Need help with RS on 05' F250

I am having a problem with a customer's truck.It is an 05' F250 diesel and I am using the DEI T56 and using their timer.The truck will start sometimes but most of the time it seems to get right to the point of starting then shut off.This is the first time we have done a remotestart on a diesel using the fact. keyless but we have never had this problem.Any ideals on what is going on?

make sure to get the tach diesel no tach i did one and by mistake i get just tach, i read the notes and it said use tach dieselhow own your mind, control your life.

MECP certified. always use a DMM

Glow Plug Wire:7.3L Diesel- WHITE/ LT GREEN (-) At 42 Pin Conn. Located On The Driver Rear Of Eng. Under Intake. 6.0L Diesel- VIOLET/ORANGE At PCM Located On Driver Fender Well In Engine Compartment. FORD, F SERIES SUPER DUTY, 2005, Tachometer On diesel vehicles the tach wire is lt. GREEN / WHITE in a 5 wire harness held up with white tape behind the parking brake release. Tachometer NOT RED / lt green or RED / yellow AC any ignition coil or fuel injector Be careful whose advice you buy, but be patient with those who supply it.

I have the tach wire and I have never had to tap into the glow plug wire.I was under the impression that all diesel trucks from about 00'-up you don't have to us the glow plug wire.This thing acts like it is dropping power right as it is about to start..