Tylerjdmgsr

So I'm preparing to boost my 1999 gsr. I recently installed a 255 walbro fuel pump and some rc 650 cc injectors. I'm leaving the car in the garage, and I just wanted to see if it would start. My problem is that since then I tried started the car but it wont catch idle. My fuel pump is working and my injectors are injecting fuel,but It just wont stay started. Could this be flooding it? possibly too much fuel? Id like to get some feed back from someone who has experience with this. thanks all much love.

thewrai6th

What fuel management are you using?
Even without the high pressure pump... You are dumping an additional %170 of the needed fuel in, if you are on a stock ECU.

Hidenplanvew

need a tune to run the larger injectors... be careful you can "wash" the cylinders

GagnarTheUnruly

iTrader: (3)

^^^ what they said. If you need to run it for any reason before you get the tune done, you can replace the stock injectors and it should run fine.

If you have a tuning system that will let you make adjustments (eg. Crome, S300 or Neptune RTP), you can add a trim for the new injectors on top of your stock map and it should run more or less OK.

Tylerjdmgsr

Sorry guys I forgot to say I'm running a chipped p28. So should I just unplug the injectors and crank it to burn the extra fuel?

Tylerjdmgsr

I can just take out my 650s and run my stock injectors with the 255 and it will run?

GagnarTheUnruly

iTrader: (3)

Short answer: Yeah, no problem.

Long answer: The fuel pump provides enough flow to keep the pressure regulator happy. The regulator is what determines the fuel pressure, so everything downstream of the regulator is the same pressure regardless of the max flow rate of the fuel pump. The reason for the larger fuel pump is when you ask the pump for a lot of fuel, the stock pump can't keep up. Below that level, the stock pump and the 255 are functionally no different.

The problem with changing the injectors is that the ECU tells the injectors how long to stay open, not how much fuel to add. If the injectors are larger and the ECU doesn't 'know' that, it will add too much fuel. Closed-loop can handle the problem within limits, but you're beyond those limits.

You run into the same problem if you change the fuel pressure regulator. So you can run the aftermarket pump without a tune, but only on the stock FPR and stock injectors.

Since you can't modify your chip yourself, replace the injectors with stock until you're ready to tune, if you need to run the car for any reason.

thewrai6th

Good info! Are you sure this would apply to the HP 255 vs the LP 255? I wish I knew that when I spent so much time diagnosing a rich condition at idle. I replaced the fuel pump with stock and back to the 255HP a few times.

To the OP, I would just run the stock injectors until you get tuned. If you can burn your own basemaps, you could burn one for the larger injectors.

Schister66

Did you do any research before turboing your car? This issue comes down to tuning. Either you have a rich basemap or no tuning system at all. I'm leaning toward the latter

Washing out cylinders with fuel is a concern for new engines only. After cross-honing a newly bored cylinder, the new rings must seat themselves through a gradual wearing down of those cross hatches. Adding a bunch of fuel lubricates the cylinder walls and prevents proper ring sealing.

SleepyPanda

Get fuel pressure regulator with a gauge. then you'll be dumping way too much fuel without a proper tune. get it tuned.