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Bad Fuel Pump?

2K views 5 replies 2 participants last post by  Mogman 
#1 ·
My 03 X - 3.3 116k needs me to turn the key to AC on and off a couple times to fully prime the fuel pump to start in cold weather. It starts fine in warm weather and it will sometimes start in the cold it will be just bog down before getting up to normal RPM's. The car justs fine. A previous owner has already had the recall with the fuel sending unit. Could this be a bad fuel pump or would i experience symptoms while driving?? or is this an electronic issue associated with the ignition?

Plugs, timing belt, fuel filter, fuel pressure regulator, coolant temp sensor, MAF sensor has all been recently serviced.
 
#2 ·
The fuel pump doesn't have any effect on your engine bogging down before getting up to normal RPMs during start (unless it's completely gone TU and you crank and crank until you kill your battery). An inop fuel pump means your X won't run. It's possible that you have a fuel leak somewhere, but my bet is your battery is toast. Cold weather will weaken the battery, especially if your electrolyte level is low. Weak battery and / or loose cables, which are very common problems on the Xterra, will make it hard to start, and even harder in cold weather. The battery cable clamps (even on the second gen) are absolute junk.
 
#3 ·
The thing is my battery is only about 18 months old and I got a new negative clamp at the same time. This is a problem I have been having since last winter - only in cold weather. The shop thought the fuel pressure regulator and coolant temperature sensor would solve the problem (luckily I was already getting a new knock sensor so the regulator didn't cost too much). It did help its tolerance of cold weather however when it dips below 32 it still really bogs down..... I am leaning towards a leak in the fuel line seeing how lately I have had success with priming the fuel pump a few times before starting....Could it be possible that this problem only manifests itself in cold weather though?
 
#4 ·
Cold weather has a tendency to make poor electrical connections worse due to contracting metal. Check the other end of your battery connections for corrosion and security.

As I mentioned earlier: The fuel pump shouldn't need to be "primed" since it's in the fuel tank. Turning the key on is all you need to do. Turning it off then on won't help. If there is air in the line due to a leak it may take longer to get fuel up to the engine, but it has no effect on how fast your engine cranks during the starting procedure. Your engine should crank at the same speed regardless of the availability of fuel.
 
#5 ·
the starter does turn it over just fine all of the time - when it fires up it bogs down badly and hovers around 500 RPM while feeling like it is missing for about 5 to 10 seconds before it seems to get it together and idle/run normally. This makes me think I need to check for leaks in the line.


Or possibly a bad check valve causing the gas in the line to leak back into the tank therefore taking more time to get gas in the lines
 
#6 ·
the starter does turn it over just fine all of the time - when it fires up it bogs down badly and hovers around 500 RPM while feeling like it is missing for about 5 to 10 seconds
OK that makes much more sense.
 
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