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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Ben_Greenberg on February 07, 2015, 08:55:59 am

Title: 78 looking to go TBI, but a question about fuel return
Post by: Ben_Greenberg on February 07, 2015, 08:55:59 am

Hey guys,
I have been looking at TBI conversions for my 78 and the only part I'm worried about is fuel return.
I've got the 350 with a mechanical pump at the moment, and if I go with the TBI and an electric pump I need to run a return back to the tank. Will there already be a place for me to run something or am I going to need drop and drain the tank and drill a new opening for a new fitting, etc.? 

I'm looking at the setup offered by pfisys.com which is off a 1990 truck.

Any and all help is appreciated, also my truck is currently surrounded by several feet of snow, otherwise I'd be crawling around trying to get answers.

Thanks guys!

Title: Re: 78 looking to go TBI, but a question about fuel return
Post by: Captkaos on February 07, 2015, 09:07:45 am

Looks like their setup runs an external pump.  Me personally I wouldn't run an external pump, I would run the one in a 1987 Sending unit.  But I would also call them and ask for what they recommend for their system.  The 87 EFI has a return port on it, so you could (if you had to) run a EFI rated hose from the TBI return back to it.  You could also purchase 87 Fuel lines.  But for starters I would ask them what would they recommend.

Title: Re: 78 looking to go TBI, but a question about fuel return
Post by: Ben_Greenberg on February 07, 2015, 09:58:46 am

Captkaos,
Thanks a bunch! I will look into that!

Title: Re: 78 looking to go TBI, but a question about fuel return
Post by: roundhouse on February 08, 2015, 07:02:02 am

To use the 87 in tank pump you have to use a 87 tank

You probably need a new tank anyway

If yours is original it's dented and has a lot of dirt in it


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Title: Re: 78 looking to go TBI, but a question about fuel return
Post by: Captkaos on February 19, 2015, 11:47:07 pm

You don't have to use an 1987 tank for the 87 sending unit..  Just don't run it really low.

Title: Re: 78 looking to go TBI, but a question about fuel return
Post by: Ben_Greenberg on February 20, 2015, 09:03:29 am

Was there another part to that sentence?

Title: Re: 78 looking to go TBI, but a question about fuel return
Post by: Captkaos on February 20, 2015, 04:49:33 pm

No.

Title: Re: 78 looking to go TBI, but a question about fuel return
Post by: roundhouse on February 20, 2015, 11:56:56 pm

We have a frame mounted pump
Works fine as long as you don't run it dry

Then you have to prime it with a hand held vacuum pump or fill the tank  almost full


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