Category Archives: Fuel System

New Propshafts

Fuel and Battery Gauge on DashBoth the front and rear propshafts have been on the “hit list” for a while due to the amount of play in the splines. On my competition motor I fitted a Bailey Morris heavy duty prop shaft after snapping a rear one and decided it was worth the extra money for the quality of the splines and the larger UJs so decided to go the same way with the 90. 2 propshafts along with 2 spare UJs for the spares kit arrived last week.

So, I ticked off a few jobs in the end this weekend – I added a foam rubber strip between the tyre rack and the roll cage at the front as it was whistling quite loudly above 40mph, all quiet now. I also fitted both new propshafts, fitted a new steering damper with relocation bracket to the steering drag link – removing the one from the track rod. In an effort to fix the annoying slight oil leak from somewhere around the transfer box I took the bottom plate off it and resealed it while changing the oil. I had a play with a number of ideas to try and mount the ground anchor somewhere and decided in the end it really is too cumbersome to fit in a 90 !

Sunday was spent doing a final fit and gauge calibration for the infamous battery and fuel monitor, in the afternoon we took it for a long run out to make sure the props and steering felt good and that the fuel gauge and fuel consumption was something like. All seemed good, the new propshafts have fixed the vibration we were getting on overrun, the steering wobble is completely gone and the spare tyre rack was quiet at all speeds πŸ™‚

Just to prove that the battery/fuel gauge thing is actually fitted and working at last I even took a picture of it ! It sits quite neatly above the normal centre dash switches…

The countdown has started

IMG_0383It’s been a busy few months but things are really starting to fall into place now with the official agreement from work for me to take the time off etc… The shipping date is more or less finalised so I now have a deadline to work to and that in itself has certainly focussed our attention on what still needs to be done between now and then !

Near the top of the list is the fuel and battery monitor as that will play a key part in the trip, giving a more accurate view of the current fuel status across the two tanks than we could hope to get from the standard gauge. The wiring for the unit is now completed in the vehicle, along with a bypass plug that allows the unit to be removed and the normal fuel gauge to work as normal. This should give some redundancy should the unit fail for some reason.

The monitor is on the second design and is now full functioning with just a few software tweaks needed and some calibration of the fuel levels. The auxilliary tank has been calibrated now and I just need to put the values into the software, the main tank is next to calibrate. I’ve calibrated the tank/sender in 5 litre steps so we should have a reasonable idea of the remaining fuel at any time if the sender unit stays consistent. I still need to decide exactly where the lcd display will be mounted, a 3D printer would be very useful right now to make a custom pod for it !

While calibrating the auxiliary tank we managed to get 57 litres into it before it started to overflow, 55 is probably a more sensible amount to put in but it shows how much you can get in, using a 5 litre jug.

Fuel and battery monitor goes beta

20130621-131829.jpgThe fuel and battery monitoring system is now ready for the next stage, transferring the design from a prototyping board to a custom board design. The new 2×8 character display seems to be clear enough and is small enough to mount in the dashboard somewhere. I’ll add/maintain support for in situ programming of the PIC chip so I can tweak the calibration and display functions as required.
Hopefully I’ll get the PCB Design finished and the board etched this evening.
The module itself has suffered from a bit of bloat ware during the design process but hopefully it’s now got all the hardware features it needs to support and anything beyond that can be tweaked in the software. Once it’s all finalised I’ll create a page with the design for anyone that wants something similar.

Fuel revisited, again !

Having had some time to go over our experiences of the last week or so it seems that yet more “tweaks” will need to be made to the fuel system although, thankfully, nothing too painful.

The good news was that with the 90 fully loaded in “overland” mode the new MAF sensor I fitted just before we left has brought the fuel consumption back into the realms of “reasonable”. With a mix of motorway, dual carriageway, narrow B roads and some town driving we were getting just above 24MPG during the trip. Having the twin tanks really let us push the limits on range without having to worry about running out of fuel. The main tank gave us a range of just over 430 miles without running out – I’d have let it run out just to see how far we could have got on it but we were on the motorway at the time and I didn’t fancy having the engine stop in that environment. We haven’t taken the front tank more than 200 miles yet but it’s looking as if the combined range is going to be in the region of 750 miles.

The only problem we’ve encountered is that the fuel gauge isn’t directly connected to the sender on the TD5, instead it’s controlled by the Speedo… really, it is ! The speedo prevents large changes in the gauge reading which probably serves to stabilise it off road. The problem is that when you change tanks, if the fuel levels are very different, the gauge takes 30 mins to adjust unless you turn the ignition off and back on again.

As a result I’ve been pondering on a way to resolve this and also to give a more believable fuel gauge reading for the current selected tank. The battery/fuel monitor will now drive the dashboard fuel gauge directly, bypassing the normal speedo circuit. The monitor will be connected directly to the two fuel tank senders and I can then calibrate the sender for each tank in the firmware. It will also light up the dashboard “low fuel” warning light (another job the speedo does at the moment). I got the gauge driver hardware/software working today, I just need to change the display to a smaller 2 rows x 8 characters display to make it easier to mount it somewhere in the dash.

Packing it all in…

20130610-001304.jpgSpent a good part of today packing, unpacking and repacking the 90 in preparation for our latest mini expedition. This will probably be the last real shakedown before we ship to Australia so lots to learn and test !

We eventually managed to get everything we need in and still have some space to spare… It is starting to get a bit crowded in there though. In the next couple of weeks we should finalise the list of what’s worth taking and what can be left behind and hopefully we’ll also get an idea of the fuel consumption we can expect when fully loaded.

Fuel and Battery Status Display

Battery monitorThe dual battery system has been missing a couple of things since I first installed it and I’ve spent a few evenings this week playing with a PIC chip and an LCD display. The aim is to have some way of checking the charge level of both batteries and to control the automatic charging of the secondary battery when the main battery is at a reasonable voltage. It will always have the manual overrides of either permanently connecting the aux battery (to jump start the main) or having it disconnected if I want to put all the charge into the main.

As the PIC chip I’ve chosen has plenty of spare capacity I also added provision for it to display the fuel level in each fuel tank too, alternating every 10 seconds between the fuel levels and the battery levels/voltage.

I’m currently using a 16×2 character display but the finished version will be 2×8 characters, allowing it to take up less dashboard space. The programming is just about done apart from calibrating the fuel levels against the two sender units, just need to build the design into something a bit smaller now !

The chip I’m using has another 4 spare analogue inputs so I might add some additional warning monitoring into it yet. Maybe gearbox temperature, fuel pressure perhaps, turbo boost pressure, I’m fitting a dedicated monitoring system so I’ll see what that’s missing and maybe add them into this chip/display. It’s always better to know when something’s starting to go wrong rather than a complete failure being the first sign of trouble.

Fuel system completed ?

Switchover valve, pump and filterFinished the fuel system this weekend, well it might get a few more tweaks yet but it’s all working now at least. I may well end up changing the fuel pump for a higher throughput version and having a pre-filter for each tank rather than a single pre-filter at some point.

The picture on the left shows the under seat fuel tank and to the right of it the changeover valve (top right), filter and pump.

The pipe work was all fitted yesterday and today I made the mounting brackets for the valve and pump and wired it all up. I had to cut into the chassis loom to break the feed to the fuel gauge and wire it through the valve and the fuel pump wires needed extending as the fuel pump is now further forward than it was.

The extra fitting on the pickup plate is for the breather pipe and valve to be connected to as we’re not using a fuel cap with a breather.

To put some fuel into the auxiliary tank and do a basic leak test I decided to disconnect the return pipe from the changeover valve and connect it to the vent connector on the top of the tank. That way the pump would pump from the main (rear) tank, through the engine and into the auxiliary tank. What I hadn’t thought about was that pumping it in through the vent meant there was no where for the air to go… The tank and the filler pipework was all nicely pressurised and when I took the filler cap off it went with a loud pop πŸ™‚ Not sure what pressure it had got up to but the metal tank had expanded ! Fortunately no harm done and, on the plus side, I know now that the custom pipework I made up for the filler is all air tight.

The changeover valve works well, changing the fuel gauge and the fuel pump/return simultaneously, controlled by a switch on the dash. With the engine running you can switch from one tank to the other without the engine missing a beat. The sender on the auxiliary tank seems to match the fuel gauge too giving a reasonably accurate picture of the fuel level.

More fuel capacity

Under seat fuel tank and guard finally fitted

Under seat fuel tank and guard finally fitted

The next stage of adding more fuel capacity is well under way now. In total we should end up with approximately 145 litres, around 32 gallons.

Now the ECU and associated wiring is out from underneath the driver’s seat the next step was to remove the under seat box. That in itself was pretty straight forward as it’s only held in by pop rivets, albeit around 30 of them ! Once they were all drilled out the box itself was easy to remove. I’d not realised until I removed it that the box also fills part of the seat box aperture so I needed to make an aluminium filler plate to close the gap. Fortunately I had some 2mm plate in the garage that was ideal for the job and it’s all closed up now and relatively water tight with the removable cover clipped in place.

New filler cap... and my thumb... :)

New filler cap… and my thumb… πŸ™‚

The fuel pump was also mounted on the side of the ECU box so I had to make a bracket that attaches the fuel pump to the chassis. One immediate effect of that was that the fuel pump is a LOT quieter now it’s not bolted to a box that amplifies the sound.

Getting the fuel tank, the fuel tank guard and the sill bars all fitted at the same time took a lot of work. The tank guard mounting brackets are designed to connect to the same mounting points as the sill guards. This meant that the tank guard brackets all needed to be modified so they could all exist together without getting in each other’s way. the tank guard mounting bracket also seemed to be the wrong size to match up with the body so that had to be cut and welded.Β All in all just getting the tank guard fitted at the same time as the sill guard took the best part of two days work.

Under seat fuel filler pipe

Under seat fuel filler pipe

I then spent a day manufacturing the filler pipe that will allow the new tank to be filled using an aero style filler on the side of the back body. Hopefully I’ve got the angles and venting right so it’ll be easy to fill, nothing worse than a tank that has to be filled slowly or with the pump nozzle at strange angles to avoid the pump cutting out all the time.

The filler cap more or less had to be mounted where it is to get enough drop on the tank and be able to fit the pipework in, I’d have liked to get it aligned with the old LPG filler, in fact with hindsight I wish I’d mounted the LPG filler higher so I could have replaced it with the new one.

The pipe is made of 50mm stainless pipe and bends, cut and welded to fit. Hopefully the welds will be diesel tight, never easy to do with a MIG welder but I’m pretty confident I got it right… I’ll find out for sure when I fill the tank !

The next job is to re-plumb the fuel pump and pipework so it can work from either tank as well as having the ability, with a small amount of re-plumbing, to transfer fuel from one tank to the other.

Fuel capacity

Original fittings and cage mountA few months ago we looked at fitting a Safari Equip auxiliary fuel tank as it looked like a good solution to add extra fuel capacity without using up any storage space. It fits under the wheel arch, replacing the pipe between the filler cap and the fuel tank and adding an extra 30 litres of fuel capacity allegedly.

At the time we couldn’t see a way of making it fit though as the roll cage mount clashed with it so we ruled it out. Having talked to Brendan at 4×4 Overlander at some length he offered to “loan” me one so I could try and see if I could modify the roll cage mount to move it out of the way.

Modified cage mountIt took a couple of days to fit due to the changes required to the roll cage mount but, in the end it was possible. On the P&P cage the roll cage brace that goes to the chassis goes to the rear cross member next to the chassis. The aux fuel tank has a cutout in it that looks to be to accommodate a roll cage brace BUT it is for a brace that goes to the end of the cross member.

By spinning the bracing bar through 180 degrees and making a new bracket from the old one and some 6mm plate I managed to reverse the direction of the bracing bar, allowing the tank to fit around it. It’s a close fit and I had to grind the plate down as close to the tube as possible but the tank would just squeeze in.

Fuel tank installedLike many of these jobs it took a lot longer than expected but after two days of fitting, measuring, removing modifying and fitting again it finally went in and was plumbed in, ready for it’s first fill. We still need more fuel capacity but the current thinking is that I look at moving the electrics out from under the driver’s seat and fitting an old style underseat fuel tank which, with the standard tank and auxiliary tank will give us around 140 to 150 litres in total.

Found the missing power

Since fitting the TD5 the performance has been a bit flat at higher revs. While this has been good for fuel consumption figures it’s been a bit annoying. I rigged up a makeshift fuel pressure gauge today using an oil pressure gauge and sender.

Turns out we were only getting 20 psi at the rail, the TD5 is supposed to run at more like 65/70 psi at the rail. I replaced the pickup in the tank with a 300TDi version and it’s transformed the vehicle. A good constant 70 psi at the rail and it shows in the performance. Were it not for the diesel rattle you’d almost think the V8 was back.

Still need to sort the exhaust out though as it’s still running with the “temporary” one I hooked up using bits of the V8 system.