BJ60 - poor mpg.

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You probably don't have a fuel line leak if the truck runs. A fuel line leak would suck in air causing the engine to quit.
your high pressure line may be leaking, but there should be diesel everywhere in the engine bay.

do the same thing as the previous guy and test for drag on a wheel, or through the driveline
 
There could be a leak in the return line and not cause problems with air in the fuel.

Don
 
Dont want to create a new thread on this and one of mine exist. Here is my fuel economy numbers:
275km per half tank. That equals to 170 miles per half tank or 320 miles per tank full.
-I have had the injectors rebuilt. Verified the spray pattern and was excellent after the rebuilt.
-Hot oil change with seafoam.
-New Air filter
- not a new fuel filter yet. Dealer wants to charge 60.00 for a new filter
-Just adjusted the valves. Only a few really needed adjusting.
-Brakes do not drag! I can go some distance at 5 mph and it comes to a very very slow stop.
-I hyper mile those those fuel economy numbers. Not sure if hyper miling making a different with a diesel fuel economy.
-I have a small ladder on the roof but removed it does not make a noticeable difference in fuel economy.

So, what else could be the problem? Compression is great! Last time checked with borrowed compression gauge from a Ih8muder it was over 400 psi per cylinder or, his compression gauge may need to be calibrated because the reading was close or exceeded new compression reading for a new truck..

Can I adjust the mixture on the IP to bring it down, without sacrificing to much in performance? The truck is slow on bridges driving to the crown.
 
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Have you checked your timing? Really retarded or advanced timing can do this. Look on the side of the pump to see if the lines are matching up or if they've been adjusted. It wount tell you what the actual timing is, but will tell you if its been monkeyed with. As a rule, having the marks lined up is generally a good place to start. These pumps wear and slowly retard timing as afar as I understand. Turning the fuel screw down wont alter the air fuel ratio, you can only do that with turbo boost. Your truck will always require a set amount of fuel to drive unless you alter the way it burns it. Turbo?
 
no turbo. My bj60 factory manuals are some where just have not unboxed them. I read that to time the engine, remove injector line numbr 1, put a standoff tube on top of the ip, turn over the engine, then when fuel starts to appear at the top, then see where the timming mark is. Adjust to specs.
 
My brakes are fine. I can coast from 10 mph for some distance and it will slooowly come to a stop. I was almost at the last notch at the Empty in my fuel gauge in the last fuel up and was at the 600km mark. So, refueled and reset the odomoter and the other day was in a bit of a rush. The fuel economy dropped so fast I was think where did the fuel go to? It was almost at the half way mark and the odomotor was at the 190km mark!!! What in the inline IP can cause a massive fuel drop this fast in 1 to 1.5 days? I am suspecting the IP is the issue, because everything else has been replaced except the fuel filter.

Items changed include air filter, valve adjustment, hot oil change to free up any sticking rings. Not to much do troubleshoot on these engines as they are simple compared to a gas engine. The timing has not been changed. I have not taken it into a shop since I do all the maintenance. But what is important is the fuel economy. Its really bad at times. When I purchased the truck 7 years ago, the fuel economy was great! was getting almost 900 km to the tank full.
 
gerg,

I know its a strange thing. some times a poof of smoke will happen under acceleration. thinking of taking it into a LC shop like EBI or another and see what they can find out. So the engine has 450,000 kms. What should be the fuel consumption at the half way or full mark under mixed city/highway driving?
 
My truck has 425. I've been getting around 10-11 l/100km

900 km is a heroic tank. I don't think my truck ever got that. It can get over 800 before I fill up, but I don't like to push it.

I have run out of fuel at 650km before

The problem with truck milage is that I am always pulling a trailer or loaded up with gear. The 3b tends to be affected more by drag then weight.

What about the vacuum line to the fuel pump. I know when guys turbo their trucks it pops off, maybe yours has split or is sucking in air?
 
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