Isuzu Trooper Owners Club UK™

Matt Quinn

Vehicle is a 3.1 Bighorn... Jap Import...

As per my previous thread I've now taken delivery of my £100 fuel tank via Europarts... And also taken note of the 'fuel tank replacement guide" noted herein...

https://sites.google.com/site/trooperdieseltankremoval/

What Europarts have sent appears to be pretty much correct; one or two niggles though...

1) The new tank, whilst it DOES have the long 'cross pipe' that normally connects to what are called in the guide 'balance valves', has NO HOLES to fit the said 'balance valves'!

2) My old tank has some sort of electrical device connected between the pipe that goes from this 'cross pipe' and the one that leads to the front of the car.

Now... I can glean little or nothing about the purpose of this 'cross pipe', the 'balance valves', the electrical doofa or really why there is a third 'fuel' pipe running apparently back to the air filter??? I note page 1684 of the 'malual'[sic] shows that vehicles destined for Argentina were fitted with these cross pipes but that 'general export' vehicles weren't... Referring to an "evapo fuel hose" where it exits???

I also see that page 1668 has a diagram that seems to indicate the electrical doofa is a "Control valve" and that these cross pipes connect through it via a "breather pipe" to the 'air cleaner' - And that the black things are a "Roll over & float valve" or two... NO idea what those are or why I'd want them....

I am currently considering just connecting up the fuel send and return pipes... Ignoring or even ripping out the 'breather' to the air filter and as for the electrical doofa?????

Any thorts ladies and gentlemen of the forum???? - And everyone else too of course! Wink

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Grandad · ******* Joined: 22 Sep 2005 Posts: 1902 Location: NORFOLK

Have you looked closely at your original tank as the breather pipe next to the fill pipe can be in front or behind the fill pipe if it is not right then it is awkward to fit
I fitted that tank you have in the pic to a vehicle that had the breather in front to get it to fit I bent that pipe so it came out in front as the tank would not go up into the body work
the roll over valves were left out as well
when the tank was filled with diesel and running with the fuel cap tight the tank pressurised and it is possible could have imploded the vehicle now runs with the fuel cap loose
in retrospect the tank should not have been fitted as those rollover valves and the breather that goes to the air filter need to be fitted for the system to work properly. But at the time the customer insisted that it was and he did not have time to find the right tank

Grandad · ******* Joined: 22 Sep 2005 Posts: 1902 Location: NORFOLK

the roll over valve is to stop diesel or petrol running down to the air filter in case of a rollover causing a fire hazard

Matt Quinn · Posted: Sat Apr 25, 2015 19:52 Post subject:

Thanks Grandad,

Not got the old tank out yet as I wasn't expecting the new one to arrive 'till next week BUT... I do have it disconnected. I've cut a pretty large hole in the floor - with the intention of going to some trouble in making up the 'replacement' inspection plate.

Yes the main vent IS in the wrong place, but I'd be pretty confident of being able to re-route it. - I'd just shorten it and extend the rubber hose from the filler vent. Not sure I understand why the tank would pressurise... That main vent is a plain pipe coming in about 1/2 inch above the top of the tank surface - And as far as I can work out the vent opening just under the filler is just a hole is it not? - Certainly I can blow and suck right through mind; there's no kind of valve or anything in there.

The function of the vent to the airfilter really isn't clear to me at all... And as it's apparently missing on some vehicles I'm wondering how 'necessary' it is?

One idea that occurs if this 'does' really have to be retained - as I probably do need to extend the rubber vent hose from the filler - is to make up a 'T piece' using copper plumbing fittings with a reducer to make one side of the 'T' 8mm to fit the 'air cleaner vent' - this of course retaining its strange little electric valve thingy...

One other point... There seems to be no internal strainer on the new tank. As I've 'fitted' and inspection port I'm thinking it might be wise to place a simple inline filter at the tank end. That shouldnt cause any adverse effects should it?

Grandad · ******* Joined: 22 Sep 2005 Posts: 1902 Location: NORFOLK

the vent to the air filter is the main pressure relief vent for the tank the one to the filler tube is to let air out of the tank when filling other wise you would have a blowback at some stage of the refuelling process, the tank cap is non vented your suggestion of T ing in is a good one and would over come the problem (wish I had thought of that years ago)
The tee should be at the top of the filler vent pipe and you should try to incorporate the pressure relief valve if possible in the line to the filter
the article on removing the tank is a very good find describes the grief quite well

Grandad · ******* Joined: 22 Sep 2005 Posts: 1902 Location: NORFOLK

you say the vent to the air filter is missing on some vehicles not so it is on all diesels on the ones where it doesn't come from the tank it comes from the filler pipe above the filler vent pipe and also has a pressure control valve in the line

Matt Quinn · Posted: Sun Apr 26, 2015 1:03 Post subject:

I'm only going by what I see in the manual Grandad... Where it also says the filler cap is supposed to incorporate pressure release mechanisms - both positive and negative. Can't help thinking a 4mm drill bit though that guy's filler cap might solve his problem.

What I meant was that the vent to the air filter is missing on some vehicles - the diagram does indeed seem to indicate a relief hose in the fuel pipe area venting to atmosphere.

I think the answer must be to just 'T' into the main vent and hook up to the original valve/vent system - Whether there is space to fit the T high up is something I'll need to look at... Why high up though? - Given that the originals were down lower.

Either way - Pretty certain I can solve this one with a couple of Yorkshire fittings...

Aragorn · *** Joined: 23 Aug 2014 Posts: 203 Location: Fife

The cap is supposed to be sealed.

If you drill a hole in it, its going to piss fuel everywhere when the tank is full.

Cant you just get a suitably sized holesaw and cut the holes in the tank for the breather fittings?

Matt Quinn · Posted: Sun Apr 26, 2015 12:14 Post subject:

I'm not going to be drilling a hole in mine... I'm suggesting that the bloke who's been left running about with his loose might benefit from that trick. Believe it or not, some older cars have small holes in the filler cap for that very reason. And, actually, if you read the manual you'll find the cap is supposed to have pressure relief valves built into it

And no... I see no logical reason to be taking a dirty great hole saw to my new tank; it probably wouldn't help anyway as these 'valves' are normally held in place with tabs on a 'locking ring' arrangement that would still be absent.

Clearly - according to the manual - SOME Troopers/Bighorns had the simpler arrangement whereby the tank was vented via the main filler vent pipe. My aim at this stage is to 'reproduce' that scenario.

Matt Quinn · Posted: Sun Apr 26, 2015 13:21 Post subject:

Just for Clarity... According to the manual...

Some Troopers are like this...

Some - including (apparently) JDMs and European models are like this...

Rather than serving any practical/operational function I believe this arrangement has to do with 'handling' the emission of fuel vapour for regulatory reasons. -If anyone can correct me and tell me how it affects the running of the car (and is actually necessary) I'd be grateful.

Having obtained the tank shown above - and with every intention of fitting it - This is where I intend 'going with it'...

Can anyone see any pitfalls with this approach?

Additionally...

i) I've just popped out and checked - even with the fuel cap firmly on, air can pass freely in both directions along the main breather hose... Yet to get the filler spout out to examine its construction; but it does seem to be vented to the atmosphere.

ii) Managed to pull the little 'valve' thing up to get a good look at it... Seems the 'wiring' is for something else and merely passes through the same bracket... Some sort of three-port valve with one 'leg' open to the atmosphere on about 2" of pipe...

iii) The filler cap DOES have a valve in it that yields under slight vacuum - i.e. SHOULD prevent implosion...

Now wondering how many variations on the system there are, and if your customer Grandad has the correct filler cap for his vehicle. According to some sections of the manual there are variations.

Grandad · ******* Joined: 22 Sep 2005 Posts: 1902 Location: NORFOLK

As I have said previously Isuzu have built many variations of the trooper/bighorn so many that although working on them from 87 to the introduction of the 3.0ltr i have never seen 2 vehicles exactly the same depends which manual you have as to which pics of the fuel system are in it the original paper manual for the 3.1ltr trooper uk version only has one version in it and that is the one marked for argentina (notice the small a)in a 2002 cd version it gives the argentina version as for europe as well. it also shows the other versions all that aside at the end of the day it is what works that counts and your solution will work
Matt the cap in question was the correct one as fitted from new and at the time it was easiest to just loosen the cap and since then he has covered many miles and it has gone through quite a few mots and he seems very happy that he isn't pouring fuel on the ground every time he fills up

Matt Quinn · Posted: Sun Apr 26, 2015 15:49 Post subject:

Once again I'm very grateful for your input Grandad,

What I have is a 'short' manual downloaded some six or so years ago when I got the beast; and the drawings are from that. I see actually that the equivalent pages for one of the other engines lists the 'Argentinian' version for Europe too...

I'm going to hold fire 'till tomorrow and I get the filler hose down - see how it's arranged - and decide then if I really feel the need to plumb-in the air-cleaner vent. As I say; I can suck and blow quite easily through the vent hose even with the cap firmly closed; so whatever arrangement mine has at the filler end must be different to that of your client.

I note also that this issue of the position of the vent hose has caused folk problems in the past... Is the answer (in some cases at least) as simple as re-routing or replacing a rubber hose? - If, as was your experience, the tank won't sit up into the body - with this bloody great hole I have in the floor I should at least be able to work out why; and where/how the pipework needs to cut and/or extended.

Might help the next poor *beep* who has to go through all this palave! Very Happy

Especially if it saves then £70 or so on the price of a Milner's tank.

gt-nick · Posted: Sun Apr 26, 2015 16:15 Post subject:

just to add my findings, I had the same origional tank you are describing (with roll over valves and associated pipeing) on my mk1 lwb 2.8

but the new replacement came without these fitted ( no holes, no pipeing) and the breather pipe was in the wrong place. It contacts the chassis as you lift the tank to bolt it up.

my solution was to take the tank to a garage have them move the breather pipe to the right place, and after pressure testing it I simply fitted it omitting all now redundant

pipe work. As I don't intend to roll my truck over now or in the future don't see the need for the valves, it has been in use now for over two years as my daily drive and I have

had no problems.

just thought I'd share Smile

Matt Quinn · Posted: Sun Apr 26, 2015 16:27 Post subject:

Thanks Nick...

I guess the sticking point is going to be whatever's fitted at the filler end... Clearly Grandad's client's car has a filler vent that becomes 'sealed' once the cap's on. - My own (thus far) seems to be open to the atmosphere. As indeed would appear to be the case with your car...

Like the man says... No two alike!

Not measured it or offered it up yet - But I can see a piece of floor-rail that might well contact; or at least make things VERY tight if you were offering it up with a pipe attached. The solution to this could be as simple as trimming 2" off the vent pipe and fitting a slightly longer rubber hose.

Looks like I have an appointment with the angle-grinder tomorrow! Laughing

Matt Quinn · Posted: Mon Apr 27, 2015 19:37 Post subject:

Well rain (or more precisely hail!) stopped play today. But the old tank is out, and I decided to take heed of Grandad's experience and fit a 'T' piece...

Photos below in the hope they'll be of use to someone in the future.

The 'T' piece is an ordinary (plumbing) solder-ring 'equal T' with short lengths of ordinary 15mm pipe in the straight legs and a 15mm-10mm adapter in the other 'port'. The whole thing 'extends' the rubber vent hose by about 4" - 5" allowing it to be routed to the 'back' of the main filler inlet as suits the new tank... And the sections of 15mm pipe also allow the 'T' to slip neatly into the existing vent hose...

The 'thin' hose connects to what I now understand to be the 'pressure control valve' - Note the 'splice' in the middle is achieved with a short (1") length of 8mm copper inside the thinner pipe - This allows the jubilee clip to be tightened down without the joint simply collapsing under its pressure. This allows whole arrangement to 'terminate' in a pipe suitably-sized for the PCV... You could equally well use a continuous length of thin pipe - I just happened not to have one laying around.