Microtech fuel pressure issue
Thread Starter
pwned
Joined: Sep 2005
Posts: 1,296
Likes: 0
From: Northern Indiana
fuel pressure issue
im running a microtech ecu and have a rewired 3rd gen fuel pump. its running through a relay to turn on and off with the car and microtech. the problem is that while the engine is CRANKING the fuel pressure drops to 0psi. with the key in the accessory position the pump primes itself to 40psi for 30 seconds, as it should.
im not exactly sure what the cause of this problem is yet, but im thinking that the 12v ign. wire that i have running to the relay isn t getting power when the engine is cranking. does this sound ab out right to you guys?
im also thinking about eliminating that 12v ign switch wire and replacing it with a constant 12v wire to the battery and a switch to turn it on and off. what do you guys think?
im not exactly sure what the cause of this problem is yet, but im thinking that the 12v ign. wire that i have running to the relay isn t getting power when the engine is cranking. does this sound ab out right to you guys?
im also thinking about eliminating that 12v ign switch wire and replacing it with a constant 12v wire to the battery and a switch to turn it on and off. what do you guys think?
Joined: Feb 2001
Posts: 29,798
Likes: 128
From: London, Ontario, Canada
Sounds like the + side of your relay is connected to the ACC line instead of the IGN line.
DO NOT connect the pump to a constant 12V through a switch. In the event of a collision, this creates a very dangerous situation.
DO NOT connect the pump to a constant 12V through a switch. In the event of a collision, this creates a very dangerous situation.
You can connect 12v straight power to the relay instead of ign as the computer still controls the trigger at the end of the day.
So if you are in a crash, and you kill the ignition, you also killing the computer which inturns kills the fuel pump etc.
But in the case were the computer for some reason stays on then your fuel pump will keep going, so it is definitely safer to hook up 12v ignition(with reds and crank, black/yellow wire that goes to the coil packs is ideal for this).
So if you are in a crash, and you kill the ignition, you also killing the computer which inturns kills the fuel pump etc.
But in the case were the computer for some reason stays on then your fuel pump will keep going, so it is definitely safer to hook up 12v ignition(with reds and crank, black/yellow wire that goes to the coil packs is ideal for this).
Joined: Feb 2001
Posts: 29,798
Likes: 128
From: London, Ontario, Canada
The the wiring diagrams in the Microtech manual show the + side of the relay connected to the pink wire, thus if it is wired per the manual the relay is already getting 12V from the IGN switch.
Trending Topics
Thread Starter
pwned
Joined: Sep 2005
Posts: 1,296
Likes: 0
From: Northern Indiana
gettin a little lost in translation here....
there is only one pink wire in my harness that i am aware of. its connected to a 12v ign wire under the driver side dash. im planning on running the ign wire from the fuel pump relay ( located next to my auto door lock relay in the drivers rear corner) to the the same wire. its a thick wire, so i know the voltage is strong.
there is only one pink wire in my harness that i am aware of. its connected to a 12v ign wire under the driver side dash. im planning on running the ign wire from the fuel pump relay ( located next to my auto door lock relay in the drivers rear corner) to the the same wire. its a thick wire, so i know the voltage is strong.
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
Jul 1, 2023 04:40 PM