I have a 2008 Nissan Pathfinder LE, V6, with 200000 miles on it. I am having an issues getting the car to start when it is cold. When I say getting the car to start I mean for the engine to actually start. The engine is turning over well and strongly so I don't think it is the starter but I guess it could be.

Here are what I have been able to determine as the contributing factors:

Outside temp - only happens when it is cold out, this doesn't happen any other time then when it is cold, close to freezing is where it seems to start but I don't have hard data on that

Incline - seems to be worse when facing uphill but only an issue when starting the car, no issues driving up hill once the car is started

Quantity of fuel - seems to be worse when fuel is low but I had trouble starting it last night with a full tank

Length of time car sits - if I have recently driven the car and make a stop at a store there normally isn't an issue starting again. I mainly notice the problem after the car has sat in the driveway overnight or if I haven't driven it for a day or so and is in my driveway.

So far I added dry gas and that didn't seem to make much of a difference. I have since added a fuel system cleaner on the current tank (only a few gallons into that tank). No appreciable difference from either of those. The fuel filter is part of the pump but if there was a clog, even partial, I am not sure why the temperature would make a difference.

So I am thinking its a fuel pump issue but I am not sure. Please help!

Sounds a lot like a clogged fuel filter. If it's 200K miles old, the amount of contaminants trapped in that filter would be sludge-like, and even more viscous when it's cold, blocking the flow of fuel and making the pump work harder until it too gives up working well enough to keep the engine running. Whether it's the fuel filter, the fuel pump, or both, they are integrated as one replacement unit, which is the dumbest idea in automotive history. IMHO

A fuel pressure check test will confirm if the pump/filter needs to be replaced.

Thanks! I should have added that if I leave the car in the on position for 30 seconds before attempting to start then I normally have better success. All signs seems to be pointing to fuel pump/filter.

hazmat1121 wrote: ↑

Mon Dec 05, 2022 9:16 am

Thanks! I should have added that if I leave the car in the on position for 30 seconds before attempting to start then I normally have better success. All signs seems to be pointing to fuel pump/filter.

Yep. Takes time to build pressure downstream of a clogged filter. Until you test check or replace the pump/filter assembly, don't use any more fuel additives. It may dissolve some of the yuk trapped in the filter, sending it downstream to give your fuel injectors a heart attack. After you replace the pump/filter, I recommend feeding your ride a couple cans of Seafoam into the tank so that the entire fuel system is cleaned out well. https://seafoamworks.com/product/high-m ... treatment/

Hook up a gauge and check fuel pressure before replacing any parts. Thirty bucks on Amazon for a decent gauge. If fuel pressure is within spec, hook up a scan tool and see what air temp your computer is reading.