Ok, looking for some help here.
Long story short, I've been trying to solve hard starting issues on the viper on and off the last couple years. I have changed fuel, fuel filters, and spent $300 getting the injectors fully serviced and balanced.
It's a common thing for them, which essentially boils down to the fuel pump not running for long enough to fully pressurize the fuel system before you crank. The PCM energizes the pump for 1 second (by connecting ground to the pump relay) before it cuts out due to no engine rotation being detected from the crankshaft position sensor.
For whatever reason the fuel pressure reg, the screen or the pump just don't quite get it done in time. works fine when its running. annoying as ****, you have to keep priming it and then it goes. I want it to prime for longer.
There is a fix, it involves using an ELK-960 delay timer, ( https://www.elkproducts.com/product-catalog/elk-960-delay-timer-module ) a small circuit board, and hooking it up at the back fuse/relay box in the boot to extend the inital prime time by a few seconds. I couldnt get to said relay because the ******* that owned the car had a sub box PERMANENTLY INSTALLED in front of it. This resulted in me dismantaling the rear of the car (splash guards, rear bumper) to try and see it it was bolted on. Nope, said ******* just drilled the bottom plywood piece of the box into the fiberglass then glued/made the box around it. Had to rip it (with screws) out, so now i CAN get to the rear box. Lots of wasted hours.
before doing this i ****** around and tried to make the delay timer work at the PCM. I failed, and in doing so I seem to have stopped the PCM from connecting the ground to the fuel pump and energizing it. I confirmed this, if i just connect that wire to ground the fuel pump runs with the start/run circuit and car is fine.
However, I do want that safety feature such that if it gets crashed and the engine stops, the fuel pump stops running and passengers have a better chance of not being fireballed to death.
I'm trying to figure out if there is a way to use another 960 or similar to essentially replicate the safety feature, tap into the crankshaft position sensor wire (output ~5V, enough for the 960 module) but I don't think I can do it with just one, or maybe i need a seperate product.
here's what I think needs to happen:
- initial start/run power energizes fuel pump, but uses a timer such that if no rotation is detected within.... say 7 seconds (this is configurable on the 960) it cuts it off
- if rotation is detected (cranking or running) it keeps it on, but either a loss of signal from the crankshaft sensor OR no power from the start/run circuit it stops.
i THINK its something like example 9 on this sheet for the 960. https://www.elkproducts.com/_literature_63602/ELK-960_Instructions
I'm just not a car electrician and am scratching my head a bit. I'll keep noodling. Will draw some pictures and update if anyone is keen or able to help...
Long story short, I've been trying to solve hard starting issues on the viper on and off the last couple years. I have changed fuel, fuel filters, and spent $300 getting the injectors fully serviced and balanced.
It's a common thing for them, which essentially boils down to the fuel pump not running for long enough to fully pressurize the fuel system before you crank. The PCM energizes the pump for 1 second (by connecting ground to the pump relay) before it cuts out due to no engine rotation being detected from the crankshaft position sensor.
For whatever reason the fuel pressure reg, the screen or the pump just don't quite get it done in time. works fine when its running. annoying as ****, you have to keep priming it and then it goes. I want it to prime for longer.
There is a fix, it involves using an ELK-960 delay timer, ( https://www.elkproducts.com/product-catalog/elk-960-delay-timer-module ) a small circuit board, and hooking it up at the back fuse/relay box in the boot to extend the inital prime time by a few seconds. I couldnt get to said relay because the ******* that owned the car had a sub box PERMANENTLY INSTALLED in front of it. This resulted in me dismantaling the rear of the car (splash guards, rear bumper) to try and see it it was bolted on. Nope, said ******* just drilled the bottom plywood piece of the box into the fiberglass then glued/made the box around it. Had to rip it (with screws) out, so now i CAN get to the rear box. Lots of wasted hours.
before doing this i ****** around and tried to make the delay timer work at the PCM. I failed, and in doing so I seem to have stopped the PCM from connecting the ground to the fuel pump and energizing it. I confirmed this, if i just connect that wire to ground the fuel pump runs with the start/run circuit and car is fine.
However, I do want that safety feature such that if it gets crashed and the engine stops, the fuel pump stops running and passengers have a better chance of not being fireballed to death.
I'm trying to figure out if there is a way to use another 960 or similar to essentially replicate the safety feature, tap into the crankshaft position sensor wire (output ~5V, enough for the 960 module) but I don't think I can do it with just one, or maybe i need a seperate product.
here's what I think needs to happen:
- initial start/run power energizes fuel pump, but uses a timer such that if no rotation is detected within.... say 7 seconds (this is configurable on the 960) it cuts it off
- if rotation is detected (cranking or running) it keeps it on, but either a loss of signal from the crankshaft sensor OR no power from the start/run circuit it stops.
i THINK its something like example 9 on this sheet for the 960. https://www.elkproducts.com/_literature_63602/ELK-960_Instructions
I'm just not a car electrician and am scratching my head a bit. I'll keep noodling. Will draw some pictures and update if anyone is keen or able to help...