P0300, P0172 Problem Solved

[leadalto]

There were a few people with similar symptoms which pointed to a leaking or malfunctioning fuel pressure regulator (FPR). Those symptoms were a smell of gas after starting and hard starting. In my case, the engine would crank for a while even after it was warmed up and left standing for a short time. After a long crank, it would start and then kill unless the accelerator was pumped slightly to keep the engine going. Then, a smell of gas like an over-rich mix.

This condition went on for at least 6 months but once the engine started, it seemed to run fine and no codes were set. Finally, last week, once started, the engine would not idle and killed at traffic stops or lost power on turns, and the dreaded P0300 code was set (random misfires). Rather than pulling the plugs and wires, and other suspects, I decided to replace the FPR based on the gas smell symptom. It was not an easy replacement because of lack of easy tool access and tightness of the parts.

I hope that my description of the FPR replacement will either make it easier for those who want to tackle the job or to take their car to a shop.

My Venture is a used 2005 LS with 62,000 miles that I bought 8 months ago for a great price! It had a few parking lot dents but its main features are fold-down 3rd row seats and that it holds 8 passengers. I digress!

The images of the FPR show a vacuum line at the top, a fuel return line at the bottom, a connecting tube to the fuel rail, and a screw which fastens the unit to the engine.

The fastening screw was extremely tight so use a penetrating solvent on its threads. It is a Torx T30 screw and not an Allen screw. If you use an Allen, you might strip the inside of the head and then have to drill it or cut it out.

The hex nut holding the fuel return line is a 15/16" or 24 mm which has limited space for a wrench. Disconnect this fitting before removing the Torx screw because the fitting was extremely tight. My disaster on this point is that I had forgotten that I owned a 15/16" open end wrench! Nothing else that I tried would fit into the space. So, I removed the Torx screw, pulled the unit out of the fuel rail, and tried to loosen the return line nut with a vise-grip. No dice. I had to put another vise-grip on the body and pull like hell to loosen the connection. It didn't move slowly, it just "popped" open and could then be unscrewed by finger.

The replacement unit was a BWD 23091 from O'Reilly auto parts which was $50. An easy replacement. Again, not so easy. There is an internal o-ring that the return fuel line has to go through in order to seat. The nut will not pull the line through the o-ring because the line has to go though the o-ring in order for it to grab some threads for tightening. I first lubed the o-ring with that old standby "petroleum jelly". No way could I exert the amount of force necessary to penetrate the o-ring. Maybe its my age (76). I thought that the new unit had the wrong dimensions so I pulled the o-ring and the tube went in perfectly. Next, I used a very light machine oil that got behind the ring holding shoulders and I noticed a slight difference. What worked was to push the tube on an angle through the o-ring (not easy). That reduced the forces of trying to push it through at right angles by a lot. Once that obstacle was overcome, the rest was a breeze.

The photos that are attached, show a pipe in the way. That's the PCV valve pipe and can be easily pulled out of the way. I disconnected a lot of other things like the throttle plate and connections (probably unnecessary) but I thought I had to go after bigger fish like the EGR.

[leadalto]

Just wanting to record a reply.

A lot of times on a search I filter for one or more replies.

[LMP]

But then...?????...you said that solved the problem you mentioned from the start .....could you identify the fault with the original FuelPressureRegulator ? I can see some similarities with mine...though mine is definitely not as severe....yes I have to start it just a little longer than usual...and from there it will run flawlessly even without revving it ..and there is some fuel scent...but very light...for a short time..So if it worsens, I'll have some idea where to look for....

[leadalto]

I don't know what the failure mode of the pressure regulator was. I bent it up removing it but then it doesn't come apart so you could look inside anyway. I think there is a spring-loaded vacuum operated diaphragm inside. If the diaphragm leaks, gas will be sucked into the vacuum line. I would guess that to be the major failure mode. That would also result in the wrong pressure in the fuel rail.