Heres whats going on. Lately the cutlass has been very sluggish, like its starving for fuel (Chugging). If I have the car in park and give it fuel the car will want to die unless I pump the accelerator pedal to revive it. My fuel pressure gauge also reads anywhere between 3psi and 8psi. 8 psi mainly on start up. Then after warming up the car and driving around the fuel pressure drops to 3 psi and I can see it steadily drop. Prior to this I had my Holley 670 street avenger adjusted (electric choke,fast idle and accelerator pump). The car ran great for about a month after the adjustments. I have also tried 3 different fuel pumps thinking it was that. I also replaced the rubber hose connecting the fuel tank sending unit to the fuel line and the rubber hose connecting to the fuel pump. Fuel filter is new as well. I am thinking the fuel tank sending unit filter is getting clogged as the car is in motion. This is for a 70 Cutlass supreme w/350

Any suggestion would be great.

thanks,

 

maybe the gas tank vent is plugged, try leaving the gas cap open and check to see if the pressure drops still

Johann

 

Or, replace the sock in the tank.
Might check the bottom of the tank for rust chunks, too.

 

Also check the rubber lines at the tank and see if they are old and rotted. You might even consider replacement of those. While you have them off, blow the line out.

 

Try connecting a old fuel can with a tube jb welded close to the bottom, then attach a rubber fuel hose long enough to reach the supply side of fuel pump, and then test again.

Pat

 

I plan on dropping the tank this weekend and doing some investigating.

 

Dropped the tank today and inspected the sending unit, and sure enough it was clogged. The sock was floating around in three pieces and portions of it stuck inside the line. So I replaced the sending unit and plan on reinstalling later this week. Thinking about replacing the gas tank pad as well since it appears to be very brittle.

 

I was going to pipe in after reviewing your quandary and was going to suggest REPLACING THE GAS TANK PAD as THAT WOULD GUARANTEE YOUR FUEL FEED PROBLEM WOULD BE SOLVED!!!

It WILL run better if you replace the pad....I sell a pretty nice one if you are interested....click on the link at the bottom of my posting.

 

I sent you a PM.

 

You're a funny guy Patton!
So why does the 70 have a gas tank pad and the 71/72 doesn't. I was thinking of putting one in my car even though we both know it doesn't need one. I like to support my fellow enthusiasts . Probably talk to you later this spring when I drop my tank - it's leaking. IF I would have had a tank pad you just KNOW it wouldn't have leaked.

 

Finally got around to installing my fuel tank with a new sending unit. I put four gallons of gas in the tank and it fired right up. Drove it to the gas station and filled it up. Then drove around town for a bit and everything seemed great. Got home and parked the car, I let it sit for about 30 min and then I headed out again with the cutlass. The car fired right up but wouldn't hold a steady idle. I had to give it gas to keep from stalling. Then I tried another time and did the same thing, but after giving it gas to keep from stalling the car backfired through the carb and then the car started to idle normally. I took it out for another spin and everything seemed normal. Since then the car is idling nicely and driving great. Any ideas what would cause the odd idling and backfire through the carb.

Thanks again.