Question about 2006 Nissan Sentra

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Slow to crank when hot

I have the same problem, I used a fuel pressure testing kit to figure out why it does this. Here is what I found.
1) Fuel pressure drops when the vehicle is turned off, this *might* be normal because I do not see a return line for the fuel rail.
2) My vehicle is a standard, so it will not start without pushing the clutch in. If I try to crank the engine without holding the clutch, the fuel pump *should* activate. However when I attached the testing kit, the fuel pump did not activate until I cranked the engine a few times. After that, the fuel pump activated EVERY time without the clutch pushed in with a constant 51psi of fuel pressure.
Something tells me a sensor, possibly the fuel pump regulator is bad. it could also be a air leak at the injector or fuel rail somewhere, if that is the case it would explain the drop in fuel pressure as soon as the vehicle is turned off.

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    yadayada May 11, 2010

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Fuel pump has defective check valve check fuel pump m and fuef tank and replace.

Posted on Jun 29, 2009

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1993 Geo tracker fuel injector is not working right. i have to pour fuel into it. any suggestions on what i should do?


Important to know if it's not working at all, or if it is working some, just not enough? If not at all, then you need to check the injector wiring circuit, it's pretty simple really, just a hot wire with key on, and a ground wire that goes into the engine computer. Test with a voltmeter, best practice.

You should probably first check fuel pressure. The injector won't work unless the fuel pressure inside it is at the specified pressure. If the fuel pressure is too low, you have a bad fuel pump or a clogged fuel filter. If the fuel pressure is correct, you could have a clogged injector. The best way to clean that is with the injector off the engine.

Dec 09, 2015 | Geo Cars & Trucks

2 Answers

Gas line is clog gas is not getting to throttle. Where do you begin in uncloging the fuel line.


95 rodeo. not the Diesel right>? gasoline engine, the diesel has a timed pump....
GAS:
what engine? car has 2 or more as options... and fuel systems vary by ,(drum roll) engines.
my guess is this is your first EFI fueling system?

to test fuel rail pressure and its zero,
this must be done cranking, i bet you didnt know that 1/2 the cars
made, it must be cranked to get the pump to run..... right?
my second guess, is you dont own a $10 volt meter.
?
the engine has a ECU, this ECU sends 12vdc to the fuel pump using a Fuel pump relay.
does the relay close, cranking?
1/2 do just key on for 2 seconds.
while cranking. and running. so we use a voltmeter to see if that happens, not replace every part on car gue$$ing, wow are you rich?

The ECU/:PCM brain can cut fuel for 2 or more reasons
More facts:
the ecu cuts fuel cranking if the throttle is stuck wide open. (TPS sensor errors, do that....) (this is a FEATURE)

this is a "unflood feature in all EFI cars made" (modern say 1988 to now)"a feature stated in the operators guide, btw)



and if the ECU has an immobilizer OPTION, same thing, cuts fuel. (some cars cut fuel then spark)

the ECU also cuts fuel if the ECU even suspects spark is missing. (feature 3)
Does engine run on test fueL.
we do that first. the 3 second test fuel tests.
if that sounds good, we attach fueling next.
if it sounds bad, or engine is dead, we fix that next (timing belt slip?)
This feature prevents the crash and burn deal.. as seen on T.V... (ecu computer logic )
(and is by laws here... (called the Spark monitor inside the ECU...)

got 12vdc to the pump cranking, ?
at the pump 2 wires. not 6v, no 8v but at least 11vdc there... (it will be whatever battery volts are... cranking, (measure that too)


on cars that need to be cranked, to get pressure
you will ru not be able to hear the pumpn, with the Starter motor banging away.... so we use the volt meter and the fuel pressure gauge
to not get fooled... Dribble tests are ok, if no dribble cranking, but is in no way proof of good pressure.. if pump runs....
The injector dont work at 0 to 20PSI, sorry...

on some cars you get a prime pump action for 3 seconds, keyon.
but not all cars do that. so we just assume they dont and WIN. (Isuzu diffr, rules on diffr. engines.... sure are...)

got a meter? even a $10 walfart meter works..
end general rules and vast experiences...
------------------------------------------------
now the FSM pages, of facts: (factory serv. man)
the 2.2L runs for "2 seconds key on",
this is the prime signal.
its best to repeat it 3 times to build pressure from a breached system. (gauge breached it)

quotes from FSM: 3.2L
Turn the ignition ON and listen for the pump to run (it should run for 2 seconds). If necessary, cycle the ignition OFF for 10 seconds and then ON again, in order to build maximum system pressure.
2.2L
Note the fuel pressure with the pump RUNNING; it should be 41–47 psi (284–325 kPa). When the pump stops, pressure may vary slightly, then should hold steady.
"
now the other engine. 3.2L
it say it needs to be cranked or run to check
fuel pressure. in my book.

the fuel rail at the loop end has the fuel pressure test port. there. see it?
seen here,
41-46psi is running pressure,(or cranking)
and 35psi for the smaller gas engine.

the pressures matter, its not carb car its EFI.


do not be tempted by the dark side and hot wire
the fuel pump relay, if you do , most guys
burn to H3ll the ECU relay driver, ive repair so many ,its a crime.
they hot wire this relay socket slip for a second and boom, you just blew up a $400 ECU
pay me to fix that..... (nah , im retired, )

never hot wire, the EFI system.

2418d1a1-7ef1-4220-a4be-1ba1995afef8.jpg

May 30, 2015 | 1995 Isuzu Rodeo

1 Answer

1998 toyota corolla hard to start when hot


hot soak ,no starts 101:
which engine?, cant guess that. say it. please."name /size"
is it flooding or starving
hard to start , so that is easy you are parked, and makes diagnosis so easy, (no need to move)
you skipped the fuel filter:?
why not use a scan tool now.?
you crank for 5 seconds, see P03xx errors. DTC'
THE ECU REPORTS ALL CMP AND CKP SENSOR ERRORS!
bingo now you have your answer , finding this, scan tool free is hard hard work. am i to tell you that hard way, sure.
1:test spark on all cylinders ,same way 100 years, google it.
2: ok sparks good, i check all spark plug tips, for wet and dry or soaked in fuel.
3: i see dry, , i use test fuel (same way for 100 years,)
run on test fuel (my Model a ford, same way works.....)
4:; ah one plug is soaking , ah leaking injector
5:ah, all plugs wet, (too high fuel pressure, ECT stuck cold
if all are wet, I stop, there are lots of tests for this.(bulleted below)

  • fuel pressure (KEYON, cranking and running and W.O.T.)
  • injector leak down tests. all of em;'
  • injector balance test (ALL)
  • Fuelpump regulator 4 tests

all this perplexing, get your ASE mechanic in the loop.

Dec 26, 2014 | 1998 Toyota Corolla

1 Answer

1988 2.5E s10 no fuel


you mean,cranks ok, but will not start and no fuel , right>?
s10 no fuel. 1988 ( S10 blazer )
please do say , what that means.
1: car cranks and will not start. so must be out of fuel?
(over 50 causes, or better is 10 or less tests (ask)
2: same, and fuel pressure is 0 psi (spec.9-13). gauged.?
3: fuel dribble test?
4: sparks good so tired test fuel and it ran on test fuel ok? proving
loss of fueling>?
5: injector dead cranking, (eyeballs)

which was it?

1988 cars in the USA are BIG TIME TRANSITION year.
we went from CARBS to EFI.
2.5L (what is E)?
gear cam, roller HLA lifters.
your car, USA , is TBI engine,
TBI started on THIS car in 1985 (1/2 and 1/2)
Throttle body injection
an on all TBI engines, one can see it inject with eyes.
does it?
if not it can be the following things.
1: no fuel pressure, 9-13pis.
2: ECU is cutting fuel. Pressure good cranking.
2a: ECU is sending error for bad crank/cam sensors, and cuts fuel.
2b: ECU sees rpm or tacho line dead.
2c. ECU sees TPS sensor output as 4v or more cranking, this cuts all fuel.
3: if ECU is happy, it sends 12vcd to the pump, cranking.
all tests must be dont cranking or chase tail.

Jun 17, 2014 | 1986 Chevrolet S-10 Blazer

1 Answer

2001 acura mdx wont start. cant hear fuel pump.


going backwards, ? (yes, i to check volts first) but...
you check fuel pressure cranking, (is press in spec or not?)
the FSM covers this, 1/.2 the cars only get pump activation,,
cranking and running, never just key on (the fsm shows this fact, i didnt look for you)
Yours is older loop system, not dead head.
there are 5 test just for the pump, (actually more)
pressure cranking and running, (leakdown test and injector balance tests and shut test for loop version) on V6 that 6 +4 ,10 total tests.
once the gauge is in place we do all 10s tests on v6.

ok say my pressure spec. is 40psi cranking and i get 10.?

spec: 32-40 running, pSI, vac, hose conn. (cranking will be more)
in loop systems the cranking pressure is about 10 PSI more.
after it starts, the vacuum sucks pressure from say 50psi to 40.
(its also altitude compensating)

Voltage checks, (any voltmeter)
use a voltmeter to see if full power reaches the pump.
i check voltage and its 8v. (bad) cranking volts can be near 11v due
to battery load, 200amps or so... what i do is measure battery crank
voltage and expect same to pump , using the 0.5v rule. (drop)
the connector over here to pump is all corroded. ,,
fix that and bam, now full presssure
or i find a bad fuel pump relay, replace that and bam.
or i find 0v, to pump.
i find relay bad. (simple tests on relay) (its not bad ECU)
ok i find 12v. at pump. so what is wrong?, i check my fuel pressure
regulator at the fuel rail, its stuck wide open because the shunt test
passed (one of 4 tests above) so new reg and bam, 40psi to rail.
i can test the reg with my hand vacuum tool that all shops have.
i can see pressure, running and cranking and check fuel pressure
with no vacuum (50psi?) then pump it to say 20 "hg (simulates idle)
and see 40 pSI, and check the diaphram for leak down.
my reg was bad.
there are other tests:
1: fuel pump current. (if excessive, its a bad pump)
2: scope test or use a current probe on pump and see it spiking
like made, , it has bad commutator and will die so.

there great videos on all this at. Duane's site.
http://www.youtube.com/results?search_query=fuel%20pump&sm=3

check the pump cranking

do not hot wire the fuel pump relay
if you slip 1/.8" you blow up a nice $400 ECU, (or more)
the ECU drives this relay (with a transistor, you dont want to explode)
if you feel compelled to hot wire things, disconnect the pump
and hot wire that.
now the relay.
it has 4 pins 12vdc in, 12vdc out to pump (contacts)
and 2 coil pins.
you put your meter to coil pins (across) i get 12v to coil cranking and running, that is the ECU working right
i get 12vdc in and zero out the contacts, the relay is bad.
lets say you see 3v out, that can be a shorted pump. or wire grounded out to pump. I check the current with my amp clamp and see 15amps
the pump is bad. most draw 4-6amps. normal.
i keep an open mind, what is bad, its only the pump 1/2 the time
or less. maybe 1/3? (reg, pump, wires and friends)
corroded connectors big time...some even burned up.





Feb 09, 2014 | 2001 Acura MDX

2 Answers

Fuel pours into cylinders


very strange and rare problem. something is keping the injectors open instead of pulsing them. The command to ground the injectors comes from the PCM, Powertrain Control Module. It may be a good idea to pick up a used one from a salvage yard. car-part.com is a good place to look. You will need the info off your module to match up.
Do you have 2.0L SPI engine or 2.0L Zetec engine?
Look on the page with the * to find the lowest price part.
aso, check for shorted wire going to injectors
---------------------------------------------

Mechanical Returnless Fuel System The fuel system consists of a fuel tank with reservoir, fuel pump, fuel pressure regulator, fuel filter, fuel supply line, fuel rail, fuel rail pulse damper, fuel injectors, and schrader/pressure test point. Operation of the system is as follows (Figure 62):
  1. The fuel delivery system is enabled during crank or running mode once the PCM receives a crankshaft position (CKP) sensor signal.
  1. The fuel pump logic is defined in the fuel system control strategy and is executed by the PCM.
  1. The PCM grounds the fuel pump relay, which provides VPWR to the fuel pump.
  1. The inertia fuel shut-off (IFS) switch is used to de-energize the fuel delivery secondary circuit in the event of collision. The IFS switch is a safety device that should only be reset after a thorough inspection of the vehicle (following a collision).
  1. A pressure test point valve (schrader valve) is located on the fuel rail. This is used to measure fuel injector supply pressure for diagnostic procedures and repairs. ON VEHICLES NOT EQUIPPED WITH A SCHRADER VALVE, USE ROTUNDA FUEL PRESSURE TEST KIT #134—R0087 OR EQUIVALENT.
  1. Located on the fuel rail is a pulse damper. The pulse damper reduces fuel system noise caused by the pulsing of the fuel injectors. The vacuum port located on the damper is connected to manifold vacuum to avoid fuel spillage in the event the pulse damper diaphragm were to rupture (the pulse damper should not be confused with a fuel pressure regulator).
  1. The fuel injector is a solenoid-operated valve that meters the fuel flow to each combustion cylinder. The fuel injector is opened and closed a constant number of times per crankshaft revolution. The amount of fuel is controlled by the length of time the fuel injector is held open. The injector is normally closed and is operated by 12 volt VPWR from the power relay. The ground signal is controlled by the PCM.
  1. There are three filtering or screening devices in the fuel delivery system. The intake sock is a fine, nylon mesh screen mounted on the intake side of the fuel pump. There is a fuel filter screen located at the fuel rail side of the fuel injector. The fuel filter assembly is located between the fuel pump and the pressure test point/schrader valve.
  1. The fuel pump (FP) module contains the fuel pump, fuel pressure regulator and the fuel sender assembly. The fuel pressure regulator is attached to the fuel pump in the fuel pump module located in the fuel tank. It regulates fuel pressure supplied to the fuel injectors. The fuel pressure regulator is a diaphragm-operated relief valve. Fuel pressure is established by a spring preload applied to the diaphragm. Excess fuel is bypassed through the regulator and returned to the fuel tank.

    v22~us~en~file=aa1837a.gif~gen~ref.gif

    Figure 62: Fuel System—Mechanical Returnless
Electronic Returnless Fuel System The fuel system consists of a fuel tank with reservoir, fuel pump, fuel rail pressure sensor, fuel filter, fuel supply line, engine fuel temperature sensor, fuel rail, fuel injectors, and schrader/pressure test point. Operation of the system is as follows (Figure 63) and (Figure 64):
  1. The fuel delivery system is enabled during crank or running mode once the PCM receives a crankshaft position (CKP) sensor signal.
  1. The fuel pump logic is defined in the fuel system control strategy and is executed by the PCM.
  1. The PCM commands a duty cycle to the fuel pump driver module (FPDM).
  1. The fuel pump driver module modulates the voltage to the fuel pump (FP) to achieve the proper fuel pressure. Voltage for the fuel pump is supplied by the power relay or FPDM power supply relay. (For additional information on FPDM operation, refer to PCM Outputs—Fuel Pump and PCM Inputs—FPM.)
  1. The fuel rail pressure (FRP) sensor provides the PCM with the current fuel rail pressure. The PCM uses this information to vary the duty cycle output to the FPDM to compensate for varying loads.
  1. The engine fuel temperature (EFT) sensor measures current fuel temperatures in the fuel rail. This information is used to vary the fuel pressure and avoid fuel system vaporization.
  1. The fuel injector is a solenoid-operated valve that meters the fuel flow to each combustion cylinder. The fuel injector is opened and closed a constant number of times per crankshaft revolution. The amount of fuel is controlled by the length of time the fuel injector is held open. The injector is normally closed and is operated by 12 volt VPWR from the power relay. The ground signal is controlled by the PCM.
  1. A pressure test point valve (schrader valve) is located on the fuel rail. This is used to measure fuel injector supply pressure for diagnostic procedures and repairs. ON VEHICLES NOT EQUIPPED WITH A SCHRADER VALVE, USE ROTUNDA FUEL PRESSURE TEST KIT #134—R0087 OR EQUIVALENT.
  1. There are three filtering or screening devices in the fuel delivery system. The intake sock is a fine, nylon mesh screen mounted on the intake side of the fuel pump. There is a fuel filter screen located at the fuel rail side of the fuel injector. The fuel filter assembly is located between the fuel pump and the pressure test point/schrader valve.
  1. The fuel pump (FP) module is a device that contains the fuel pump and the fuel sender assembly. The fuel pump is located inside the reservoir and supplies fuel through the fuel pump module manifold to the engine and the fuel pump module jet pump.
  1. The inertia fuel shut-off (IFS) switch is used to de-energize the fuel delivery secondary circuit in the event of a collision. The IFS switch is a safety device that should only be reset after a thorough inspection of the vehicle (following a collision

Mar 21, 2009 | 2003 Ford Focus

2 Answers

2.9 rough idle/lopes when LR/1st gr


Presumably you mean slow cranking. Check for weak battery or bad starter.

If not slow cranking so much as long cranking time check for loss of fuel pressure overnight using fuel pressure gauge. If so, suspect leaking injector or possibly leaking regulator.

Jun 20, 2008 | 1986 Ford Bronco II

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