Engine Problem - MK II Jag

--amadeus--

Hello!

I've done it again - took a beautiful classic in from teh UK and once again it's come home on the back of a flat bed having died on route... Trouble is I'm not sure what teh problem could be - any of you have any bright ideas?

It's a 1963 Jag MK II, 3.4l. It cruised brilliantly at perfect oil pressure and temp for a few hundred miles. Then, climbing a hill, it just lost all power. I changed down and it jump started but has repeated the same stunt ever since. Leaving it sitting though seems to rectify whatever it is and it then tuns perfectly.

Main symptoms:

- Driving at speed over a period of time power just falls away
- Ignition light comes on and it sounds as though the engine is being turned by the wheels and is not firing
- Droppping a gear restarts teh car at first and it then runs for a few minutes before repeating the process. It then gets progressivly worse with the "clean running" periods getting shorter
- Pulling over - even for a few mins - seems to fix the problem, at least for a while
- At standstill everything runs like a charm, all cylinders fire as they should and it sounds like a peach
- 99RON unleaded with unleaded additive in the tank
- Slight smell of petrol and a small fuel leak in teh engine bay. I don't have a set of axle stands but it's under teh engine block somewhere
- No variation in oil pressure or temp while any of this is going on.

The last AA man suggested that it is tied to teh fuel leak. His theory is that the car runs for a while but then teh leaking petrol freezes (I assume in teh airflow). This blocks the pipe, strangeling the engine. Stopping the car tehn melts the petrol and off she goes again.

I haven't heard of petrol freezing before - is this plausible? Any other suggestions? Also any reccomendations on classic Jag specialists??!

Thanks!

PaulK_CCI

Sound very much like Fuel starvation. Generally with old classics, the car could have sat in a forecourt for a very long time and the tank would be dirty.

I would go and look for any fuel filters, and you may find an almost completely blocked fuel filter. If there is no filter, cut the fuel line and stick in a cheap plastic filter as it will make life a lot easier. See how if after a short run, it stays clear. If it's immediately very dirty after a few miles, you know you have a dirty fuel tank! However, your 1st priority would be to to FIX that fuel leak!!!

Another giveaway sign is the uphill starvation! When the car is at a different angle, the pump needs more pressure to get the fuel to the engine, and an almost blocked filter will then suddenly be the last straw and the engine will struggle... So if the filter and the tank are fine, you may look at the fuel pump, it may be on its last legs.

franksm

Sounds like it could be the fuel pump - maybe it goes "bad" once it gets hot ?

Suppose you could measure fuel pressure, but you may not get a true reading until the pump really heats up, etc.

And fuel-filter - change that out as a matter or course.

Can you pop out the sparkplugs and see what state they're in after the engine dies ? If they're wet, then it's not a fuel problem but maybe a weak coil, or distrubtor/condensor parts.

As a matter of course, since the car is new to you, I'd change the oil, the filters (oil, air, fuel), the distributor cap, rotor, sparkplugs, condensor & points. Probably 60 or 70 quid there, but it's worth it.

PS. have heard of fuel starvation due to the fuel pipes getting hot, etc, but have never heard of fuel freezing There is something known as "carburretor icing" (http://en.wikipedia.org/wiki/Carburetor_icing) - maybe that's what he was talking about - but don't know if that makes sense here

--amadeus--

Thanks!

The freezing thing sounded good when he explained it but the more I thought about it the less sense it made!

Filters sound possible - the car has seen a lot of use (20K miles in 6 years) so I don't know how dirty the tank is but the way it started after a certain point and when teh car is under load (hills or cruising fast, acceleration) does sound like fuel starvation and teh filter, or a combo of a leak and a dirty filter, would explain it.

Top tip on teh spark plugs as well - my other thought was that it could be the coil cutting out when it gets hot and popping the plugs will give a good indication as to if thats the case or not.

Any other bright ideas?

8~)

Agree it sounds like fuel starvation.
If it runs fine at idle (not under load, low fuel consumption) but fails up hills, at speed, etc. then as you say, you have a leak or a failing pump or blocked filters or a combination!

Probably not applicable to the Jag, but have you noticed any change in behaviour between when the tank is full and empty? I had a Volvo that used to run fine on a full tank of fuel but cut out at much below 1/4 tank. I investigated and found it had an in-tank pump and a 'main' pump. The in-tank pump had failed and the main pump worked okay when the tank was near full (due to gravity pressure?) but not when nearing empty.

Eric318

Fuel starvation caused by blocked fuel pipes/filter (most likely caused by rust in the tank) or by blocked air vent.

I am on my second XK engined Jag and both had both of the above.

The next Jag I buy, sorting out the fuel system will be the first thing I do...

Good luck

LHS

Don't dismiss the possibility of freezing - not the petrol but the water vapour in the air. In a car that maybe does 17 to the gallon at 60 mph you are converting 0.25 litres of petrol into vapour every minute. That sucks up a lot of heat and can turn the water vapour in the air going through the carbs into ice. Stop for a while and the stuff melts and on you go again. Check that any pipes orginally fitted to either take air from the back of the rad or from above the exhaust manifold are fitted.

Good luck.

--amadeus--

Thanks for all your help!

I have taken the car to a local mechanic who is pretty good with classics and he tells me that the issue is twofold. First the diaprams in teh carbs are leaking and secondly the fuel pump is prone to intermitant failure. Easy enough to fix - if you have teh parts. Trouble is his supplier has gone out of business.

So does this explaination sound resonible and does anyone know where I can get carb repair kits and a fuel pump for a '63 MK II???

8~)

I've used the following for Jag parts:

Martin Robey
SNG Barratt

Both UK-based.

Both have web sites with a level of online searches available. Go google.

MercMad

J&D Dickenson in Artane Dublin, as used by the Irish Jag Club !