andy2986 Posted February 5, 2012 Share Posted February 5, 2012 Hi, 3.9 V8 LPG single point using a Lambda control And the ignition is Mega jolt OK Started over-fuelling like crazy (see other post) have replaced plugs, leads, and coolant temp sensor. Discovered loads of petrol in the oil, changed the oil. Still runs like a bag of spanners Disconnected the fuel pump and the injectors so it runs LPG only (thought I might have a dual fuel thing going on) still runs like a bag of spanners,rough tick over, on a spin mid range is OK ish once its cleared its throat but no real top end. pulled the plugs... R/H set spot on (1357 ) L/H set (2468) all wet but don't smell of petrol (oil?) Ive been at this on and off for a few days now, was getting stressed as I need it for work tomorrow, (am going in on the motorbike now !!) would appreciate some ideas I'm quite sick of the bloody thing now and am so close to breaking it and selling off the bits, Ive always enjoyed working on my motor but now I just hate the thing Andy (Very cold been working in the snow on his damn Disco again) Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted February 5, 2012 Share Posted February 5, 2012 Is it over fuelling or have you loost a bank spark ? Nige Quote Link to comment Share on other sites More sharing options...
Tanuki Posted February 5, 2012 Share Posted February 5, 2012 Not sure about the specific petrol-system you have there (carbs or injection?) but I recall a similar 'running massively rich on one bank' issue on a Ford V6 some years back. The engine had a fuel-pressure-regulator which was dedigned to respond to manifold-vacuum so had a small-bore vacuum-hose running from the regulator to the intake plenum. When the diaphragm in this device leaked, fuel went up this vacuum-hose and because of the plenum-shape and where the hose connected, all the excess fuel went into one bank of cylinders. --Tanuki. Illiterate? Write today for free help. Quote Link to comment Share on other sites More sharing options...
andy2986 Posted February 5, 2012 Author Share Posted February 5, 2012 Hi Nige. Ive got sparks on all the leads on the L/H bank, although, If I disconnect any of the plug leads from the coil packs for the L/H side whilst the engine is running there is hardly any loss in revs as opposed to the R/H side which falters as soon as I disconnect any of its plug leads. I was convinced it was an ignition fault, but feel I'm going round in circles. If I've disconnected the fuel pump (pulled the fuse) and permanently turned of the injectors (relays with the LPG system) can fuel still get through? Tanuki. Its an EFI. I will have a look at the FPR, that could explain why all my fuel seems to finish up in my oil ?? Andy Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 5, 2012 Share Posted February 5, 2012 Yes, check the FPR for definite, they can fail and fill up the plenum! Quote Link to comment Share on other sites More sharing options...
andy2986 Posted February 5, 2012 Author Share Posted February 5, 2012 This sounds like it might be the badger !! Explain the petrol stink and " thinking outside the box " the Disco is on a camber by the side of the road and its the L/H side that is lowest... Would also explain my 100 proof oil :blink: I guess If the FPR is failed it will dump petrol into the plenum as fast as the pump will let it ??? Thanks guys I feel a bit better now, am working tomorrow but will have a look on tuesday Fingers crossed Andy Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 5, 2012 Share Posted February 5, 2012 As fast as the probable pin-hole in the PRV diaphram will let it at ~ 35PSI. Quote Link to comment Share on other sites More sharing options...
davyd8899 Posted February 6, 2012 Share Posted February 6, 2012 Not sure about the specific petrol-system you have there (carbs or injection?) V8 3.5 had carbs 3.9V8 was fuel injection. just my 2 penneht worth Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 6, 2012 Share Posted February 6, 2012 There was EFI 3.5s a well you know Quote Link to comment Share on other sites More sharing options...
teabag Posted February 6, 2012 Share Posted February 6, 2012 V8 3.5 had carbs 3.9V8 was fuel injection. just my 2 penneht worth Only up till 1990 then the 3.5 got EFI, untill 1993 when it became a 3.9 EFI.. You not a disco V8 owner then. Quote Link to comment Share on other sites More sharing options...
andy2986 Posted February 7, 2012 Author Share Posted February 7, 2012 OK an update, I have removed the fuel pressure regulator, blocked the vacuum tube that fed it, removed the fuel pump relay, and disabled the injectors (they can be turned off by two relays as part of the LPG system) cleaned up the plugs and tried to start it on LPG only and BINGO fired first time perfect tick over. let it warm up and took it for a gentle run round the block and it runs great on LPG. Im not sure how to test the FPR so might just bang a new one in there and see... Andy Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 7, 2012 Share Posted February 7, 2012 Put the FPR back in and see if the problem returns, then you have a diagnosis, rather than stabbing in the dark Sounds to me though that one of the injector-switch-off relays has died and not disconnecting them when it should, otherwise you would still have a plenum full of petrol, just not being topped up any longer. Quote Link to comment Share on other sites More sharing options...
andy2986 Posted February 7, 2012 Author Share Posted February 7, 2012 You are one step ahead of me !! Ive metered the injector/LPG relays and they operate as the should. (good call though) Before I fitted the cleaned up plugs today I spun the engine over with no plugs in and some petrol did come out of the holes... I think it is "dual fuelling " or flooding with petrol. With no petrol at all (completely disconnected fuel pipes ) it runs sweet as a nut. On Sunday, it did start to run fine on gas. I then noticed that it had run out of petrol (it has a real small tank and LPG tanks where the tank should be) I changed the oil again and took it down to the local petrol station to fill up thinking I had fixed it.. (I was still thinking it was electrical) filled up gas and petrol but this time started on petrol. straight away it wouldn't run properly on petrol switched to gas, still wouldn't run. Pulled the fuel pump fuse but It still wouldn't run properly, got it home and pulled the plugs and ... flooded, almost instantly I gave up on it then as I was freeeeezing cold and Mildly miffed off. I have ordered a new FPR from rimmers, my reasoning being if its new I can discount it from the problem, if it still over fuels then I have to find another reason for how the petrol is getting in. maybe bad injectors ??? anyway one step at a time. I really appreciate all your help so far, it can get very depressing when you are on your own working on a sick motor and not getting anywhere... Andy Quote Link to comment Share on other sites More sharing options...
andy2986 Posted February 7, 2012 Author Share Posted February 7, 2012 Just tried to test the FPR. If I blow air into the fuel-in part with the vacuum pipe in some water (via a short rubber pipe) I definitely get air bubbles out of the vacuum pipe. I'm using the compressor for my lockers so only get short 40psi puffs, but if the air was petrol then the bubbles would be petrol going into the plenum... wouldn't it ?? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 7, 2012 Share Posted February 7, 2012 Yes Quote Link to comment Share on other sites More sharing options...
Tanuki Posted February 7, 2012 Share Posted February 7, 2012 Yes And remember that if the FPR has a leaky diaphragm, the engine manifold-vacuum will still merrily suck petrol through the fuel-lines, up the vacuum-line and dump into the plenum *even if the petrol-pump and injectors are all totally inactivated*...--Tanuki. Quote Link to comment Share on other sites More sharing options...
andy2986 Posted February 7, 2012 Author Share Posted February 7, 2012 And remember that if the FPR has a leaky diaphragm, the engine manifold-vacuum will still merrily suck petrol through the fuel-lines, up the vacuum-line and dump into the plenum *even if the petrol-pump and injectors are all totally inactivated*...--Tanuki. Thus explaining the mystery of the disappearing petrol ( I hope ) Quote Link to comment Share on other sites More sharing options...
Tanuki Posted February 7, 2012 Share Posted February 7, 2012 Thus explaining the mystery of the disappearing petrol ( I hope ) Yes. The excess petrol, being dribbled randomly into the plenum and not being atomised/vapourised by the injectors, won't have had any chance of being burned-off either - explaining the oil-contamination you had. Here's hoping your problems are now at an end! --Tanuki. News-from-the-Future - 20-May-2037: Public holiday declared in Vatican City after Pope Elaine gives birth to Twins. Quote Link to comment Share on other sites More sharing options...
andy2986 Posted February 8, 2012 Author Share Posted February 8, 2012 Just a quick update, got the part today but it was wrong. right for the chassis number but wrong for my Disco !! ah well they have the right one and its on its way. Im in Newcastle from tomorrow till monday so will have to leave it for now. will post up when the correct part turns up and Im back home !!! Andy Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted February 8, 2012 Share Posted February 8, 2012 Efi fuel pump can pump up to 120psi and regulator maintains at around 35 psi Nige Quote Link to comment Share on other sites More sharing options...
davyd8899 Posted February 10, 2012 Share Posted February 10, 2012 Only up till 1990 then the 3.5 got EFI, untill 1993 when it became a 3.9 EFI.. You not a disco V8 owner then. my bad!!! had a disco V8 but as a toy, when it started being a workhorse/tow vehicle it had to go! so 300tdi now Quote Link to comment Share on other sites More sharing options...
andy2986 Posted February 15, 2012 Author Share Posted February 15, 2012 OK Then Good news and Bad new.. Good news is, Ive fitted a new fuel pressure regulator Bad news, it didn't fix it Although the day is not completely lost. It runs on gas. I have a question. 1. how are injectors wired ? 2. how are they fired ? My reason for asking is this. After a process of elimination I have worked out ( i think ) that if fuel injector 4 is connected it floods. If i unplug the connector by its lead it all runs fine. (all be it on 7 on fuel) When on LPG, If I unplug all the injectors on the even bank it runs on LPG, if I connect the injectors one at a time it falters when i connect injector 4. If I only connect injector 4 and leave all the others unplugged (even bank only) it falters (the engine) if I plug any of the injector connectors onto 4 it falters. if I plug connector 4 to any other injector it makes no difference I had an idea that the injectors are fired off 1 bank at a time, not individually? i.e. injectors 2,4,6,8 are opened together. so any of the even leads could be connected to any of the even injectors. If this is so, if the lead to injector 4 doesn't open any other injector then It must be good. (conversely any of the other injector leads can open injector 4 and not their own) there is an injector interrupt for the LPG system. It (when the LPG is on) interrupts both the blue and yellow wire and the blue yellow white wire in the footwell area, I didnt install this part of the system but if this has isolated the injectors how is the injector wiring still operating the injectors. Are they fed a live all the time ? and the earth is switched, if so do injectors fail to earth ?? Sorry for all the questions, but if anyone has any thoughts I would appreciate it (or questions for me to answer to make it clearer) Andy Quote Link to comment Share on other sites More sharing options...
andy2986 Posted February 15, 2012 Author Share Posted February 15, 2012 Ive just metered the pins on the injectors for continuity to earth. All the injectors on the problem bank, 2,6,8 have no continuity to earth but my suspect injector shows continuity to earth on both pins. so if they are fed a constant live and switched on their earth that might be my problem...???? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 15, 2012 Share Posted February 15, 2012 Yes, they are switched earth They are also bank fired, i.e. 2468 at the same time and 1357 at the same time. Any wiring deviation from this needs fixing Check how the injectors are disabled when on LPG (probably a coupl eof relays) and test them, I reckon one is failing... Quote Link to comment Share on other sites More sharing options...
andy2986 Posted February 15, 2012 Author Share Posted February 15, 2012 OK. All is good ! No 4 injector is knackered. It meters out for continuity between its body and either of the two pins. so I guess as soon as it gets a +ve it would open up. The LPG relays (i believe) isolate on the earth side of the injector. so even when I disconnected the relays, injector 4 was still getting an earth through its fault so didn't care ! Not being familiar with the switching of the injectors. If they are controlled by their earth then this little bugger would be on all the time !!! and may well be giving a false earth to injectors 268. So I have replaced the injector and the Disco would appear to be good on gas and petrol. Need to do yet another oil and filter change as the oil stinks, once again, of petrol will do that tomorrow. I was convinced today it was the LPG relays as well and even though they metered out OK I swapped them with two new ones but to no avail. Im very quick at changing plugs now !!! Quote Link to comment Share on other sites More sharing options...
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