sahtt

91 LS. Had the best shop I know of in Houston, C&C Northside Automotive, try to diagnose my car further and Kurt said it was DEFINETELY fuel related and probably the fuel pump. I changed the pump, no difference. It is either the fuel pressure regulator, which I'm having a VERY difficult time finding discounted, or one of the sensors that allows the fuel pump to activate. Anyone have a resource I would use to check which sensors it is and what Ohm reading each should be in? Anyone know of a better place to get a fuel pressure regulator for a 91 LS400 for less than 166.xx$?

VVT-i

Check your fuel pump ecu. The 91 LS has 2 speeds fuel pump.

sahtt

Unfortunately, that is A LOT to check. I work 60hrs/wk and do not have the free time, even if I used all of it, to test all of that. I'm going to attempt to bypass the fuel pump ECU to see if that helps any. I've finally given up on this battery and am going to replace it as well. With my luck it's not the battery's fault it keeps needing to be recharged.

I've replaced the timing belt, waterpump, cam seals, crank seals, plugs, entire coolant system, and so on with nothing more than bare bone write-ups and 100 bucks in tools, but I'd need step-by-step directions for testing things like cranking pressure. The cold start injector was replaced a couple thousand miles ago, though for some reason that doesn't mean a whole lot to me considering other maint. supposedly done on the car by the PO.

All the fuel pump ECU stuff I find is quite old, and all the pictures are now red 'x's. The ECU is located just behind the driver's side back seat's door correct? It's NOT under the door panel correct? I just replaced my fuel pump and put the back seats in YESTERDAY. Awesome luck. The bottom portion of the seats were a COMPLETE PITA btw, not looking foward to removing those.