Hi all, just thought I'd share my experiences for you.
I got my Hiace ('93 2.4) in february and all has been fine apart from my veg oil experiment leading to a very leaky fuel pump. Searching the net for info and advice led me to believe that my only options were to replace the pump with a new one for £300 or to have the old pump overhauled at an unspecified amount ( I couldn't find anyone local who would even attempt it) Now I hate spending money if I don't have to so I got one of these http://www.roughtrax4x4.com/index.php?doc=16&vid=1242 and decided to change the seals myself.
There is a brilliant site with lots of useful info and pictures here http://www.toyotasurf.asn.au/techsite/index.htm
And so to the nitty gritty...
All the seals apart from one are easy to change, just remove the covers and replace, apart from the distribution block o-ring (the distribution block is where the 4 injector pipes attach to the pump) this must not be removed as the pump will need recalibrating. However there is another way. First remove the timer control valve (the bit on top of the distribution block) this needs to come off as it has an o-ring to replace, then undo the bolts on the distribution block but not all the way - I undid the first one all the way then screwed it back in a couple of turns and then undid the rest to the same point. The spring pressure inside will force the block out to the point that you can get to the old o-ring, which was so perished on mine that it came out in pieces! Then stretch the new o-ring (carefully) over the distribution block and then remove one bolt at a time to get the o-ring in place, replace the bolt and repeat for each bolt. Once the o-ring is correctly seated tighten bolts back up and refit the timer control valve with new o-ring. The only other issue is that the seal kit doesn't come with an o-ring for the very top part of the pump - there is an electrical connector on there which I re-sealed with silicone.
When refitting the pump it is a good idea to advance the pump timing slightly as you will gain performance and economy at the expense of a tad more noise.
I've done 3000 kilometres since and my Hiace is running perfectly! I've posted my findings on several Toyota forums and have been met with silence, no-one has suggested I shouldn't have done it so I can only imagine there are lots of people saying D'oh!
Cheers all
Brendon

Was the veg oil new clean stuff ? i have been using quite a bit for 2 years now with no problems on a 2.8 which im sure will have the same pump on

It was clean veg oil, I think it was only a matter of time before my pump started leaking whatever fuel it was running and it was not helped by the unusually cold weather at the time. I know of a few people with leaky pumps who have never used anything but diesel so it is probably a problem most of us will face at some point. The fact that most of the old o-rings came out in pieces is a sure sign I was going to have problems anyway. Apparently later pumps are less likely to fail as the industry has been gradually adapting to the changing fuel requirements. Interestingly most of the major seals in the kit I got were green in colour whereas the old ones were black which suggests to me they are biofuel compatible unlike the older ones. This is something all diesel owners should be aware of as our government in its infinite wisdom has decreed that biofuel should make up 5% of the total sold in this country. Petrol cars cannot cope so it's all being mixed into diesel, I wouldn't mind betting that lots more older diesel powered vehicles are going to run into similar problems over time.

Good on ya for giving it a go!!!
The only thing that sounds a bit worring is blindly advancing the timing! Unles you used the proper gauge to measure the timing you really dont know how far you advanced it. The problem with this is the possability of excessive combustion and exhaust temps etc which will greatly shorten your engine life. But again good on ya for giving it a go, and hopefully you guessed the timing right enough! How have you found the power/ fuel economy since you did the work?
Cheers Dill.

Fuel economy and power are fine Timing was only altered by 1mm off the timing marks on the side of the engine which my clever friend worked out to be less than a degree so not really a significant change. Cheers for the feedback.

So... to advance the timing did you set the mark on the pump body 1mm lower or higher than the mark on the timing case?

You turn the pump body towards the block to advance, towards the nearside wheel to retard.

SO in this case, the pump body timing mark will be higher than the timing case mark?

I will have to check as I was moving the pump as my friend was spotting the marks...

Were the new seals green coloured compared to black of the originals? Veg oil is known to eventually damage black ones but greens are designed to be used with biofuel