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nissan problem

okay this girl I know has a nissan frontier
she seems to be having trouble starting the thing once in a while 1 out of 15 starts lets say. and she says she sometimes gets it started while giving it gas
it turns over when it doesnt start for her
and it doesnt die out on her while driving

so could it be a sensor, fuel pump any of you guys have an idea

I dont like messing with newer vehicles

thanks in advance

James

I think a few more details might be in order here.

First, how old is this Fronteir, and roughly how many miles are on it? Under what conditions does the truck fail to start- does it do it when the engine is warmed up, cold, or indifferent? Is the fuel pump making a lot of noise when the truck is running- a fuel pump failing generally sounds like a sick lawnmower.

I'll take a couple of guesses, even though I'm not the most familiar with the Fronteir in general and don't know exactly how old this one is.

One guess at the moment is a possible crankshaft position sensor. It can cause no start or extended crank but often (at least at first) won't die once the engine is running. Failure of the CPS doesn't always set the check engine light either.

Another guess is that the fuel pressure regulator is beginning to fail. I've seen this happen before and cause symptoms much like you described. Cycle the key a few times and once started the car will run fine- this is a good indicator of a fuel pressure regulator, although it can also mean another part of the fuel system has failed. This will not set a check engine light either. To test this theory you need a fuel pressure gauge to attach to the fuel rail. Get a partner to turn the key to the on (but not start) and off again. You should consistantly get a 40-60 PSI reading that will bleed down. I saw a similar problem in a Ranger that came into the shop that was solved by a new fuel pressure regulator.

A dying fuel pump could also cause the symptoms you listed.

Right now though, these are just guesses, and a guess is not a substitute for diagnostics. It is also not a substitute for a well maintained vehicle. Each little variable can play into your diagnostics, so it might not be a bad idea to get a new fuel filter and new air filter and making sure that general maintainance is complete before beginning your diagnostic tests. My thoughts are based on my conjecture from experience with a few other models and such, so I could be right or wrong. I hope this give you a few ideas though.

okay it is a 2000 frontier with 96,000 miles on it
which is when some parts need to be seviced usually
I havent been able to make a trip up to her place but
would like to help her out when I go up there to help
her out. weather doesnt matter it just does it one out of 15 times


I thought about the crank position sensor my friend with a 240 sx had that problem which actually might be the problem cause it has to do with part of ignition hmmm a 16 dollar part hopefully thats all it is a fuel pump is like 270 bucks ouch.

for the fuel pump how do you check if it is good with a voltmeter? or just by ear?

yeah a fuel filter would be a good idea but its not the problem cause it doesnt die out while driving she said but still it probably has never been changed haha. its too bad I didnt have a lil diagnostic tester

thanks

more info would be appreciated

James

Yes, the CPS is tied in with the ignition system. Failure usually begins with extended crank across the board, but I saw a Grand Cherokee once that had the extended crank and intermitently would crank but not start.

The way to test a fuel pump is by testing the pressure it creates. You will need a fuel pressure gauge. Normally you can hear a fuel pump cycle when you turn the key to the on position and this will tell you if the pump is working. This doesn't garuntee that you're getting the correct ammount of fuel pressure, but if you hear an ominous silence, or if you can hear the pump howling like a banshee when the truck is running, it can be an a somewhat more obvious indicator of a problem.

If you're getting silence and you have reason to suspect the wiring, I would get a good test light to look for breaks in the wiring. It can happen but usually wiring for the fuel pump is relatively well shielded.

You really don't want to guess at this stuff though. First of all, replacing the fuel pump is a really nasty and expensive job. Second, I am presently doubting the fuel pump hypothesis anyway. If there was a check engine light you could look for codes. If you have access to a more advanced scan tool, you could check on the various sensor outputs and look for anamolies.

Oh yes, I just had one more thought that I somehow forgot. Had a helluva cold and the brain has been farting lately. The more obvious problem I think is a neutral safety switch. The truck would NEVER die when it was being driven. When the truck is in park (or neutral with the clutch in if it's a manual), the truck will refuse to start. The next time it behaves like this, if it's an automatic put the truck in neutral, and if it's a manual, put it in gear with the clutch in. If it start right up, it's the neutral safety switch. I've seen this happen in a lot of other cars actually and it's an easy problem to miss at first.

In the old days, it used to be possible to just remove the neutral safety switch. This is technically unsafe- the truck will be able to start if the transmission is in gear. On a modern truck, it might set a check engine light with some kind of general transmission code, particularly if it's an automatic. Then again, it might not, so disconnecting might be the cheap trick to making the truck work temporarily.

Beyond this, I can't think of much else useful I can offer. My last name isn't Chilton unfortunately and I don't have the same experience level that my dad has with these kinds of things.

haha

well hey it helps having advice

yeah I didnt plan on having her drop $250 or whatever it is for a fuel pump without making sure first.


yeah I would like access to a diagnostic tool but they are like 50 bucks to buy one. ouch

thanks buddy

James