Hi I'm doing a conversion into a 1980 chevy. I need help with the brakes the cummins has the vacuum pump on power steering pump, when I hook up the vacuum line to the chevy master it sucks the the peddle to the floor and when I take the vacuum line off the peddle comes back up. I don't know if the booster is bad or the dodge vacuum pump has touch vacuum. Need help!!

 

I am going to say a bad booster.. on my suburban with a cummins 12 valve and the later vacume pump to the stock booster mine work great! good luck!!

 

My blazer works great also must be the booster do you have a check valve on the vacuum line idk if that makes a difference cause my blazer already had one so kept it in place

 

I don't have a check valve I can try that. Thanks for the help

 

ya mine has the check valve in that plastic elbo that pops into the grommet on the booster. works great