1974 series 2 4.2 difficult to start after 60 mile run

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supersonic62
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1974 series 2 4.2 difficult to start after 60 mile run

Postby supersonic62 » Sat Jul 13, 2019 12:10 pm

Hi Folks, just wondered if anyone could throw some light on to an issue I have experienced this morning, I ran the car along a dual carriageway a couple of miles from me ( about 15 miles between roundabouts ) continuous at 60mph and covered about 60 miles as car is going to garage to have the anti-roll bar kit ( David Manners ) fitted on both sides next week as thought spring or shock absorber was broken after hitting pot hole, but when garage fitted a new SU fuel pump two weeks ago, they said was drop-link bushes on offside, so are getting both done as they are original so play safe, and ran it today just in case any other issues were to arise.It ran lovely until almost home and I had to stop at traffic lights for about 6 seconds, car was still in drive and I as I pushed the accelerator it coughed and spluttered and stopped as I crossed opposite lane ( Phew was close )changed to other tank , no change turned ignition off and on again and it fired straight away and got home without issue. I did notice from then on in the two minutes to get home the oil pressure went down to virtually nothing.After checking under the bonnet ,no leaks visable. I left it for 30minutes to cool down and it wouldn`t start and the oil light came on with the ignition as it was being cranked,I added about half a litre of oil and on cranking the engine with foot pushed down on accelerator hard it eventually fired up and idled in the drive ok. Seemed odd behaviour as I had topped oil up monday of this week to usual level.Any ideas much appreciated ( just add as have said in previous times it`s had a new luminition system, coil, ballast resistor, dizzy cap, rotor arm, plugs, ignition leads , fuel pump this year)Regards Paul

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piman
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Re: 1974 series 2 4.2 difficult to start after 60 mile run

Postby piman » Sun Jul 14, 2019 11:49 am

Hello Paul,

semple checks like what colour are the plugs which would give an indication of mixture, (as does the colour of the tail pipes).

If there is nothing very obvious then a systematic check of ignition timing, carburettor settings is the way to go (Coil polarity is another that can weaken the spark, negative terminal to the distributor (white\black cable). A compression check is always worth while also if you have the means to do that?

Alec
Mk 2 3.8 (long term restoration), MK1 Triumph 2.5 P.I.,2.5 X Type Estate, 564 Hymer Motorhome

mike020150
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Re: 1974 series 2 4.2 difficult to start after 60 mile run

Postby mike020150 » Tue Jul 16, 2019 10:49 am

Another item to think about is the oil pressure operated fuel cut-out. To ensure the fuel pumps don't operate after the engine stalls/stops, very low oil pressure cuts the power to the fuel pumps. Your mention of seeing the oil pressure light illuminated and adding engine oil etc may be clues. Of course, if the engine is short of oil pressure, solving that will also sort the stalling. Mike.
2014 XK Dynamic R convertible; 1977 Daimler Double Six Coupe; XE S

supersonic62
Posts: 34
Joined: Tue Jun 28, 2011 1:47 pm
Location: cambs

Re: 1974 series 2 4.2 difficult to start after 60 mile run

Postby supersonic62 » Wed Jul 17, 2019 9:48 am

Hi Folks, I have checked all new wiring which was done by the garage when they fitted all the new illuminition system etc as much had become brittle and can`t find anything suspect. And yes I thought about the oil and stopping engine starting even though it had plenty in it ( could it be the oil pump failing ) it went to the garage yesterday afternoon after they rang and asked if I could take in that afternoon as were able to look at it ( was due in wednesday morning) probably also to understand why the new SU fuel pump is and has been leaking where it bolts to the fuel lines since it was fitted two weeks ago, when I came home and opened the boot in order to put everything back in the smell of fuel was extremely overpowering, more than the aroma you normally get and I put my finger around the joint and it was wet with fuel.I had to ring an order through to david manners that afternoon ( where pump came from) for the drop link bar kit that the garage said it needed in order to fit this week and I asked the chap who took the order if they knew of an issue with these Su pumps not sealing or similar and he said no , he said it probably needs an extra turn with a spanner. I didn`t touch it as I didn`t want to perhaps make it worse.On emptying the boot yesterday to take to the garage it had been leaking enough to wipe it up.So I don`t know what they can do to try and stop that ( something I hope).This seems to be the year the car is getting it`s own back for the many many years it has been so well behaved( perhaps it`s the British Leyland era we remember kick back, chuckle)thanks everyone for your advice regards Paul

supersonic62
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Location: cambs

Re: 1974 series 2 4.2 difficult to start after 60 mile run

Postby supersonic62 » Fri Jul 26, 2019 6:06 pm

Hi folks, just an update , the fuel pump needed new washers as it seems they have only one use and needed replacing.( why can`t the supplier tell you this and they could have been ordered with the SU pump ) We were able to fit them ourselves ,so that issue is sorted and the anti-roll bar kit was fitted by the garage and the car drives as nice as it did before the droplinks etc started failing.As for the coughing and spluttering that occurred it hasn`t happened since so that may be a blip , time will tell ,Regards Paul

mike020150
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Re: 1974 series 2 4.2 difficult to start after 60 mile run

Postby mike020150 » Sat Jul 27, 2019 10:51 am

Fingers crossed! :D Mike.
2014 XK Dynamic R convertible; 1977 Daimler Double Six Coupe; XE S

supersonic62
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Location: cambs

Re: 1974 series 2 4.2 difficult to start after 60 mile run

Postby supersonic62 » Tue Aug 20, 2019 8:28 am

Hi folks, I have just returned from a approx 50 mile drive as I did before ( which is four trips along the dual carriageway near to me ) as I didn`t want to drive it on a single lane road( as I have had it breakdown before on this dual carriageway and was the luminition system and was a hairy experience ) as I was not a 100% sure how it would behave.It started first time and I did one round trip on the dual carriageway ( approx 12 miles ) and stopped for fuel, it started again first time and I continued with the run. As I was returning home the traffic lights were green so I didn`t have to stop as I did before ( where coughing and spluttering began and engine died previously ) but just before I turned into my road I had to let another car come out first so I had to stop. Then still in drive I pressed the accelerator and the car coughed and spluttered and before it died I stopped and put it in neutral and it idled perfectly. I selected drive to try to get the car home, and it again coughed and spluttered as before and even only now yards away from home I didn`t think I was going to make it ! Again when in my drive and in park it idles as it should with no issues and up to this point the drive I had undertaken couldn`t have gone better, the car ran as smooth as smooth.I checked everything as advised to do before by you folks and nothing appears to be suspect. But clearly something is ! The garage who does the work on it plus my two modern cars aren`t particularly keen to work on old cars it seems ( but happy to take the money ) as I said to them about it before and they couldn`t come up with anything. If any of you folks have any answers, again I would appreciate your input,Regards Paul

mike020150
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Re: 1974 series 2 4.2 difficult to start after 60 mile run

Postby mike020150 » Tue Aug 20, 2019 10:23 am

Did you rule out the low oil pressure switch in your search? I note once again that the car failed after a period of hot idling when the oil pressure would be at its minimum. Assuming the low pressure switch is fitted, it will cut the power to the fuel pumps at very low oil pressures. That action will leave the float chambers full for a short while and the car will be capable of idling for some time. However, as soon as you open the throttles, with lowered fuel levels in the float chambers, the carbs will only be able to supply a very weak mixture, causing coughing and stalling. If, during the coughing, the engine manages to add some extra revs, that may be sufficient to increase the oil pressure above the cut-off point which restores power to the pumps. Then, rather than stalling, the engine will return to normal running. Running a temporary ignition powered wire directly to the pumps and repeating the hot idling exercise would be the simplest way of testing the switch and its wiring. Mike.
2014 XK Dynamic R convertible; 1977 Daimler Double Six Coupe; XE S

supersonic62
Posts: 34
Joined: Tue Jun 28, 2011 1:47 pm
Location: cambs

Re: 1974 series 2 4.2 difficult to start after 60 mile run

Postby supersonic62 » Wed Aug 21, 2019 10:39 am

Hello Mike, what you are saying does seem to make sense of the behaviour, as after pulling in the drive it idled ok and I took it to the top of the road and back while it was still hot and as soon as I put it in reverse it done exactly the same up the road and back. I could have pushed it quicker. I would certainly say in my humble opinion it is fuel starvation due to its behaviour. It certainly has enough oil in it as I do all the checks before any journey is taken as it does sit for a while before it is used again as its not the only older car I have ,and and it isn`t used in the winter months.The problem I have is I don`t have the confidence to touch the electrics apart from replacing like for like if I am able, and as I said in the earlier post the garage I use are just a regular garage ( non specialist ) although I have used them for many years for modern cars apart from the annual mot, up until this year that they have done the work listed previous they have never worked on it, as it`s just needed general things like a service ( which we have done ourselves ) and general wear and tear items. When I have called into the garage previously and mention this car you almost feel them saying to themselves Oh No not that car. My problem is where to take it as I have mentioned before when I went into the specialist in Peterborough, Cambs I was told by the wife of the proprietor..We don`t work on the old ones...and the specialist in Ely, Cambs only work on the later models it says in their advert.I need someone who is able to work on these vehicles and I don`t know where to go as there isn`t anyone local to me. That is my dilemma...Regards Paul

mike020150
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Re: 1974 series 2 4.2 difficult to start after 60 mile run

Postby mike020150 » Wed Aug 21, 2019 10:48 am

Does anyone in East Anglia know of a good Jaguar specialist for Paul to use? I'm afraid it's not my geographical area. Mike.
2014 XK Dynamic R convertible; 1977 Daimler Double Six Coupe; XE S

ace
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Re: 1974 series 2 4.2 difficult to start after 60 mile run

Postby ace » Sat Aug 24, 2019 12:36 pm

This may be of use to you from my experience.

If you still have the AED fitted and it isn't woking correctly, giving an over rich mixture, it will dilute the oil to such an extent there is very little oil pressure. I changed the oil and filter and the pressure returned to an acceptable level. Junked the AED completely and put on a manual choke, one of the best things I have done to the car.

What I would be most concerned about is running it with little oil pressure. This is one quick way to knock the crank out. I discussed this with a very experienced mechanic who worked on these cars "back in the day" and confirmed this. If you have low oil pressure then I would sort this out first.

If you think it is the fuel / oil pressure cut out switch then you can disconnect the lead from it, connect it to earth, and the pumps will run continuously. If the cutting out then stops you have found the problem.

Another thing that happened to me was the low tension wire from the points broke internally. Looked fine from the outside but the conductor inside was making intermittent connection and giving all sorts of weird running problems.

Hope this helps.

Dave


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