Delayed Hot Start Issue - My tentative Solution

My thinking is that if the pump runs for a sufficient amount of time before start-up the fuel in the rail will be new and much cooler, hopefully lowering the rail temperature and purging some of the fuel vapor.

Easy to implement with an adjustable delay ON relay connected in parallel to the Fuel Pump Relay.
I’ve set it to run the Pump for 12 seconds, but can be very easily adjusted if needed.


Delay relay:
The FC-32 relay has the advantage that it will turn Off after the set delay time.
This means that when an accident happens the original 2 seconds delay ON from the ECU will be mentained.


Found a box that fit very nicely and modified the LED light so it’s at the right height.



My first observation was that the fuel pump needs at least 4 to 5 seconds to built enough pressure on a cold engine. You can hear the difference on the noise the FPR and pump make once they reach full operating pressure.

Haven’t had a chance yet to see the most critical condition, i.e. 20 minutes after a long/hot run but I have already seen a difference in both warm and cold starts, a second or two of less cranking time.

I have a turbine style pump which I think is a bit slower in building pressure than a roller style pump.

All the best,