Car lost power and stalled

Yeldaw · Post by **Yeldaw** » Sun Apr 29, 2012 4:31 pm

I have a serie 3 e type and have just come back after taking it for a drive. I noticed when I started the car on choke it did n't have the normal acceleration until it warmed up but then it was fine once warm. However just on the final leg before home it lost power, would n't run above 20 mph and had no acceleration before it stalled. I opened the bonnet had a look for anything obvious and checked the fuel filter and every thing looked ok. It then started 1st time and ran fine home any ideas what the problem could be
Thanks Dave

JimmyS · Post by **JimmyS** » Sun Apr 29, 2012 10:40 pm

Sounds like the loss of power could have been due to carburettor icing. I ran a Mk1 Escort Mexico with no air filter as a lad and had similar symptoms with it on two occasions. The first time it happened, I pulled over, popped the bonnet and gave the usual suspects the once over. Not finding anything amiss, I was delighted to find that the car started first time a few minutes later and got me home as it should have. It niggled away at me though and a couple of days later I remembered reading about carburettor icing. As luck would have it, the power dropped off one week later on the same stretch of road at the same time of night. This time, I popped the bonnet and shone my torch on the carb to see a coating of frost on its exterior. I just waited for it to thaw in the heat rising from the engine and set off a few minutes later. If it happens again, have a quick look at the carbs before the evidence disappears!

Post by **Heuer** » Mon Apr 30, 2012 10:34 am

Dave

Did you check to see how hot the Opus (I assume you have a V12) was? Also worth checking the temperature of the coil as both are associated with the symptoms you describe. Other thing to check is the fuel tank sump filter which can get clogged up with debris after the car has been driven but after standing for a while everything settles to the bottom again. Did you refill with fuel by any chance just before the symptoms started?

More info here which might help with diagnosis:
http://etypeuk.com/forum/viewtopic.php?t=3265
http://etypeuk.com/forum/viewtopic.php? ... light=opus
http://etypeuk.com/forum/viewtopic.php? ... light=opus
http://etypeuk.com/forum/viewtopic.php? ... light=opus

Yeldaw · Post by **Yeldaw** » Mon Apr 30, 2012 6:31 pm

My V12 e type is fitted with a 5.3l HE engine from an 87 XJS. It has the Lucas AB14 ignition module rather than the OPUS system. I thought it might be that but on the basis I really only let it cool for 2mins I did n't think it would be overheating. I wonder if it could be a lose connection. I had a problem with the rev counter not working a few days before and then being OK again. From memeory I think the Rev counter might go into the ignition module.
Thanks for the Feedback
Dave

Yeldaw · Post by **Yeldaw** » Tue May 01, 2012 7:52 pm

Ok a few more symptoms. I started the car this morning and it sounded like it was missing on a couple of cylinders. Started it tonight and engine ran fine for about 3 miles and then loss of power and stalled. I had a spare ignition module and replaced it inside the AB14 ignition amplifier. I thought that had solved the issue car started first time and ran fine for approx 5 miles before loss of power and then stalled. If I leave it for 5mins the car starts fine runs great for a couple of miles and stalls. There is no back firing just a gradual loss of power before it stalls. Could it be the coil? or any other ideas?

Post by **Heuer** » Tue May 01, 2012 8:16 pm

Process of elimination so change the coil.

Yeldaw · Post by **Yeldaw** » Thu May 03, 2012 7:10 pm

Ok I have changed the coil and problems persist. Does anyone have any other ideas?

Thanks
Dave

vacbag · Post by **vacbag** » Thu May 03, 2012 7:33 pm

Dave, it sound like a problem i had a few years ago and after much searching i found out it was a cracked rotor arm. When the rotor arm shaft gets hot it opens the crack in the rotor arm and shorts out to earth, Once the rotor arm stop revolving and cools down it is ok.
The suspect arms are a tight fit on the shaft even when cold.
Steve.

PeterCrespin · Post by **PeterCrespin** » Thu May 03, 2012 9:00 pm

JimmyS wrote:Sounds like the loss of power could have been due to carburettor icing. ....If it happens again, have a quick look at the carbs before the evidence disappears!

It's generally a good idea to check a few basics, even if advice is offered in the most helpful spirit possible. V12 carbs will ice up a few seconds before hell freezes over, due to being heated by coolant exiting the cylinder head and running through the manifold plenums. Not only that, they are situated right over the exhaust manifolds.

The first thing is to check if it is carbs or ignition. Check for spark when the car fails to proceed. Until that basic parameter is clarified, there could be a lot of wasted parts replacement. Normally I would suspect the OPUS amplifier as a classic hot failure point. If it is an AB14 it is still quite possible but unless the fuel sump and filter bowl are spotless (which are sensible maintenance anyhow) I would suspect fuel starvation.

Pete

JimmyS · Post by **JimmyS** » Fri May 04, 2012 11:27 am

Hi Pete,

It sounds like carb ice is an unlikely culprit on V12s then. I must confess to being completely ignorant of their fuel induction lay out. To see if it was still a possibility however, I had a look on-line for information on the subject and found the following:

http://www.caa.co.uk/docs/33/ga_srg_09w ... ctober.pdf
This is aircraft biased being from the CAA but it explains the phenomenon well and has a useful chart on page 3. (mogas = normal car petrol)

This shows a motorcycle carburettor icing up; viewers can probably skip through the first 5 minutes(!)

Finally, http://preview.tinyurl.com/d89g3c9
An interesting report that combines the subjects of E10 fuel and carb icing.

You are probably correct in thinking carb ice unlikely. I have only knowingly experienced it twice in all the years I've been driving. If Dave eliminates all the other possibilities and the problem persists, he may like to take note of the atmospheric conditions and relative humidity prevalent at the time and get back to us.

Regards,
Jim

PeterCrespin · Post by **PeterCrespin** » Fri May 04, 2012 10:34 pm

I haven't looked at your links but there is no dispute carburettor icing is a real phenomenon. I remember Kawasaki had a problem with their water-cooled GPZ900 in the early 80s (?).

The point is simply that engines with adequately-heated intake systems don't suffer from it. Given that a V12 E-type which has run for a while has hot plenums, sitting above hot exhaust manifolds, you can be sure that carb icing is never going to happen (assuming it is not flying through cloud at 25,000 ft)....

christopher storey · Post by **christopher storey** » Sat May 05, 2012 7:23 am

Strangely enough, Peter, I cannot agree. The only car on which I ever suffered ( knowingly) carb icing was my TR7 V8, which had a water heated manifold . The icing there took place at the butterfly, and manifested itself by the throttle becoming very sticky as the shafts froze to the carb bodies ! Incidentally , those of you with infra red thermometers should try pointing one at the inlet manifold(s) of an E when it is hot. You may find the results very interesting indeed

PeterCrespin · Post by **PeterCrespin** » Sat May 05, 2012 8:55 am

Hmm, interesting.

However, before I concede an egg-on-face occurrence (of which there have been plenty and which always result in a learning experience) I would reinforce my view by saying that the V12, like the Federal E-types before it and the XJ too, draws in hot air from around the exhaust manifolds. This is to assure a blended 40C inlet temp for the Stranglebergs. Again, on any engine which has run long enough to get warm (when this misfire occured) the prospect ofV12 inlet tract icing is effectively nil.

Icing occurs inside the carb becuase that's where the fuel first evaporates (and potentially close to there and slightly downstream I suppose). The temp always drops due to latent heat of vaporisation, but with certain percentages of moistness in the air and cool inlet conditions the cold can cause the water vapour to forim ice on the throttle parts giving the symptoms you describe. Sounds liie Jimmy's Mexico had more of an icing in the jets issue if that lbockedo fueling?

Anyhow, I remain, yours sincerely

Doubting Thomas

Yeldaw · Post by **Yeldaw** » Sat May 05, 2012 9:33 am

Hi thanks for all the feedback, it does n't seem to be showing signs of carb icing. I only changed the fuel filter about a month ago and it looks pretty clean. Is there a sump filter on the v12 if so where is it. All I can see is a drain valve

JimmyS · Post by **JimmyS** » Sat May 05, 2012 3:21 pm

Pete/Thomas,

I meant to say in my last reply that my carb icing took place during some spirited driving along some quiet A class country roads at about 10pm. My car's engine & engine bay were as hot as the ambient temperature would allow. I had a sheet of metal gauze over the top of the mighty twin choke downdraught Weber to stop anything larger than a bluebottle being sucked in; so no air filter with the rotating summer/winter air intake. This allowed me to have a very good look at the carb when I lifted the bonnet. I was taken aback to see it's exterior covered virtually top to bottom in frost despite a water heated inlet manifold. This incident almost caused me to review my air filtration arrangement, however I lay down until the notion passed. I was, and remain, of the opinion that more power is obtained from a colder denser induction charge. The rpm drop experienced during the pre-flight check of an aircraft's alternate air intake is adequate evidence of this for me. Bottom line is, I suppose, that Jaguar's engineers will have designed the the V12's inlet system to heat the charge adequately so that the carbs don't ice up regularly (if at all), but surely they will have tried to stop the charge from getting so hot as to squander power unnecessarily? It's a fine line between both requirements. I bow to your superior knowledge of the V12 sir.

Regards,
Jim

PeterCrespin · Post by **PeterCrespin** » Sun May 06, 2012 9:13 pm

Yeldaw wrote:Hi thanks for all the feedback, it does n't seem to be showing signs of carb icing. I only changed the fuel filter about a month ago and it looks pretty clean. Is there a sump filter on the v12 if so where is it. All I can see is a drain valve

You have to go right through the system, from tank to float bowl. It's not just a question of debris but also water. After running the tank low I drained it and cleaned the pick-up and main filters then put flat cigar tins on the frame rails under the carbs with the float bowl drain plugs removed. I cleaned until the fuel from the bowls ran clean. On the V12 you have the extra issue of a return circulation to check/clean.

Yeldaw · Post by **Yeldaw** » Thu Jul 12, 2012 6:31 pm

Hi I thought I would give an update on my stalling problem which has now been solved. Having replaced ignition leads, coil, dizzy cap, plugs, rotor arm and ignition module the problem persisted. Eventually the car stalled and started but only ran at 20 mph before stalling. Managed to get it home and work out that the starter relay had failed. The starter relay will disengage the ballast resistor when you turn the ignition to start the car and then turns back on the ballast resistor circuit when the car starts. The problem with my car was that whilst driving the relay would switch off the ballast resistor circuit and the coil was getting a reduced voltage and therefore a poor spark. Hence the reason why the car would not rev properly and stall. When I restarted the car the switch would re-engage the ballast resistor circuit until the next bump in the road made the switch in the starter relay to turn off the ballast resistor circuit. I have never seen this problem before but thought it may help someone else in the future.

Dave

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Car lost power and stalled

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