Originally Posted by SRT6 Gang Member
Although the title states SL55 Fuel Pump, this thread should be all encompassing for our fuel system. Lets discuss.....
Brief History:
After having a wideband a/f gauge installed about 1 ½- 2 years ago, I noticed a slight leaning out issue in the top of 3rd @ 5200 through redline. This issue would get significantly worse as the ambient temps dropped, winter months a/f went into the 17-18 range. Believing it was a tuning issue, I received several updated tunes and none corrected the issue. Then I thought since it isn’t a tuning issue, it has to be something mechanical with our fuel system…….Fast forward
Present Day:
I purchased and had an SL55 Fuel Pump installed in preparation for the Dallas Tune Day. The-6 was tuned and all leaning signs in the top of 3rd @ 5200 through redline disappeared. I was then asked to make a 4th gear run to redline too validate no lean issue would be present. The results in 4th gear @ 5300 were LEAN, LEAN, LEAN, LEAN, LEAN and did I say LEAN! I never made it to redline because once I saw the a/f, the foot was removed from the accelerator. However, I did make several 4th gear runs on different days and they all ended with a 16-17 a/f.
Theory:
The SL55 Fuel Pump was able to correct the 3rd gear leaning issue because it flow’s more fuel than the stocker with less pressure. To assume that it doesn’t because none of the fuel flowing orifices have changed is faulty logic. That would mean the stock fuel pump flow was maxing out the current fuel path, which is not the case.
The SL55 Fuel Pump is able to flow more with less pressure on the OEM regulator, preventing the bleeding off of fuel in 3rd. However, in 4th gear I assume the pressure being produced by the SL55 is equivalent or greater than the stocker in 3rd gear. This is why the same leaning condition in 4th presents itself with the SL55 Fuel Pump, the regulator is being taxed and bleeding necessary fuel back into the fuel tank. Moral of the story, I think we need a better fuel pressure regulator.....
Out of curiosity how many miles on the car. I'm thinking maybe the fuel filter is getting dirty, I have 3000 miles on the SRT and posted the AFR' from the tune