Outer Limits 4x4 Board

G'day everyone,
went on a little trip on the weekend and noticed that whenever I accelerated hard the truck would start to cough a bit at around 3k. Any ideas on what the problem might be?

88 GQ LWB with about 220k on the clock.

thanks

maybe its time you change your fuel filter.

or injectors or injector pump shitting itself...

fuel starvation... its been known to happen on GQs.
some people run extra pumps...

Check the filter at the fuel pump if your main filter is new

bogged wrote:fuel starvation... its been known to happen on GQs.
some people run extra pumps...

i have this drama, but only noticed it in the past 6-8 monnths when booting it around corners,

will the extra pump only keep a constant supply at the injuector pump, or should there be a surge tank or something,

who has done this?

it'll be that thimble style filter at the injector pump full of shit
if it sounds like its knocking ur injectors are prolly stuck open
cause of the shit thats gone through the pump cause u haven't serviced
it properly = $$$$ to get pump and injectors done

ozy1 wrote:

bogged wrote:fuel starvation... its been known to happen on GQs.
some people run extra pumps...

i have this drama, but only noticed it in the past 6-8 monnths when booting it around corners,

will the extra pump only keep a constant supply at the injuector pump, or should there be a surge tank or something,

who has done this?

i have an extra electric fuel pump cause mine starves at high revs
3500 it started chugging

we figured it was cause of the CAV filter setup was restricting flow
the modded injector pump couldn't pull fuel through it quick enough

ozy1 wrote: ...or should there be a surge tank or something....

Thats what I was tryin to think of.. I think they would be an option. AWILL knows a bit about them, with some of the gino drag cars, and sprint cars he works with.

Hoonz wrote:

ozy1 wrote:

bogged wrote:fuel starvation... its been known to happen on GQs.
some people run extra pumps...

i have this drama, but only noticed it in the past 6-8 monnths when booting it around corners,

will the extra pump only keep a constant supply at the injuector pump, or should there be a surge tank or something,

who has done this?

i have an extra electric fuel pump cause mine starves at high revs
3500 it started chugging

we figured it was cause of the CAV filter setup was restricting flow
the modded injector pump couldn't pull fuel through it quick enough

Do you run the CAV filter only or do you run the std Nissan filter and the CAV together? I have a few GQ's in the family and one had alot of issues with filter and pumps. After installing dual fuel filtration it seems ok. The secondary fuel filter collects very fine black dirt so the primary filter must have let alot of shit past. That little problem caused a pump rebuild $750

I have recently installed a secondary CAV in my rig and a few weeks later I have a power loss and surging in 3rd gear at 2400rpm. Also I have noticed more black smoke than before. I'm thinking a blocked fuel filter or the pump is struggling to suck fuel.

PS. I have no turbo and std exhaust. My pump and injectors were rebuilt before I bought it. Done 60 000km since then.

Adsman wrote:

Hoonz wrote:

ozy1 wrote:

bogged wrote:fuel starvation... its been known to happen on GQs.
some people run extra pumps...

i have this drama, but only noticed it in the past 6-8 monnths when booting it around corners,

will the extra pump only keep a constant supply at the injuector pump, or should there be a surge tank or something,

who has done this?

i have an extra electric fuel pump cause mine starves at high revs
3500 it started chugging

we figured it was cause of the CAV filter setup was restricting flow
the modded injector pump couldn't pull fuel through it quick enough

Do you run the CAV filter only or do you run the std Nissan filter and the CAV together? I have a few GQ's in the family and one had alot of issues with filter and pumps. After installing dual fuel filtration it seems ok. The secondary fuel filter collects very fine black dirt so the primary filter must have let alot of shit past. That little problem caused a pump rebuild $750

I have recently installed a secondary CAV in my rig and a few weeks later I have a power loss and surging in 3rd gear at 2400rpm. Also I have noticed more black smoke than before. I'm thinking a blocked fuel filter or the pump is struggling to suck fuel.

PS. I have no turbo and std exhaust. My pump and injectors were rebuilt before I bought it. Done 60 000km since then.

yep just a CAV .. changed the whole lot over to their system
i don't see why u would put it as a secondary cause the CAV unit is gonna pick everything up as it filters a finer micron .. some one maybe able to get some figures for it

I have a power loss and surging in 3rd gear at 2400rpm. Also I have noticed more black smoke than before.

more black smoke seems weird .. wouldn't happen if u weren't getting
enough fuel .. black smoke is unburnt fuel ..
was it tuned properly after the injector and pump rebuild?
or maybe u have a sticky injector

I rang up the supplier for CAV filters and they are the same micron diameter paper as the Puroilator filters I use and RYCO, Donaldson, etc. are the same. The difference is apparently the CAV filter spins the fuel and this action causes more shit to drop out of suspension. Therefore this is their claim to fame for better filteration.


I was talking to a diesel fitter about the black smoke and he reckoned that a blocked filter can cause black smoke as you lose power and therefore give it more pedal, resulting in a shitty combustion. What are your thoughts?? My fuel economy is still good, providing I don't rev the motor past 2400rpm its fine to drive and sounds good too. ie. no engine rattles or other odd sounds. It revs fine standing in the driveway all the way upto 3000rpm just not when driving.
My pump was tuned for the new injectors 60000km ago and has run really well until recently.

Also I have noticed more black smoke than before.

Black smoke suggests too much fuel for the amount of air being delivered. Replace your airfilter first.

Have you check all your fuel lines.....one may have a small pin hole...or a clamp may not be tight. dose not need much for them to suck air in the fuel system.....

GUpatrol wrote:Have you check all your fuel lines.....one may have a small pin hole...or a clamp may not be tight. dose not need much for them to suck air in the fuel system.....

Did service and rechecked the clamps this arvo will see how it goes in the morning.

Blew out the air cleaner and it was clean. (Currently disconected the pre-cleaner.)

i think
injectors or injector pump

whitmanoz wrote:G'day everyone,
went on a little trip on the weekend and noticed that whenever I accelerated hard the truck would start to cough a bit at around 3k. Any ideas on what the problem might be?

88 GQ LWB with about 220k on the clock.

thanks

After service and new tank of fuel, slightly tightened up all the fuel line clamps, new pre-cleaner element, same secondary air element (just blown out with compressor).

It has been driven 500km and seems to be fine.

I had checked the fuel line clamps already but must have missed the same one twice.

Also no more smoke now.
Pre-cleaner must have been blocked up even though I had blown it out. I need to organise a snorkel as
that element had only been in for two trips.

Change fuel filter 1st.

Bazzle

This happened to me the other day. Just done 200 000 service - new filters and checked thimble filter, two days later filled up with fuel and went to work. Drove out in the morning OK, was sumbling at 3000 rpm by lunch and could not pull 2000 rpm on the way home. Used over 100L fuel for 400km.
Eventally got home and checked in with my mechanic, thimble filter was partially blocked and main filter had some crap. Cleaned out filters and flogged the piss out of it for half hour and all was good, went to the wreckers the next day and got a cruiser/rodeo filter mount and got a bosch filter to fit ~ $50 total. Now has dual filtration and Bosch filter bolts to the same bracket the main filter is on so everything is still all together. Done another 1000 k's since and no probs

Curious!!!!
I have been working on this problem my self. Mine started doing it after i had the injectors replaced and the engine tuned. It now goes like a cut cat, people think its turbo'd!!!
It only does it after alot of slow running and idleing, like on a slow track with lot of stopping and starting waiting for people etc.
You when you do need to put your foot up it, it coughs and splutters through 3000rpm and then winds right out to red line with out any probs. It only does it once, if you have to have another go, its fine. Then you idle around for a bit and the next time it splutters again. Very strange. Like it gets an air lock in the fuel filter after a lot of slow running. I could't seem to find the gauze filter at the pump, the scew driver just went down and down, and i have tried two new main filters. Next thing is to replace all the factory spring clamps on the fuel lines with proper hose clamps.
My fuel filter set up and injector pump is mysteriouse though. The Filter housing has four fuel lines coming from it, and on the pump where the bleed screw should be is an electrical connection. Buggered f i can figure out what it does, my manual doesn't mention any thing. I wondered if it was a fuel preheater of somthing stupid, but why would it be??
It just makes me wonder if my problem lies with not being able to bleed the system properly after changing filters, or some auto bleeding system is not working. I will have to take pic's!!
Is there any way you could pressure test the system??

what model?
pics would be good

fuel lines (aftermarket hose cut to length) and clamps are cheap:
GQ less than $10
MQ/MK less than $20

If you cant bleed it at the pump and have removed the fuel filter hoses or changed the filter then you would have air in the line. I would fix that problem first before anything else, then change your fuel lines and clamps if it continues.

[quote="DieselBoy"]Curious!!!!

It only does it after alot of slow running and idleing, like on a slow track with lot of stopping and starting waiting for people etc.
You when you do need to put your foot up it, it coughs and splutters through 3000rpm and then winds right out to red line with out any probs. It only does it once, if you have to have another go, its fine. Then you idle around for a bit and the next time it splutters again. Very strange.

Mine does this too - has been for about 30k. I am not sure if it still does this of late as i don't rev it like i used to since i go offroad less

The weird shit you find on a Jap import!!!





Buggered if i can see what they are for!!!

my gq was doing the same thing and i replaced the fuel filter and all flex aball fuel lines and fitted a low pressure i line fuel pump before the filter and i have not had a probly sence and it goes better in the top end and generaly more torquey

Ok, this low pressure fuel pump sounds like the deal.
Can you give me more info on it.
No surge tank?
Volume and pressure figures so i can sort out an equivilant over here in NZ.
Cheers,
Pete.

the pump i used was approx 6-8 psi and 180l/hour and it was werth $100 i think these numbers are all approx.
and it is a diaphaim pump and i wired it to ign relay

Cheers for that, i will see what i can get hold of.
Was there any reason in particular you went for the diaphram pump??

So this kind of thing would do the trick ya reckon??
http://www.fuelflow.co.nz/pump.htm

Ok, this low pressure fuel pump sounds like the deal.
Can you give me more info on it.
No surge tank?
Volume and pressure figures so i can sort out an equivilant over here in NZ.
Cheers,
Pete.

Pete,
Ring G. Guy Motors in Wellington and speak with Grant or James. Ask them what elec fuel pump they used on Simon Guy's GQ race truck. Should be able to give you a starting point.

Cheers
Mitch

Sweet, that things a beast, will do!!!
Cheers!!