Car stalling intermitently after fuel system upgrade and tuning

I apologize in advance to this being a bit of a long post I just figure I'll give you all every but of info I have at once.


So Thursday got my car back after almost 6 weeks of it being in the shop getting a bored out fuel rail, 800cc injectors, walbro fuel pump, FPR, and haltech sprint 500 installed in my 92 gt-s. when I picked it up the guy told me that "because of the new fuel pressure regulator it may take more time to build up pressure so it will more than likely stall right when you start it up and you just have to start it up again and it's fine". Well it does do this to me every time I start up, but i have to start it more than 2 times and keep my foot on the throttle to keep it from stalling for about 10 seconds. The guy also told me that he thinks my battery is on its las leg, that if you let it sit for more than a day or 2 he finds he has to jump start it. ( idk how old the battery is so sounded about right to me) so before I paid I had a test run with him and it went fine and then when I went to leave after paying it stalled while I was reversing out and wouldn't start so he had to jump it for me. I had a 15 min drive home and about 2 min from my house in traffic when coming to a stop, I put my foot on the clutch to put it into neutral and it just died... I was still rolling and scared it wouldn't crank over so I popped the clutch and kept the revs up, then another 45 seconds later it did it again this time at a full stop so I cranked it and it started up. Then as soon as I pulled into my parking spot at home and got out of the car (leaving it running to check it over) and closed the door it died. Then 10 min later went to start it up and it wouldn't start at all. So I went next door to the mechanic and he lent me a battery while we put mine on his charger to test it. With the new batter it seemed fine other than the occasional trouble getting it started, usually at night with my HIDs on. For example after I fueled up Friday night I started it up I had to keep the revs up for a bit but it leveled out then as soon as I put my lights on it died. But then started back up again. So this morning I picked up my old battery to try it out again after it being on the charger for about 36 hours. with the car off it was at 12.6v car on 13.6v
So this morning I drove over to my brothers house. About 15 min away and as soon as I turned left to park on the steet outside his house it died. (while trying to park it died again and I gave up half parked infront I his driveway)
So luckily I brought the mechanics battery incase my old battery was still having issues so I swapped the battery back to the known good one (by the way my old battery when I took it out was at 12.9v)
So I then drove around a bit and drove home and it was all fine. Then I went out to the store, another 10-15 min drive and as soon as I turned left into a parking spot I was half in and it died. When I left the stores and was leaving the parking lot and came to the roundabout to leave as soon as I came to a stop to yeild, it died. Drove home alright and as soon as I turned right into my driveway foot on the clutch it died...

So basicly every so often when I put my foot on the clutch coming to a stop, it dies. And it seems to happen at the luckiest time, right when I'm parking lol

I'll be taking it back to the shop Monday because Im pretty sure I've ruled the battery out, it appears to be charging so it looks like the alternator is working, it also seems to happen more often when I'm turning while having my foot on the clutch. (but not always, the first 2 times where dead straight)
And it doesn't happen EVERY time I come to a stop. Also all the electrics stay on its only the engine dying.

Any ideas would be really helpfull, as of now I'm gonna guess they need to tune the idle maybe, or they have done something wrong with wiring some how when wiring up the haltech

also, what FPR and what pressure are you running?

I was on their case a bit about it taking too long so they could of rushed the instal a bit. And they where having issues with it for a while he said the fuel pump relay was acting up so he replaces it with one he had sitting around the shop

I was on their case a bit about it taking too long so they could of rushed the instal a bit. And they where having issues with it for a while he said the fuel pump relay was acting up so he replaces it with one he had sitting around the shop

When I was there the guy said it was at 60. But when I looked at it today it did look lower, the gauge screen is really messed up so it's hard to read ill double check tomorrow. And I can definately say tho that it definately isn't priming until I start the car

Oh ok that makes sense. I'll double check tomorrow but I was told 60 when i asked him what its suposed to be at. But it did appear lower when I glanced at it today

Its always a hard balancing act trying to get your car back from mechs when theyve had ample time and are past their orig eta for completion, but not hurry them too much that they cut corners.

If you could get a wire at or near the +ve terminal of the fuel pump and run it back to the cabin, put a small lamp in line and maybe a switch before earth (steering column etc), you would have an indicator of whether the fuel pump is still powered when the fault occurs. Might narrow the field..