[CptKaos]

I have a new Mighty Demon 850 on my 496 and the truck developed a stumble on acceleration, have narrowed it down to no secondary pump shot. The diaphragm is good, the passage is clear and the umbrella valve is good. Any tips?

Larry

[steve392]

I had the exact same thing with a brand new Mighty Demon. Remove the fuel bowl, and find the matching hole in the metering block that receives the fuel from the bowl. You can trace the passage in the block as it rises up and turns to the left (looking at the metering block from the fuel bowl side) and goes to the center of the block where it mates up to the holes in the main body. It is a raised, machined passage and easy to spot.
Right at the top of the passage there is 90 degree change in direction. At each corner of the passage, look for two tiny brass plugs threaded into the sides of the passage. These plugs were left out on my Demon, and without them the accelerator pump just pushed the fuel back into the bowl, and therefore no squirt...
It looks like the passage is drilled from both directions, and these plugs are needed to seal off the holes after drilling.
I called BG, told them the problem and they shipped me put a couple of plugs. After installing the plugs, the squirters worked fine.
This may or may not be your case, but it's a place to look. When you push down on the pump arm, does it compress, and seem like its pumping gas, or do you get resistance, like the gas has nowhere to go? Hope this helps,
Steve

[CptKaos]

When the pump is activated you can see turbulence in the fuel bowl and a little fuel dribbles out of the nozzles. I guess I will call BG tech support.

Larry

[Tech @ BG]

Originally Posted by CptKaos

When the pump is activated you can see turbulence in the fuel bowl and a little fuel dribbles out of the nozzles. I guess I will call BG tech support.

Larry

Larry,

If you're seeing turbulence in the bowl it could be what Steve392 mentioned about the blocks, or it could be the rene' valve in the bowl. It should prevent the fuel from coming back up from the pump housing when the accelerator pump is depressed. The valve may not be completely seated.

[CptKaos]

if you are talking about the umbrella valve, it is sealing. with the bowl off and the port blocked the accel pump holds pressure. how do I get the blocks for the passage?

Larry

[Tech @ BG]

Are the cross over plugs in the metering block?