A month ago my bonneville was starting hard in the morning similar to when the coil-pack fails. However, a quick check of the fuel rail indicated 0 psi fuel pressure with or without the fuel pump running. Obvious fix, replaced the fuel pressure regulator. After replacing the fuel pressure regulator the rail fuel pressure was normal with and without vacuunm attached to the fuel pressure regulator and the rail would maintain pressure after the car was shut off i.e. the fuel pump was not running. After a test drive of about 5 miles I connected the pressure gauge again only to find no fuel pressure on the rail with or without the fuel pump running. Must be a faulty regulator. Replaced the regulator and the exact same thing happened. I tried a different fuel pressure regulator brand from a different parts store only to find the same results. I thought it must be relieving through the fuel pump so I plugged the return line on the fuel pressure regulator and the rail held all the pressure the pump could deliver each of 5 attempts. So I replaced the fuel pressure regulator agian thinking the vacuum line to it was causing a problem. Now the car will develop pressure on the rail as long as the pump is running, but as soon as the pump stops running the fuel pressure immediately returns to zero. This is still better than when the vacuum line was attached to the fuel pressure regulator. If I use the vacuum line on the regulator there will be zero fuel pressure on the rail with the fuel pump running after the first time the car is driven. Basically, once the car is driven with the vacuum line attached to the fuel pressure regulator you can throw the regulator away because it will never develop pressure again. Has anybody ever seen such a thing? I am completely lost.
Sep 13, 2010 at 2:24 PM