You don't give anywhere near enough information to even begin - please be more specific.
I replace engine but now it wont start.
your fuel pump could be bad if it runs for a few seconds .
The car will have to be taken out of failsafe mode to get it to start. The specific way to troubleshoot the problem will vary between brands.
If the engine turns over the batteries are fine. Diesels require special equipment to troubleshoot, take it to a shop that is competent in diesel engines.
Start by having the fuel filter changed.
When a vehicle won't start first check to see if the battery is dead. If not then check the gas, if neither of these are the issue contact a mechanic.
one of the sensors are between the two fans with wires going into it
Blown FuseDefective fan motorDefective Thermal RelayFault in the wiring
security lock out had same problem with our 2004 grand am
combustion engines need 3 things to run: fuel,spark,air
Put gas in the tank and try again.
Maybe check your fuel pump pressure.