Intermittent Prime shot issues
Hello all! I've had my fitech 600hp installed in my 66 Mustang 302 for a bit over 2 months now and its always been a little wonky since the start. My main issue with the system lately is during key on before cranking. As usual the fuel pump primes the lines but sometimes the system does not fire the priming shot of fuel for the engine to turn on! (before I would have to prime it twice for it to shoot the prime shot at all but it was reliable) I've checked many things as far as installation goes and I had not changed any settings relating to the pump prime or prime shot other than a 10 second pump prime over the original 5 seconds. I have grounds to the throttle body, am running relays for both the fuel pump and white wire, and have fuel pressure coming from the pump and can hear it doing its thing. I don't know what is going on anymore and it seems to do it at random since sometimes it just works fine regardless of heat so I don't think that is the issue. If anyone can help me out or has experienced similarly. Thanks in advance!
Why do you have a relay on the white wire? It is not necessary and may be your issue. What voltage is @ the white wire and what voltage is your battery? Is your pump in-tank or in-line and what brand?
Quote from SodaPop on August 29, 2021, 6:48 pmWhy do you have a relay on the white wire? It is not necessary and may be your issue. What voltage is @ the white wire and what voltage is your battery? Is your pump in-tank or in-line and what brand?
It was my understanding that the fitech is very picky to the voltage being received at the white wire and that any voltage drop would cause problems for the ecu, hence the relay. The relay was just installed during the troubleshooting process and it seems to have helped with some of the wonkiness. I have an inline Walbro 255LPH pump on a relay with pwm disabled
I now understand your relay on the white wire, but it is not necessary if you get above 11 volts on the white wire when cranking. The white wire triggers the Main relay on the ECU. But have you checked your voltages when cranking to see if your voltage drops? One thing to do if you dont drive your car alot, is to install a Battery Trickle Charger on your battery when not using your car to maintain the battery. How old is the battery on your car? What is the voltage of the battery when the car is off? Just to confirm a few things: When you turn the key to the on position, do you hear the fuel pump priming the system? When it is priming have you looked in the 4 barrels to see fuel coming out of the injectors? There should be. If not, it may be your ECU as there seems to be a run of ECU's going bad on the Go EFI 4 600HP
Yeah I've concluded its the ecu. When I key on I can hear the pump prime but the intake is completely dry. The battery is brand new and I just upgraded to a 130amp alternator with minimal accessories. No voltage drop while cranking but oddly the handheld will show a voltage drop when turning the key on and priming the pump. and it will restart the pump prime a few times but will randomly fire the prime shot after dozens of tries
I am not into electronics, stand correction, but I understand the pressurised fuel from the pump enters the throttle body through the relief valve and then into the injection rings, the icu controlling the elapsed time of power to the pump. Is there another valve before the injection rings that controls the fuel flow?
Quote from Geoff_The_Giraffe on September 7, 2021, 1:19 amYeah I've concluded its the ecu. When I key on I can hear the pump prime but the intake is completely dry. The battery is brand new and I just upgraded to a 130amp alternator with minimal accessories. No voltage drop while cranking but oddly the handheld will show a voltage drop when turning the key on and priming the pump. and it will restart the pump prime a few times but will randomly fire the prime shot after dozens of tries
what gauge of wire is going to the fuel pump? while it is priming have you put your finger in one of the four barrel's of the throttle body to see if it is wet. At this point most likely it is your ECU or your in-line fuel pump as in-line pumps tend to go bad compared to in tank pumps.
Quote from Geoff_The_Giraffe on September 7, 2021, 1:19 amYeah I've concluded its the ecu. When I key on I can hear the pump prime but the intake is completely dry. The battery is brand new and I just upgraded to a 130amp alternator with minimal accessories. No voltage drop while cranking but oddly the handheld will show a voltage drop when turning the key on and priming the pump. and it will restart the pump prime a few times but will randomly fire the prime shot after dozens of tries
Also have you checked to see if there are any fault codes on the handheld?
There are random codes that change every time I turn the key on that range from 02 to injectors 1-4 but disappear once the engine decides to run. When it runs it runs beautifully . I have 12 gauge going from the relay to the pump and back directly to the battery. I have stuck my fingers in each one of the barrels while priming and not one of them shoot gas when this problem is occurring. The inline pump is also producing the required pressure and the gas is making it to the fuel rails
Quote from Geoff_The_Giraffe on September 7, 2021, 9:12 pmThere are random codes that change every time I turn the key on that range from 02 to injectors 1-4 but disappear once the engine decides to run. When it runs it runs beautifully . I have 12 gauge going from the relay to the pump and back directly to the battery. I have stuck my fingers in each one of the barrels while priming and not one of them shoot gas when this problem is occurring. The inline pump is also producing the required pressure and the gas is making it to the fuel rails
So just to be sure, you turn the key to on and you hear the pump priming, but no fuel coming out of the injectors. Sounds like a injector driver issue, which means ECU. If it is new you will have to send unit back to Fitech for repair. One thing to do is to use a Phenolic Thermal Insulating Carburetor Spacer that prevents heat soak. I used it on my setup and the throttle body is warm to the touch even on very hot days. What is also good to have is a electric fan with a PWM fan controller which allows my fan to run for several minutes after I shut off my car. It really cools off the engine including the throttle body. There just seems to be a run on bad ECU's on Go EFI 4 600HP units. If your unit is new you may want to talk to Fitech about exchanging it for the Go EFI Classic Part #30020 as the ECU is external and you can mount it inside you car away from heat.