I recently installed a Walbro 255lph fuel pump along with a nitrous kit. When I did my NA run on the dyno, I noticed that I was running really rich, 10.5 or so. the car is on the same tune as it was before, and it was in a lot better shape, with an AFR in the 12s. Can simply adding a higher flowing intake cause my 94 LT1 to run rich, without adjusting the tune or injectors?

 

Well, from the looks of it, a larger intake should make it more lean, that is a powerful fuel pump. Im putting a similar pump on my engine build this summer, but on a 383 build. Looks like you may just need a tune for it. Probably a chassis tune is in need here. But look on the bright side for now, running rich isnt as bad as running lean like i am now .

 

Depends on exactly how it was tuned before. The fuel pump shouldnt make a diff unless it has bumped the pressure up alot or the previous pump was not cutting the mustard with supply at high rpm depends on how they tuned though. A dirty maf will do exactly what you're describing. Hard to diagnose with no datalogs or other info.

 

Aren't you asking about a higher flowing fuel pump?

 

if your old pump was dying and he had to tune it to make the fuel operate on a heavier demand to get the required fuel I could see it happening I guess

 

If your old fuel pump was able to keep the same pressure you're running now, no. If your old fuel pump was slacking and pressure was dropping off then the addition of a new fuel pump adding pressure would cause it to run rich without the tune being adjusted. For instance, putting a walboro on a bone stock car would change nothing at all. Putting a walboro on a previously fuel starved engine would cause it to no longer be fuel starved.

 

Yes, I meant fuel pump. This is what I figured, and my tuner has confirmed it. Time to save more money and get the tune adjusted.

 

Learn to do it yourself? Its not the voodoo many would have you believe.