Carburetor trouble

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Don Bagwell

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Location
Gillette Wyoming
I have a quick fuel 950 on a 630 hp 360 stroked to 423 running down the road at 80 it performs well start punching it up to and above 100 mph and it starts loading up on me and makes my fuel pressure go crazy any help would be appreciated
 
What do you mean by fuel pressure goes crazy? If it's loading up under WOT I'd double check your timing and check rear jet size.
 
Welcome to the forum.
You come to me on the day of my daughter's wedding and you want me to do you favors and yet you haven't even offered me a cup of coffee !?? LOL
 
Maybe your fuel pump is not regulating the pressure well and at high speed is Conjuring 2 much?
 
What RPM, what vacuum, what fuel pressure, secondary's open 1/2 way all the way? The more info the better.
 
What do you mean by fuel pressure goes crazy? If it's loading up under WOT I'd double check your timing and check rear jet size.
Fuel pressure consistently runs at five pounds in town and on short runs once I start accelerating hard on long runs the fuel pressure starts bouncing between 0 and 3 until something like the carburetor loading up and choking out and I smell gas then the fuel pressure goes back to 5 this continues to happen until I stop for a couple of hours then it’s back to normal with no problems
 
Fuel pressure consistently runs at five pounds in town and on short runs once I start accelerating hard on long runs the fuel pressure starts bouncing between 0 and 3 until something like the carburetor loading up and choking out and I smell gas then the fuel pressure goes back to 5 this continues to happen until I stop for a couple of hours then it’s back to normal with no problems
Also I have a crank trigger with the distributor locked out, I’ve tried different fuel pumps still the same I think it lies in the carburetor
 
Do you have a PV on the secondary's? is the pressure drop consistent with RPM, what RPM does this happen, What size fuel line do you have? filter plugged up? filter in tank? Electric pump in the rear? mechanical pump? A lot of things can cause pressure drop but not normally carb.
 
Do you have a PV on the secondary's? is the pressure drop consistent with RPM, what RPM does this happen, What size fuel line do you have? filter plugged up? filter in tank? Electric pump in the rear? mechanical pump? A lot of things can cause pressure drop but not normally carb.
PV on secondaries yes, pressure drop consistent with rpm no,eyes on the road not on tach,3/8 fuel lines, I’m going to say no filter plugged up only three thousand miles on everything from fuel tank threw the motor, electric pump in rear, fuel will at some point actually squirt up into the air filter
 
Almost sounds like the float needle sticking? Like it goes all the way down and then all the sudden the float drops and the gas comes rushing in and maybe can't get close and time to overspill? And then get stuck up until it empties and starts sucking dry and drops open again? Just spitballing....
 
I'm sure it has baffles in the bowl? sound like float hanging for sure, needle open pressure drops and fuel overflows. That thing would have to flow a lot of fuel to drop the pressure to 0 or 3 psi,
what is the gph on the pump.
 
PV on secondaries yes, pressure drop consistent with rpm no,eyes on the road not on tach,3/8 fuel lines, I’m going to say no filter plugged up only three thousand miles on everything from fuel tank threw the motor, electric pump in rear, fuel will at some point actually squirt up into the air filter
I'm sure it has baffles in the bowl? sound like float hanging for sure, needle open pressure drops and fuel overflows. That thing would have to flow a lot of fuel to drop the pressure to 0 or 3 psi,
what is the gph on the pump.
100 gph
 
YOur fuel pressure should not be dropping like that under load, definitely not down to 0-3psi.

When you say loading up, smelling fuel, I have to wonder what the afr is and also what the plugs look like.

I'd like to see you strap that thing to a chassis dyno and see what its doing under a controlled environment.
 
Description sounds like vapor lock. If it is, it may be occuring on the suction side and that's why the pressure drops and then burps up. You smell fuel because its coming of the carb as all vapor instead of mostly a dispersed liquid. At moderate throttle the engine acts something like a combo of its too lean for the load and running out of fuel.

Go over the entire fuel line. Look for any possible pin hole leaks on the supply side to the pump. Look for all locations that may transfer heat from exhaust and headers etc. Insulate as needed.

I've added insulated firesleeve and then covered that with reflective type insulations since having a problem last April. I'd run the car the previous summer no problems at all. So sometimes all that's needed is summer fuel. I just preferred to take the extra precautions against very warm days in the Spring.

This is the worst time of year for using pump fuel. Temperatures are often into 70s and 80s but we're still using winter fuel. Winter fuels are allowed much higher Reid Vapor Pressures (RVP). This helps cold weather starting, and is also cheaper to manufacturer. In our favor, every retail outlet must be be selling 100% summer fuel by June 1. Refiners and distributors must be supplying it by May 1. A few states also have fuel drivability requirements, and others have lower RVPs than the US EPA allows. So not all fuel across the US and Canada is the same.
 
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