[rabbit16v]

the signal goes to the ecu, and ecu tells the fuel pump to fire if i'm not mistaking.
the fuel pump wont run if the engine isn't turning.
it's a safety feature if you were ever in an accident, you don't want the fuel pump to keep pumping to an engine that isn't running.

[rabbit16v]

any luck?

[black vengeance]

Originally Posted by rabbit16v

the signal goes to the ecu, and ecu tells the fuel pump to fire if i'm not mistaking.
the fuel pump wont run if the engine isn't turning.
it's a safety feature if you were ever in an accident, you don't want the fuel pump to keep pumping to an engine that isn't running.

Pump should still prime for 2 seconds when you first turn the key to 'run'.

[rabbit16v]

not if there isn't a signal from the hall sensor

[budsdubbin]

The fuel rail is primed in the on position before the engine is turned over. As soon as u turn the key on you should hear the relay click and close the circuit from the battery to the fuel pump.

[Bad Bunny]

Thanks for the input gentlemen. Yesterday I ended up switching to a mk2 relay. It didn't work, so i ran some tests. Now I know now that there is definitely something wrong with the signal that I'm getting from the ECU.

Pin 12 of the ECU is supposed to be a negative switch. That is, it should complete the ground, thus completing the trigger circuit in the relay, which then sends power to the fuel pump. I measured the potential difference between a constant 12v source and this red/yel wire hich is connected to pin 12 of the ECU. What i found doesn't seem to make sense. I would think that the pot diff should read 0v with the key off, then full 12v for only two seconds with the key switched, and then a permanent 12v with the engine running. Instead, I got the following results with two different ECU's:


Passat Motronic ECU - Key Off = 11.8v, Key Switched = 11.8v
Jetta Motronic ECU - Key Off = 7.8v, Key Switched = 0.4v

At this point I'm thinking that my ECU isn't getting signals from certain sensors in the harness, which is preventing it from sending a signal to the FPR. Like Steve suggested, it may be the hall sender or the coil.

I've been spending less time on the car lately due partly to frustration and partly to school/work, but it's so close and I hate npot being able to drive it, haha. I rolled it out of the garage this weekend:

[Bad Bunny]

Another fun night last night.

I found that the hall sender seems to be working fine. It's got 12v across it, and pulses a 12v signal (when the engine is turning,) which it sends to the ecu.

I still have no spark, and no signal for the fpr from the ecu. The ECU is clearly not seeing something it needs to, and is therefore not giving the signal to the fpr or the coil.

[rabbit16v]

let me know when you're gonna work on it.
I'm just finishing up the bathroom and will have some free time next week

[jettatrek01]

this car seems soo close to being done...!

[Bad Bunny]

Adam, Dan, and Steve (in no particular order other than alphabetical,) are the best.
I'm ditching Motronic bc I was having too many issues, and going to a simpler rocco setup. Fingers are crossed. Thanks so much for your help guys! <3.