Jumpster74

iTrader: (1)

It seems I have no luck when It comes to my new fuel system. Im just a self-taught enthusiast and I've exhausted my knowledge on how to fix this problem, so any ideas are appreciated.

- Car was running normally beforehand but now won't catch when cranking.
- Added new FPR, fuel rail, ethanol compatible lines, and ethanol sensor/gauge. Previously working setup was running fine with a hardwired DW300, ID1000s, and the same tunefile. Only messed with a few of the MS3 option wires which to my knowledge are entirely unrelated to the fuel system.
- Spark tested with test mode and works as it should
- Now, with the key on, I'm only getting 0.02V at the red/white injector power wire and injector plugs (instead of 12V)
- Main relay is working fine
- Fuel pump is supplying 60psi at the rail

Here's where it gets weird:
- If I test the injectors with test mode, they click as if they are working and rail pressure drops to 0psi as if they are injecting. However, If I put a rubber hose into a cylinder, leave the fuel pump on, and test the injectors with test mode, the hose comes out dry showing no gas is being injected.
- If I attempt to crank with everything assembled, ill get some little puffs and backfires, and sometimes the plug comes out wet, sometimes dry.

Im at a total loss as to how or why I'm getting these symptoms, but I'm assuming the first thing to dive into is why I'm not getting 12v with the key on at the injectors. I've tested the main relay which works fine, so what's the next thing to check?

Jumpster74

iTrader: (1)

Like I said, self-taught... Turns out I was using a bad ground for my multimeter, and I actually am getting 12V at the injectors, which makes a lot more sense.

Now to figure out why the injectors aren't consistently firing, or at least why the engine isn't catching.

Ted75zcar

iTrader: (2)

Did you swap the routing to the hard lines on a return style chassis?

Jumpster74

iTrader: (1)

Yes

I hold late nights and caffeine accountable for this lapse of observation

Jumpster74

iTrader: (1)

Ok, now I've realized that when I look up which lines are feed/return, I get both answers...

This is what I just switched too but the gauge now reads zero after priming, and the engine will start to catch then die.



I'm thinking I might have had the orientation correct the first time and the above is incorrect. Can anyone verify?

Ted75zcar

iTrader: (2)

front is return, rear is feed, looks like you are backwards.

Were you running 60psi before?

Jumpster74

iTrader: (1)

Ok, I'll switch it back and play around with the fuel table scaling to see if I just was running too lean/rich.

I was running the stock fuel pressure before with the OEM FPR. The AFPR is a new addition since I want headroom for the 6758.

EDIT: I did just triple confirm with test mode that all injectors fire and all plugs spark, so the issue is between the tune or incorrect flow AFAIK

Ted75zcar

iTrader: (2)

Did you adjust reqfuel with the pressure change? I would simply start by going to the stock 3 bar base pressure and getting the car running. Then you can make changes to the fueling.

Jumpster74

iTrader: (1)

That's exactly what I should have done, but I switched the fuel lines back, had the req fuel around the ballpark of where I imagined it should be, and it started right up with no issues.

No clue why it wouldn't catch before, but I'm a happy camper now. Of course, as I did this, I powered on/off the car and my tuner studio stopped recognizing the MS3 (i.e. "not connected") but I'm just happy to be done with the new fuel system I've been troubleshooting for 4 weeks