The title has been my question for a few days while I tuned my friends truck. It's a 383, comp cams computer cam(dont recall the part# off hand but it's mild), polished intake/exhaust port swirl port heads, flat tops, edel tbi intake, stock 5.7 tbi and injectors/fpr, shorty headers, stock fuel pump...
So, after trying multiple bin mods to get the blm's off of 108, I decided it had to have a "mechanical" issue(since I zero'd out the idle ve cells and still dumping fuel into the intake).
Since he doesnt understand the importance of an adjustable regulator or a pressure gauge it only made my job harder. My first thought was a plugged fuel return line since the truck sat without an engine for a year and the fuel lines were open to the elements(bugs, dirt, etc). Using air pressure regulated to 20psi I blow through the return line which was free as the air we breathe so that was eliminated. So he had another tbi setting around which we slapped on and voila! BLM's went the other direction, and I was able to tune the engine to get more ideal numbers(125-132). Haven't had a chance to inspect the fuel pod yet to see where the restriction is but I will this weekend and I'll post it here.
This is for anyone who may run into a similar issue and to emphasize to the newbies that not all issues are software based. How many times have we chased a tune issue to find out its a mechanical issue? It threw me for a loop for a minute and made me look bad as a "tuner" which I disliked lol. Now my reputation is restored and work carries on.
Have a great day everyone.
Buddrow
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