40 psi fuel pressure is waaay too much!

[Huey130]

Hey yall, sorry for being so quick but this is killing me on the fourth day of a build due to parts getting to me late and starting with a bad platform...
I swear I'll come back and "give back" to the forum some.

I'm a shop owner but that doesn't mean I know everything. (I know a crap load though!)

New Velocity stage 1 install. Everything seems to be installed OK.
Bike starts and runs no issue just rich as hell!!!!!!!!!!

Tuneing w/o any boost is asking for -40 through -60s in the PC-3!!!!!! With Exactly 40 psi on the fuel pressure.
I know that the bike shouldn't know theres a turbo until boost kicks in... So these numbers should be more normal-ish. Have been on every other bike I've tuned. Slight variations but not like this.

I've checked a different MAP sensor, used a different fuel pressure gauge, tried a different ECU, started to look for a stuck injector but the plugs look good and it responds sort of to these weird numbers..

I'm hoping someone will go: Oh yeah it's_____________________
Help, please. I'm tired and I want to go home.

 

[BusaWhipped]

I've had that problem on a NA Gen 1 Busa when the water temp sensor went bad. It thought it was alway cold and was dumping fuel in. Don't know if you have the same problem, but start with the basics.

 

[Huey130]

Thank you for the reply! Yes it is a first gen. A 99.
Good idea on the temp sensor. Swapped it out... No go.

Will start fresh tommorow. Customer was ok. I'm being harder on myself....

 

[SKnight]

Damn the folks you run into around these parts! What's up Huey?

MPFI injectors, as you know, simply don't spray right at less than 30 PSI or so, in fact you have low pressure unless there's something to boost it once the turbo comes in. I have a first gen service manual around here somewhere but of course I can't put my hands on it. I'll go with typical fuzzy memory.

I'd check the duty cycle of the injectors. Is it too much pressure, too big an injector or too much duty cycle? It's not too much pressure, go lower and you won't have the spray pattern you need. Are they stock injectors? If not then trimming back would be in order. If they're stock then what's the duty cycle, is it too long and why is it too long? A DVOM can tell you the duty cycle. Like I said my book isn't handy but more than 1ms at idle will likely burn your eyes.

Finding out what the injector is being told to do will get you started. Then you get to figure out why the ECM is commanding that much fuel.

I know you said you swapped the MAP but is it getting a good vacuum signal? Just popped to mind.

 

[OZBooster]

I know you said you swapped the MAP but is it getting a good vacuum signal? Just popped to mind.

same thoughts here, nothing makes it go so rich as the map sensors either faulting or wrong signal or incorrectly plumbed
second place would be the gauge reading low

 

[Huey130]

Screw you Oz! Where were you yesterday! Hahahaha Sorry, my frustration is still ebbing.

Got it this morning.... Not only was his MAP sensor bad but when I kept swapping the new one on I kept being lazy cause I had ziptied all my vacuum lines. So I'd plug it into a different part of the vacuum rail. Turns out where I was plugging the new one into had a leak!!!

So bad sensor versus good sensor with crap line!!! No wonder it was driving me nuts.

I ended up rebuilding the whole little vacuum "rail" (the one with all the t's) with new hoses and bam: ran like it was supposed to! In hingsight it was staring me in the face the whole time.

What's up Steven!

 

[OZBooster]

Blame the time zone differences This stuff realy tests the patience sometimes

 

[SKnight]

Same old same old Huey, selling parts but wishing I was installing them. Hey, how much for a basic dyno run to baseline my bike? I'm wanting to change a few things starting with ditching the converter but would like to know where I'm actually starting.