flashZR1/Z06

Could a bad fuel pressure regulator cause the LT5 to run rich on the passenger side? Enough to foul plugs and the oxygen sensor?

A26B

You have 3 different threads going about the same issues. You will find it works better to maintain continuity by posting in the same original thread for the problem you are having.

ZWILDZR1

In my first 91 ZR1 the fuel pressure regulator took a dump on me. The reason I knew was because the cars power was off on wide open throttle. Now this car had headers and no cats. So I began searching for the problem. First was the stock original fuel injectors. Some were marginal and some were toast. The idle was better it still wasn't quite right. I replaced both fuel pumps, the sock, and fuel filter. When I did the injectors I did plugs and wires. I went to Carlisle that year and it was still not as much power. I tried blocking of the vacuum to the FPR and it ran a bit stronger but still seemed a bit off. After talking to Marc Haibeck he said well you've replaced everything but the FPR. So I replaced it and WOW! The car was running so strong and pulled harder. In the end it probably only needed the fuel injectors and the FPR. But hey the new pumps and everything made it run even better than I remembered. I can't remember if it had any codes but if it did would have been code 45 and 65 both sensors reading rich. The FPR sits almost between the two fuel rails at the back of the plenum. Like I said the thing I noticed first and fore most was WOT power was down.