I have a 2003 GMC Sonoma 4CYL 2.2L with 140K miles. It has had a recurring issue where it is hard to start when the fuel gauge reads 1/4 tank or less. Usually have to knock on the fuel tank to get it to turnover. Recently replaced fuel filter, still the same. I thought that is usually indicitive of a faulty pump that is seizing. Additionally, I am continually battling a P0171 code in the computer. Is this all related to the same issue, or do I have multiple issues (fuel pump, 02 sensor, etc)?
Ok, so you said the gas gauge is off and you have to bang on the fuel tank to get it started, so you replaced just the fuel filter. You need to replace the fuel pump assembly to replace the pump itself and the fuel level sensor should be part of the assembly. P0171 is usually a lean condition, look for a vacuum leak..http://www.obd-codes.com/p0171
Thanks, Tom. Gas gausge isn't off, it works fine - shows full when full, etc. But when I get to 1/4 tank, is when I have trouble starting. I know of the service bulletin regarding gauge misread (1/4 tank actually = empty) but I don't think that is the issue. I never stall when driving, just have a hard time starting - also not sure why banging on the fuel tank seems to work - can you explain? I've heard of that working for a siezed pump, but never heard of a "faulty" pump (i.e. low pressure), I thought they either worked or didn't work. Will check for leak for error code. Was hoping they would be the same issue though. :-)
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