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'70 SS 454-she just won't run out!


Grapejuice1998

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When I got this car several weeks back I knew about the fuel system problem and thought, yah, no problem. I can fix that. Well, I guess I can't. At least, not without the help of someone more knowledgeable than myself.

 

Here's the deal:

When you go w.o.t., it will start to run pretty hard and then it will act like it's run out of gas and just fall over on it's face.

Here's a short video of the bog out.

 

 

What I have done, so far:

The fuel system is mostly new. Everything has been replaced, except the carburetor (QJ). This includes a new tank, which was a single line in/out at the time. It was suggested that perhaps that was the problem, so I bought a dual line pickup and pump and installed all new fuel lines (except the metal ones, which I blew out with an air hose). I also tried removing the paper filter in the carb, as well as running without a gas cap (the new tank doesn't have vents like the old one did).

 

As I said, the only piece that hasn't been changed, out is the carb. A local builder said there's nothing wrong with it though. Has anyone ever seen this type of thing happen due to a carb problem? If so, does anyone here build a good QJ, or is there a better option out there?

 

Thanks y'all. This is really starting to get to me. I really want this thing to run like a 454 should!!

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well new tank, sending unit, pump and filter

 

time to take the carb apart and put a kit in it, new float and needle and seat

 

Cliff's is where I get all my Qjet stuff, he has the best quality parts

 

http://www.cliffshighperformance.com/

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fuel volume. verify pump is putting out correct gpm and make sure all fuel hoses are the right size and not kinked (saw a lot of new lines get kinked when tank is installed)  I had a van come in the shop once that would do that and I stayed on the gas until it stalled, pulled over and pulled the top of the carb off and found it empty. here the body mounts were sagging and pinching the fuel line closed.  ran fine all day until you "got on it" also saw cam lobe for fuel pump wear...

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I had the same problem with my 454. I put a 3/8 inline filter after the pump and removed the paper filter in the carb. That fixed it. The paper filter wouldn't flow enough to keep the carburetor full.

 

Dan

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My thought is it just isn't getting enough fuel. Runs fine on 2 but when that 4 barrel kicks in it is starved for fuel. Either the pump isn't working properly or a line is kinked or the needle and seat and float problem. Should be interesting to see what it actually is.

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Sounds like what my Nova was doing when the fuel pump went bad. Is your fuel pump electric or mechanical?

It's brand new mechanical and the proper p/n for the car. It was doing this before I swapped pumps though.

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I would guess your advance is malfunctioning. Keep us posted on what you find though. Dale

 

 

It's a long shot but maybe a distributor problem advance may not be working properly

 

It's worth a look. I had planned to blueprint the distributor anyway. Thanks!

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fuel volume. verify pump is putting out correct gpm and make sure all fuel hoses are the right size and not kinked (saw a lot of new lines get kinked when tank is installed)  I had a van come in the shop once that would do that and I stayed on the gas until it stalled, pulled over and pulled the top of the carb off and found it empty. here the body mounts were sagging and pinching the fuel line closed.  ran fine all day until you "got on it" also saw cam lobe for fuel pump wear...

 

The car had the same problem before I changed out everything. I did verify that the fuel lines aren't kinked though. The carb is the only other unchanged item in the entire fuel system.

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Had a similar problem in my camaro. Turned out the float level was too low so if I got on it enough, I'd eventually starve for fuel. 

 

 

My thought is it just isn't getting enough fuel. Runs fine on 2 but when that 4 barrel kicks in it is starved for fuel. Either the pump isn't working properly or a line is kinked or the needle and seat and float problem. Should be interesting to see what it actually is.

 

I pretty much have no other choice at this point. I will start with a carb rebuild, then I'll work on the distributor. I just wish I had a spare carb to swap on it first.

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First thing I'd look at is to see if your float is saturated with fuel. it  could have been adjusted when saturated and now float bowl running out of fuel. How are the rubber fuel lines? are they soft? could be closing on you when at full throttle (one before the pump). 

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  • 2 weeks later...

Grapejuice, are you still having this issue? I had the same issue about 3 years ago. Do you have a high volume fuel pump say 120-130 gpm? I couldn't hear the video to well but is it popping out of the carb? It sounds like you are sucking a hose. It is the short one from the pass side where the steel line ends. The hose between the steel line and the pump. Make sure it is not excessively long as it will have a tendency to crimp. I ended up using a shorter piece of trans cooler line as the outer diameter was thicker. Problem was solved.

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  • 4 weeks later...

Been there, done that. It's a fuel starvation issue. At wide open throttle, the engine is pulling more fuel than the carb can deliver. Eventually you drain the float bowls and the engine bogs, or shuts off. If you were to leave your foot planted on the floor, after a couple of seconds the engine responds again as the bowls fill.

 

Check your float level. A little high is better than having it low. This is probably your issue.

There are also better needle and seat assemblies available that flow better than the stock pieces. They just have a bigger hole through the center.

The filter in the carb is a problem... from a design standpoint. Very restrictive and hard to change without stripping threads or causing a leak. I leave them out and use a good in-line filter.

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