems to last longer than the 2port &using the second port for teh return. A couple posts on thins in the engine swap forum.

 

Shameless ebay plug

 

Here's the deal with what I'm doing (3.4 & using a Carter electric fuel pump to pull gas, this is the 85 Blazer 2 se Carb'd conversion).
I asked & scoped out options...
To regualte the current what ya got down to the 5PSI ya need to NOT BLOW OUT THE JETS OR SEALS, the regulator is expensive.
Available but expensive.
What I'd suggest is other tank for the project & hook up electric pump OR even wiser is the TBI fuel tank & it's pump & a regulator & that'll give ya constant & lower pressure.
Me?
I'm hoping to just install a TBI (12-14PSI) pump in my 85 Blazer tank & be done with it. I already have the regulator.
As with your V8 conversion, new stuff must be engineered.

 

Oh, that Ebay thing must have just slipped out...ha ha.

I did a tpi to carb swap a few years back and used the mallory 3-port regulator with tank pump. It worked good once I got it to stop leaking. But with that route I'd be at the mercy of a 16 year old pump.

 

On my set up I used the carter pump, a filter before the pump and after the pump,
I found a 3 way fuel filter, the one line used as a return to tank line. Then the regulator.
Works fine no leaks.
My thinking is low pump (what 7 PSI max?) pressure is the key for my no leak set up.
Once I get more bugs sorted out then I feel safer using/converting to a TBI pump in tank using same filters & regulator

 

Would ANY tbi pump work (from a van, etc)?Do they all have similar pressure?

 

Assembly MUST FIT TANK
Get a TBI set up from F Boody & ya good to go.
Ya thinking of swapping the pumps onto your current assembly?
Why not give it a try?
I'm using a TBI assembly from S Series to make into my TBI set up for my Blazer tank (they different style tanks & different length assemblies)
Here's pic of my set up now & leak free.

 

sorry to sound stupid but why not hang the mechanical pump to the block like any normal carbed car has.........? then it'll only cost like $30.....or even go with a holley or the likes for what $100 to $150? Y'all like to be complicated....lol

 

You'd have to own one to understand why it's wise to not "go original".
Bad design.
And if ya knew, 3.4 has NO mechanical fuel pump attachment ability.
This is temporary until I install the factory TBI assembly into my gas tank.
Still regulating it down to necessary 5PSI.

 

No....wait.....I was talking about the guy with he V8 carb or did I read wrong?? But even still go with holley lol.

 

there is no provision for a mechanical pump on later smallblock motors, otherwise I'd just use one.

 

ok.....you didn't say it was a gen 2 block, I don't know if it'll work but jegs has a carter electric pump that runs 4 - 6 psi. like I said though no idea if it'd work for ya but check it out if ya want.

 

That's the pump I have in my picture!

 

oh lol. I tried