oldfordisbetter

It takes alot of pumping the gas and trying one twice three times to get it to crank ovr. Then it starts out real low idle then slowly raises in idle untill its idling normal. Has new ford racing plug wires. Autolite plugs. Msd cap n rotor. Msd blaster coil but stock duraspark ignition box. When i turn key i dont hear fuel pump enguage. But wile running and driving i uear a hiss or ppppssssssshhhhhhhttt noise when driving. It goes away when i apply breaks. Was told its hard starting hc the master cyl should b replaced? Help please i want to get this thing going again....

dawson1112

that sound you hear until you apply the brakes could be a vacuum leak in the brake booster. That would cause a hard start.

nitrous_bob

im 99% certain its a vac leak as well

vac leaks will cause basically EVERY drivability problem out there, and they wreak havok on the 5.0 EFI

fix all of them (there will be more than 1...trust me) then come back and repost whats up

dawson1112

He has a carb. But a vacuum leak will still wreak havoc with starting.
Your carb pulls fuel from the bowl using vacuum , a leak in the system when the car is cold especially will starve the engine of fuel .
Try to plug off the vacuum line going into the brake booster and see if it helps the starting.

oldfordisbetter

so would i have to replace the barke booster?

dawson1112

if it has a internal vacuum leak yes you would need to replace it.
First though I would make sure that's what is causing the problem by unhooking the vacuum line from it and plugging the line. If it starts up better you found your problem