Isuzu Trooper Owners Club UK™

Twister

I think I may have just had a Eureka moment with regards to the smoky start-up issue I'm still having on the first start up of the day, but I'm not sure if my logic is right....so I thought I'd throw it out there.

I've checked the whole of the supply and return fuel lines several times, including on the top of the tank, which was refurbed a couple of years ago, and I can't find anything. I've tested the fuel filter housing and it's fine, as is the pipe from the filter to the pump. I've even been down the route of changing temp sensors thinking it may have been an issue on the electrical side of things.

I've long since come to the conclusion that it's down to either oil or fuel starvation, but according to Ted's Tech 2 the oil pressure is fine, and the ORPCV is working exactly as it should, which I reckon leaves only fuel starvation.

This has got to be either due to air getting in the system overnight somehow, or fuel syphoning back down the supply line.

Would I be right in thinking that the whole fuel system (Tank, pipes etc.) would normally be under a positive pressure ?, and the whole point of the Tank relief valve is to open when a certain pressure is reached, venting into the air intake pipe under the bonnet.

My line of thinking is that if this relief valve was faulty (i.e stuck open) then the fuel system, especially the vapour above the fuel in the tank, would never reach a positive pressure, and could even end up under negative pressure due to the Bernoulli Principle at the junction of the pressure release hose and the intake air duct.

Question is, could this lack of positive pressure cause a fuel starvation issue after being left overnight ?

Or am I over thinking this and way off the mark ? Rolling Eyes

_________________

"Tongue-tied and Twisted; just an Earth-bound misfit, I..." - PF

LTM # 000002

Google · Sponsor

eithan h · Posted: Sun Mar 23, 2014 22:50 Post subject:

no positive pressure in the tank where would it come from?

does it crank for a bit before it starts?

Gribble · Posted: Mon Mar 24, 2014 0:09 Post subject:

Leaking on the turbo compressor side seal a tiny bit when stopped ,burns that off at start up then alls well for the day .

You could also say its not a new engine so its not going to be 100% ?
_________________
2 New Troopers !

Twister · Posted: Mon Mar 24, 2014 11:48 Post subject:

I'm pretty sure it's not a turbo issue Mr G, as I've tried running her with the intercooler to throttle body pipe off of an evening, leaving it off overnight, and starting her in the morning with it off. Same results. That and the fact I'm pretty much 100% sure that the smoke is white diesel smoke, and not blue oil smoke.

This is a similar issue that Pete88 had with his, and as far as I know he has never got to the bottom of it

Sods law says I've just tried to video it this morning, and apart from my camera battery dying, it didn't actually do it. She just smoked slightly on firing up, then ran fine. It seems to be quite random, and considering we had a frost this morning I was expecting her to be quite bad.

Normally when she's been left for a couple of days or more she'll take 5 to 6 seconds on the key before she fires, which I reckon is reasonable. She fires up with a small amount of white smoke, then she'll run fine for 10-15 seconds, then she'll start hunting, diesel knock to the point of almost stalling, and clouds of white smoke for 7 to 8 seconds (to the point I'm surprised the neighbours haven't complained yet), then she clears and runs fine for the rest of the day. It's as if there's an air bubble getting into the fuel rail (or possibly the oil rail ???)

TBH, I'm clutching at straws here. This has been going on for 2 years or so, some mornings worse than others. Bearing in mind that she's not used every day, and can sometimes go a couple of weeks without being started. In those 2 years she's had 2 oil / filter changes, 2 fuel filters, 2 air filters, a replacement throttle body, a replacement ORPCV, a full set of glow plugs and a new coolant temp sensor, and the NRV in the return line has been removed and replaced with an anti-syphon loop. I've also done the glove test on the fuel filter housing, and have even tried bypassing the fuel filter housing. I've checked the afterglow on the glow plugs, and it is exactly as the book says it should be. I've also tried the white wire trick to no avail. She's also been on Tech2 which showed nothing out of the ordinary, and the injectors were click tested.

As I said, I'm clutching at straws, as I've reached the point where I've run out of ideas.

I could just leave it as it is, as it doesn't seem to be getting any worse, but I don't like knowing that there is something amiss. That and the fact I'm aware that one day the neighbours are going to mention it.

As a last ditch attempt I'm going to try putting an anti-syphon loop on the feed line just before the fuel filter today, but I can't see it making any difference.
_________________

"Tongue-tied and Twisted; just an Earth-bound misfit, I..." - PF

LTM # 000002

eithan h · Posted: Mon Mar 24, 2014 13:34 Post subject:

Apply a slight vacuum to the fuel system through the head and see if it drops away over night

Twister · Posted: Mon Mar 24, 2014 16:05 Post subject:

I presume you mean through the outlet (return) pipe at the back of the head ?
_________________

"Tongue-tied and Twisted; just an Earth-bound misfit, I..." - PF

LTM # 000002

Twister · Posted: Mon Mar 24, 2014 18:11 Post subject:

Right, vacuum applied. See what tomorrow morning brings.

If the vacuum is gone in the morning, then presumably if I do the same at the top of the feed pipe at the fuel filter housing, that will narrow it down to either forward or aft of that point, although if it is aft then it has to be the union on the top of the tank, as it's a 1 piece rubber hose from there to the fuel filter.

Cheers for that Mark Cool

, something I wouldn't have thought of Cool

.
_________________

"Tongue-tied and Twisted; just an Earth-bound misfit, I..." - PF

LTM # 000002

eithan h · Posted: Mon Mar 24, 2014 19:10 Post subject:

lol don't thank me yet you aint found the fault!

Twister · Posted: Tue Mar 25, 2014 11:26 Post subject:

Well, vacuum was still there after an hour last night, reset it again, and this morning it's gone, so wherever the leak is, it's tiny.
It's going to take a few days now to pinpoint it exactly.
_________________

"Tongue-tied and Twisted; just an Earth-bound misfit, I..." - PF

LTM # 000002

eithan h · Posted: Tue Mar 25, 2014 12:39 Post subject:

So what section did you test?

Twister · Posted: Tue Mar 25, 2014 12:49 Post subject:

The whole lot for now. I've just reset it to test from the back of the head to the rubber fuel filter "out" pipe. If it holds there then it's either the filter housing or the top of the tank, but I have bypassed the housing with no joy in the past, so it'll probably end up being the tank end.
_________________

"Tongue-tied and Twisted; just an Earth-bound misfit, I..." - PF

LTM # 000002

Twister · Posted: Wed Mar 26, 2014 10:44 Post subject:

Well, she's held that vacuum overnight.

Now to test the same again with the filter housing in the line, and a separate test on the tank to filter line.
_________________

"Tongue-tied and Twisted; just an Earth-bound misfit, I..." - PF

LTM # 000002

eithan h · Posted: Wed Mar 26, 2014 10:56 Post subject:

lol at least that shows the injectors and seals are good, the end is almost in sight keep going!

Twister · Posted: Wed Mar 26, 2014 17:54 Post subject:

Latest results.....

I put a clear filter at the top of the tank to filter line, pulled fuel through to half way up the filter, marked the level on the filter, clamped the open end and left it for 7 hours. It hasn't gone down at all, so at least I don't have to drop the tank again.

I've put a vacuum right through from the back of the head, through the filter housing and onto a gash piece of fuel line, and that has held too.
By my reckoning that means that if air is getting in anywhere on the feed side it has to be at the joint where the line from the tank meets the filter housing, so the next test is going to be through the head and the filter housing with the tank feed line attached but clamped off.

However, and I'm not sure how relevant this is to this particular problem......

On taking the filter off the housing, I can't get the reed valve to seal properly for love nor money. I did have this issue a while back, but I managed to get it to seal repeatedly after cleaning it up last time. It's only leaking very slightly, but enough to be able to suck a tiny amount of air through it, so I'm going to have to replace it.
_________________

"Tongue-tied and Twisted; just an Earth-bound misfit, I..." - PF

LTM # 000002

Twister · Posted: Thu Mar 27, 2014 11:20 Post subject:

Well, she's held that vacuum overnight too, so that means there's no leak anywhere in the feed line now.

Only change I've made is to put 2 new pipe clips on the filter housing. Started her up and took her for a short spin just to make sure she's bled properly.

Have to wait and see what happens when I start her up this evening now. Fingers crossed.
_________________

"Tongue-tied and Twisted; just an Earth-bound misfit, I..." - PF

LTM # 000002