98 V6 Jackaroo fuel help

Submitted: Wednesday, Apr 18, 2007 at 18:49
ThreadID: 44464 Views:5442 Replies:11 FollowUps:3
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Wondering if owners of V6 Jackaroo's could share their fuel consumption figures and weather or not its worth putting it on gas and what system if so?? Seem to be getting bad .... hang on... VERY bad fuel figures (20lt per 100kms) and its seems to blow black smoke when kicking down (Auto). Ant suggestions or info much appreciated.


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Reply By: wbsl - Wednesday, Apr 18, 2007 at 18:54

Wednesday, Apr 18, 2007 at 18:54
Hi Phill

My 98 V6 auto does about 16 per 100kms around town and 13 per 100 highway unless towing. Heard the Jackaroo engine does not like Gas, you may want to look into it a bit further

Regards Wayne
AnswerID: 234282

Reply By: FZJ 80 - Wednesday, Apr 18, 2007 at 19:13

Wednesday, Apr 18, 2007 at 19:13

Black smoke is usually rich fuel mixture which means high fuel consumption.
Start by checking the air filter.it may be almost blocked,if so replace it. If it's not that,off to the mechanic for a diagnosis.


AnswerID: 234286

Reply By: madfisher - Wednesday, Apr 18, 2007 at 20:32

Wednesday, Apr 18, 2007 at 20:32
Mate their is a Jack section on australia4wdforum, their guys seem pretty cluie on jacks.
I also seem to remember reading somewhere their is an oxygen sensor in the exhaust, which if it is stuffed gives very poor economy. apparantly their is also a restrictor in the exhaust manifold which if removed gives better power and economy
Cheers Pete
AnswerID: 234317

Follow Up By: Ford Rodeo - Thursday, Apr 19, 2007 at 08:38

Thursday, Apr 19, 2007 at 08:38
Thanks Pete, will give Australia4wdforum a shot also. Got the restictors out already and it has helped.
FollowupID: 495358

Reply By: Boldjack - Wednesday, Apr 18, 2007 at 20:36

Wednesday, Apr 18, 2007 at 20:36
We did a 4,000 km trip, loaded with 3 jerry cans and a spare tyre on the roof.Add to that tools, some spares, esky and food and all the gear you need for a family of four, including some toys etc, and averaged 17.6 litres per 100km and we weren't putting around at 90 km/h either if you know what I mean :) Around town we seem to get about 500 plus km out of a tank 85 litres.
Hope this helps, you obviously have a tuning problem with black smoke (running to rich)
Cheers Boldjack.
AnswerID: 234318

Reply By: nowimnumberone - Wednesday, Apr 18, 2007 at 20:50

Wednesday, Apr 18, 2007 at 20:50
them figures seem about right.
as said clean/replace air filter.
oxygen sensors play a big part in fuel economy(black smoke sounds rich)
i have a 3.2 ltr jack auto 22 per 100 city.
also v6 jack dont like gas conversion about $2500 plus head work $2500 plus fuel tank. gets to expensive.(going back a cpl of years when i looked into it)
AnswerID: 234322

Follow Up By: Member - Bradley- Sunday, Apr 29, 2007 at 00:38

Sunday, Apr 29, 2007 at 00:38
yep clean air filter, air flow meter, throttle body etc. pump up tyres, let them use the torque band etc etc....

LPG - Jim, mate give Terry at smithys car repairs and gas in bayswater a call. Most installers and kit makers cant get the emulators set up right and so just say "cant be done". Smithys have been doing jacks since early 90's and have em well sussed, heads are no prob, same as rodeo and they love gas. It is pricey for jacks because you have to get a new aux tank, i got quoted 3800 for an old school venturi gas system, and 4800 for sequential injection, five year 100 warranty from memory, got the paperwork somewhere if you want a copy. im going the injection when finance allows.

cheers Brad.
FollowupID: 497622

Reply By: Member - Arkay (SA) - Thursday, Apr 19, 2007 at 08:14

Thursday, Apr 19, 2007 at 08:14
We had a 1997 3.2 auto Jackaroo for 103,402 km. We did all sorts of stuff with it, 4WD, heavy 4WD, Camper trailer, 1900kg caravan, city driving, country driving not towing anything, etc.
I keep meticulous records and can give you fuel consumption for each type of driving, but I suspect you are talking about the 3.5 litre motor if it is a 1998 model. Just as sample, for the whole of its life we averaged exactly 17.78 litres per 100 km, around 18.5 in the city, about 20.5 towing the caravan , and about 18.3 towing the camper trailer, about 25.0 heavy 4WD, about 14.0 country without the trailer. Most of these were done with the airconditioner running.
We now own a diesel and get much better fuel consumption figures. I am not a "fast" driver.
AnswerID: 234400

Reply By: Ford Rodeo - Thursday, Apr 19, 2007 at 08:46

Thursday, Apr 19, 2007 at 08:46
Thanks to all for your help. Restrictors from exhuast gone already and has a new K&N filter. Its has also had a dyno and they recon its all good. Maybe a second opinion might be in order. Or maybe the fuel figures are normal but the black smoke doesnt seem right!!??
Thanks again
AnswerID: 234406

Reply By: Gerhardp1 - Thursday, Apr 19, 2007 at 10:39

Thursday, Apr 19, 2007 at 10:39
Black smoke is not normal, you need a diagnosis on this.

Don't put it on Gas, as the head material is very thin around the water jackets, and the extra heat from the Gas combustion will cause the heads to crack. Then you will have wasted the conversion cost, plus have to spend HEAPS on fixing the head(s)

The engine itself is not inherently less economical than other 3.5 engines, but the fuel map programmed into the computer is very rich. Mine does the same mpg at 110 as it does at 80, both car only and car/trailer. I get 440ks from 75 litres around town (auto) in summer and less in winter due to more running with "choke" on

A tuning shop in Launceston replaced a Jack computer with a Haltech with impressive results. www.fueltech.com.au/auto_servicing.html I should have done the same when I first got it......
AnswerID: 234433

Reply By: Steve63 - Thursday, Apr 19, 2007 at 12:24

Thursday, Apr 19, 2007 at 12:24
We used to get 16 around town and a tad better out of town. Black smoke is not normal. It will be a stuffed sensor with any luck. O2 sensors seem to be a frequent cause of problems. The computer often records things about the sensors so a visit to someone with a reader may be helpful.

AnswerID: 234452

Reply By: Robbg - Thursday, Apr 19, 2007 at 17:21

Thursday, Apr 19, 2007 at 17:21
Hmm, those who claim better than 15 lit/100kms around town in a 3.5 Jack must have feather-foots. The best I can do is about 420kms out of 70 litres - that's nearly 17 lit/100. It doesn't change much if I'm doing highway towing, but I can do better if I'm not towing - say 450 kms out of the 70 litres. I'm interested that some people talk about 85 litre tanks; mine doesn't seem to hold much more than 75.
Cheers. Rob.
AnswerID: 234528

Follow Up By: Member - Bradley- Sunday, Apr 29, 2007 at 00:46

Sunday, Apr 29, 2007 at 00:46
:-)) geez rob if you have seem me drive sometimes im using the whole chook not just the feather LOL...

I dont dilly dally anywhere, but i also dont have it labouring down low, they really dont like it.

my 98 3.5 manual base model used 11-13 and when lifted and running 265/75/16 MTR's it still only used 13-14.5.

the 03 3.5 manual se has winch, aux tank heaps heavier etc. and uses 13.5-14.5 all the time, city/offroad/120kph highway etc.. feather free :-).

its all in how you drive them, gota let em rev out with 1/4 - 1/3 throttle etc.....

cheers Brad.
FollowupID: 497623

Reply By: madfisher - Friday, Apr 20, 2007 at 19:31

Friday, Apr 20, 2007 at 19:31
Picked up a 3.5 Jack today, covered 400ks in 4hrs and used 53lts to 402ks not to bad. Its a manual which seem to be better than autos

Cheers Pete
AnswerID: 234811

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