remote start not working

i have an 02 f150. viper 791xv. had it on about 2 years now. alarm works fine. the remote start has not been working right. when i remote start it it will start up and work fine sometimes. or it will start up for maybe 10 seconds and then shut off.  when it does start and stay running and i hop in turn the key and press the brake normally on the key chain it will beep and the remote start symbol will go away. it no longer does that. i have no idea what it could be. the only thing i thought possible was my bypass kit is going in and out. but i dont know how that would affect my key chain. any help or suggestions would be great. thanks.

as far as your first problem, the tach signal needs to be reprogrammed. it may not even be hooked up and may be using voltage sensing. thats the first thing to check and change if need be. for your second problem, check to see that the brake light shutdown wire from the remote start is still connected.