Been trying to solve a hard starting issue that has plagued me for a few years now. On cold start, goes thru a phase of high/low rpm, and on the lows, may die if you don't feather the throttle. This happens primarily during open loop. Car has no real mods, as things are replaced, it has been kept close to OEM. At first, fuel pressure was not holding, so I replaced regulator (replaced with AFPR), pump (omitted pulsator/damper), injectors (22lb from TPiS). Now it is holding. Measuring 46-47 psi, engine warm, idling, vacuum hose disconnected, 38± with vacuum hose on. I think stock is 43 without hose but AFPR is fully backed out so I can't decrease any more. Also have replaced spark plugs and IAC valve. Been doing a lot of reading on the forum pertaining to INT and BLM thinking it may be contributing to my issue. I have Tuner Pro and have been monitoring these values and it seems my INT is in the ballpark of 128, but my BLM holds high at 150-160. At WOT it will be 136 but these values are suggesting more fuel. I am already 3-4 psi higher than stock. I did try to increase fuel pressure by 4 psi and it the issue persists, BLM in the 150-160 range. Any thoughts on other values to check to bring the BLM back in range?

 

What injectors did you get? Bosch-III?

If so, my bet is you need to get the ECM calibration updated to account for that. My personal experience with this (over a few different cars) has been that symptoms of the "Bosch-III effect" is high-BLMs.

On an otherwise factory car that's in good working order, simply putting in the right voltage offsets for the injectors should get your BLMs back in line.

 

I put in the 22lb injectors from TPiS. Not sure what brand they use, no distinguishing features on them to tell. I did do a bunch more testing today and raised the fuel pressure. My last test was at 50 psi at idle with the vacuum hose on, so likely 58-59 with it off. The max BLM I saw during my 15 minute drive was 147 and it looked to average about 140. It is having an effect and bringing the number down, and the car is running great, but it sure feels extreme. Maybe it's a low flowing set of injectors?

 

I'd smoke test it for vacuum leaks and replace the afpr with another unit that allows you to achieve 43.5psi with the vacuum disconnected.

 

TPIS... TPI Specialties?

Can you take a picture of them? There's no part number on them?

 

I think tpis mainly sells matched sets of holleys but could be mistaken.
I was going to tune a customers delphis with stock engine just base and runners were high flow. Had to put fuel pressure to 50 psi and average Blm was much better.