87' Ram D100 sluggish throttle after fuel pump swap

[J Cartner]

1987 Dodge Ram D100 - 318 V8 - Edelbrock four barrel carb swap

My mechanical fuel pump went out on my truck a month or so ago, and I changed it to an electric pump due to believing the cam lobe had spun after putting a new one on it. Basically the original was leaking fuel, so I replaced it with a new one, and after about twenty miles or so worth of driving it, the truck died off like it had no fuel, despite me having put five gallons in it before starting the test drive. Pulled the pump since that was the only thing that had been changed recently. Checked it and it was still working just fine, nothing was loose and the lever was still perfectly fine. Checked the filter and it was good, and I hooked up a spare electric fuel pump to the line from the tank to make sure the line wasn't clogged, and it was fine. Hooked up the line from the carb to the electric pump and got everything tightened down, turned the truck on, and it started just fine. So basically my only guess left is the cam lobe itself spun after putting a new pump on it. So, I elected to just put on an edelbrock 38 gph electric fuel pump on it from autozone since thats what I had on hand. Got it running and I took it for a drive after making sure there were no leaks, and I noticed that it was substantially more sluggish. I would have to press the throttle a lot more than normal in order to make it accelerate, and even then it wouldn't accelerate very quickly. It seemed like no matter how much I pressed the throttle, it wouldn't do much of anything till I was almost flooring it, and even then it still wouldn't do much.

Any tips would be of great help because I want to start driving my truck again and not feel like its going to be the next week before I get down the road.

 

[B250]

What I remember about carburettors from my childhood days is that the float height can affect performance. But if the only thing that's changed is the fuel pump, it must be that causing the problem. Just one thought - a mechanical fuel pump is very low pressure and has a diaphragm that stops it pumping when the carb float valve closes. Modern electric fuel pumps are designed for fuel injection and are higher pressure. The new pump could be forcing fuel past the float valve and messing up the fuel/air mixture. There used to be an electric version of the old mechanical pumps designed just for carburettors. It maybe worth checking out if you can still get them