GQ first start problem!!!

[907PSI]

G'day Guys, I have a quick question to ask you. I've got a GQ Patrol 4.2 petrol/gas its done 195000kms and have a problem with its first start after its been sitting for more than 8 hrs. I've just a major service done leads, plugs, air filter even changed coolant temp sensor but still not fixed. The car has to start on petrol then it switches to gas automatically. What happens is it cranks for a bit then almost starts then dies eventually it splutters a bit and it starts then there's no problem. Do you think the injectors need to be serviced or is it a sensor thing? I noticed on the Patrol forum some other people are having same issues is this a common problem? Any help would be much appreciated as its driving me crazy!!! Cheers, Anthony.

[growler2058]

G'day mate welcome aboard jump over to the intros and and say g'day something we ask all members to do
Could well be injectors or fuel filter


Tap, Tap.......Who's there?

[malcolm]

Hi , I have lots of practice on this sort of problem with a classic BMW i run . May not be relevant but while my coffee cools:

Check fuel pressure is correct - rig up a gauge with a T piece etc. If fuel pressure is wrong/ sporadic, nothing else will work properly .

If fuel line does not hold pressure check if non return valve/ check valve is leaking - most systems are designed to to hold some residual pressure to aid starting after standing.

Check for air leaks in hoses - unmetered air will cause lean running and poor starting .

may be than move to things like coolant temp sensor - wrong reading will not signal cold start conditions to CPU . check earths /connections etc.

Also grubby air flow sensor will mess up cpu signal .

have fun - be methodical - often these things are cheap but very time consuming to nail .

If all else fails trade in for TD42 diesel - i did and never looked back.........

Cheers

[907PSI]

Hey guys i was just about to send my gq for a injector service this morning and I gave it one last check for any problems and notice that one of the vacuum lines coming from the charcoal canister purge solienod was disconnected!!! Does any one know if this affects first start-up? Anyway will find out tomorrow morning fingers crossed that I've saved $500!!!

[malcolm]

Did fixing the loose vac hose fix your problem ? Just curious , cheers

[907PSI]

No it didn't fix problem and just had injectors done today and it still seems to start poorly it's look like its gonna be one of those problems that annoy the crap out out me!!!

[malcolm]

yes it does get more than a little annoying.......... may be one of the other members knows more about the specifics of the nissan system . It's also annoying how garages plump for injectors as the cause rather than run diagnostics on the whole system .

Anyway , based on my own limited knowledge sorting out the old beamer, i would be checking the fuel pressure against spec . You can do this by removing a hose from the rail and inserting a t piece with a gauge - i used a tyre pressure gauge from super cheap . And yes it works - you can also see what happens to the pressure when you turn the engine off. You kind of need a reasonable idea what you are doing and avoid spraying fuel around a hot engine etc etc . There is good general info at www.hiperformancestore.com - but its mostly about bosch systems .

Anyway, from my understanding the cpu on most systems controls the duration of the injector opening - it assumes that the pressure is correct - if its not then it doesn't know - so therefore its a good place to start.

Of course you might have other air leaks etc which will throw things out - cheap to replace vac lines etc.

From my experience you have a choice between giving someone a blank cheque to fix it, or nutting it out yourself over time . If you are running ok otherwise then consider giving it ago - you'll learn heaps and spend time rather than money .

One final point ; check how the choke system works - doubt it, but some systems have a 7th choke injector - when it fails or sticks you have a start problem .

hopefully someone with more nissan efi knowledge will have an opinion to share .

Cheers,
back to work

[907PSI]

Just an update guys tried new coil still nothing but seems to be a bit smoother when running gonna try crank angle sensor, rotor button and new dizzy cap next. I have also found the problem definately happens over time if it sits more than 12 hours that's when it's hard to start

[malcolm]

OK, still suggests to me a loss or residual fuel pressure - leaking fuel line or check valve (ie one way valve) somewhere in the system. As well as above mentioned pressure checks you can put an additional check valve in the fuel delivery line to the fuel rail which should hold fuel pressure - if the return fuel lines are ok and not leaking . This is usually just a few dollars and a couple of jubilee clips and 10 mins to install . If it fixes the problem great - if not then you can be reasonably sure that you need to look elsewhere and check the fuel return lines and pressure regulator . If you fit the gauge as suggested you can see if the fuel pressure falls whilst clamping off fuel line at the end of the rail (etc)

Cheers

[Yendor]

I was in a TB42 the other week that has the same problem. On first start it would give a bit of a sputter and then after a fair bit of cranking it would eventually start.

I would say it's fuel related.

It's a bit of a long shot, undo the fuel cap before trying to start it in the morning, maybe it's a vacuum lock??

[NissanGQ4.2]

Anthony, has this always been a problem since you have owned the GQ or something that has just started happening

Cheers

Todd

P.S: Don't forget that intro

[907PSI]

My mechanic has already ready checked fuel pressure as we've left the car over nite at the work shop and there is fuel pressure. I've even undone fuel cap before starting and no success lol. Just now whilst driving home turned car on and off a couple of times and noticed it was a tiny bit hard to fire but not as bad as left sitting over time. That's got me thinking it's sensors as it has a little miss when idling. One of my mates said that a common problem with starting vl commodores was crank angle sensor and being these motors are in the same family I thought I'd give that a try.