FAST XFI help... stopped running.

[anarchy99]

I figured I'd pose the question on here since I'm at my wits end searching for the problem. Here's the scenario.

Car was running fine. (69 camaro, SBC, FAST XFI, close tune but not all the way finished). I took the car out on the weekend (2 weekends ago) and it ran fine. Changed the oil and washed the car, then drove it for a little while and parked it like normal. No spirited driving, didn't get in it once. Came back on monday and the car would turn over but wouldn't fire for some reason. I sprayed starting fluid in the throttle body and it would fire but die... something fuel. I unhooked the fuel line at the crossover and it came out like a fire hose... plenty of fuel, plus you can hear the pump running so it's not the pump. I figured it was the 30 amp relay that is on the wiring harness, or possibly the 30 amp fuse in the fuse holder, also on the wiring harness by the computer. Both are good to go, I double checked them with a test light. Checked all the grounds I could find and they were all good grounds, verified with a test light. The lights on the box all flash, though the injector ones look really dim when they are firing. Here's the kicker. With all 4 plugs that plug into the back of the FAST XFI computer plugged in, the car will turn over but not fire, even though all lights are flashing correctly (though the injector ones are dim, like previously stated). If I un-hook the blue plug from the back of the FAST XFI computer, the car will fire and run for a few seconds, then die. If I un-hook it and let the car fire off, then quickly plug it back in, the car will run for a little while, though if you touch the throttle, it instantly dies. I'm stumped here!!!!!!! Sorry for the long winded explanation, I've tried to explain everything as best I could. Any help would be awesome as this is killing me!!!!!!!!!!!

[GregWeld]

Originally Posted by anarchy99

I figured I'd pose the question on here since I'm at my wits end searching for the problem. Here's the scenario.

Car was running fine. (69 camaro, SBC, FAST XFI, close tune but not all the way finished). I took the car out on the weekend (2 weekends ago) and it ran fine. Changed the oil and washed the car, then drove it for a little while and parked it like normal. No spirited driving, didn't get in it once. Came back on monday and the car would turn over but wouldn't fire for some reason. I sprayed starting fluid in the throttle body and it would fire but die... something fuel. I unhooked the fuel line at the crossover and it came out like a fire hose... plenty of fuel, plus you can hear the pump running so it's not the pump. I figured it was the 30 amp relay that is on the wiring harness, or possibly the 30 amp fuse in the fuse holder, also on the wiring harness by the computer. Both are good to go, I double checked them with a test light. Checked all the grounds I could find and they were all good grounds, verified with a test light. The lights on the box all flash, though the injector ones look really dim when they are firing. Here's the kicker. With all 4 plugs that plug into the back of the FAST XFI computer plugged in, the car will turn over but not fire, even though all lights are flashing correctly (though the injector ones are dim, like previously stated). If I un-hook the blue plug from the back of the FAST XFI computer, the car will fire and run for a few seconds, then die. If I un-hook it and let the car fire off, then quickly plug it back in, the car will run for a little while, though if you touch the throttle, it instantly dies. I'm stumped here!!!!!!! Sorry for the long winded explanation, I've tried to explain everything as best I could. Any help would be awesome as this is killing me!!!!!!!!!!!

CALL THE FAST TECH LINE....

[anarchy99]

well, nobody was working at the fast tech line today apparently, since I kept getting a recording. The number listed on the website just kept ringing with no answer. I found the problem. It was the TPS sensor of all things. I finally got my computer to hook up to the ECU and noticed a TPS reading of 100% at idle and it was idling high. I unhooked the TPS sensor and it cranked right up and idled between 850 and 900 consistently. If the ECU sees a TPS reading of 80 or higher, it will fire the spark, but not fire the injectors, which is why my spark was good but my injectors wouldn't fire for some reason. I'll figure out the part number for the TPS sensor and go ahead and get another one installed. Other than that though, she is running good again, and I'm going to start logging and tuning. More to follow.

[camcojb]

Originally Posted by anarchy99

well, nobody was working at the fast tech line today apparently, since I kept getting a recording. The number listed on the website just kept ringing with no answer. I found the problem. It was the TPS sensor of all things. I finally got my computer to hook up to the ECU and noticed a TPS reading of 100% at idle and it was idling high. I unhooked the TPS sensor and it cranked right up and idled between 850 and 900 consistently. If the ECU sees a TPS reading of 80 or higher, it will fire the spark, but not fire the injectors, which is why my spark was good but my injectors wouldn't fire for some reason. I'll figure out the part number for the TPS sensor and go ahead and get another one installed. Other than that though, she is running good again, and I'm going to start logging and tuning. More to follow.

makes sense. If the TPS is 100% when cranking the ECU goes into clear mode and will not pulse the injectors. This is to help start a flooded car. Glad you got it figured out.

Jody