Viper 5706V Remote Start Fails 1st Try, 2005 Chevrolet Avalanche

My installer is stumped.
Vehicle: 2005 Chevrolet Avalanche {same as a Suburban}
Alarm:: Viper 5706v
Problem:Remote will start on first try if vehicle is dead cold in the morning. After using vehicle and now warm, vehicle sits for 10 minutes and will not start on first remote start try. Will start on second try every time. Happens 90% of the time not starting when warm. Also, if I hit Door lock or unlock first then try Remote Start it works first try.
Installer had Tach hooked up virtually.Tried switching it to Voltage. No better. Tried no tach or voltage. No good, would not restart.
Tried to increase crank time for .6 to .8 and to 1.0 no improvement.
Any help??

Thanks Art

Virtual tach is not reliable. Tachometer      white      ac      instrument cluster, gray 24 pin plug, pin A5      

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Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB

Thanks.If I run the wire and hook it up, do I need to change setting or will the Wired Tach know it self?

Ok, so I hooked up the tach wire. I programed the Viper to tach input. I have still having starting problems. First attempt to start fails but now it tries to restart much faster. It always starts on second try.
If I hit lock or unlock on the remote first and then hit remote start, it always starts first try. It's like hitting the lock or unlock wakes it up.
Any things I should try next????

Could be a mechanical issue. Maybe the fuel pump is losing its pressure.

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Steve G