Issues with Walbro 450 and "stock" fuel pressure regulator

I have a walbro 450 and a "stock" 4bar fpr from a dodge daytona. I am having SERIOUS issues with drivability 1200-2500rpm. Everything above that is amazing.

It is on microsquirt and a turner has spend hours with it. He is saying the only thing he would put his money on is the fpr. Any help or suggestions?

IS it possible the pump it too much for a stock fuel pressure regulator?

Has anyone adapted an aftermarket FPR (like a Nuke or Aeromotive) to a stock Fuel Rail? Fuel system has been upgraded from to back with e85 safe lines... lost done to the rest of the engine... built bottom end, stage 3 KL cam, microsquirt, arp headstuds, springs, ported in head (intake and exhaust side).

I think a pressure gauge test would provide the answer. See if the pressure is spiking up a bit in low-flow situations. is the return line still the same size? It's possible that's the restriction, but more likely the FPR.

I adapted one of those chinese adapters with this setup, after a rebuild, as they contain shavings when shipped:
<img src="https://i.imgur.com/T6HYbGwl.jpg" title="source: imgur.com" />

<img src="https://i.imgur.com/5YfcRuQl.jpg?1" title="source: imgur.com" />

This might also work for you, and is available from several sources (also in AN):
https://shop.klracing.se/sv/artiklar/fuel-rail-adapter-volvo-saab-vw-ford-rover-till-8mm-slang.html

Interesting. I have seen this part you linked me too before. It seems as though I might need to go this route. I would be interested on how to actually test my FPR.

JKnuck6 said:

Interesting. I have seen this part you linked me too before. It seems as though I might need to go this route. I would be interested on how to actually test my FPR.

Click to expand...

Buy a cheap 1/8 npt fuel pressure sensor off ebay and connect it to your fuel line somewhere. I connected at the banjo bolt on the fuel filter. Then connect to your microsquirt and log it.

What are your injector dead times? If the dead times are not set right the injectors can shut off on small squirts.

If you don't know the dead times, google your injector part #?