ok the problem is the car starts no problem when cold it fires right up but if i drive it hard or for longer then 15 minutes is doesnt want to fire. turns over but no fire. what could this be?
wont start when hot
- Thread starter BoostnLoose
- Start date
Well, it could be a few other things but you can't expect too much with little more than a "help, car broke" post.
Fuel pressure is supposed to stay up to prevent vapor formation after the engine is turned off. Depending on how long a hot engine sits (typically 30-45 minutes) a loss of rest pressure (Toyota calls it residual pressure but I'm using the Bosch term) will result in a hard/no start. The Fuel Pressure Up system also has a hand in preventing this but a loss of rest pressure will render it useless.
Bottom line is to check your fuel pressure either after jumpering the fuel pump on and then removing the jumper or checking it right after the engine is turned off. Pressure should hold at or above the value listed in the manual for the specified time.
Fuel pressure is supposed to stay up to prevent vapor formation after the engine is turned off. Depending on how long a hot engine sits (typically 30-45 minutes) a loss of rest pressure (Toyota calls it residual pressure but I'm using the Bosch term) will result in a hard/no start. The Fuel Pressure Up system also has a hand in preventing this but a loss of rest pressure will render it useless.
Bottom line is to check your fuel pressure either after jumpering the fuel pump on and then removing the jumper or checking it right after the engine is turned off. Pressure should hold at or above the value listed in the manual for the specified time.
If it's not a loss of pressure test FC on the AFM while the AFM is hot. If there's a fracture in the traces or if the reeds are dirty or not make good contact that'll cut power to the fuel pump.
BoostnLoose;971407 said:
There's a switch in the AFM which will cut the power to the fuel pump if the vane is fully at rest (ie: there's no air entering the intake or the AFM (and as a result the switch) is disconnected).
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=94
From my dealing with the MAFT Pro I've found that on my car the pinout was incorrect. In my car E1 and FC are swapped from what's shown in the diagram. FC is pin 2. So check that you're testing the right line.
The TEWD shows FC as being pin #2:
http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=57
It could also be your starter connection... Mine was doing this all the time... Sometime i had to wait for an hour. When I Changed the motor (old one blew, crank bearing), for another 7mge, i kept the same starter, but I double checked all the starter wiring. Since then, never had that problem.
You didn't say if it starts at all or starts and dies but if it doesn't start at all FC is unlikely to be the cause.