Oddly, my factory Bi-fuel still burns Petrol

[Pete_c20]

Bit more of an update...
I'm short on time so for now this is my first shot at an investigation and possible fix.
I pumped the incoming 2nd hand fuel rail with its injectors to about 4 bar with compressed air and sprayed it with leak tester - No leaks, not a jot.
I operated the injectors with a DC power supply a couple of times to see if they resealed as effectively. They operate at about 4.5volts and release at between 1.5 and about 1.7volts and pull about 0.3Amps at 4.5volts. Without measuring it I'd guess they live on a 12 volt rail. So forget all this madness about operating them from a 1.5V AA dry cell you see on some of the online videos. Again no leaks.

A reminder - the injectors can carry enough fuel in them to give a significant cloud of petrol for a second or two when operated until they run out.

The fuel rail in my S40 seemed to depressurise itself without me needing to do it before taking the rail off. I padded out the area directly below the rail with kitchen towel to absorb the little flood of petrol that came out when the injectors left the rail. The injectors came out of the rail itself easily but were right buggers to pull out of the inlet manifold. Despite 127K miles both top & bottom sets of Orings, which I assume to be original, were in excellent condition, no cracks and still very pliable. The 2nd hand rail Orings showed mild cracking on the inlet manifold ones, on the inward facing side, when rolled between the fingers.
The set of injectors from the 2nd hand rail was put into the car with new Oring seals. The injectors removed from the car went back into the compressed air test rig. These also proved to be completely leak free.
The Oring packet says lubricate with DOT4 brake fluid only to ease their insertion. I used standard engine mineral oil as I've no DOT4 to hand and I wasn't going to crack open the brake reservoir. Avoid anything with silicone in it as the Lambda sensors don't like it apparently.
Make sure the orings are not twisted after mounting. Be sure that they're clean and that the inlet manifold, injector body and rail seats for them are also very clean and free of stuff like little hairs etc.
With the fuel rail back on and initial leak check done without starting the car, the car fired back up like nothing happened. I expected it to run a little rough for a short while but it didn't even do that. A brief listen to the engine suggests it runs a little smoother than before. After that I turned it off and disconnected the battery for about 1/2 hour with the leads shorted together just to help things discharge, to reset the ECU, and we'll see where it goes from here.

Other notes: Some of the injectors sounded different to the others when operated dry and on the bench, some sound like a dull click, others have a ping or a ring to them. As I'm only bothered if they seal shut I've not looked at this further.

I haven't cleaned the set of injectors that's gone into the car, only checked to see if they leaked when they're supposed to be shut.

Make sure that the long plate or individual spring clips that lock the injectors into the rail are properly home and/or clicked in after reassembly. I did notice that the 2nd hand rail which had a one piece plate to secure the 4 injectors could not hold them as effectively if the injectors are free at the nozzle end. At not much more than the 3 bar rated pressure in the test jig this one piece plated bent enough for the Oring seals to begin to escape their seats.

Having watched a few of the injector test videos showing various injectors piddling fuel these were nothing like that. That might be a different story dynamically but I'm only interested in their closed position.

But from what I've just seen, the injectors don't leak.

Originally Posted by CNGBiFuel

It's reassuring to me that I'm not the only tragic anorak that does this stuff

It's a bit warm for an anorak at the moment, but maybe this explains it?

http://www.youtube.com/watch?v=CmYDgncMhXw

[CNGBiFuel]

Quote: Can he lead a normal life? No, he'll be an Engineer.

http://www.youtube.com/watch?v=CmYDgncMhXw

Yes, you have it about right. Tragic innit? Love Dilbert.

I'm going to have a plug at this, I've done about 1600 odd miles since putting in the 'Injector-cleaner' but with only 90 of it petrol, so I'm not proving much. I'm loathe to use petrol to find out I'm wrong. Enough damned petrol to flush through would cost me more than the problem is csoting me unfixed! I'm going to get a used rail.

[Clifford Pope]

It it be occasional vacuum in the inlet manifold drawing petrol out, rather than pressure from the supply side?

[CNGBiFuel]

I've now put about 4-5 gallons of petrol thru' loaded with injector cleaner. It may have helped but certainly it has not fixed the problem. I carry on... I've just got hold of a complete used rail from ebay. Paid £11.00 delivered and I'm about to play with it. I also see ebay has 5 x recon set for £85 all-in. Almost wish i'd got a set of htese instead, but hey-ho.

My thinking, easier, my wasted petrol has cost me £30.00, my injector cleaner £20. Silly idiot-economics at work here, and it is still not fixed.

Does anyone know what the thread is on the petrol connection. It looks like a 6JIC but I've only got 4JIC connectots so that is a guess. My plan to get my foot-pump and test via the scharder valve to 45ish psi hte second hand rail before putting it on. Pete - I'm confused, if you say your rail did not leak so apart from a differerent sound in your static test, where was the fault.? For our purposes all we want is a leak-free set, and you appear to have had that, on your own and your bought set.

If i can't find something to cap that thread I'll have do it live with petrol, hooked-up to the car. Don't fancy it.

I'll report back. How are you gettign on pete. Is it sorted?

Edit to thsi post: See the pic. Ordered this rail in error. Marked 1270568 It may have been £11.00 delivered, but it does not fit my 1999 Factory Bifuel V70. Stupidity on my part, back to square one. I'll keep you posted Mine is marked 9186836

[CNGBiFuel]

I'm sorry i don't buy it

I think my solenoid idea will work.

I've now looked at thsi in more detail, soemthing that I should have done far earlier, up to thsi point I'd not looked at the issue clsoely enough. I'd been doing laptop mechanics. I even bid on a rail and ordered the wrong part becasue I hadn't look properly.

Now I am looking. This idea that the injectors are pumped to keep them cool unless I'm missing something doesn't fly. If you look the quatity of fuel, it is kept at pressure in the fuel rail, but it is not flowing, thus if fuel is needed at the injector for cooling , as long as some is present, to disipate heat, it'll make not a jot of difference, if it is under pressure or is pumped.

I think a solenoid-valve in the line (or cut the pump) is far more viable and we know it will work. Have I missed soemthign here? I will report back.

[Pete_c20]

Originally Posted by CNGBiFuel

Does anyone know what the thread is on the petrol connection. It looks like a 6JIC but I've only got 4JIC connectors so that is a guess.

Can't help you with this as you appear to have a different rail to me. I swapped the injectors in the old rail without removing it from the petrol supply line.

Originally Posted by CNGBiFuel

My plan to get my foot-pump and test via the schrader valve to 45ish psi the second hand rail before putting it on. Pete - I'm confused, if you say your rail did not leak so apart from a different sound in your static test, where was the fault.? For our purposes all we want is a leak-free set, and you appear to have had that, on your own and your bought set.

Neither the original injectors out of the car or the 'new' 2nd hand injectors were found to leak. And that was using air at about 50-60psi and using gas leak detector spray, so that would detect minute leaks.
The different sound of the injectors was noted driving them dry on the bench.

Originally Posted by CNGBiFuel

If i can't find something to cap that thread I'll have do it live with petrol, hooked-up to the car. Don't fancy it.

I know what you mean, if you get to that just make sure you don't turn the car over. If you do from what I saw in testing you'll get a substantial petrol cloud. Not good!

Originally Posted by CNGBiFuel

I'll report back. How are you getting on pete. Is it sorted?

Too early to say I'm afraid as I'm not doing anywhere near the miles you are. The petrol gauge doesn't seem to have moved since, will keep my eye on it and let you know. Okay this 'fault' doesn't cost me as much in petrol, but my reason for looking at it was as a potential source of poor running which does make a big difference on LPG. With Reggit's help I've discovered that the knock sensor has likely failed. So that'll be next. At the moment fuel economy is only about 1/2 to 2/3 of what it should be.
Do let us know how you get on.

[Pete_c20]

Originally Posted by CNGBiFuel

I'm sorry i don't buy it

I think my solenoid idea will work.

I've now looked at this in more detail, something that I should have done far earlier, up to this point I'd not looked at the issue closely enough. I'd been doing laptop mechanics. I even bid on a rail and ordered the wrong part because I hadn't look properly.

Now I am looking. This idea that the injectors are pumped to keep them cool unless I'm missing something doesn't fly. If you look the quantity of fuel, it is kept at pressure in the fuel rail, but it is not flowing, thus if fuel is needed at the injector for cooling , as long as some is present, to dissipate heat, it'll make not a jot of difference, if it is under pressure or is pumped.

I think a solenoid-valve in the line (or cut the pump) is far more viable and we know it will work. Have I missed something here? I will report back.

I originally mentioned the possibility of fuel cooling the injectors as you sounded pretty keen on the idea and I wanted to make you aware of a possible pitfall that might cost you dosh. Like yourself I'm new to this particular bit of the car but not new to mechanics. Having now had the rail out and messed with it I would now say the following and this may add weight to the idea of turning off the petrol.
When I pressured the spare rail up with air I was looking at the 2nd pipe coming away from the fuel pressure regulator. I was expecting that to vent at, or just above, about 45psi. It didn't, it remained closed as the input went over 45psi. Even at about 70psi it hadn't opened. Which left me wondering is it a) faulty and stuck, or b) doesn't perform the function I thought it did.
I thought the configuration I have with its 2nd pipe would do something like this -
Fuel pump pumps to above 45psi, fuel comes to front, pressure reg regs to 45psi ish, excess vents into return pipe, rail takes what it needs.

But even if it did work like this the fuel in mine doesn't flow across the rail. The pressure reg and its pipes are at one end. The only thing at the other end is the Schrader valve.
Soooo my best guess is that in mine turning the petrol off once on gas wouldn't change much from a possible injector cooling point of view.
Apologies for the extended explanation but I've not fully investigated this bit but I'm letting you know what I've seen.

How would you turn off the fuel at the right time. Hooking it in to be driven from LPG relay would make sense as that goes live when you select LPG but I'd verify that it behaves the way we'd like it to if LPG is still selected but no LPG is left, so maybe a static test to verify what happens when the car runs out of LPG.

[CNGBiFuel]

Yes, I'm glad your thoughts concur with mine. Now... how I wire it up I'm not sure, that could be a headache or at least messy. But having done it, if it works we can kiss the leaky injector problem goodbye which buying new expensive injectors does not do.

I'm now doign some proper digging. If I can get a relay to cut power to teh pump, that might be neater and easier than a shut-off vlave in the fuel line. I'm going to have a ferret about in there.

I 'm hoping I can get a feed from the distributor control valve to fire a relay which drops the pump exacctly when needed, but thsi might be my rear-end talking. At the moment I'm embarrassed to say, becaues it is so tight in there I can't trace back the fuel line to any pump. But then, I'm used to working on 60s Land-rovers, not this damned thing, I'm expecting to see everything...
I'll come back.

I'm looking to see which fuse it is at presnt.[And praying the pump has its own - now that would be handy. Just looked it up. Fuel pump has a separte fuse as does fuel injection. Looking good. Back to you Pete, going in your direction what did you achieve?

[Pete_c20]

Originally Posted by CNGBiFuel

Yes, I'm glad your thoughts concur with mine. Now... how I wire it up I'm not sure, that could be a headache or at least messy. But having done it, if it works we can kiss the leaky injector problem goodbye which buying new expensive injectors does not do.

Apart from one outstanding thought - The problem wasn't there from new. And only appeared for me at about 70K miles I think. It does leave me wondering which bit of the car isn't doing its job. In theory there shouldn't be a need to modify it away from stock as it's not a design fault. But its finding the damn thing!

Originally Posted by CNGBiFuel

Back to you Pete, going in your direction what did you achieve?

Not sure what you mean there.

[CNGBiFuel]

Quote:
Originally Posted by CNGBiFuel View Post
Back to you Pete, going in your direction what did you achieve?
Not sure what you mean there.

Sorry I was not very clear. You appear to have found no leaks to speak of in either of the rails you have. If I understand correclty you found soem sounded a bit different in a bench test, but for our pruposes, they were leak free. If there was no leak and the problem is still with you, what conclusion are you coming to? Agreeed thsisi not a design fault. More I suspect this was designed in!

Progress for me: I've establised that the fuel-pump is in the tank and a right sod to get to. I understand there is a access hole in the boot. but...

I've established on mine MY1999 the fuel pump does not have a separately fused circcuit. Damnit. I'm still digging.