Im not sure if I have a tranny problem or a fuel problem i am getting a p0171 code off and on. At first I thought the tranny wasnt shifting right. It would seem to want to shift pause then stay in the same gear, give it a little more gas then it would shift. It pauses long enough to think it died but it didnt. Now Im having the same pause going down the hwy at any speed. Doing about 65 out of the blue i thought it died but it didnt. Its driving me nuts it has 66000 on the clock I have changed the timing belt, fuel filter, plugs, pcv, wires, input and output sensors tranny fluid is fine and red it was flushed at 34000. [:@] im now wondering if I have a fuel pump problem it seems to turn over longer before it starts..any thoughts?

 

P0171 = System too lean, bank 1 Intake/exhaust leak, AIR system, MAF/VAF sensor, fuel pressure/pump, injector(s), HO2S

Your transmission is not to blame. Like you, with the pausing, long starts and intermittent loss of power I suspect the fuel pump or the pressure regulator. The sensor issues listed might cause a rough idle, but other than bad mileage would be hard to tell that anything is wrong at speed. Same for the intake/exhaust leak. I think when the pump gets hot, it starts to cut out. Have you notice this problem is worse or more frequent with a low tank rather than a full one?

 

Its really bad 1st thing in the morning now that Im looking for it Im going to see about fuel levels and how it reacts. Im guessing the pump is in the tank and you have to drop it to get it out. Should I look at OEM pump from the dealer or aftermarket from the local parts store?

 

I think there is a small access panel under the rear seat that can be removed for access to the top of the tank where the pump is at. It seems like with Hyundais, the OEM part from the dealership is the safe route. I trust you only want to fix this once and have the replacement part fit correctly the first time.

 

there is no access under the seat. You have to drop the tank. I unplugged mine and it kept running anyway for 10 minutes till I shut it off so I couldnt even purge the fuel line enought to change the filter, then I couldnt get the fuel filter bracket to open so I couldnt get the filter off either +1 for hyundai making there cars easy to service