Could an improper seal on my fuel suction assembly be causing these issues? - Toyota Yaris Forums

ThrowingChicken · 04-10-2018, 10:02 PM

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.

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04-10-2018, 10:02 PM	#6
ThrowingChicken Drives: 2007 Toyota Yaris Join Date: Apr 2018 Location: TX Posts: 11	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.