Excessively underpowered 1HZ + poor fuel economy

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Your fuel economy is excellent considering a 1HZ and auto driving in BC mountains!

As for performance, 3rd gear in the auto and about 3000 rpm should be what you use climbing these hills. You should be able to maintain 60 km/h or 35 mp/h up most of them.

I don't think you should be having any performance or power concerns with this set up and the results you are seeing.
 
Looks like you've got a light load. I've seen 7800 LB camper conversions pulling 60 km/h in the Rockies with 1HZ's. Why did your truck sit for 4 years?

Might want to stop in and talk to Edit: John at ATEB if you're going back that way. Sounds like you need a good tune. I won't bore you, but he turned my truck to 11.

Have fun in the Rockies....
 
Last edited:
seriously, if any of my diesels gave me 14L/100km i would go back to driving a gasser. that fuel economy sucks the big one.
combine that with the sluggish power you are experiencing and that truck would have been out the door after the first trip.
but
you turbo that engine and you will find it much more enjoyable to drive and your fuel economy MIGHT go up.

my last tank of fuel with the FU75 was 15L/100 or 15 mpg canadian. (steady 90 km on the flat).

i do remember a HZJ73 that was auto that i had here and it was gutless as all hell (really clean truck), i installed a mapped turbo on it and the thing came alive, give it a try and you will be much happier.
 
crushers said:
my last tank of fuel with the FU75 was 15L/100 or 15 mpg canadian. (steady 90 km on the flat).

.
Click to expand...

Just what kind of shenanigans is this?LOL
15l/100 is about 18.8 mpg in imperial gals or has canada switched over to those southern gals?

Its certainly doing better than my 3F.I dont think I bettered 18/100 in the FJ73.
Do have the 4.11 diffs?
 
sorry, my bad ...
73L squeezed into the tank
453 km of road covered
http://www.eforecourt.com/calc_mpg.htm
17.5 mpg canadian ...

4.11 diffs, 32" tires, bone stock otherwise, light on the acceleration and steady speeds.
if i drive agressively then i am down to about 13 mpg or if i drive 100+ then the mileage suffers badly.
 
Comparing fuel mileage on flat lands to mountain driving is useless and gives the wrong impression of performance to the original poster, IMO.

14L/100km with a NA diesel mated to an auto is excellent economy when driving in the province of BC. It will not get much better than this, period.
 
crushers said:
sorry, my bad ...
73L squeezed into the tank
453 km of road covered
http://www.eforecourt.com/calc_mpg.htm
17.5 mpg canadian ...

4.11 diffs, 32" tires, bone stock otherwise, light on the acceleration and steady speeds.
if i drive agressively then i am down to about 13 mpg or if i drive 100+ then the mileage suffers badly.
Click to expand...

Thats not bad for a gasser.

I got exactly 600klms from my troopy,all city driving from 84 litres this week,which 14/100.I can get it to under 13/100 on longer trips at 120kph
I actually managed to squeeze 84 litres into the rear tank without it overflowing which is a new record for me.
My front tank record is 87 litres I think.
Which is nice to know because I can get in excess of 1200klms from both tanks
Im also on 32 inch tyres,seems to be about the best all round size IMO
 
that is real decent for a troopie, heavy with the aerodynamics of a huge brick.
the 32s do seem to work well, still decent power if you need it but the RPMs are 2100 at 90 k/hr
 
I cant see the troopie having different aero dynamics to any other 7* series ,except maybe the new style
 
well, the roof is about 4" taller and the truck is about 4 ft longer. other than the weight and length and height, you are right.
<grin>
they all are bricks on wheels.
 
Wow, this thread has taken on a life of it's own! I suppose that's always the case when you talk diesels and fuel efficiency... Since I'm driving around so much at high elevations (4500'-7000' at the moment), I've turned the fuel down another 1/4 turn and have seen a lot less black smoke. I've been gearing down as well as I can, but when it gets too steep, I can't hold it in 2nd without it trying to accelerate up the hill or go to 3rd. I end up in Low with the rpm's around 3000 and just holding steady at 20 mph/30 kph. It looks like my average mpg (US) up here is around 17-17.5 mpg or 13.5l/100k. I'm fine with that as I expect it to go up a bit when I'm finally out of the hills. As for the glow issue, it's feeling like I'm in need of some new plugs as there is no way they are all working with the rough starts I've been having...
 
Leitrum3 said:
As for the glow issue, it's feeling like I'm in need of some new plugs as there is no way they are all working with the rough starts I've been having...
Click to expand...

You may have some air in there as well. The fuel line that connects to the fuel pump is a good one to check.
Did you try a direct connection from glowplugs to battery? IDI engines will never start well without glowplugs.
 
roscoFJ73 said:
You may have some air in there as well. The fuel line that connects to the fuel pump is a good one to check.
Did you try a direct connection from glowplugs to battery? IDI engines will never start well without glowplugs.
Click to expand...

I haven't tried the direct connection because the timer actually works, proven by not even thinking about starting when it's turned down to a shorter time. If I glow it for 8 seconds it usually starts, but really rough with a good amount of smoke for a minute (compared with almost no smoke ever a month ago while we were in Portland still where it was quite warm). At the moment, it feels a whole lot like my 3B when starting as it's been 30-35F in the mornings here. I wouldn't be surprised if there was air that was getting through some how - I still don't trust my fuel filter/pump. As I mentioned way back when I first got the thing, it has the Airdog 100 and it has only gotten noisier since I've driven it. I figured out recently that when I'm pointing down hill that it quiets down, indicating that there is air getting in (I think at the tank based on some posts at the dieselstop forum - no one talks about air dog here...).
 
A little update on this thread, bringing it full circle to the original post. Currently the fuel is turned down a little more than 1/8th from where it was when the engine was installed and the fan clutch that was spinning at rpm was fixed (as stated previously, in Kamloops). I also started using a Lucas additive on this trip and I've seen my mileage spike up now that we're not doing tremendous passes. My last couple of tanks have been as follows and I couldn't be happier.
Banff to Sandpoint, ID (via hwy 40/940 to the highest paved point in Canada): 18.9 US mpg
Sandpoint to Missoula, MT: 19.34 US mpg
Missoula, MT to Twin Falls, ID: 19.8 US mpg

So, at this point I don't think I need to worry so much, from what I hear about NA 1HZ's, that's as good as it gets. The only things that need attention is the glow issue and my tranny not holding 2nd when I manually drop it to '2'. But that's another issue and probably another post after I review what the FSM says.

Highwood Pass along route 40, 2206 meters/7239 feet
image-2397271031.webp
image-2397271031.webp
 
kim said:
Not being able to hold second when you put it in 2nd? When in Drive, does it shift from first to second to third or go first to delay to third?
Click to expand...

It shifts fine from drive, goes something like this under moderate acceleration: 1st from stop, 2nd @ 10 mph, 3rd @ 25 mph, 4th @ 40 mph, 4th lockup at 52 mph. When I hit moderate hills, I usually manually kick it down to '3' so I can hold the rpm's at 2600-2900 in 3rd. But if the hills are steep or long, I usually have to slow down more as I can't keep the rpm's up and manually dropping to '2' at that point makes no difference, i.e. - it stays in 3rd. The only way I can hit 2nd is to kick down hard, but then it only stays there long enough to accelerate up a bit. Quite annoying as I end up having to just drop it to 'L' and run up to 3000 to hold 20 mph. Slow and steady wins the race as they say, but I know 2nd would really help. it's all surprising as its a brand new rebuilt a442 from Wholesale Automatics.
 
Leitrum3 said:
It shifts fine from drive, goes something like this under moderate acceleration: 1st from stop, 2nd @ 10 mph, 3rd @ 25 mph, 4th @ 40 mph, 4th lockup at 52 mph. When I hit moderate hills, I usually manually kick it down to '3' so I can hold the rpm's at 2600-2900 in 3rd. But if the hills are steep or long, I usually have to slow down more as I can't keep the rpm's up and manually dropping to '2' at that point makes no difference, i.e. - it stays in 3rd. The only way I can hit 2nd is to kick down hard, but then it only stays there long enough to accelerate up a bit. Quite annoying as I end up having to just drop it to 'L' and run up to 3000 to hold 20 mph. Slow and steady wins the race as they say, but I know 2nd would really help. it's all surprising as its a brand new rebuilt a442 from Wholesale Automatics.
Click to expand...

Sounds like adjusting the tranny kickdown cable could help, made a huge difference in my truck. It actually holds gears long enough to make use of the powerband now, rather than racing for top gear.
 
IanB said:
Sounds like adjusting the tranny kickdown cable could help, made a huge difference in my truck. It actually holds gears long enough to make use of the powerband now, rather than racing for top gear.
Click to expand...

I had the kickdown adjusted to within factory specs, but for my underpowered engine, it wouldn't drop down the gears easily enough so I actually adjusted it out of spec to make the hills less stressful.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom