1975 Suburban questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Tyler · 09-20-2005, 10:14 PM

Hello....

I am in the process of buying a Suburban from an elderly neighbors, and I am curious what everyone thinks and also a couple questions:

It's a '75 C20 Silverado 2wd. 454/TH400. It is very straight, no rust. It has 90,000 and has been sitting for 3+ years. We got it running finally and it runs great.

The owner says it has a towing package...it has a huge 4-core radiator and an oil cooler, so does that seem to indicate a towing package or did all 3/4 tons get that?

What rearend and gear options would something like this have?

Finally, we had a problem with gas leaking. I'm pretty good mechanically, so I think I know the answer to this but I'd like other opinions:

On the fuel pump there are 3 connections..one inlet from the tank, the outlet to the carb and another which is either a vent or return line to the tank.The gas was spraying out of this third line, and I didn't think there was supposed to be that much fuel pressure on that line. It did take a long time to get gas up to the carb.

Thanks for the help....

**JIMs70GMC** · 09-21-2005, 05:30 AM

Probably a 14 bolt with 4.10 gears. Not sure on the fuel pump.

Welcome to the board!

toroflow · 09-21-2005, 12:54 PM

on the fuel pump problem (other than the obvious replacement of the line) I can only think that perhaps the little bronze fuel filter that is located in the Q-Jet carb is plugged, thus allowing lots of backpressure in the return line and also takin forever to get fuel into the carb....give that a try.

jimfulco · 09-27-2005, 12:45 AM

Cap that third line, or fix it so it returns the fuel to the tank. It's there to help prevent vapor-locking, but it will run OK if you just cap it. I've seen some that spit gas everywhere, and others that don't, but you need to at least cap it.

09-20-2005, 10:14 PM	#1
Tyler Registered User Join Date: Jan 2004 Location: Albertville, Al Posts: 14	1975 Suburban questions Hello.... I am in the process of buying a Suburban from an elderly neighbors, and I am curious what everyone thinks and also a couple questions: It's a '75 C20 Silverado 2wd. 454/TH400. It is very straight, no rust. It has 90,000 and has been sitting for 3+ years. We got it running finally and it runs great. The owner says it has a towing package...it has a huge 4-core radiator and an oil cooler, so does that seem to indicate a towing package or did all 3/4 tons get that? What rearend and gear options would something like this have? Finally, we had a problem with gas leaking. I'm pretty good mechanically, so I think I know the answer to this but I'd like other opinions: On the fuel pump there are 3 connections..one inlet from the tank, the outlet to the carb and another which is either a vent or return line to the tank.The gas was spraying out of this third line, and I didn't think there was supposed to be that much fuel pressure on that line. It did take a long time to get gas up to the carb. Thanks for the help.... __________________ 1990 GMC Sierra SLE X-cab

09-21-2005, 05:30 AM	#2
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	Probably a 14 bolt with 4.10 gears. Not sure on the fuel pump. Welcome to the board! __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

09-21-2005, 12:54 PM	#3
toroflow Registered User Join Date: May 2005 Location: Anaheim, CA Posts: 103	on the fuel pump problem (other than the obvious replacement of the line) I can only think that perhaps the little bronze fuel filter that is located in the Q-Jet carb is plugged, thus allowing lots of backpressure in the return line and also takin forever to get fuel into the carb....give that a try. __________________ Ken '60 GMC 3/4T 4x4 '60 GMC Suburban 4x4 '64 GMC Suburban 4x4

09-27-2005, 12:45 AM	#4
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	Cap that third line, or fix it so it returns the fuel to the tank. It's there to help prevent vapor-locking, but it will run OK if you just cap it. I've seen some that spit gas everywhere, and others that don't, but you need to at least cap it.



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