LPG Forum


All times are UTC



Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next
Author Message
PostPosted: Wed Aug 21, 2013 7:42 am 
New member

Joined: Sat Oct 20, 2012 4:54 pm
Posts: 37
Do Normally Open 12V Petrol Shut-off Solenoid Valves Exist
I'm trying to keep my installation simple and want to cut my petrol when gas is on.

All the 12V solenoid valve I have found operate such that they are Normally Closed. I want mine to be normally Open. Thus no power supplied and it is open. Yes I know I can put a relay in to reverse thsi but that is messy.
Why do I want to do this? I've got some leaky petrol injectors that are pricey to replace but work well enough on the odd occassion I'm using petrol so are not worth repalcing, but they mean at present I burn some petrol when running CNG.
I'm found a simple to get at trigger via the existing gas solenoid valve that opens for gas, so I want to use this same trigger to shut my petrol down. When it triggers I want it to shut off my petrol.

Yes I know, if I substitute my gas solenoid valve for an additional relay and then open the gas valve with the new relaaly and close the petrol solenoid via a changeover on the same realy this is very simple, but I want to try to avoid another relay. The gas valve already has a relay, (unfortuantley not a changeover contact spare or room to substite it with another relay with one). It'll look messy and require fusng etc etc, and by the time I'm done be another £15-20.00 and actually be a worse job for it.

Do Normally Open 12V Petrol Shut-off Solenoid Valves Exist?

I can't seem to find a normally open solenoid valve.


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 9:06 am 
Installer

Joined: Wed May 23, 2007 5:51 pm
Posts: 8096
Images: 0
Location: Wiltshire
Yes they do, but you'll probably have to look outside the LPG trade. Easiest is perhaps to adapt a changeover valve by blanking one port. Old vehicle spares - original XJ6, some series Land Rovers. Bio-wotsit trade -
http://www.biotuning.co.uk/PartsValves.htm

Beware that many gas injection systems operate the gas solenoids without expecting petrol to cut off e.g. to pre-pressurise the system or achieve sequential per-cylinder chageover.

Beware that petrol injectors robbed of circulation nearby may be more prone to gumming up with heat etc.

Turning off the petrol pump may be easier.

_________________
www.blazegas.com


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 10:26 am 
New member

Joined: Sat Oct 20, 2012 4:54 pm
Posts: 37
Thanks for that Rossko, of course - Jags run twin tanks or did. It had occurred to me to drop the pump instead but getting to the feed is more hassle. And i'll still run petrol in the 1-2 minute warm up before the thing flicks to gas, (I run a factory fit Bifuel Volvo) so it should flush through.

Somone else said there might be dry injector issues. My factory Bifuel Volvo alwasy starts on petrol. My theory (if I dare call it that) is that the rail has only static petrol normally under pump pressure, it is not being pumped across the injectors, and with no pressure it'll still sit there disipating heat just the same. Every time I resttart it'lll repressureise run a bit of petrol flick to gas when at temperature, then until the leaking injector drops it down sit there, and no more fuel is wasted, we ahve pretty much the same status. Just no fuel pressure in the injector rail, thus nothign to feed the leak.

Does that make any sense or is a little knowledge here a dangerous thing?

Only issue I see it when swapping back to petrol or when my gas tank runs empty until the pre-pressure gets up to level, the transition will not be so smooth, which I think is what you're saying.

In which case I get it . Woe is me, sniff - I'll just have to live with the misery.


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 1:39 pm 
Intermediate Member

Joined: Mon Jun 21, 2010 9:19 am
Posts: 928
Images: 0
Location: North Wales
All the petrol systems I know of recirculate petrol from the fuel rail back to the tank, otherwise the fuel would be moving through too slowly to stay cool.

_________________
Another member of the YCHJCYA2PDTHFH club


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 2:04 pm 
Installer

Joined: Wed May 23, 2007 5:51 pm
Posts: 8096
Images: 0
Location: Wiltshire
I was thinking more of interruption to petrol supply whilst running petrol, when the gas system pre-operates its solenoids to establish pressure.

I would expect a petrol rail with its inlet locked off to vaporise the fuel somewhere, and push the rest of the liquid back into the tank via the return line. That's not terminal of itself, but probably bad for injectors ... especially as some may be already gummed up.

_________________
www.blazegas.com


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 4:13 pm 
Advanced Member

Joined: Wed Apr 09, 2008 9:00 am
Posts: 7882
Images: 0
Location: Peterborough
How about using a normally closed petrol shut off solenoid in parallel with the fuel pressure regulator? That way the petrol will continue to flow but will be at very low pressure as it will bypass the regulator when on gas so shouldn't have enough pressure to dribble through your poorly injector. As soon as you go back to petrol, the valve will close and petrol pressure should come up quickly enough for it to not die on you.

_________________
'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 6:48 pm 
New member

Joined: Sat Oct 20, 2012 4:54 pm
Posts: 37
It sounds like you're all talking aboiut more sophisticated systems than mine.

I've looked at my fuel rail, there si definitley only one line in, I'll not count the schrader to bleed off. It has a diapham which I assume acts as teh regulator, and thats your lot.
Quote:
I was thinking more of interruption to petrol supply whilst running petrol, when the gas system pre-operates its solenoids to establish pressure.

That may be the real issue, , I'll end up having to put a delay circuiit in, messy. I'll take chance on it, but at thsi rate I'm at £60.00 and my time.Before I knwo wherre I am I'll have spent more tiem and money on thsi kit thatn I would have done on teh petrol I don't burn.

Stand back, I might have caught The Stupid here. It's catching.

Perahps I need delay relay?


Last edited by CNG on Wed Aug 21, 2013 7:16 pm, edited 1 time in total.

Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 7:00 pm 
Advanced Member

Joined: Wed Apr 09, 2008 9:00 am
Posts: 7882
Images: 0
Location: Peterborough
CNG wrote:
It sounds like you're all talking aboiut more sophisticated systems than mine.

I've looked at my fuel rail, there si definitley only one line in, I'll not count the schrader to bleed off. It has a diapham which I assume acts as teh regulator, and thats your lot.
There may well be but you will have a pressure regulator that bleeds off excess pressure back to the tank before it gets to the fuel rail. Even the old L Jetronic as fitted to the Citroen DS in the 1970's had one, that was how you adjusted the mixture, by varying the fuel pressure. In fact, I don't know of any petrol injection system that doesn't incorporate a pressure regulator.

_________________
'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 7:20 pm 
New member

Joined: Sat Oct 20, 2012 4:54 pm
Posts: 37
I must be dim, how does that work? As I see it, one line in, I'm assuimg a chamber in the rail split by the diaphagm... but without a return line back to teh tank, nope I can't picture it. The pump just chunders away doesn't it?


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 7:31 pm 
Advanced Member

Joined: Wed Apr 09, 2008 9:00 am
Posts: 7882
Images: 0
Location: Peterborough
Fuel fed from the pump goes to a chamber with a spring loaded diaphragm with an adjuster screw to adjust the pressure, one pipe comes off it and feeds constant pressure to the injectors while the other pipe returns excess pressure to the tank. What breed of Volvo are we talking about as a Google search for Volvo fuel pressure regulator brings up numerous different sorts although most have a fuel return.

_________________
'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 8:03 pm 
New member

Joined: Sat Oct 20, 2012 4:54 pm
Posts: 37
I've since Google many a "How it works" video and they expalin it as you do. Makes sense to me, pretty much as I thought, but look...

This is my Rail. No vacuum bleed to the diaphagm, With a schrader at one end. 1 x line in the other, 5 x injector

Part VOLVO C70 V60 V70 2.4 2.9 TURBO FUEL INJECTOR RAIL Part 1270568
[url]
http://www.ebay.co.uk/itm/121161839318? ... 1555.l2649[/url]

1 x line in. Nothing out? What gives, reason i ask is my plan rather falls to bits. Agreed there must be circulation somehow, but how?
[url]
http://www.ebay.co.uk/sch/i.html?_trksi ... &_from=R40[/url]


Last edited by CNG on Wed Aug 21, 2013 8:20 pm, edited 1 time in total.

Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 8:19 pm 
Installer

Joined: Wed May 23, 2007 5:51 pm
Posts: 8096
Images: 0
Location: Wiltshire
You have a single-ended fuel system. The mechanical regulator is incorporated with the pump at the tank. (later systems still have a pressure sensor on the rail and control pump drive effort electronically)

The "regulator" on the rail itself is just a fluctuation damper.

If you fit a lockoff to such a rail, the pressure will be trapped (unless it leaks out). Warning; you should make sure the shutoff used will bleed backwards under excess pressure, or you could make a hydrostatic lock and burst something as things warm and pressurise further. The damper might take care of that - or it could be the first casualty.

You really sure you don't want to find the fuel pump relay instead? Or buy a set of used injectors?

_________________
www.blazegas.com


Last edited by rossko on Wed Aug 21, 2013 8:24 pm, edited 1 time in total.

Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 8:22 pm 
New member

Joined: Sat Oct 20, 2012 4:54 pm
Posts: 37
Thank you Rossko, I was scratching my head there. And THANKYOU for the warning, that would neve have occurred to me! Not in a million.

You're right, this has got Stupid enough, like it or not, I will have to find that pump relay. I can't get to the pump, stuck under a CNG tank and I'm NOT touching that thing!


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 8:33 pm 
New member

Joined: Sat Oct 20, 2012 4:54 pm
Posts: 37
Yes a used rail might be OK, but the issue I have likely would not show if I was burning petrol, but even slightly leaky injectors are fine when burning hte stuff. I assuem the metering compenastes. Only when you're not buring petrol I see the fuel wasted.

It can't be doign my engien much good eitehr

Thank you for all your help in correcting what when considered was frankly daft.


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 10:06 pm 
Advanced Member

Joined: Wed Apr 09, 2008 9:00 am
Posts: 7882
Images: 0
Location: Peterborough
It won't do the engine any harm and the lambda control will reduce the amount of gas that goes in to keep the mixture correct, even if it is an air/gas/petrol mixture. It'll all burn just the same and is no different to some LPG systems that can be set to add a little petrol at times of high demand. As you say, you just aren't saving as much money as you could be as you are still using a small amount of petrol when running on gas.

_________________
'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.


Top
 Profile  
Reply with quote  
PostPosted: Wed Aug 21, 2013 10:50 pm 
Installer

Joined: Fri Oct 21, 2005 7:56 pm
Posts: 2581
Location: North Wales
But not all the injectors will be leaking the same amount causing some cylinders to be rich and other lean.

Cutting the fuel pump is the best bet

_________________
http://www.classicswede.com/
http://www.classicswede.co.uk/LPG/cat17 ... 10800.aspx

LPG installer Anglesey North Wales

DIY LPG Kits

07824887160


Top
 Profile  
Reply with quote  
PostPosted: Thu Aug 22, 2013 3:41 pm 
New member

Joined: Sat Oct 20, 2012 4:54 pm
Posts: 37
Gilbert, Dai, thanks for that, (Dai) I'll put my findings on that 'other' site when I'm done. Yes as I see it I've one or perhaps two injector persisting petrol in their bores, the Lambda will correct for it, but globally so that won't help, some will be lean whilst others are dripping petrol.

A used rail will likley have similar issues, so if I cut the pump suppply with a delay relay, it'll fly. I've since found the pump relay (lableelled 103 in my fuse box) and when running on gas I pulled it, and then pressed the schrader to bledd off the frail uel-pressure. It worked,. I've also foudn the gas-shut of relay, so will use the output on it to fire the delay relay, to in turn drop the pump. Now to wire it up.

Did I mention I run CNG? I run CNG I do. Did you know I run CNG?

I run CNG.

Ask me what fuel I use?


Top
 Profile  
Reply with quote  
PostPosted: Thu Aug 22, 2013 4:45 pm 
Installer

Joined: Wed May 23, 2007 5:51 pm
Posts: 8096
Images: 0
Location: Wiltshire
CNG wrote:
A used rail will likley have similar issues

Why so? Yours is probably a consequence of the gas conversion, gummy due to heatsoak due to blind-end fuel delivery. Make sure you source a used part from an unconverted car, they usually do see out the car after all.

_________________
www.blazegas.com


Top
 Profile  
Reply with quote  
PostPosted: Thu Aug 22, 2013 5:01 pm 
Installer

Joined: Fri Oct 21, 2005 7:56 pm
Posts: 2581
Location: North Wales
Gummy injectors are more common than you would think even on Petrol only cars. Modern petrol just aint the same as the good old stuff.

Forte injector clearer is good stuff and well worth a try if you have issues with poor spray from your petrol injectors.

_________________
http://www.classicswede.com/
http://www.classicswede.co.uk/LPG/cat17 ... 10800.aspx

LPG installer Anglesey North Wales

DIY LPG Kits

07824887160


Top
 Profile  
Reply with quote  
PostPosted: Mon Aug 26, 2013 11:50 pm 
New member

Joined: Sat Oct 20, 2012 4:54 pm
Posts: 37
Mine's a factory fit gas car. Rossko, you're likley right anotehr rail might be fine, and I have to agree with Dai, re the injector cleaner. I am always sceptical of mechanic-in-bottle snakeoil products but I put in some Lucas Cleaner(USA Lucas not Prince of Darkness Lucas) and it definitely reduced the problem a lot and made it run smoother, which if i used petrol I'd be very pleased to see.

If you bought all those B*llSh** products and added up the claimed improvements, it would be possible to drive a million miles taking more fuel out than you put in. So whilst LUcas did work, as I might have mentioned 98% of the tiem, I run CNG, and now I've looked at it, stuffing a relay in there is going to be very easy, and a gauranteeed perm. solution. What took tiem was researching the where and how of the wiring. I've an electronics background so wiring 'per se' was not the issue, but reading half-baked Volvo diags that don't include anyhting on my factory Bifuel variant was!

It turns out both relays, petrol-pump (marked 103) and gas shut-off are in the same fsue box, so it's a £10.00 fix and 30-40 mins of my time.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next

All times are UTC


Who is online

Users browsing this forum: No registered users and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group