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73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: biodiesel84 on June 30, 2008, 11:43:51 pm

Title: 40 gallon tank questions
Post by: biodiesel84 on June 30, 2008, 11:43:51 pm
I need to know how to tell by looking whether a 40 gallon tank out of a suburban is an EFI or non EFI tank...also, can I tell whether the tank was used for diesel or not...my truck is diesel and there is a tank on fleebay that I would like to buy, but don't know how to tell the kind of tank it is...thanks...

Chuck.
Title: Re: 40 gallon tank questions
Post by: biodiesel84 on June 30, 2008, 11:45:51 pm
I also need to know what the dimensions of the 40 gallon are because the title says 40 but the description says 31, but it gives the dimensions...thanks again for the help...

Chuck.
Title: Re: 40 gallon tank questions
Post by: DnStClr on July 01, 2008, 02:36:57 am
A tank used with fuel injection will have 3 steel tubing lines coming out of it.
3/8 line for the fuel delivery
5/16 line for the return line for unused fuel at the fuel pressure regulator inside the tbi unit.
1/4 line for tank vent line going to the evap cannister. (Tank needs a vent so it won't build up too much pressure)

A carbureted fuel system typically only has two fuel lines coming from the tank.
There is no return line. So the 5/16 tube will not be there.
Title: Re: 40 gallon tank questions
Post by: biodiesel84 on July 01, 2008, 09:43:31 am
I'm correct in thinking that's on the pump though right...there is no pump, just the tank...the pump is in another auction...how do I know whether the pump is for diesel or gas...thanks for the help on the outlets...

Chuck.
Title: Re: 40 gallon tank questions
Post by: ccz145a on July 01, 2008, 10:33:13 am
I do not think there is a spec of difference in a diesel tank and a gas tank. My 84 donor truck is a deisel and the tank is identical to my gas tank on my truck from 10 years earlier.

all 87 tanks had internal baffles so that the internal fuel pump would not run dry. So you might be able to find some tell-tale dimples where the baffle walls are welded to the outer wall.

The number sender outlets are a function of emmisions equipment. many trucks had the return line. my 75 has a supply, return, and open atmosphere vent... 3 outlets on each tank sender.


Glad to muddy the waters a little, A good source of information is on one of Chris' competitor's site, I cannot name it, but the online catalog will let you xref years and sender types. Just don't buy from anywhere else.
Title: Re: 40 gallon tank questions
Post by: Captkaos on July 01, 2008, 12:55:02 pm
As far as tanks go, the only difference in an EFI vs non-EFI is the EFI has plastic baffles in the bottom. 
A 40G tank should have an indentation on the rear or the tank at the top.  I don't have dimensions for them though.

Sending units will interchange with each other up to about 1996, and the EFI vs non-EFI versions will be as Don described.