Engine won't rev and hunts

[ANDTWENTY]

Originally Posted by Laird Scooby

If you look at the size of the spare wheel/tyre, that's about 640 x 200 give or take and there's plenty of room round that so a 650 x 250 should easily fit with a bit of breathing space above between it and the boot floor. Less chance of compromising the gas tight seal on the tank lid that way.

If you've already got a stainless mounting plate for the filler on the towba not much need for this but i'll post it incase anyone else who happens to be reading wants to know :

https://tinleytech.co.uk/shop/lpg-pa...el-for-filler/



Pic shamelessly stolen from Tinleys website but as i've already linked to it i doubt they'll complain!

Handy having a workplace like that where you can find such things in the scrap bin! Really need to get on with mine, i've been doing a bit of wiring work on a loom for someone which in fairness has taken me a lot longer than it should have done but that's how life is for me these days.
Hopefully be able to get on with mine soon, looking forward to getting it gassed!

the full toroidal tanks don't have the gas tight seal because the multivalve is put outside the car so that isn't such an issue, in my Volvo no I have the floor raised about 50mm to get a bigger tank and the floor just sits on the tank which is bolted to the floor.

haha yea its not bad except being stainless it did chew up my hole saw after about 3 rotations!

Yea I know what you mean, always doing other peoples stuff and not enough time for your own! its fairly straight forward to do though and satisfying I found.

[Laird Scooby]

Originally Posted by ANDTWENTY

the full toroidal tanks don't have the gas tight seal because the multivalve is put outside the car so that isn't such an issue, in my Volvo no I have the floor raised about 50mm to get a bigger tank and the floor just sits on the tank which is bolted to the floor.

haha yea its not bad except being stainless it did chew up my hole saw after about 3 rotations!

Yea I know what you mean, always doing other peoples stuff and not enough time for your own! its fairly straight forward to do though and satisfying I found.

Ah, yeah, talking at cross-purposes! Not sure the full toroidal tank would be the best idea in a 7/9xx as the floor of the spare wheel well slopes down towards the front. There are drainage holes built into the floor but obviously with the multivalve at the back on the outside, it's not the lowest point. Two possible problems there, one is water ingress that could fill the wheel well up (if the drains are blocked) and also if there were any leaks from the multivalve, it could result in a pocket of gas in the bottom of the spare wheel well.

That pre-supposes the multivalve is at the back of the tank which is about the best place for it to be if you hoof it out of a junction.

The other solution is raise the front end of the tank so it's more or less level - still thinking on that one!

[ANDTWENTY]

Originally Posted by Laird Scooby

Ah, yeah, talking at cross-purposes! Not sure the full toroidal tank would be the best idea in a 7/9xx as the floor of the spare wheel well slopes down towards the front. There are drainage holes built into the floor but obviously with the multivalve at the back on the outside, it's not the lowest point. Two possible problems there, one is water ingress that could fill the wheel well up (if the drains are blocked) and also if there were any leaks from the multivalve, it could result in a pocket of gas in the bottom of the spare wheel well.

That pre-supposes the multivalve is at the back of the tank which is about the best place for it to be if you hoof it out of a junction.

The other solution is raise the front end of the tank so it's more or less level - still thinking on that one!

levelling the tank could be an issue then, in mine I used some thick plate washers to level it which worked well, I also put the valve out the side as this
gave me the most room with tow bar frame at the back, exhaust one side and the axle at the front. Surely though the donut style tank would have to be level too or is the pickup at the front?

I just grabbed a few pics of my tank.



Here is the multi valve that pokes through, I used a sealant/adhesive to seal around the hole in the floor and the neck of the tank to prevent any water ingress or gas coming back into the car, so far the wheel well seems to be bone dry but u can't see right under the tank as its tight int there, I also sealed up all the bolt holes and used some big thick square plate washers to secure it down.




having had a quick look under the 940 it looks as though I can get the valve out the side in the same place which would work even better as the wheel well is square up the side which might be better.

[Laird Scooby]

I use one of these mats under the tank :

https://www.diy.com/departments/dial.../262197_BQ.prd



They're about 10-12mm thick so my plan is to get a second one, cut it in half and fit half under the front end of the existing one. If that doesn't level it out completely, add the other half. I don't mind if the front is still a little lower as that gives a little bit in reserve for hills with the multivalve at the back of the tank.
Then as mine are the donut types, the pipework comes out in the middle of the tank underneath, 8mm straight back to the filler then 6mm along the underside of the floorpan to the reducer.

[ANDTWENTY]

Originally Posted by Laird Scooby

I use one of these mats under the tank :

https://www.diy.com/departments/dial.../262197_BQ.prd



They're about 10-12mm thick so my plan is to get a second one, cut it in half and fit half under the front end of the existing one. If that doesn't level it out completely, add the other half. I don't mind if the front is still a little lower as that gives a little bit in reserve for hills with the multivalve at the back of the tank.
Then as mine are the donut types, the pipework comes out in the middle of the tank underneath, 8mm straight back to the filler then 6mm along the underside of the floorpan to the reducer.

Thats a good idea with the mats underneath, I just had a piece of foam under mine but is bolted tightly so doesn't shift about at all.

[Laird Scooby]

Originally Posted by ANDTWENTY

Thats a good idea with the mats underneath, I just had a piece of foam under mine but is bolted tightly so doesn't shift about at all.

Foam can absorb water and cause rust, also rubber tends to be more non-slip than foam. Once bolted in tightly with the bolts that secure the donut tanks, the rubber mat also forms a secondary (untested) gas-tight seal which is useful. I have one of the closed-cell foam mats Tinley sell but it's so thin i doubt it does much good.

The other thing is the natural vibration of the bodyshell can cause contact points to wear between the tank and body.

[ANDTWENTY]

Originally Posted by Laird Scooby

Foam can absorb water and cause rust, also rubber tends to be more non-slip than foam. Once bolted in tightly with the bolts that secure the donut tanks, the rubber mat also forms a secondary (untested) gas-tight seal which is useful. I have one of the closed-cell foam mats Tinley sell but it's so thin i doubt it does much good.

The other thing is the natural vibration of the bodyshell can cause contact points to wear between the tank and body.

yea when I do it in the 940 ill use rubber but it was just what I had at the time and I wasn't too bothered about the car

Also got hold of a second hand MAF sensor through someone on this forum so hopefully be here beginning of next week, fingers crossed that sorts the problem and I can get it on the road for the 1st October

[Laird Scooby]

Remember that connector you couldn't find? Here it is :





Second pic is a close up of me holding the end of it.

First pic is the "geography" of where it is and you can see the end of it poking out from behind the cable coming from battery +ve up towards the ABS modulator. I suspect it was originally further back behind the ABS modulator where the coolant tank is and some clever idiot has tied it up out of the way as they didn't know (or care) what it was for.

[ANDTWENTY]

I have been having another look and I really can't find anything, unless its inside the loom tape. Do you also have the pink connector on the other side like I do? I also notice you have a relay or connector there, perhaps your wiring is different?

[Laird Scooby]

Originally Posted by ANDTWENTY

I have been having another look and I really can't find anything, unless its inside the loom tape. Do you also have the pink connector on the other side like I do? I also notice you have a relay or connector there, perhaps your wiring is different?

My wiring might be slightly different but i know of a 1990 744 with LH2.4 that had the connector in a similar place. Have a look under the coolant tank and all round that general area.

If all else fails, if you can physically block the AICV off, whether by clamping or by taping over the end of it or whatever to set the base idle speed, that's a work-around.