2002 Qx4 starting problem

[mtlrover]

2002 Qx4 3.5 engine.In recent months I would have to crank the engine a couple of times to get the truck started. It was almost as if while cranking it would skip or get out of rythym. Now this morning the truck would crank but not start almost as if it was starved of fuel. I therefore put the gas peddle to the floor while cranking and it stated after a long crank.Any ideas on the problem.By the way no warning lights are on.

[tbsbiker2]

when was the last time you changed the fuel filter, have you checked your airbox for any debris? Hopefully it's that simple....could be fouled plugs or bad coils but you should see a code on that...i'd start with the basic and cheaper fixes first.

[mtlrover]

Thanks for the response, Fuel filter not been changed since I own the truck, about 20,000km.I recently changed the air filter thinking this might help.By the way where is the fuel filter located.

[TheReplay]

those are my problems to a "T" ---> 2001 QX4

I needed a new battery, however that wasnt the problem.

I changed the fuel filter, did not help.

Cleaned MAF and throttle body. Didnt think this would help, but decided to do it anyway.

But my problems are exactly as you describe, my vehicle would start to crank for a split second, then almost skip/hesitate the crank rhythm. Usually as a reflex i would stop cranking at the point and start over, at which point everything was normal.

This past sunday, it was colder than it had been recently (maybe 20 degrees as opposed to past days around 32-35 degrees) and it took an abnormally long time to crank (no skips, just a long time maybe 4-5 soconds or so) at which point instinct told me to feather the gas pedal just a touch, then the car started up.

Theres many who will say feathering the pedal on a fuel inejcted vehicle will do nothing, but in my own experience with this incident and past incidents with other fuel inj cars, sometimes it helps...

I was getting misfire codes about 5 months back on cylinder six, i would clear them and they would spring up again here and there, so know the coil/plug needs to changed, however the the past couple months i havent been getting any codes on the coils/plugs at all. Maybe changing them will prove to be helpful, maybe not.

If i turn the key to the ON position without turning to crank and let it stay there for a few seconds the problem has tendency of occurring less. Maybe signs of a fuel pump on its way out? Dont really know.

[tbsbiker2]

There are several threads on this if you do a search (it's in the back near the rear wheel well drivers side if I recall)...I have a 2001 and purchased it with 45K on it...I had several misfires and codes lots of stumbling and such but it would usually start run poorly and throw a code in those cases. I decided to replace ALL of my coils since I planned on keeping it for a long time. I'm no mechanic but your problem could be a bad fuel injector or as I say some fuel delivery issue/filter/fuel pump. Really sounds like a fuel problem??? can you smell gas when you are cranking it or does it blow lots of black smoke once you get it started...I'm totally tossing S$^% out there on this.

[mtlrover]

Wow I read your post and yes we are definitly having the same problem. I have parkrd the car in the garage for a couple of days to see if the warm garage would have some diferent result, but to no avail, the problem persits in the heat as well. I am kind of suprised to have no check engine light on. I don't know what to do or how to proceed, I mean with no check engine how are the mecanics supposed to diagnose the problem. If anyone has ideas please let me know. I am a little overwhelmed.

[01qwhite]

sounds like it could be a cam or crank sensor but i could be wrong

[Pwnin O'Brien]

sounds like it could be a cam or crank sensor but i could be wrong

A malfunctioning camshaft or crankshaft sensor would definitely throw a DTC and illuminate the SES indicator.

[Chuck Tribolet]

Does the SES light come on during the lamp test the first couple seconds afteryou turn the key? I'm wondering if maybe you have a burned out SES bulb.

[ugharin]

Id consider the cam or crank shaft sensor or crank angle sensor or something like that. It happened with a buddys 99 grand cherokee sometime back.

[oasisx]

sounds like you got a bad/clogged fuel pressure regulator. this happened to me on my old car(which had the FPR valve located @ the fuel tank and most likely got clogged up from driving around with way below empty too many times. the FPR valve keeps pressure in the fuel lines after you have run the car, this way next time you go to start the engine you have fuel readily available. a bad FPR valve would cause this pressure to be lost and therefore would require the car to crank a number of times before finally starting.

not saying this is definitely what you're experiencing, but its worth looking into.

[Pwnin O'Brien]

sounds like you got a bad/clogged fuel pressure regulator. this happened to me on my old car(which had the FPR valve located @ the fuel tank and most likely got clogged up from driving around with way below empty too many times. the FPR valve keeps pressure in the fuel lines after you have run the car, this way next time you go to start the engine you have fuel readily available. a bad FPR valve would cause this pressure to be lost and therefore would require the car to crank a number of times before finally starting.

not saying this is definitely what you're experiencing, but its worth looking into.

The fuel filter would have caught any contaminants in the fuel before they got to the FPR; this would result in a clogged fuel filter instead of a clogged FPR.

[mtlrover]

Saturday my buddy is bringing home the super computer from were he works (Bently, Range Rover). I'll let you know the results. |And thanks for all the brainstorming..

[01qwhite]

actually no not always i have seen cars that wont start due to bad cam crank sensors an the light not come on for a while

let us know what happens

[mtlrover]

Finally my mechanic was able to hook up my Qx4 2002, it shows no faults, zilch, nada. I have been driving with no problem for about a week, like it fixed itself . Mechanic suggests a tune up, I have 203000km on it with the original plugs. I guess a tune-up can't hurt.

[mtlrover]

Did a complete tune up. New plugs, cleaned maf. fuel filter, changed all oils (diff's, trany, engine, transfer case) All filters, including cabine. Had a slight rattle in front suspension, changed 2 links. new front brake pads. Truck runs perfectly again, I'm at 211000km.. No more starting issue..

[ARKQX33V6]

Congratulations!