Nissan GU sub tank,,,,,,,,wanna change things

Submitted: Monday, Jul 03, 2006 at 23:20

ThreadID: 35502 Views:10393 Replies:11 FollowUps:12

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Bilbo

Hi all,

Looking fer some advice. The current fuel tank set up in the Chev/Nissan GU is the standard (but stupid) one of a 95 litre main tank and a 35 litre sub tank. (What earthly use is 35 litres to 6.5 litre V8 diesel?).

In the long term I will be fitting an additional, bigger tank of about 150 litres inside the truck where the 2nd row seats once were, but for now I wanna sort out this stupid idea.

The standard set up on the GU is that when you start up and the main tank is less than 3/4 full, the sub tank will AUTOMATICALLY pump (drain?) from the sub tank to the main tank for a period of 5 seconds - at every start up. Thus depleting the ridicuously small 35 litres in the sub tank. So when you really need that 35 litres in the sub tank and you press the sub tank switch, it's now only 25 litres - very quickly. The set up on my former 100 series was 2 entirely seperate tanks and you simply switched from one to the other at the press of a button. A much better idea where I had control of what was happening.

I would like to set the GU up as per the 'Cruiser set up. Has anyone ever done this? Any probs?

I need the range as the places I get to are a long way out in W.A. and this current set up is driving me nuts.

Plus - because of this stupid set up and the fact that my main tank gauge is about 25% out, I ran out of fuel in the main tank and had a hell of a job bleeding the injection pump from the sub tank. SWMBO was not impressed at all. BTW - did you know that on a GU when you switch to sub tank and run on it for a while and then stop the engine, the sub tank goes off and the main tank comes back on line again - automatically. Bloody useless when yer trying to bleed the damn thing from the sub tank, only to find that when you've bled it, run the engine and stopped it to wash yer hands etc, the empty main tank is back on line again - and _Affordable_Storage_Drawers.aspx in another load of air!! THIS has got to be changed my friends.

Any help out there - before I rip out the whole bloody lot and rebuild/rewire it the way it should be!!

Bilbo

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Reply By: Waynepd (NSW) - Monday, Jul 03, 2006 at 23:45

Monday, Jul 03, 2006 at 23:45

I know there is an alternative setup that was spoken of in the Yahoo Patrol list, years ago. You can get a different set of manifolding ports that allow you to use the tanks in the way you describe for your cruiser....I just can't remember where you get them, sorry but at least they exist its a start.....
will investigate if no-one else comes up with the right answer....

AnswerID: 181697

Follow Up By: Bilbo - Tuesday, Jul 04, 2006 at 00:25

Tuesday, Jul 04, 2006 at 00:25

Thanks Wayne. I'll check it out.

Bilbo

FollowupID: 438007

Follow Up By: Waynepd (NSW) - Tuesday, Jul 04, 2006 at 10:34

Tuesday, Jul 04, 2006 at 10:34

Bilbo,
After my post last night I checked the archives on both the Patrol and GU lists and that info isn't there any more. A lot of stuff was pushed out the back end of the archives due to a lack of storage in the early days of the list.
Maybe someone here has more info.....the post referring to the 6-port thing sounds like what i was talking about...good luck

FollowupID: 438043

Follow Up By: Member - Scooby (WA) - Tuesday, Jul 04, 2006 at 15:57

Tuesday, Jul 04, 2006 at 15:57

Hi Bilbo,
When I had the long range tank made by K&N Fabrication in Canning Vale fitted to my Hilux they fitted a six port valve.
I can use either tank using a dash mounted switch. The fuel level reads out on the standard gauge and is switched also by the same switch.
This system has been operating well for three years now.
Regards
Scooby

FollowupID: 438103

Reply By: howie - Monday, Jul 03, 2006 at 23:54

Monday, Jul 03, 2006 at 23:54

i have been wrong before, but i was of the opinion that the the gu always runs off the main tank and when the 'sub tank' switch is pushed, it merely empties into the main.
there is a reason for the 5 second pump on start up, something to do with condensation and/or ensuring the pump is used.
when i'm in town and stopping/starting a lot i do notice the sub tank go down.
but it has not bothered me out in the bush.
my main tank also indicates about 3/4 full on a full tank, is there an easy cure for this anyone?

AnswerID: 181698

Follow Up By: Bilbo - Tuesday, Jul 04, 2006 at 00:27

Tuesday, Jul 04, 2006 at 00:27

.............."my main tank also indicates about 3/4 full on a full tank, is there an easy cure for this anyone?"

That's another problem that's gonna get fixed...............

Bilbo

FollowupID: 438008

Follow Up By: howie - Tuesday, Jul 04, 2006 at 01:25

Tuesday, Jul 04, 2006 at 01:25

me too!
especially now, as i have all my _Affordable_Storage_Drawers.aspx and shelves out due to a small accident with a carton of milk.
i remember a few years back the nissan dealer had to take out the _Affordable_Storage_Drawers.aspx & shelves to replace the fuel pump thru an access panel in the floor and while its accessable..........................

FollowupID: 438014

Follow Up By: dj Patrol - Tuesday, Jul 04, 2006 at 14:08

Tuesday, Jul 04, 2006 at 14:08

My 4.2 TD did the same everytime I hooked my van on so when I told nissan about it they said It did not.Well to get to the point when I was in Alice Springs the ........ service manager told me he had also heard of this and it was Earth related but could not help me as it was a ........ problem.So off I went to the local Sparkie and had a big Earth fitted to the near side engine mount and onto the block YEP Problem fixed never had another all OK.Gauge stays on full now..

dj Patrol

FollowupID: 438075

Follow Up By: Member - Roachie (SA) - Tuesday, Jul 04, 2006 at 16:15

Tuesday, Jul 04, 2006 at 16:15

Howie,
You dead right.....the fuel is always supplied from the main tank to the donk. The sub tank ONLY drains into the main tank and if you are in the process of transferring fuel across to the main and happen to switch the donk off, the pump will stop and won't re-start when you fire up the donk again, unless you push the button again.

I have become used to the system and tend to pump across when I'm on a trip and see that the main tank (a 145 litre Long Ranger) has got down to about half. It takes about 20 minutes to pump a full sub tank across. I certainly wouldn't consider changing it around to the landcruiser type set-up....... not that I've got anything against it as such, just can't see why there's any need to change a system that works just fine as it is.

I've recently fitted an extra lift pump (sits on the side of the chassis just in front of the existing transfer pump and behind the gearbox support cross member), so if I ever need to prime the fuel system in future, it's as easy as turning on the ignition (and the facet pump comes on.....runs all the time when ignition is on).

I would like to get a 81 litre replacement sub tank too, but am having trouble justifying the expense to myself at this stage.

Cheers

Roachie

FollowupID: 438105

Follow Up By: rolande- Monday, Jul 10, 2006 at 10:06

Monday, Jul 10, 2006 at 10:06

G'Day Bilbo and Howie,

Incorrect fuel gauge reading sign of poor earth. Fit another earth lead directly to the chassis and problem should go away, poor earth caused by amount of extra accessories compared to standard vehicle

Hope this helps

Rolande

FollowupID: 439077

Follow Up By: Bilbo - Tuesday, Jul 11, 2006 at 00:46

Tuesday, Jul 11, 2006 at 00:46

Rolande,

Thanks for that. By "fit another earth" I assume you mean from the dashborad instrument cluster to the chassis. Or have I got it wrong?

Bilbo

FollowupID: 439332

Follow Up By: rolande- Tuesday, Jul 11, 2006 at 19:50

Tuesday, Jul 11, 2006 at 19:50

G'Day Bilbo,

I assume when they fitted the engine they left the orginal earth lead which goes battery - body - engine.

Not guaranteeing a result but if you add a short lead from the body to the chassis at this point you may see a difference.

GU Patrol known for poor earth.

Hope this helps

Rolande

FollowupID: 439498

Reply By: Member - andrew B (Kununurra) - Monday, Jul 03, 2006 at 23:59

Monday, Jul 03, 2006 at 23:59

Gday Bilbo

I actually like the setup on the GU (everyone has their own opinion of course). For myself I like the way it pumps from the aux to the main - the aux empties, then when you run out on the lot you are out on the lot, wharas with the cruiser setup if things got tight you would be gambling with which tank is the emptiest(?), ie could run out on 1 and still have 10 litres in the other.

I think the 5 second or so run on the aux is to stop some unknowing person having stale fuel in the aus through ignorance - it slowly drains so has to be filled every now and then. I do not like this function. I agree the 35 (actual about 31 - 32 useable) is a bit on the small side, but it is a reliable 200km for me if I back off a bit - and haven't done too much stop/start driving to suck 5 litres or so of the top with that bloody 5 seconds.

An easy fix for the 5 seconds would be to find the relay for this 5 seconds and remove it with a suitable tool (crowbar), or re-wire it directly to the ffactory switch or a second switch, making the origional redundant.

As for capacity, I have considered the 70l replacement available from 4wd systems, possibly rerouting the exhaust and putting it on the passenger side and keeping the origional, fitting the 145litre replacement main, and/or fitting a 30 litre gas tank on the pass. side and going down the lpg fumigation road.

I'm not sure if the chev will like the gas, it is suposed to be a little better in direct injection diesels, but I think the chev will be very tolerant of what you throw at it. Please let me know if you try the disabling of the 5 second transfer at startup, and I will tell you how (if) I get around to trying it.

Cheers Andrew

PS I, like most others here, am very jealous of your conversion, mine being the powerhouse 2.8!

AnswerID: 181700

Follow Up By: Bilbo - Tuesday, Jul 04, 2006 at 00:24

Tuesday, Jul 04, 2006 at 00:24

Andrew,

As far as I know, all replacement after market tanks for Patrols result in the tank bottoms being lower than the chassis rails. I don't want that as I do too much rock work. I'll be mig welding my own tank that will be fitted inside the truck. I'll use a Repco electric pump to transfer from this internal tank to the main tank. This worked very well on my old Ford Maverick trayback ute, where the home made (it was out of an old Valiant Charger) aux tank was fitted under the tray at the back.

Re-routing the exhaust looks to be a difficult option. The 4 inch system on the V8 is brand new and I don't wanna blow dough changing that.

Yer right - LPG is a good option on direct injection motors. It's not really cost effective on indirect injection engines - or so I've read.

Thanks for the info on the tank switching. I'll be attacking it some time this week.

Bilbo

FollowupID: 438006

Reply By: Muzzgit (WA) - Tuesday, Jul 04, 2006 at 00:36

Tuesday, Jul 04, 2006 at 00:36

Bilbo, as stated above, I too like the setup of pumping from the aux tank into the main. I can understand your frustration though.

A good mate of mine has the diesel 80 series and he cannot get his head around the way the Nissan works, but I like it.

AnswerID: 181702

Follow Up By: joc45 - Tuesday, Jul 04, 2006 at 03:24

Tuesday, Jul 04, 2006 at 03:24

Hi Muzzgit,
When I had the old Mav, I had dual tanks fitted with a solenoid valve changeover for the fuel (it had two changeovers; one for the delivery and one for the return so that the fuel returned to the correct tank). Worked well, except when some cr@p from the tank got stuck in the solenoid valve, then everything went wrong. I had to remove it and take it apart a few times during its life to clean it out.
The GU system seems to suit me, but I agree that the 30 litre capacity is not much better than one jerry can. At least I had about 75 litres on the old Mav's subtank (but it did hang low).
cheers, Gerry

FollowupID: 438015

Reply By: Member - BBB - Tuesday, Jul 04, 2006 at 06:46

Tuesday, Jul 04, 2006 at 06:46

Bilbo

Ther is a GU long range tank in the Trader section of this site.

Might Help

BBB

AnswerID: 181713

Reply By: Robin - Tuesday, Jul 04, 2006 at 08:15

Tuesday, Jul 04, 2006 at 08:15

Hi Bilbo

For reasons as per Andrew and others I also prefer the current setup and have modified GQs to that way. Sure you can fit a 6 port valve in but your reliability is likely to go down.

Very little fuel is transferred on startup , and I think best policy is simply to
always fill up both tanks, on this basis the sub typically takes around 1 lt per 2 weeks.

Re-did my 4800 petrol GU to give 1000km+ range which meant adding , not the largest but the best rear main tank (OOT 145lt) to preserve ground clearance.

As part of this process I optimized the fuel sender and pickup which meant that I shifted the guage reading. My guage now reads full until the tank has used 20lt
and is much more precise at the lower end and will pick up fuel with under 2 lt in the main tank.

In the petrols the combined main tank fuel pump sender unit is pretty complex, and required breaking some spot welds and rewelding with everthing in place to extend the pick up point 1cm.

Just changing the way the sender arm works (and the resultant guage reading)
is easier, you just unbolt it and bend the sender arm (2 bends) such that the float
is closer to the bottom of the tank.

The sub tank sender unit can also be modded this way.

Robin Miller

AnswerID: 181720

Reply By: Truckster (Vic) - Tuesday, Jul 04, 2006 at 12:25

Tuesday, Jul 04, 2006 at 12:25

>>> The standard set up on the GU is that when you start up and the main tank is less than 3/4 full, the sub tank will AUTOMATICALLY pump (drain?) from the sub tank to the main tank for a period of 5 seconds - at every start up.

the reason it does this is to keep the pump lubed... Stop it and kill the pump. Is it that much of an issue?

AnswerID: 181750

Reply By: Patrol22 - Tuesday, Jul 04, 2006 at 13:15

Tuesday, Jul 04, 2006 at 13:15

Nissan must have put bigger subs in the later model GUs - my 2.8tdi GU 1998 has a 30ltr sub and Nissan kindly pointed with an erratum to the owner's manual to the effect disregard the 40ltrs sub we said we put in...it is only 30ltrs.

AnswerID: 181760

Reply By: Fast_Patrol - Tuesday, Jul 04, 2006 at 15:11

Tuesday, Jul 04, 2006 at 15:11

I believe it was a brown-davis part that allowed the patrol to be modded to work like a cruiser (based on memory from the patrol forum - I couldn't find any record of it in my own archives)

cheers
Andrew

AnswerID: 181777

Reply By: Member - Matt M (ACT) - Tuesday, Jul 04, 2006 at 17:40

Tuesday, Jul 04, 2006 at 17:40

What is the set up in the 100 series Cruiser? My petrol 80 operates the way most of you describe, ie sub tank transfers to the main at the push of a button and the engine only feeds from the main. I am a bit confused by the references to the Cruiser system.

I now understand why my sub tank goes down slowly as I hadn't realised that some is transferred on start up. Makes sense now I realise that it doesn't do it on the highway but only stop/start around town.

One of my concerns with this system though is what happens if the pump craps itself and I am left with 45 litres of fuel I was relying on? My only guess is that you would have to syphon from the sub tank into a jerry, then pour it into the main. Anyone had experience with this?

Cheers,

Matt.

AnswerID: 181794

Reply By: Member -Dodger - Tuesday, Jul 04, 2006 at 18:04

Tuesday, Jul 04, 2006 at 18:04

I ahve a replacement tank of 85ltr where the useless sub was and this too pumps to the main tank. It suits me ok and gives me a total of 175ltrs with a usable aamount of 160ltr due to the fact that I do not let the tanks run dry.
The reason for the sub pumping for 30sec is so that the pump is kept oiled and does not get gunk building up in it. These pumps are seneitive to rubbish in the fuel so I installed a cheap petrol filter before the sub pump and this collects the gunk. I change this filter (it costs about $5 at supercheap) every second major service 20 thow .
Works a treat.