Murray_Calavera

@MBS206 yeah it's a short run from battery in boot to pump

It's 12 gauge Tefzel wire. Should be right for 20 amps. I've clamped the fuel pump wiring, it measured around 20 amps. I can't remember the exact figure, I did it a while ago now, but it was around 20 amps. Still, lots of good info in this thread now. I'll keep investigating and post back with what ends up solving the voltage problem.

It doesn't get tuned to handle the BOV as such, with an aftermarket ECU, you can use a MAP sensor instead of the MAF sensor. In short, the MAP sensor doesn't care about your atmo venting BOV and your mixtures will remain correct. An aftermarket ECU could choose to use a MAF sensor, but not many people do. I haven't used a MAF sensor in something like 20 years. They are a pain in the arse to mount correctly so that the air flows through the way the sensor wants it to (in your now custom intake to suit your bigger turbo etc), they are a restriction in the intake, they have limitations in the volume of air they can accurately measure, you can't use an atmo BOV as you've discovered, etc.

Yep, factory alternator. Fuel pump wiring isn't bad. Not perfect, but isn't bad. The gauge of wire has no issues supplying the 20 amps, the only issue is I'm using the factory connector in the fuel pump hanger which I'd be amazed if they are rated for 20 amps... but nothing has melted so far lol. It's also got the typical relay direct power from battery etc.

Basically, yep. However I can't see you fouling plugs from that alone though (not enough time spent in the rich condition to do anything meaningful to the plugs). If I cast my mind back 15 or so years ago to the I last time I saw this actually happen in person, it just made the car really grumpy for a few seconds and nearly stall and only really had any effect at low speeds/low engine speeds. For sure this is the perfect excuse to get an ecu, delete the maf sensor and keep the bov lol.

You can have an aftermarket BOV that 100% recirculates (the same way the factory one works) Does your BOV vent to atmosphere?

Well, good news. The fuel pressure situation is a million times better. Please see attached dataz. @Dose Pipe Sutututu what battery voltage would you expect to be seeing? When I'm puttering around it floats between 12.8 to 13 volts and when punching through the hills its about 13 to 13.2 volts. Are these normal values? But yeah, I'm so glad I don't have to dig this fuel pump out again lol.

I'd hate to think how many tables you'd need to have a constant perfect tune for all driving conditions without a wideband lol.

Should I be logging ecu voltage or battery?

I haven't logged any data yet, but I wanted to bounce this off everyone while I'm waiting to take the car out for a proper run. So the car was very hard to start this morning, finally fired and I took it to Supercheap to test the battery. Turns out the battery was low on voltage (can't remember the exact figure) and down about 250cca from where it should have been. Even though their simple battery tester said the battery was "fine, just needs a charge" they replaced it under warranty, pretty happy with that. Could a failing battery be the cause of the pump failing to keep up? The pump is pretty hungry, it pulls something like 20 amps from memory but I don't know how much this all matters when the car is actually up and running and the alternator is doing its thing.

Very nice On the plus side, it isn't too hard to hook up the power you have if your prepared to use semi slicks on the road... But then you'll be back to chasing more power so maybe don't get sticky tyres lol.

I wish our beer was subsidised the way our wine is lol.

Oh you sweet summer child. It might be easier to look at this from the Euro scene, in this case a Golf Gti. A super quick google... https://www.mountune.com.au/products/m52-golf-gti-stage-1-power-upgrade-mk7-5-only $1,175 for a "stage 1" tune. https://www.vagparts.com.au/products/volkswagen-golf-gti-mk7-tuning Oh it's on sale! $800 for a "stage 1" tune. So, in these instances the car never sees the dyno, no mechanic ever sees the car, no tuner touches the car. You hand over a large sum of money and you get a copy paste flash tune uploaded to your ecu. So much of the tuning industry is like this. Why would a tuner, turn down the opportunity to extract a minimum of $1,000 from you? It's an easier pill to swallow for the average customer when they sell it as a "full tune". Oh I'm sure they'll happily bill you for more if you want something special done on top, but the price of admission will always be for a "full tune". I really hate to be so cynical about this but it's reality. The obvious solution is to tune the car yourself.

This is a pretty good visual for what we are talking about

Big no vote from me. I like being able to stop when it's raining.