Tim O
Well-Known Member
I will of course keep everyone posted on the outcome, for the sake of your stress levels !:encouragement:
Engine misfiring, likely suspects list
- Thread starter Tim O
- Start date
Daydream believer
Well-Known Member
Loss of compression after the engine warms up & comes under load ?
Water in the cylinder ?
Water in the cylinder ?
<152587>
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Tim, I will explain my thought train for you.
Blocked injector? Discount, as the injector is a relief valve pressures involved would be generated far above the design and usually cause the injection pump to self destruct. Due to the said presssure injectors injectors will usually fail in open position. Of course exceptions are possible especially if they have been subjected to water contamination for some period.
Fuel runback from injector to pump? A little known device under the pipe connection called a delivery valve precludes that and you state that fuel is present when injection pipe is slackened. Disregard.
Good injection but lack of of compression. Distinct possibility, may or may be not accompanied by smoke depending on how much compression is available to commence some combustion. Remember a particular cylinder may be still combusting but not efficiently thus causing an imbalance in power. This scenario is my top dollar.
Good compression, poor fuel delivery? Completely disregard. My fellow engineers on the forum seem to favouritise this diagnoses and no doubt I will be verbally whipped for suggesting otherwise. Poor atomisation or other wise termed fuel delivery is manifested by a very unmistakable symptom. It is so apparent that it certanly be would have been mentioned in your original post. Detonation otherwise known as diesel knock.
RichardS
N/A
Water in the cylinder usually results in infinite compression .... and no engine running at all.
Richard
davidej
Well-Known Member
I'm sure my AJ26 Jaguar engine has the cylinders numbered from the front. Firing order L-1 R-1 L-4 L-2 R-2 L-3 R-3 R-4 so the classical uneven L R L L R L R R cross-plane rumble.
Richard
They fell in line with common practice at some point.
I know the old XK engines had 1 at the back and I think the V-12s also though it is a long time since I was muddling around with one. Happy days - sold them much too soon!
sailorman
Well-Known Member
Any update on this
Tim O
Well-Known Member
Not yet.....Waiting for engineer to fit it in in between some other big jobs
Tim O
Well-Known Member
Update
Engineer ran compression test yesterday and it was fine..... Good news i think
Injector ha gone for testing now so see what comes back from that
Engineer ran compression test yesterday and it was fine..... Good news i think
Injector ha gone for testing now so see what comes back from that
PaulRainbow
Well-Known Member
See what happens, but could be worth a service on the other three injectors too.
Topcat47
Well-Known Member
+1, in fact I'd have the fuel pumps done, too were it mine. Although I only have one to worry about, the pump and injector are being serviced as I write.
Tim O
Well-Known Member
What does servicing the injectors and pumps involve? Any ideas of the sort of cost we are looking at?
PaulRainbow
Well-Known Member
See what it costs for the one you sent for testing and ask the firm that do it how much to do the other three. Personally, i wouldn't touch the pump.
Tim O
Well-Known Member
Just to update anyone interested on this...
The injector tested fine, so next port of call is to look at the pump
The injector tested fine, so next port of call is to look at the pump
<152587>
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In 50 years of diesel doctoring something not adding up in my logic. Have you run the motor lately? Just give it a run before commiting yourself to more expense. When it is running slacken the fuel delivery pipe on each injector in turn, the speed of the engine should decrease equally.
PaulRainbow
Well-Known Member
<152587>
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Paulrainbow, please take your own advive, the op has already stated fuel is present at the injector in a previous post.It might help your logic if you read the thread from the beginning
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Tim O
Well-Known Member
Are you suggesting putting the injector back in and trying running the engine again? See if the problem is still present?
We did do the slacking off of the fuel delivery pipes way back that's how we isolated the issue to the fourth cylinder.
<152587>
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A injector pump look at is going to run into many hundreds of beer tokens. Do all you can before commiting to that action.
Firstly hang the injector off the pipe and crank the motor, disable the other injectors to inhibit start. It may take a minute of cranking to bleed the pipe but if the pump is doing its job a fine spray of fuel along with a sound like spitting through your teeth will be apparent.
If all is well absolutely reassemble and run up motor, you have checked compression and the above observation shows you have fuel.
Firstly hang the injector off the pipe and crank the motor, disable the other injectors to inhibit start. It may take a minute of cranking to bleed the pipe but if the pump is doing its job a fine spray of fuel along with a sound like spitting through your teeth will be apparent.
If all is well absolutely reassemble and run up motor, you have checked compression and the above observation shows you have fuel.
PaulRainbow
Well-Known Member
Ah, i see you have now gone back and read at least some of the previous posts, well done :encouragement:
RichardS
N/A
I don't follow this Third Engines.
If there is fuel present at the injector but the 4th cylinder is not firing, what is the point of running the engine and slackening the fuel delivery pipe on the 4th cylinder?
Richard