Engine Dies

[gra]

Just had BJ8 tuned, new plubs, carbs adjusted, etc. Car hard to start when hot - acts flooded. Sometimes backfires on restart and takes a few seconds to run smooth. When driving car occassionaly dies - a couple of quick gas pedal pumps brings it back. At stops car sometimes dies when clutch depressed and brake applied but at other times does not. Checked carb floats and they are working. Fuel pump ticks when key turned on and ticks at different speeds and with different frequency at different times. I have limited skills but would like to fix if I can. Anyone have any ideas. Thanks

 

[Keoke]

IT sounds like the carbs are not adjusted properly. May be just a bit to Lean.Fwiw---Keoke

 

[gra]

Thanks. I had guessed to rich but did not see how that would cause the engine to die. I just had a good mechanic who specializes in British cars adust the carbs but clearly something is not working. gra

 

[Wings]

did u check the bottom of the float bowls for dirt (shavings)

 

[gra]

Yes - checked and they were clean. Gra

 

[why]

A few questions:
1, if you stop with foot off gas (clutch and brake in or out should not matter) and in neutral does it have a smooth idle or does the exhaust make peculiar blurping sound?
2, when running along smoothly if you press throttle does it skip before speeding up or just accelerate smoothly?
3, When you say it dies, is that when driving along at say 30 or 40 mph it just quits and you have to pull over and get it started or only when stopped at idle? If it dies when going 30 mph and you leave it in gear with key on and pull out choke, does it fire up
4, Are there any fuel filters that have been put in the gas line?
5, If you stop for just 30 min or so, does the fuel pump make clicks for about how long, just 2-3 or 6-8.
6, After a smooth run at 3000 rpm for a minute, even just standing in the driveway in neutral, and then you turn it off and take out sparkplugs, are they all a light brown, some whitish, or some blackened (sooty)?
These are all diagnostic questions, also FYI, pumping pedal in SU carburettors does not give a squirt of gas into cylinder as happens with cars with normal carbs.

 

[gra]

Here are the answers exceptwhere I need to double check a couple
1. Until hot everything is normal on a stop. Once hot mostof the time it is still ok with normal idel, however, about 30% of the time the car dies with no unusal noise from exhaust until restart. On restart car does not run smoothly and sometimes backfires then settles into normal running.
2. Most of the time at 20 to 40 miles per hour it accelerates smoothly but occasionally at that speed it is if the key were turned off. Letting up on the accelerator and altenatively pushing and letting up results in a restart at speed and everything back to normal til the next time.
3. As above - I have not yet had to pull of as it has restarted each time.
4. No fuel filters.
5. Not sure on number of clicks so will need to check.
6. Spark plugs are all light brown except for number 3 which is black and sooty.

Thanks for the questions. Perhaps they will lead to an answer. I will check on number 5 tomorrow and send reply.

Thanks again - George

 

[Keoke]

1,
if you stop with foot off gas (clutch and brake in or out should not matter) and in neutral.


That is one of the well known indicators that your engine is not
producing the proper torque under the above stated
conditions and is most commonly traced to carburetor
malfunctions.--
Fwiw--Keoke

 

[Ed_K]

Welcome to the forum !

I see that you are in Florida and it has been very hot this summer so there is a good chance it may be caused by a worn down heat shield under the carbs...
If your car runs perfect in the cooler months and runs well when first started in the summer until your car is warmed up and you are sitting at a stop light for a few minutes. Then the idle deteriorates to the point that it will not run and when you restart it will probably backfire and run very rough until you are moving down the road and cooling those fuel bowls down again. If that sounds like what yours is doing just rebuild your heat shield using a piece of hardiboard to replace the asbestos sheet. My car had that problem for a very long time and I finally rebuilt the heat shield and that cured the problem.

Ed

 

[gra]

Thank you. The carb heat shield is about a year old and in good shape.

Thanks to everyone for the input. It is much appreciated. After thinking about it I am taking the car to a local repair shop later to day to get it sorted. I will let you know what happens.

Thanks again. George

 

[RAC68]

I appreciate that you are having your problem solved locally, however, I would also like to take a shot at the diagnosis. After listening to the problems, I would look at two additional areas that I have not seen mentioned.

First, a fuel pump that is partially blocked can cause intermittent fuel starvation and kill the engine. This blockage may be displaced and/or allow sufficient fuel passage for a restart and drive until the blockage reseats.

My second thought revolves around the intermittent nature and turn-off. If the distributor ground line from the cut-off switch is loose and bounding around, it can hit a ground and abruptly cause the engine to stop.

Both conditions may not have been present and would not have impeded the car from being correctly tuned and adjusted.

All the best,
Ray 64BJ8P1

 

[gra]

Thanks Ray. I left the car with the mechanic this morning. Will have him check these and will let everyone know what the answer was ---- hopefully soon. George

 

[why]

Umm, I guess it is time to introduce you to the old English car saying: "Most of carburettor problems are electrical." It was a good year or so of fiddlng and replacing fuel system stuff for a misfire at full temperature. Just for fun I pulled out the wire from distributor to coil and at one end the contact had deteriorated, put new metal connector on end of wire, pushed it back in and problem solved. A thirty second diagnosis and 5 min fix, your problem sure does sound fuel system related..........

 

[gra]

Re: Engine Dies - Update

I left the car with the repair shop for a few days so they could drive and evaluate around the rain we have been having here. Appears the issue was sticking needle and lever in floats starving engine. Part of the time both were sticking and part of the time one was sticking. A bit of tinkering and cleaning appears to have fixed the issue. Gas tank and fuel system all new and carbs rebuilt 500 miles ago by prior owner. Putting a fuel filter on the system and cleaning carbs to ensure no 'stuff' in them. Thanks for all of the input. It was on track with the issues. Will let you know if this indeed results in a fix.

Thanks George

 

[why]

Great, glad to hear it is now fixed. At one point I was managing 9 SUs on cars that I would turn on key, push a few feet and then start so if float not shutting off fuel I would smell/see it when I went to get in car, seemed every few months at least one SU leaking. Replaced the shut off system in all with something called a "Grose jet" and in the several years since I think only once was fuel coming out and the good ol' tap with hammer on float top did the trick--by the way also the first thing to do if fuel pump not clicking when key turned on--tap it with hammer. Come to think of it, if starter binds when engine hot, same deal

 

[Patrick67BJ8]

A trick to cleaning out dirty SU carbs was shown to me back in the early '70's by a "super mechanic".
With the engine running, rev the engine quickly while placing the palm of your hand over the carb throat and quickly taking your hand away. This will cause a rush of gasoline to run through the carb cleaning a lot of junk out of it.
Patrick

 

[why]

yeah but to do that you have to first take off the air cleaners, see that thread, yuk yuk

 

[Bruce Bowker]

Went through a similar problem. After doing all the somewhat obvious, rebuilding, cleaning, checking, rechecking etc. It was the draw tube in the gas tank. The recently completely cleaned and coated tank still had what looked like sand blasting material in it. After a run it would clog up the draw tube. I assume it would then fall back out when sitting so car ran great for awhile then acted up.

A really simple problem that cost a bunch to find and little to fix.

 

[Patrick67BJ8]

yeah but to do that you have to first take off the air cleaners, see that thread, yuk yuk

You do have to take off the aircleaners unless you have a big hand or throw a rag or towek over the air cleaner.
Patrick