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I've got a Bleeding problem!!


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I have honest, today I changed my fuel filter, cleaned out the water trap and the gauze filter in the lift pump on my Diesel BMC 1.8, I bleed the system following the destructions in the manual, and I'm getting clear fuel out of all the places I'm supposed to, so next I did the last bit slackened of the nuts on two of the injector pipes like it said cranked the engine but i'm gettin no fuel coming out of the two pipes, thinking I did something wrong I did it all again but still nothing coming out of the two unions, has anyone got any idea what the problem could be, I got fuel coming out of all the places it should on the injector pump, but nothing at the injectors,,,

Regards Frank,,,

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Well if it's bled right up to the injector pump and won't strike up with 2 of the unions cracked open a little then I'm as stumped as you I'm afraid :cry

The reason I asked about if you had tried to start it was, even without bleeding after a filter change, an engine will fire up and run for 10 seconds or so before the fuel that was sat in the injector pump has been exhausted. :?

Persuade the bugger with some easy start :lol:

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Jimbo! the boat has been standing for about eight months and I forgot and left the fuel tap on, so I don't know if the fuel drained back into the tank, It ran fine last time I started it but when I went to start it this time it wouldn't fire up, I checked and there is power to the glow plugs, thought I havn't taken one out to see if it glows yet, I was going to change the fuel filter and have a clean up, which I did, I've followed the manual to the letter regarding bleeding, but I can't work out why I'm getting fuel from all the bleed points on the injector pump but none at the injector unions?? Could it be that I'm opening the bleed screws too far and letting air back into the system, unfortunatly I know nothing about Diesels so I don't even know where to start to look,,

Frank,,,

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You won't get fuel to the injector by just operating the lift pump. The pressure between the pump and the injector is monsterous and very dangerous. You can bleed as far as the pump and then crank the engine with the injector unions loosened ( A LITTLE ) to bleed to the injectors. Usually the engine would splutter into life maybe on a couple of cylinders at which point nip the unions back up. If it's still spluttering, undo each union a little again, one at a time, then nip it up again, until you find which cylinder still hasn't bled to the injector.

As far as testing your glow plugs goes, people will tell you to test them with a multimeter. I can tell you from experience that this is not a reliable way to do it! I have tested them with a multimeter before and it has indicated the plug is good. I have then connected the plug to a battery using jump leads and it has been duff! So I always test them this way now.

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:grin: I did the cranking bit Jimbo! the last two bleeders on the injector pump I had to crank it on full throttle while there were open, when fuel came out of the first one I had to close it, crank it a bit more then close the last one, then it said slacken off two of the injector unions and crank again with the throttle fully open until the fuel came out clear, nothing, zip, zilch, it spurts out of the injector pump when you open the bleed screws, but as I say nothing from the injector pipes, someone told me it wouldn't be an injector pump problem because i'm gettin fuel out of it, maybe i'll just have to bleed it a few more times once I put the new batteries on, your glow plug trick is the way I test them on my car, can't remember where I learn that one though,, and by the way thanks for all your help,,

Frank,,,

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In that case Frank, I would try and loosen the injector unions more and gently pull the pipe upwards away from the injector, but still held within the union obviously. It would help if you could get someone to crank the engine while you do this. When I say open them more by the way I mean just enough so you can feel the pipe lift from it's seat a little. Keeps your hands well away from the unions at all times while the engine is being cranked and rely on the spanner to be your contact with the nuts cheersbar

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Jimbo! that may be part of my problem, when it said slacken off the unions and bleed screws I've been undoing them nearly all the way, I've just read on a diesel site you should only open them half to one turn, I've probably been putting more air into the system than I've been taking out,, :?

Frank,,,

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Ah! right. That wouldn't be the case with the injectors, but might be the case with the pump bleed screws. Your best way of doing it, is to operate the lift pump, then while doing so, open the bleed screw until diesel starts to come out on the pump strokes. Wait till no air bubbles come out with the diesel, then nip it up as the fuel is coming out.

The point I was making with opening the unions more on the injectors was that the injector pipes tend to be very well bracketed, thus it is possible your not loosening them enough to create an escape for the air. Gently lifting the pipe upwards away from the injector will indicate you have broken the seal between pipe and injector, allowing room for air to escape. It really should make an attempt to start when diesel appears at the injectors, provided the glow plugs are ok. As soon as fuel does start to spurt from the injector pipe end, nip that one up quick, likewise with the others cheers

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Did the manual mention the 8mm bleed screw on the side of the injector pump? Make sure you have a nice squirt every time you operate the lift pump. Then crack open every injector about 1 turn and spin over until you have fuel driping out of each union.

If this does not work then have you actually checked the lift pump? It's possible the membrane is worn and not pumping to full capacity. Other than that the only other option is to start back at the water seperater and work you way through to the filter on the engine and then to the pump again.

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Hi Frank has the pump got an electric stop solenoid if it has try bleeding with the ign turned on

is the stop solenoid working ok? to test it remove it carefully as a plunger and small spring is under it 24mm spanner as a rule take the plunger and spring out put safe and refit the solenoid to the pump now try turning it over and see if fuel gets to the injectors if the engine fires up you can stop it by pulling on the manual stop lever on top of the pump :wave

also try tapping the injector pipes with a spanner as you turn it over this sometimes dislodges an air lock

are you getting power to the solenoid?

crack all 4 injector pipes at once turn over if fuel comes out of any tighten while cranking till all tight pre heat twice then try to start

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Thanks for everyones help on this one, I'm not sure if it has an electric stop solenoid, it's a Thornicroft/BMC 1.8 I was told that the injector pump works directly off the engine, Mmm, lift pump, how do you tell if it is working properly?? it did take a hell of a lot of pumping to get the fuel through, I was told that the lift pumps only function was to prime the system and it dosn't actualy pump fuel to the injector pump, but on thinking about it, it has a lever thing that sits on a cam so this to me says it must pump the fuel up to feed the injector pump, when I turn the engine over with the two bleed screws open as the manual says it dosn't exactly squirt fuel out it more dribbles out, so should it squirt or just dribble??

Regards Frank,,,

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Right folks I might be onto something so Jimbo and NeilB might be right and the lift pump is shot, I've just spent hours yes hours searching the net to see if I could find any clues to the problem, at the end of last season I had a little problem where my revs would rise up for a split second then drop back to normal, the common answer I got was the fuel and lift pump filters were the main suspects, so thats why I did the filter change and clean up, now as my boat hasn't been fired up since last September I had no Idea I had a problem until I bleed it and tried to start it, now after endless searching I found a couple of instances that had the same problem as me, revs jumping (ending up with total shutdown) and then problems bleeding it, seems it's all caused by air getting into the system, and in both the instances I found the cause was a hairline crack in the lift pump, so that could explain why I had to prime it for ages to get it up to the injector pump, also if air can get in the crack surely fuel could get out which could explain the strong smell of diesel I always have in the bilges, so a new lift pump is on order and hopefully that will cure the problem, I'll let you know how I get on later in the week, once again thanks for all your help,, Oh yes! I meant to say both the boats with the same problems were both built around 1978/79 and were both on Thornycroft 1.8s, perhaps there were a batch of duff liftpumps around,,

Regards Frank,,,,

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WooooooHoooooo! problem solved, I fitted the new lift pump and got a bit more pressure all the way up to the injector pump, So I pressume the lift pump was a bit cream crackered, I still couldn't get fuel out of the injector unions so after about four hours bleeding it and a hell of a lot of swearing, I gave up and went to see David who kindly came over and within five minutes had it running, it turns out there was an airlock in the injector pump and my opening everything half a turn to bleed it was the wrong way, David took the bleed screws right out and pumped until fuel came out then re-fitted them in turn, he removed the air bleed screw on the injection pump governor housing and after a few minutes of air and bubbles we had clear fuel, it also turns out that at some point someone has lost the bleed screw and replaced it with a normal machine bolt which explains where the air is getting in as it's not forming a proper seal, anyway it's running as sweet as a nut now, the revs arn't peeking and it's nice and smooth, at least next time I have to bleed it, it won't be no half to one turn, it'll be take the buggers out and screw then back in as the fuel comes out,, so the main problem was a weak lift pump and air getting in through the bleed screw on the injection pump governor housing, and me not knowing what I was doing, So thanks everyone for your help,,,,

Regards Frank,,,

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Thats the intention Jimbo, just need the man to do my BSC first, now the Mrs and me have more or less retired I think we may be spending a lot more time out on the boat, I've got a couple of small jobs to finish first, may as well do them before the BSC tester tells me I have to,,

Regards Frank,,,,

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Persuade the bugger with some easy start :lol:

A salutary warning......I've been having an almost identical problem to Frank. Having made several attempts to bleed the system but getting only a dribble of fuel from the injector connections I was advised to try Easy Start which I did. The result was the engine kicked back, damaging the Bendix mechanism and jamming the starter in engagement. The engine was locked solid and I was obliged to get the engineer out. I'm now waiting for the starter motor to be repaired. So, more expense which I definitely could have done without :(

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That's one way of describing it. The galling thing is that the engineer would probably have been able to sort my fuel problem today if I hadn't used the Easy Start. Now I'm going to have to wait at least another week. The season's already slipping away and I haven't had a run in the boat yet :(

That can is going back in the cupboard - permanently!

Incidentally when the starter jammed I had an exiting display for a few seconds - a shower of sparks from the terminal, which glowed orange! :o

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That looks similar to Easy Start. They are normally based on Ether - model aircraft fuel.

The problem I see with using such products is that introducing fuel into the inlet manifold means there is no control over the instant of ignition. My engine really clattered because it was pre-igniting and this is what caused the kick-back. In normal operation the timing of the injection is controlled to prevent this.

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