Fuel twiddling on the 1HD-T engine

[Chris]

From my experience, the toothed wheel is pretty high as standard. Not hidden up and away perhaps as much as you describe, but pretty high. I know exactly what you mean about it being a click of the wheel or a slip of the screwdriver. Been there.

I am much happier with my truck since I twiddled. It perhaps smokes a little more when on the power and occasionally just blurts out a load of soot, but off road I don't stall the TC anymore. Bags more grunt. Haven't done enough miles to know if it's hit the MPG yet and as I have been off road with the big boots on, it's pointless trying to work it out.

I would say get the seal off, give it 1/8 to 1/4 turn and see how it is then. Turning that main screw back is the easiest thing to reset if you don't like it. But you can't 'boost' what isn't there. I made some minor changes and it had no difference to my view. Rather then wind everything up in a frenzied spanner attack, I did the main screw. As I think you indicate, I wasn't after a growing monster, just something that would pull away smartly at a roundabout. Mine does that now.

Chris

 

[IRLGW]

Brilliant chris- very reassuring and I'll go for the fuel screw next. I'll admit in being lazy to not full read the technical lit thats available and understand the mechanics of it and go for the trial and error approach. Just worried that I had fixed something that wasn't broken. I had read on another forum that the 12v screw is normally near the bottom so relieved to hear that its just as common to be at the top. I had to remove the throttle assembly, dipstick and fuel filter line to ge tmy head in far enough to see the toothed wheel but couldn't move it with my head in there! Where have you ended up with your toothed wheel relative to where you started?

glen

 

[Chris]

I used a mirror to look in there. I have only given it 6 clicks all told. Which is not much at all. So in terms of where it is visually - it's just about where it started. I don't use RVS for pump stuff as I have a chap locally. He knows these units and told me that 1/4 turn at a time on the main screw would not cause any harm. Be careful though. If you prise the seal off then slacken the nut with a deep socket you can't see if the screw moves with the nut. Better to use a flexi spanner if you can so that you can watch the slot in the end of the screw. If you do use a socket then just break the nut loose but no more then go in with the spanner.

Chris

 

[IRLGW]

yep ok I'm with you that and reckon its all probably seized together after all this time. What is the job of the shim in there - to stop the pair form seixing or to prevent the locknut from vibrating loose

I'm not too worried about using the main screw its just that I'm delighted with fuel economy of this beast compared to my previous shoguns and landrovers (with much smaller engines and even compared my old 98 colorado.) I guess that I am significantly further down the boost compensator than you so I should maybe move it someway back before adjusting the main screw.

 

[Chris]

It's to stop you screwing it in. You can undo the nut but leave the seal in place on the screw. That way you can free it all up lovely, but change nothing. Simply screw it back in up to the sleeve once you have cleaned it up, then prise the seal off. You can take the whole screw out there's nothing else in there.

Chris

 

[IRLGW]

So I got the 1/8 turn this morning and didn't even have to remove the metal collar. What I did was not the position of the fuel screw and then put a full length socket over the 12mm nut to break the tension and let it move a few degrees. I then removed the socket and rotated the fuel screw back and forward to see if it had moved from the locking nut and the two turned together and stopped at the original position. I then nipped the head of the fuel scree with a pair of small vice grips and then used a second pair to back the lock nut off approx 1/8 a turn. leaving the collar in kept the nut from spinning free. I then tightened the lock nut up by hand and then nipped it up with big socket. The slot in the head of the fuel screw is now vertical from the previous 45degrees off vertical before I started so that is as close as to 1/8 as I am likely to achieve.

The engine is now idling a bit faster as suggested in all the write ups. Is there another place on the pump where I can turn down the idle?

 

[Chris]

It's not really the pump that you turn down, it's the lever stops on the outside of the pump. If you work the cam and watch the moving parts you'll see where the cams lift off the threaded stops. Do this when it's fully warm though as there is a cold start idle up mechanism. Fiddle with that another time. Does it go any better?

Chris

 

[IRLGW]

I haven't had a chance to drive it yet because I'm doing engine and diff oils (between the showers). My mum and dad are going to take it with their caravan this weekend as its more economical than my mums petrol rav4! I'll assume that if it comes back with the caravan still attached then all is well! I'm off working again from tomorrow so will be next week before I can asses the situation and count the mpg

 

[IRLGW]

I worked it out today that towing a 4berth caravan for 140miles on 50% crap roads took approx 28litres which was an mpg of about 22.7 Before fuel pump adjustments I was getting 30mpg (without trailer) so that's a big drop but as we never had a caravan before I'm not sure how much they reduce consumption on the average vehicle.

I'm 1/8 turn on the fuel delivery screw.
approx 1/2 way down on the boost compensator
Believed to be at point of least resistance on the aneroid screw.
Aneroid adjuster @ +180 degree turn.

The true test will only be on a run without a trailer again But may take the boost compensator up the ladder a bit. Engine seems to smoke slightly on tick over but not really putting out any clouds under load. It is however much nicer to drive and and smoother through the gears and no more issues at junctions. I wonder if one could modify the pump to take thumb adjusters so adjustments could be made quickly and easily for different driving conditions.

 

[Chris]

22 mpg towing with anything is pretty good. Best I have had from mine without fuel adjustments not towing anything on a long run was 21.

Chris

 

[Graham]

I'm not sure how much they reduce consumption on the average vehicle.

I consider a loss of 33,3%

ie, Diesel:
30 mpg solo, and expect 20 mpg towing.
27 mpg solo and expect 18 ish.


Not towing a little caravan, but a decent size and weight of about 1800kg.

I would say your getting 22,7 is quite good, but then it's not a heavy caravan maybe.

Just my opinion.

Gra.

 

[Graham]

22 mpg towing with anything is pretty good.
Best I have had from mine without fuel adjustments not towing anything on a long run was 21.

Chris

.
21 ......ouch,
Is that the result of the larger tyres Chris?

Gra.

 

[IRLGW]

I have a 12valve manual with 190k on the clock. I am running slightly bigger tyres with Insa Turbo Desert Trak 265/85/16. It was in fact on the exact same run two months ago that I worked out I was getting 29.6mpg and that was sitting at around 2000rpm. The caravan is only a single axle with probably more windage than weight (approx 800kg)

I must also confess to running on a DK mix of 60/40 (for those of you who understand what that means ). I also use the 2stroke additive. Very smooth, but like for like K with give less economy than D so on D alone the economy should be better.

You truck is an auto Chris? so I guess that might be the difference. I had a few auto Jeeps in the past and the 90 series was one of the worst performers so I deliberately searched high and low for a manual this time around. I think the truck with my driving style is giving god performance by accounts but I would be reluctant to trade too much of that economy!

 

[Chris]

No Gra, with the proper tyres I am getting an impressive 13 mpg.

Oh yes, smell that money burning...


C