Hey new member, I've owned several 2nd gens and a 4th gen, but I finally got my hand on a 87 T/A 305 700R4. The car has had an earlier (80-86) 305 put in it, and in the middle of a carb swap a guy I know had to sell it, so I bought it. I noticed that it has a mechanical fuel pump already on it, so I guess my question is:
-Should I pull through the stock in-tank pump (not hooked up)?
- Should I pull out the in-tank pump?

I guess I'm not too familiar with this, I've only messed with mechanical (old) fuel systems and I just dont want to mess anything up.

Thanks in advance for any help.

Chad Boulden

 

Welcome aboard.

The preferred set-up would be to have the in-tank operating and pushing to the mechanical. If you don't want to hook up the in-tank, the best bet is to remove it.

 

how does this work? my volvo has two pumps. wouldn't the electric pump mess up my holley mechanical?

 

I'll have to see if the stock one is still pumping, if not, I've pulled 2nd gen gas tanks, any tricks/anything different pulling 3rd gens?

 

Pulling a 3rd gen tank involves removing a lot of suspension stuff underneath it. But, it is still a pretty basic operation.

The fuel pressure should be regulated when using an unregulated electric in the back. The factory just let the return-style mechanical do that. If you have a non-return mechanical like a Holley, you need to use a return-style regulator after the mechanical - the reason for that is you don't want to dead-head the in-tank, because that will burn it out.

A pusher electric won't do any harm to a mechanical pump as long as the output is regulated with a return style reg.

 

Thank you, that answered a lot of questions I had.
Guess I'll go pick up a return-style regulator and hopefully get this thing together for vacation next week.

Thanks again for all the help!

chad

 

what's the advantage of doing it like that? would I install the return regulator before or after the mechanical pump?

 

I suppose you could do it either way, but after the mechanical would give you adjustable pressure at the carb inlet.

 

ok, so what's the advantage?

 

You wouldn't be relying on whatever the mechanical puts out for the final pressure at the carb.

 

then why bother with a mechanical pump at all then?

 

This is speaking out of ignorance, but wouldn't it make more sense to put the regulator before the mechanical, so the fuel isnt hitting the mech. pump at a higher PSI (from the in-tank) and in theory wearing it out sooner, or is that not a problem.

Thanks

chad

 

personally, since the car isn't running yet, just drop the tank and put a tube where the intank pump was and be done with it, or get a carb style intank sender like this,