TD4.2 fuel adjustment screw location?

[fnqcairns]

I have now traveled almost 1k in my new GQ 4.2 diesel wagon and with much interest I calculated my fuel economy so far.
18.2L/100k
I was not driving this car hard anywhere with mostly highway trips, it does not blow smoke unless I am useing a lot of throttle up slow hills then everyone behind me tries to overtake , in normal city driving it blows almost none! I know we followed it to check.
The car does have heaps of grunt more than I thought it would from the couple I have driven before, it really holds well up hills (????because of the fuel setting????)
Air filter element is clean enough.

Sounds like I need to take it to someone so they can twiddle a screw but before then I would like to have a go myself (it's who I am ), but buggered if I can find it!!

I suspect it is actually the throttle cable linkage and where it stops, this needs to be set a bit further from full throttle thus giving less fuel throughout the range. I have only looked at it this morning, so far it is the only bit that makes sense, in my searches here I have read about people 'turning up the fuel screw' half a turn etc -but there seems to be no screw I can see.
Would appreciate any ideas.

cheers

[gqmad]

mate its located at the back of the pump.
You need to loosen of the nut over the bolt first then just get a screw driver and turn the screw anti clock 1/4 turn and see how it is then.
You cant miss it, its the last screw that sits on its own.
It may even have a cover over. Almost like a metal condom.
good luck

[fnqcairns]

Thanks mate I know the condom you are talking about, this afternoon when it gets cooler I will have a twiddle.

cheers

[fnqcairns]

Ok I went 1/3 of a turn anti clockwise, are you sure it is anti-clockwise on these for less fuel? Usually with engines and stuff clockwise seats and allows less fuel and the other way gives more. Buggered if I know anything about injection pumps though.

Not doubting you gqmad very happy to have found the location, just double checking.

cheers

[fnqcairns]

Took the car for a run it doesn't seem to be as meaty through the gears but it will now rev through 3400 easily in third, it used to hit a brick wall at those revs before and not go much further with any interest.

The idle dropped (150-200) so I adjusted that back up also, hopefully the right way there seems to be two options.

Anyone know what expect from a diesel when it has too much fuel and also too little?, it's easy in a petrol to diagnose - do diesels play by the same rules?.

A help appreciated

cheers

[Hoonz]

to much fuel it'll be sooty and run hot
not enough fuel it'll be a bag of shit

look for blue smoke that means its burning oil ...

injectors might need doing ... maybe injector pump

changed ur air and fuel filters lately?

[HeathGQ]

isn't there a fine filter in the pump inlet that restricts flow pretty badly, particularly after 3000rpms....

[Hoonz]

yeh theres a thimble lookin filter on the pump under the big nut

if ur using paper type fuel filters it tends to block up ... could be another reason .. you would definately feel it break down at high revs 3000+ if it was blocked

[fnqcairns]

Well then I guess mine has been running hot for at least 140k as this pump was replaced under warrenty at 60k and has had no further adjustment as all the tell-tail dobs of paint were unbroken. Hope it was not overfueling enough to shorten it's life somehow.
I will check that little screen sometime soon the car has been dealer service it's entire life so overall it has been neglected.
Fuel filter is 10k old, I got a Ryco replacement but got warned away form them on these engines, will do that soon with the genuine
bit.
I guess to much fuel also bogs a diesel down in the higher revs considering it now revs through?

The injectors seem fine and it uses no oil (so far) but the upper valve train is noisy, considering the low quality of nissan spec oils for these engines under warrenty, overall I suspect an adjustment will not be enough to save them.
Spooky owning an engine I cannot diagnose myself-yet!

thanks for the info.

cheers

[Hoonz]

tappets will make it run like shit and be noisey use fuel etc
make sure they're adjusted properly

my td42 supercharged revs to 4200 no problems

and the td42 turbo I/C in my ute revs 5200 no worries but thats had a bit of work

[mirkogu]

m8 i have only had a quick read and if ur car is turbo the last thing u want is not enough fuel as u will melt ur engine very quick
good luck

[fnqcairns]

Thanks for the replys, no not turbo -one day possibly I read here about Mack truck turbos that pull good boost at under 1200rpm -that sounds good!

Hoonz can you or somebody direct me some more please?

I cracked both of the big fuel bolts looking for a mesh filter but didn't find it The most likely bolt was the one where the fuel enters the pump from the fuel filter, the other one was probably just a return. I am paranoid about introducing any dirt into this thing so didn't try very hard to dig out a screen. It did have a spring I could see in the hole. Why doesn't my bloody manual have anything of basic value regarding these pumps in it!!! Does the Gregory's manual?

cheers fnq

[John H]

Not all fuel pumps will have the little thimble like filter — mine is an 89 Mav and it doesn’t have one. Apparently this is not really an issue.
Out of curiosity, are you pretty sure that turning the fuel adjustment screw clockwise increases the fuel? (as stated by gqmad)
I have just intercooled my 4.2 and wouldn’t mind adding a touch more fuel.

[InSanE]

i was lucky enough to score the factory TD42 Engine manual when i was a mech at nissan so when im out in the shed 2morrow i will have a look for you guys and let u know.

[fnqcairns]

John the adjustment I made decreased my idle rpm some, on the surface this to me makes sense if I decreased fuel supply across the board but I really have no good idea what I am talking about on these things.

Insane that would be nice - thanks Also if possibe the correct procedure to reset idle after a fuel adjustment. I noted 2 ways to do it, I took the chicken out option and only re-adjusted the stop .

cheers fnq