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Discussion Starter · #1 ·
Hello. I drive a 4-cylinder 2015 Nissan Sentra, CVT transmission.

Last month, when I got into my car that morning to go to work, the car took uncharacteristically long to start up (long crank). It ran fine otherwise, and when I finished work it would start up fine. Since then, i found the pattern: When the car stays overnight, it'll take a long time to crank, but once its up to operating temperature it'll start up fine.

The car itself ran fine. No stutter or sputter, no unusual fuel consumption, nothing on the dash, no check engine light. Yadda yadda..

That issue has continued till today, but there is a new development: there is a fuel smell inside the car that goes away when I drive. This smell also becomes stronger when the car is left overnight. The long crank issue still persists

So, what could it be?
 

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You're probably looking at two separate problems. For the fuel smell, if you don't find any obvious leaks, drop the evap and make sure the o-rings are good and the evap isn't flooded, and blow through the lines between the evap and the tank to make sure they're clear. Sometimes the charcoal bags break and fill the lines with chunks, which clots up the purge system and can cause a stink. Long cranks are usually from one of two things, either a bad check valve in the fuel pump allowing the fuel rail to empty out from siphoning back into the tank, or a misbehaving cam or crank sensor. To eliminate or implicate the fuel pump, pop the top on the airbox before cranking it cold, and spray a shot of something combustible (Brakleen, Gumout, etc) down the barrel. If that shortens the crank then your problem is fuel, if it doesn't then you're looking at a sensor issue.
 

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Discussion Starter · #3 ·
Thank you for the response! I'll look into the EVAP system later on, but regarding the check valves, is it possible to replace those valves without purchasing another fuel pump unit entirely? I looked up some schematics of the fuel pump and it doesn't appear to be within the assembly, so I'm assuming its somewhere along the fuel lines, just can't find it yet.
 

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No, the check valve is part of the pump, it isn't serviceable separately. I haven't specifically taken apart a Sentra pump, but on most of the pumps I have disassembled, it's just a spring-loaded ball bearing in the pump outlet tube.
 

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Here's an excellent vid explaining how the various types of fuel pumps are constructed and how they work. The first type, or "turbine" pump, is what you'll find in most Nissans, Infinitis, and passenger cars in general:
 

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Discussion Starter · #7 ·
Hi, just documenting this for posterity and for anyone experiencing this problem. You might get the same symptoms that I do, but the root cause might differ.

In my case, after putting this off for a while because the car ran fine otherwise, it turned out that the root cause was a broken piece of plastic holding the junction between the fuel pump and the line sending the gasoline to the engine. It was located under the back seat. this wasn't an EVAP canister that was slashed, or a faulty check valve buried in the fuel pump assembly.

It was spraying fuel into the enclosure under the seat, thus the cabin smell. I also noticed that an oil-like substance was present in the underbody of the car that turned out to be dried gas that has probably dragged all of the grime and soot in its way to the underside to give a thin veil of oil, which was under the fuel pump enclosure directly and was the cause for the outside of the car smelling like gas even after hours of shutting the car down. The presence of this oil like grime and soot on the underbody of the car under the fuel pump could function as a litmus test to rule out or in a fuel pump bathing itself in fuel.

The ideal albeit stingy solution is to outright buy a new fuel pump. Nissan, the geniuses they are championing modularity in their parts, decided this time that they are gonna play evil and make the fuel pump one giant piece of shit that cannot be disassembled into its constituents parts in order to service the culprit, and that includes the plastic structure and specifically the tab that delivers the fuel to the fuel line going to the engine. This is frustrating. My mechanic notes that this seems to be a common problem for this model year of Sentras, and the temporary solution to this fundamental problem is to glue shit together until the fuel pump dies. No joke, this is what my mechanic is gonna do tomorrow.

There you have it, hopefully this gives you a lead as to where to look for and figure out the problem yourself.
 

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Discussion Starter · #8 ·
Glue didn't work. Looks like my only option is to get a new fuel pump. Does anyone know if the OEM fixed this issue with the plastic hose being brittle? Any good aftermarkets that fixed this issue? Delphi and walboro seem to be good options from what I've heard on other forums.
 

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Does anyone know if the OEM fixed this issue with the plastic hose being brittle?
There's never really been any issue with embrittlement, so maybe something is messed up with the fuel line routing or the tank supports on your particular vehicle. I just changed the pump on an '02 Altie a few days ago with the same sort of unitized plastic construction as your Sentra, after nearly 21 years the pump was doornail dead but there was nothing wrong with the outlets or tubing.
 

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Discussion Starter · #10 · (Edited)
Thanks for the reply. I took ownership of this car 4 years ago at 76K kilometers, now 126K kilometers, and As far as I know neither the fuel pump nor the fuel tank were tampered with, and for all of these four years, never had trouble with the car until now.

Could bad road conditions have caused the pump outlet to break? The gash on the outlet wasn't that big, the smell of fuel was tolerable. Applying the glue epoxy made worse though, so I'm gonna buy a fuel pump anyway.

Weak and or brittle outlets seem to be a common issue with fuel pumps regardless of brand nowadays as they are either plastic or nylon. Wish Nissan would reinforce their pumps with stainless steel to prevent this from happening, because their fuel pumps, other than their plastic, last a really long time, seems wasteful to just plop this one in the garage, especially since its otherwise in perfect working condition and would probably be the last thing to really break on the car :/

Thanks for the help once again.
 

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Could bad road conditions have caused the pump outlet to break? The gash on the outlet wasn't that big, the smell of fuel was tolerable. Applying the glue epoxy made worse though, so I'm gonna buy a fuel pump anyway.

Weak and or brittle outlets seem to be a common issue with fuel pumps regardless of brand nowadays as they are either plastic or nylon. Wish Nissan would reinforce their pumps with stainless steel to prevent this from happening, because their fuel pumps, other than their plastic, last a really long time, seems wasteful to just plop this one in the garage, especially since its otherwise in perfect working condition and would probably be the last thing to really break on the car :/

Thanks for the help once again.
You're most welcome. Mechanical fatigue from bad roads can always be an issue, as can chemical exposure like road salts or asphalt fumes, and climatic conditions like extreme summers and winters. That will all vary from car to car and owner to owner. Most pump assemblies are made from HDPE which is pretty sturdy stuff, although nothing lasts forever. Stainless mold inserts would be a helluvan expense for a part that can normally last 20+ years without it. I'd check the slack and direction of your fuel line at the tank entry, and if it's putting any sideways pressure on the pump nipple, tie it back if possible to de-stress it.
 

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Discussion Starter · #12 ·
Bit the bullet and bought an OEM fuel pump, $225. Ill check for any unnecessary tension straining the plastic nipple before installation.

Do you know if its possible to sell the old, still functional pump? Would anyone wanna buy it for its innards at least?
 

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Not the pump itself, but I don't think the Level Sender or FTT are available separately. So you might be able to eBay those and save some other person from buying a whole pump over a bad sender.
 
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