72 fuel return - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Blue Tank · 09-10-2010, 07:43 AM

Hi Guys
First post, been reading for awhile.
When i received my replacement fuel sender for the burb it didn't have the return fitting and the vendor said they only come that way for the burb. Before i tear into it to add a return is this correct? It looks like the pickups have the return.
thanks
Mark

Monte Carlo Man · 09-11-2010, 02:37 PM

The fuel return is only needed if you use a fuel pump that has a pressure return port. The return line does not physically need to be a part of the sending unit.
You can weld a fitting onto the tank to do the same job.

Or you can change the model fuel pump you use to one that does not need the return line. Is your truck a big block?

Blue Tank · 09-11-2010, 04:13 PM

No
It's a 350 4bbl auto. I wanted to keep a return for future EFI. I could use one of the emissions fittings on the top sides of the tank, i doubt the system still works. I just replaced the pump with one from Jim Carter that wasn't a direct replacement. I hate when they don't note that in their catalog.

72GMC-Burb · 09-14-2010, 06:43 AM

does it matter with a big block? I put a BBC in my 72 4x4 and the fuel pump did not have an extra port for the return - how critical is it? I am contemplating an electric fuel pump due some issues I have been encountering - not sure if it is fuel related or not - almost acts like I am boiling the gas right outa the bowls...

Blue Tank · 09-14-2010, 07:08 AM

It's not a deal breaker by any means. I had a roller 396 in my Chevelle on a mechanical pump without a return and it wasn't a problem, i only switched the pump out for injection. The return can help with fuel delivery in a hi perf application because you don't have cavitation in the pump to maintain pressure.
What are the symptoms of your problem? Hot motor only? Full load or rising throttle? What the motor combo?
You can spend allot of time chasing a fuel problem without a pressure gauge, i know.

72GMC-Burb · 09-14-2010, 10:10 AM

468 BBC Lunati Voodoo flat tappet cam - mechanical pump - stumbles a bit when warm (first issue) - then it cooled off (temp wise outside) and it still happens - after engine is fully warm (runs about 205-210) it seems to happen more (stumbles and stalls) - if I don't pop the hood to let the beast cool down it is hell to pay to get it started. It can be at any time - barely under acceleration - and at times while jumping on it - toss up...frustrating toss up...

Blue Tank · 09-15-2010, 06:33 AM

What carb are you running? Do you have a 180 thermostat? Did you have this combo running before the rebuild?

72GMC-Burb · 09-15-2010, 06:37 AM

Edelbrock 800 cfm elec. choke, I think the thermostat is a 195, it is new to the truck (and to me) -

72GMC-Burb · 09-15-2010, 06:47 AM

It happened again two days ago - my uncle is thinking it is electrical - not sure - I plan on carrying a can of carb cleaner - if and when it stalls out I will give it a squirt - if it fires - it is fuel - if not - electrical - who knows... it is not even fun to drive it right now!

Burb · 09-15-2010, 05:26 PM

Was having the same stumbling problems with mine on a road trip to the hill country ... pulled fuel filters, blew out fuel lines thinkin it was bad gas. Running a Holley, I pulled the fuel bowls, checked float levels, the works. All on the side of the road.
Come to find out, rite about dark, it was the voltage wire going to the dizzy was grounding on the block. Of course that was AFTER I rebuilt the HEI on a curb in front of a closed NAPA.

But every stumble made me think fuel.

As for the return, mine is NIU, and sealed off near the tank.

72GMC-Burb · 09-15-2010, 08:56 PM

Rick - thanks for the info - dizzy...meaning distributor? I have contemplated redoing the wiring job up there anyways...

Blue Tank · 09-16-2010, 07:01 AM

Wow. I've never had that one.
I was leaning towards the Edelbrock carb which seem to be on the lean side every time i've used them. The other time i had a problem like that i didn't realize the heads and block were cut so i didn't cut the manifold. After pulling the manifold you could see where the print o seal wasn't compressed in a few places and i was drawing from the lifter gallery.
I guess if i had an off public road closed test track (legal crap). I would run a hot wire directly to the distributor and the only other pos lead would goto the starter. This wouldn't let you shut the vehicle off without pulling the battery lead but you'd know right away if it was fuel or elec.
That's just a theory that i couldn't recommend for safety reasons.

Burb · 09-17-2010, 03:19 PM

Yes ... Dizzy is what I called my old HEI Distributor.

My new one is called Stutter Spark it's an MSD lol

09-10-2010, 07:43 AM	#1
Blue Tank Registered User Join Date: Jul 2010 Location: CT Posts: 39	72 fuel return Hi Guys First post, been reading for awhile. When i received my replacement fuel sender for the burb it didn't have the return fitting and the vendor said they only come that way for the burb. Before i tear into it to add a return is this correct? It looks like the pickups have the return. thanks Mark

09-11-2010, 02:37 PM	#2
Monte Carlo Man Registered User Join Date: Feb 2010 Location: Pennsylvania Posts: 85	Re: 72 fuel return The fuel return is only needed if you use a fuel pump that has a pressure return port. The return line does not physically need to be a part of the sending unit. You can weld a fitting onto the tank to do the same job. Or you can change the model fuel pump you use to one that does not need the return line. Is your truck a big block?

09-11-2010, 04:13 PM	#3
Blue Tank Registered User Join Date: Jul 2010 Location: CT Posts: 39	Re: 72 fuel return No It's a 350 4bbl auto. I wanted to keep a return for future EFI. I could use one of the emissions fittings on the top sides of the tank, i doubt the system still works. I just replaced the pump with one from Jim Carter that wasn't a direct replacement. I hate when they don't note that in their catalog.

09-14-2010, 06:43 AM	#4
72GMC-Burb Registered User Join Date: May 2003 Location: Saginaw, MI Posts: 46	Re: 72 fuel return does it matter with a big block? I put a BBC in my 72 4x4 and the fuel pump did not have an extra port for the return - how critical is it? I am contemplating an electric fuel pump due some issues I have been encountering - not sure if it is fuel related or not - almost acts like I am boiling the gas right outa the bowls...

09-14-2010, 07:08 AM	#5
Blue Tank Registered User Join Date: Jul 2010 Location: CT Posts: 39	Re: 72 fuel return It's not a deal breaker by any means. I had a roller 396 in my Chevelle on a mechanical pump without a return and it wasn't a problem, i only switched the pump out for injection. The return can help with fuel delivery in a hi perf application because you don't have cavitation in the pump to maintain pressure. What are the symptoms of your problem? Hot motor only? Full load or rising throttle? What the motor combo? You can spend allot of time chasing a fuel problem without a pressure gauge, i know.

09-14-2010, 10:10 AM	#6
72GMC-Burb Registered User Join Date: May 2003 Location: Saginaw, MI Posts: 46	Re: 72 fuel return 468 BBC Lunati Voodoo flat tappet cam - mechanical pump - stumbles a bit when warm (first issue) - then it cooled off (temp wise outside) and it still happens - after engine is fully warm (runs about 205-210) it seems to happen more (stumbles and stalls) - if I don't pop the hood to let the beast cool down it is hell to pay to get it started. It can be at any time - barely under acceleration - and at times while jumping on it - toss up...frustrating toss up...

09-15-2010, 06:33 AM	#7
Blue Tank Registered User Join Date: Jul 2010 Location: CT Posts: 39	Re: 72 fuel return What carb are you running? Do you have a 180 thermostat? Did you have this combo running before the rebuild?

09-15-2010, 06:37 AM	#8
72GMC-Burb Registered User Join Date: May 2003 Location: Saginaw, MI Posts: 46	Re: 72 fuel return Edelbrock 800 cfm elec. choke, I think the thermostat is a 195, it is new to the truck (and to me) -

09-15-2010, 06:47 AM	#9
72GMC-Burb Registered User Join Date: May 2003 Location: Saginaw, MI Posts: 46	Re: 72 fuel return It happened again two days ago - my uncle is thinking it is electrical - not sure - I plan on carrying a can of carb cleaner - if and when it stalls out I will give it a squirt - if it fires - it is fuel - if not - electrical - who knows... it is not even fun to drive it right now!

09-15-2010, 05:26 PM	#10
Burb Coordinator of Synchronicity Join Date: Dec 2005 Location: West of Houston, TX Posts: 437	Re: 72 fuel return Was having the same stumbling problems with mine on a road trip to the hill country ... pulled fuel filters, blew out fuel lines thinkin it was bad gas. Running a Holley, I pulled the fuel bowls, checked float levels, the works. All on the side of the road. Come to find out, rite about dark, it was the voltage wire going to the dizzy was grounding on the block. Of course that was AFTER I rebuilt the HEI on a curb in front of a closed NAPA. But every stumble made me think fuel. As for the return, mine is NIU, and sealed off near the tank. __________________ Rick 1971 Suburban ... W.I.P. *Build Thread* Customization is ones personal touch-- not what other people think it should be Last edited by Burb; 09-15-2010 at 05:29 PM.

09-15-2010, 08:56 PM	#11
72GMC-Burb Registered User Join Date: May 2003 Location: Saginaw, MI Posts: 46	Re: 72 fuel return Rick - thanks for the info - dizzy...meaning distributor? I have contemplated redoing the wiring job up there anyways...

09-16-2010, 07:01 AM	#12
Blue Tank Registered User Join Date: Jul 2010 Location: CT Posts: 39	Re: 72 fuel return Wow. I've never had that one. I was leaning towards the Edelbrock carb which seem to be on the lean side every time i've used them. The other time i had a problem like that i didn't realize the heads and block were cut so i didn't cut the manifold. After pulling the manifold you could see where the print o seal wasn't compressed in a few places and i was drawing from the lifter gallery. I guess if i had an off public road closed test track (legal crap). I would run a hot wire directly to the distributor and the only other pos lead would goto the starter. This wouldn't let you shut the vehicle off without pulling the battery lead but you'd know right away if it was fuel or elec. That's just a theory that i couldn't recommend for safety reasons.

09-17-2010, 03:19 PM	#13
Burb Coordinator of Synchronicity Join Date: Dec 2005 Location: West of Houston, TX Posts: 437	Re: 72 fuel return Yes ... Dizzy is what I called my old HEI Distributor. My new one is called Stutter Spark it's an MSD lol __________________ Rick 1971 Suburban ... W.I.P. *Build Thread* Customization is ones personal touch-- not what other people think it should be



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