TonysMI4

2007 AP2
Hondata Flashpro
inline pro stage 1 (LOG MANI)
6265 JB
walbro 255 fuel pump
Rc750 Injectors

re-tuning because I dropped in a new motor and went from rc650 to rc 750.

THE QUESTION...

After the tune on the logs we were at 76% duty cycle at WOT at redline wit around 10.4 A/F. Then we went to drive it around so we could tune the low fuel tables real good. BUT then we did some hard pulls and the A/F would go WAY lean "13A/F" half pull, so I let off fast. We looked at the data log and the injectors are now only running up to 50% duty cycle and flat lining right there mid pull. No matter if we jack up the fuel in the high fuel table ... It still only hits 50% duty cycle and stays there and that makes it run lean. It seems the more I data log it to find out whats going on, its getting worse. Im thinking my fuel pump has gone bad and wont pump the fuel it needs. Does that sound right? The pump only has about 3500 miles on it. Could it be something else? It seems as if the pump cant pump the fuel fast enough to keep the duty cycle up and the it flat lines at 50%...

s2000Junky

I say fuel pump... or maybe something to do with the returnless fuel system?

Nyther

i THINK i have the SAME problem with my greddy kit.. ( rc 550's and a walbro )

https://www.s2ki.com/s2000/topic/885...ge-af-reading/

I got her tuned nice at an A/F of 11.5 around wot to redline under boost and suddenly after a few weeks it changed to an A/F from 13.x under wot boost :S

My pump has under < 10K miles so i'm also confused.. Seems like the walbro can go from good to bad in very low mileage..

I ordered a new HRC 255LPH fuel pump because i'm reading and hearing more positive reactions about that brand compared to a walbro.. The HRC is cheaper, ALOT quieter and you get longer warranty. In fact, HRC claimes they didnt have a single HRC pump failed until now...

To bad i don't have a fuel pressure gauge so i cannot check if that's really the problem but i THINK it's solved as soon as the new pump is in..

TonysMI4

Think im going to go ahead and order a new pump also. I just HATE where it is and how hard it is to get to. I have an audio wall built in my trunk , so I will have to take all that out to even get to it. If its not one thing ... its another. I hate the returnless fuel system I have. I would buy inline pro's Fuel Return System BUT then I would want to go E85 and thats a whole different story.. (ID 2000 "$1000", Inline Pro Fuel return system with aeromotive drop in pump "$900", new sidewinder manifold "$1200", New down pipe "$300", new wastgate and dump tube because im on a 38mm right now "$500" new oil feed line, new oil return line, new custom charge piping, and a new tune... Hummmmmmmm thats starting to sound nice.

TonysMI4

I just read your thread and you keep stating "noisy walbro" as Iv also head from everyone else that the walbro is very noisy. The thing is... Mine is only noisy when I turn the key and it primes up. After that I cant hear it AT ALL. Think I may have gottin a fake walbro? I did buy it off ebay.

DFWs2k

I have a real walbro, no pump problems, no rear tray, and thats the only time I can hear it too.

jaundice

I have a Full BLown dual pump setup with 2 walbro's if your interested. Im not going to use it.

Nyther

I can hear my walbro buzzing when the car is idling in front of a traffic light when i turn the stereo off....

But its louder when i turn the key to ACC for the first time...

TonysMI4

UPDATE:::

It was not the fuel pump... I changed my out for a new one and the same crap .... I then up the low and high fuel table again and what ya know..... Its back to how it should be... BUT!!!! the next day its back to the same old crap AGAIN!! Its like the ecu is over ruling my tune... WTF!!!!

Nyther

I replaced my walbro with the HRC pump and ive lost my lean conditions under boost! In my case it solved the problem...

I should upgrade to a emu or a aem if i were u..