Engine has a flat spot and sometimes Hesitates

[andy8688]

I have a series 2, sometimes the engine seems to die down, then suddenly picks up. The car has been fully serviced, I did have problems prior to the service but was OK after, It seems like it is starved of fuel, the problem started a few weeks ago only a minor flat spot, but has increasingly got worse.
I recently topped up the carb dampers with engine oil sae 20 50 would this be a problem.

Andy [/b]

[Heuer]

Andy

20w-50 oil is fine in the dampers. First thing to check is that all the fuel line filters are clear - the tank sump filter (generally lots of crud but you need to empty most of the tank first!), the glass bowl filter and the mesh filter in each carb. If they are clear and the problem persists it might be worth buying a cheap fuel pressure gauge to check the pump is operating correctly. See here for details: http://etypeuk.com/forum/viewtopic.php?t=164

Worth checking through the electrics and possibly replace the HT leads and coil if they are more than 8 years old. Check the distributor for wear and consider installing a 123 ignition if it looks problematic. Just a case of eliminating all the possible areas of problem

[Bill Molloy]

Andy, the oil in the carb dashpots only effects hard acceleration so it won't be that as long as there is oil in there.

I'm assuming that the points, plugs etc have been checked and are fine ?

If you think it is fuel starvation an easy test is to pull the choke out a bit when it happens and see if that helps.

have you got SU's or Strombergs on it ?

[andy8688]

I have got SUs, I will try changing HT leads and the coil, thanks.

Andy

[Moeregaard]

Andy, once you determine that it's not an ignition problems (from the symptoms you describe, it doesn't appear to be), check your carburetter float levels. If too low you will experience starvation during any form of acceleration--braking, cornering and hard acceleration.

If it's a problem that appears and then seems to fix itself after a few minutes, I would have a look at the fuel-tank venting system, especially if your car was repatriated from the U.S. and still has all the evaporative emission controls in place that were standard on the Series 2 for that market.

The only other possibility I can think of right now (it's before my morning coffee as a write this) is that you've got an intermittent vacuum leak somewhere.

[andy8688]

I went to start the car this morning to take out on a drive, as I turned the key it did not want to fire.
After about six attempts it finally fired and backfired, left it idling for about 5 minutes and the engine just died, after I got it going again it ran fine for about 10 miles and then it started losing power, I managed to keep the engine going, but I did try pulling out the choke and the engine just cut out.

I have been using shell optimax high octane fuel, would this make a difference as the compression ratio on this car is 8 to 1.

Andy

[Heuer]

Andy

Shell Optimax is 99 octane but will make little difference to your 8.1 engine although it will lighten your pocket! Suggest:

1. Check fuel supply (remove pipe from filter bowl and put into glass jar) which should pump immediately ignition is switched on.

2. If you have conventional ignition check contact breaker points are set correctly.

3. Check rotor arm for cracks or tracking

4. Check distributor cap for cracks and tracking

5. Is your ignition ballast or un-ballasted?

You need to eliminate some potential sources of trouble so we can focus down on the problem.

[christopher storey]

This is beginning to resemble the pattern part rotor arm problem which is so prevalent, where the arm becomes earthed when it gets hot because it is made of incorrect materials. Try a. substitution of the rotor arm and/or b. inserting a layer of cling film or similar between the underside of the arm and the spigot on which it fits

The other test I would suggest ( but not when driving) is to disconnect the servo vacuum hose and plug the manifold . The servos are very often dubious , and a vacuum leak would probably cause many of your symptoms

[andy8688]

Thanks to you all for your replys, today I took the the car for a tune up, he took the carbs apart only to find the float levels where to high so he had to bend a fork like shape piece.
The middle carb was slightly sticking, the other problem he found was that my radiator fans were not working, loose connection, ran the car today for about 20 miles only one small bit of hesitance, fuel pump is OK other thing it could be is fuel vapourisation. Could this be the hot weather we are having.

Andy

[Heuer]

Andy

Could have been vaporisation if the fans were not working but unlikely to be so otherwise - the weather is not that hot. You could try running the car without the air filter canister which will have the effect of making the mixture richer - no harm will come of it and it may give us a guide (it will also sound great ). Next up will be checking the distributor/rotor arm (as Chris suggested) and condition of the HT plug leads. When you took the car for a 'tune-up' did they check the timing?

When was the car last serviced by a specialist? Maybe worth booking the car in with Ken Verity at Series One Spares - 01709 838352 or CMC as they are both in your general area

[andy8688]

David

I had the car fully serviced about two months ago, I have replaced vertually everything.
I took the car for a refuel this morning before having the work done and it misfired, backfired, so he has made some improvement, I can actually drive it now with a bit more confidence, breaking down at the side of the road in an E-Type is embarrassing.

Andy

[Moeregaard]

Years ago (1980s) I had all sorts of problems with non-Lucas rotors and caps, but it usually immobilized the car completely. A tracked cap can sometimes be saved by putting it in the dishwasher with the dinner plates--this really works!

If the fuel pump is good I wouldn't suspect vapor-lock. I've run E-Types in 40C-plus conditions and the only thing vapor-locking was the driver. It's good to hear that the float levels are now correct.

David also suggested checking the tank sump filter. You may have something in the tank sufficiently buoyant to float around in there and periodically plug the pickup--not unlike the old prank of stuffing a plastic sandwich baggie in someone's fuel tank (not that I ever did this...). If the tank is full, find an area well away from the water heater and clothes dryer, and remove the pickup plate with its dip tube.

If none of this turns out to be the problem, I'll lay odds that there's an intermittent vacuum leak somewhere.