Could an improper seal on my fuel suction assembly be causing these issues?

[ThrowingChicken]

Actually I am getting a P0171 code.

While I wait for a replacement pump and filter to arrive, yesterday I decided to go back into the fuel pump assembly to see if I could clean the filter and inspect for other possible issues. When I popped the tabs off the filter housing the fuel pump slid out and I noticed right away that the o-ring was practically shredded.



It stood to reason that a bad seal there could be causing low fuel pressure, so I replaced the o-ring and took a shop vac to the filter and the accessible tubes just in case that would do anything. I got everything back together and fired it up (which took a number of tries compared to the last time I pulled the fuel suction assembly, but it got there). I drove around the neighborhood a bit and tried to force the slippage I was experiencing earlier by gunning it at a low speed, but everything seemed to be working fine for quite a while, but eventually I thought I felt some hesitation on acceleration, so I headed home and had a look under the hood and realized the ventilation hose #2 was disconnected. No idea if that affects performance any but I hooked it back up, and a couple hours later after traffic died down I went on a longer test.

I put about 30-40 miles on it last night without issue, highway speeds, everything seemed resolved. The check engine light even turned off. Then today I put on another ten or so, go get a couple tires replaced and rotated, then after leaving the tire shop, I find I was having trouble accelerating past 60mph while going on a slight incline. A little while later I am getting some fairly consistent slippage/hesitation again. It seemed to happen more often when I had the AC on, but I can't be sure that actually has anything to do with it.

The guy at AutoZone who read the codes thinks it's probably a couple of bad spark plugs, which in turn are dirtying up the MAF sensor.

[B.B._07]

Originally Posted by ThrowingChicken

The guy at AutoZone who read the codes thinks it's probably a couple of bad spark plugs, which in turn are dirtying up the MAF sensor.

How in the world a bad spark plug is dirtying up your MAF sensor is something that the Autozone guy can only know. Autozone is good at recommending you parts that you don't really need. The iridium plugs have a service interval of 120,000 miles I believe so unless your have a ton of mileage on your car they're most likely fine. I'd suggest renting a fuel pressure gauge from Autozone or another of the car part places. You should see 44.1 to 49.7 psi with the system pressurized or with the car at idle.