I have had this problem with my 78 L48 for the last month now. It came on all at once, if I floor it in low gear it will wind out but if I am in 2nd gear or drive and floor it then it will die out until I back off the gas. I can get up to about 85 mph but you have to really feather the throttle. I did replace the S-shaped feed hose to the fuel pump and the fuel pump. That made it better but still not right. This is a 30K mile car that is all original yet, including the exhaust along with the catalytic converter. Could this be plugged. Could this be an electrical issue, it does not misfire but just loses power as when you run out of gas. Possibly bad gas, I did put a can of heat in it and have put roughly 175 miles on this tank so far. So I could run this tank dry and refill and see what happens. I am open to suggestions.
Thanks
Jeff

 

I recently got a bad tank of gas and it clogged the strainer on the pick up tube in the gas tank. Figured it out after replacing the fuel filter and fuel pump. Fortunately for me, the '81 has an easy access fuel tank. I think you may have to pull the tank on a '78.

Good luck and God bless, Sensei

 

Hello,
I am having the same problem with my 73-454 so I will be reading your thread for suggestions too.

The last thing that I will try is to repalce the fuel strainer in the gas tank. I think that a friend of mine has small enough hands that she can help me out with replacing this through the filler cap. On a 73 it has a large opening.

If you replaced the fuel pump then that should rule that out. The S shaped hose is also suspect. If it is not the S shape it could collapse and restrict flow.

What about the gas filter in the carb? Have you replaced that.
There is also a flow rating for the fuel pump. You can disconnect the gas line at the carb, and connect the end to a plastic water bottle with a piece of fuel hose. Then crank the engine for 30 secs. I think that the spec for the amount of gas in 30 secs is 12 oz. I dont remember the exact amount but I found the test for this in my Chiltons manual.

If that is not it, then I agree that the strainer may be the problem.

kdf

 

It also could be a float problem in the carb which won't allow enough fuel to accumulate in the bowl to support WOT operation. But the filter, kinked hose and strainer blockage are more likely. Since you were just working on it, I suspect a kink in that fuel hose is the problem.

 

I have 25,000 mile 1975. It was a clogged filter sock on the fuel pickup in the tank. One tip was that the car ran better with a full tank of fuel.

Make sure that you replaced those two hoses to the fuel pump with molded hoses that have the S shape cured into the hoses. Otherwise they will kink and cause a fuel starvation problem.

Jim

 

You don't have to drop the tank to clean out any bad fuel in there. I had this problem with my 74 after getting a bad tank of gas. You can gain good access to the tank by removing the filler neck. This opens up the top of the tank enough to see well and get your hands in there. Just buy a new gasket for the neck before you start. Once you have the neck off you can take a look in the tank with a flash light. You most likely will see a lot of crud around the bottom. You will need the following to build a vacuum system to clean the tank. Get a 1 gallon plastic bottle with a screw on cap and some clear vinyl tubing sized to fit a hand held vacuum pump. Drill two holes in the cap slightly smaller than the vinyl tubing so the tubing will seal airtight once its pushed in. Insert one piece of vinyl tubing into the cap until it reaches about 1 inch from the bottom of the bottle and leave the other end long enough to reach the top of your gas tank. Get a piece of aluminum tubing the same size as the vinyl tubing and insert it in the other end of this tubing. This will be your vacuum hose for sucking out the gunk in the tank. Insert a second piece of vinyl tubing into the cap until its about 1 or 2 inches into the bottle and hook the other end up to a hand held vacuum pump. You can then pump the hand held pump and draw the crud from the tank into the bottle. The aluminum tube can be moved around the bottom of the tank where ever you see dirt, scale, or other debris. I did this on my 74 and vacumed out about 1/2 gallon of crud without having to drop the tank or disconnect any lines.

 

cheap & easy, try needle & seat .............

 

I would say fuel filter if it hasnt been replaced already.

 

I have replaced the fuel filter, pump, and the S-shaped hose with the proper preformed hose. Problem is better but still there. Could be a bad tank of gas or the pickup sock I guess.

 

Why do you think needle and seat?

 

I wrote earlier about the same problem that I am having with my 73. While each problem may be different, I will suggest the fuel sock be checked.

For my problem I discussed this with a friend who told me it was the float level on my Holley Carb. not setup correctly. To check it we put the Quadrajet carb from my 75 vette. The same exact problem occured.

That is why I am suggesting the fuel sock. You said you replaced the fuel filter, fuel pump and S hoses. All that is left for the delivery system is the pickup and the fuel sock.

kdf

 

There is also the rubber hose from the tank to the hard line.

 

I had the same thing happen on my 79 L82. Could get up to about 70 mph and would cut out, let off the gas and everything was fine so I replace the S hose, Pump, Filter and rebuilt the carb and still had a problem. Removed the fuel sock and problem solved. On my 79 I was able to unbolt the sending unit from the tank and slowly twist the entire sending unit out (counter clockwise)to remove the sock, you should be able to do the same on your 78, I decided to leave the sock out and go with an inline fuel filter after the pump and have had no problems. It's a lot easier to replace an inline fuel filter then a sock in the tank.

 

Sounds like you've checked all your filters and the fuel system.

Sometimes, a distributor can co to shet and will offer similar results. I would check my timing and make sure I was getting advance.

Just a thought.

 

I have that exact problem! But my problem persists in the gas tank. I have a rusty gas tank that shoots the debris into the fuel pump and the in-line fuel filter.

So I had to replace the fuel pump! And then I have to replace the iniline fuel filter(s) about every two weeks. Try this first before getting in deep with replacing carbs and a exhaust!

You'll beat yourself silly if its just a $25-$50 dollar part!!!

 

What's the part number for the "S" shaped hose at the Fuel Pump?

 

I bought the hose from Ecklers for $12.99 + $8.00 for shipping

 

I've followed this thread hoping to get an answer for a similar problem. My 78 feels like I turn off the key at about 4200 RPM. Is this what others are getting?

Blain

 

Got a 74 with same issues. After reading (Chilton) through fuel pump section, this “Starve-Out” is more likely a weak ignition system or the factors already discussed. I’m going to test my ignition coil and replace to see if that’s my issue tonight.

 

It could be sucking air at the hose top of the fuel tank.