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HT leads?

Just reminds me of the coil, even though its been replaced.

sounds daft but if its got an su carb check theres oil in the dashpot.....no oil could be causing it to flood too much fuel when warn but enough to start it from cold..............sadly a lot of garages carnt fix old stuff....its a dieing art lol

I had a Mini which normally ran OK but
on a long run would misfire. After cooling
down it would be OK. It was fitted with HT
leads with what seemed like carbon conductors
presumably acting as TV suppressors? Anyway
I replaced them with copper cored HT leads
(coil and plug) and it cured the problem.
When I cut open the old leads there were gaps
in the conductors.

Earlier I had a Ford 100E with a mechanical
fuel pump which also failed when the engine
was hot. Pump replacement cured it.

Might also be worth checking if the fuel tank
is developing a vacuum while running if no
venting. This can stop fuel flow. Test by
leaving petrol cap off on a run but don't
leave it that way!

Folks

A few good pointers there. I am sure the HT leads (and dizzy cap/ rotor) were replaced within the last 1500 miles.

Vac forming in tank - unlikely but a good point.

Let us see what Village Motors will say. I went there this morning and demonstrated to them that the car would start easy when cold - it did, first turn of the key. Then ran nicely. Told THEM to run it to hot and see

Snod

Demented Update

Still no "answer" to the problem
The garage confirm all I have said. Starts from cold perfectly and runs with a nice even tick-over. However, when it gets hot it will not re-start

They report
- SOMETIMES there is no/ weak spark at all plugs
There is a 12V feed to the coil when this happens but they will do a hot wire job as a secondary check

A duff coil cannot be ruled out but the first step is to try new HT lead coil to dizzy. It is unlikely to be an HT to plug because logically that would probably not affect all 4 plugs

- SOMETIMES there seems to be no fuel to the engine ie plugs are dry even after cranking the engine a lot to try to get it to start.

Carb has been opened and the float seems to be working OK.
Sound like the classic "vapour loc" problem but the mechanical pump does work OK (so not a diaphragm gone) when tested. I have suggested making SURE there is no tank vacuum problem (take the cap off) and to blow the tubes, even back from the pump to the tank if that is technically possible.

Yesterday I had a problem with another engine - on a motor mower. Would not start/ run except on a bit of petrol poured directly into the air intake. When I stripped the carb it was full of JELLY. Modern fuels with biofuel components will do this ie pick up moisture and make jelly. The mower had been in a shed all winter. The car had been in an unheated garage.

Humm

Snod

Turnips Dad here. give me a call if they cant sort it. these cars are my era. worked on these at Windsor's in the early 80's.

Has it been laid up with an empty fuel tank? I mention this as you may have internal corrosion in the tank causing a restriction at the pick up (stack pipe)when the vehicle is moved/driven.... just a thought as you mentioned it sometimes gave the impression of no fuel delivery to the engine. also check the wire from the coil to the distributor and the wire from the base plate to the connection on the distributor which attaches to the negative wire as it may have a high resistance which is aggravated as the engine gets hot. Check the King Lead HT lead, if this fails there will be no spark to the dissy cap.

Turnip - thanks to your dad. Comments noted and will follow up.
If dad worked in Windsors in early 80s he has likely even worked on the car at some time.

There is bound to be some sediment / corrosion in the tank after 42 years. The old in-line filter I replaced did contain some fine black sediment - although not a lot. This potential problem is why I suggested the garage should (if it is possible) blow air back to the tank from the fuel pump inlet.

Snod

I am now convinced this is a fuel delivery problem!

I brought the car back from the garage because they are too busy to do anything other than some preliminary tests.

It started fine because the engine was cold and it is only a short drive to my house.

This afternoon I checked fuel flow from the pump (cold engine) and no problem

Also checked the filter to carb pipe was fully clear/ the float valve worked ok etc and I cleaned the carb jet/ needle/ float chamber well with proper cleaner.

This evening I ran the engine from cold up to normal working temperature while watching the fuel in the transparent in-line fuel filter

After 8-10 mins small bubbles started to come through with the fuel. After a minute or so more these became larger and more frequent until eventually the bubbles filled the outlet pipe of the in-line filter. At this point the engine started to falter and then eventually stopped. Trying to rev the engine did not clear the bubbles.

Removing the top of the float chamber showed it to be near empty.

I checked the spark at the plus (easy when it has gone dark) and there was spark there at all plugs.

The fuel filter DOES GET warm - not a lot but definitely warm. Understandable given the mechanical pump at the back of the engine and that the pipe to the carb runs up past the exhaust manifold. There is no other way it can run.

Looks to me like the fuel pump has a fault but .. but others may have advice

- esp Turnip's dad !!!

Snod

Could the in line filter be the wrong way around?.

Difficult to answer that one Zip. There is now "flow direction" indicator on the filter body and as bought no instructions. I can TRY changing it around tomorrow. Bit late now.

I suspect the diaphragm in the fuel pump has developed a few leaks and when warm it does not deliver enough pressure

Snod

I have just been reading on this link, might be of use
http://forums.tdiclub.com/showthread.php?t=342025

Nice find Zip. Will take me a while to read through it though. A lot does not apply to an ancient petrol engine with an SU carb but maybe some good pointers.

Thanks

Snod

Hi Snod, this is what I would do.......Using the process of elimination I would isolate the fuel supply from the tank by removing the delivery pipe at the inlet of the pump, blank off this pipe to stop any fuel loss.
Use a container (an old plastic fuel can) as a second source to act as a fuel reservoir, drill the top and place a delivery tube with an equivalent internal diameter as the original delivery pipe.
I would, at a later point fit a hand primer pump to the line.
Place the fuel tank in the passenger footwell and also have a passenger to assist you.
You have now eliminated the fuel tank and associated fuel delivery equipment. Now take it for a run, if it operates without any problems you have located that the problem lies with the tank or the fuel system delivery; if it does fail fit and you use the hand primer as a back up to the pump and deliver the fuel by hand, if it now runs ok you have identified that it is the fuel pump. The fuel pump uses poppet valves to allow the one way flow of the fuel, it is possible that these are not seating properly due to debris in the system and if this is the case then the hand primer has a one way valve and will compensate for this.
I could put the above equipment together and I can assist if you wish, give me a call – 07973402021.

Have you checked the choke is working correctly? Starts well when cold, won't start when hot maybe suggests choke is not working. Just a thought.,