Part I: Not Enough Fuel
I've been having some fuel related issues off and on. To make a long story long... I bought a 69 SB and have put about 5 tanks of fuel through it since I got it on the road. Three times I've had to change the fuel filter in the QJet due to lack of fuel when the fuel demand was high. It usually runs great for a while and then it starts bucking due to fuel starvation (I think). At that point, I can drive it easy and it runs fine. Each time this happened, I changed the fuel filter and it goes back to running great for a while. I'm sure there's still some residual crap in the tank/lines that keeps clogging it up. I’ve added an inline filter to catch more crap before it reaches the carb. After the last fuel filter change, I took the Vette out for a test run and at first, it ran great, but after I got on it to test the fuel flow, I was coasting to a stoplight and the engine died.

Part II: Too Much Fuel:
Basically, it wouldn’t start because it was flooded. Fuel was just oozing from the secondarys into the manifold. I had to get the wife to help me tow it back home (luckily it was only 2 blocks). After a couple days, I went out and started it up. I looked into the secondaries and again, fuel was just pouring in. The engine didn’t run but for about 30 seconds before it died. Later I checked the fuel pump pressure and it was pumping around 12 psi. Upon searching the forum I discovered, that pressure is too high, and while searching through the assembly manual, I noticed that I was missing some plumbing. I noticed the return line to the tank was not connected to anything other than a piece of rubber hose with a bolt in the end. The main fuel line runs to the pump then is connected directly to the carb, so the carb is seeing 12 psi. I've since pulled off the carb and I am going to take it apart to see if there’s crap in the float valve seat.

So my questions are:
Can anyone provide pictures of their fuel plumbing under the hood for a 69 SB?
Is the return line necessary?
If I put a regulator between the pump and the carb, will that be sufficient, or do I still need to run a return line to the tank?
Can the pump be damaged if it can't bleed off some of the fuel pressure via the fuel return line?

My apologies for the long winded post. If anyone can shed some light on this I'd be most appreciative! Thanks.

Dave

 

first,clean out your tank it's full of crud. if you have a stock fuel system you shouldn't have that much pressure.something isn't adding up is there an electric pump too?

 

This is what your fuel filter should look like... it does have a provision for a return.

https://www.paragoncorvette.com/p-35...er-gf-432.aspx
Fuel filter, GF-432, exc. 3x2. $40

I would also order a fuel line set from one of the vendors. It should be 3 pieces, one form the pump to the filter and a similar sized line from the filter to the carb (assuming you have a stock set up). A third line is much smaller and is the return line from the filter to the return line on the frame near the pump.

https://www.paragoncorvette.com/p-35...ne-kit-sb.aspx
Carburetor fuel line kit, all with 327 and 350. Includes (3) lines and clip. Lines run from carburetor to fuel pump. $46 steel; $50 SS

The return line does us two small lengths of rubber fuel line to connect it to the return line on the frame and the filter at the other end.
Your fuel pressure does seem higher than normal, but if you connect the return and go through the carburetor to check for gasket integrity you may lower the pressure to the normal range.

Do look inside of the tank carefully for any evidence of rust. If the inside of the tank is rusting you will never get all of the rust out and the problem will just continue to plague you.

Good luck... GUSTO

 

7t9l82 - The only pump on the car is the mechanical fuel pump. I checked the fuel pressure 2 different gauges, one was the typical vacuum/fuel pressure gauge which pegged at 10 psi, so I hooked up a tire pressure gauge to measure past 10 psi and find out how high it was going. The pressure hovered around 12 but the needle was bouncing from about 10-15 psi. For the most part,the tank is clean but there are a few big flakes of rust. I got most of them out with a magnet but some of the flakes wouldn't stick. But the tank does look clean and not all rusted up. I poked a mirror and a flashlight into the tank and i can't see any rust on the tank so I'm not sure where the flakes came from.

GUSTO - Thanks for the links! Looks like I need to do some plumbing. I'm thinking, with the fuel return line, the pressure should drop to a more reasonable level. If not, I'll add a fuel regulator of some sort.