MK1 fueling issues?

[sahtuning2000]

Hi folks!
Been a long time since I,ve been on here but my dad still has his LHD MK1 owned 44 years this year!!
So at the moment he has an issue with the car,it starts fine but after a short time maybe 2-3 minutes its starts to splutter and cuts out....
The fuel is good,he has stripped and rebuilt the fuel pump,fuel is getting to the carbs and he has replaced the floats and checked the valves etc,there is a very strong spark,it is as if its just running on the fuel in the lines and carb chambers then stopping,but my dad says that when it happens the fuel pump glass bowl is full which suggests the fuel is getting to the pump and there isn,t a blockage from the tank to the pump?
Any ideas,when fixed I will be getting the old girl to give her a bit of TLC.......

[Dave B]

Fuel tank breather blocked? Try running it with the filler cap off for a while.

[Alec]

Hello SAH,

another possibility is debris in teh fuel tank blocking the outlet. However I had a problem in a Scimitar I owned which gave symptoms of fuel starvatiuon but actually was a defectice capacitor in the distributor. I found that the cause was electrical by using my timing light which showed no spark as being the cause of the engine stopping.

Alec

[johnnydog]

Is there pressure / vacuum created at the fuel pump - ie if you take the fuel pipes off, and put your fingers over the inlet pipe, and then operate the thumb lever, you should feel / hear air being sucked in when you release your finger on the fuel pipe. Equally if you just release the outlet side, and operate the thumb lever, are you getting fuel through (don't forget a recepticle to catch the fuel!)? If the car stands for a period before a start up, if the supply of fuel is partially restricted, either through crud in the bottom of the tank, or a blocked fuel filter if an external one has been fitted, or corrosion in the metal pipe running between the carbs by the cylinder head, some fuel may get to the carbs whilst standing sufficiently to start the car, but not to keep it running when the fuel in the float chambers has been used up.
You say the carbs have been rebuilt. Did you replace the float / needle valves with new? Did you set the tabs on the floats at the correct height? If you did replace the float / needle vales, then I would seriously consider putting the old original ones back. The new ones do not seem to seal properly when shut i.e. when the fuel is at the correct level and the tab supposedly should shut the valve, fuel is still allowed into the float chamber, and it basically floods the carb which will then cause the engine to cut out.
Have you noticed a smell of fuel, or signs of fuel leaks either in the air filter box, or trickling out of the brass vent tube on the flange behind the air filter box?
If fuel is getting through correctly on a cold start up, but then it splutters and conks out after a short time, this is exactly what was happening to both my Mk1 and Mk2, surprisingly both after I rebuilt the Strombergs with genuine Zenith kits. Also surprisingly, both were cured by refitting the original float / needle valves.
Just something else to check.

[Clifford Pope]

Yesterday mine suddenly started misfiring. It ran perfectly up to a certain speed, than faultered and wouldn't rev up or pull hard, yet it idled perfectly.
Classic fuel starvation problem, I thought.
But no, it was the the condensor. It was only a year old from one of our very reliable sources, but it was evidently breaking down.

There's an old saying - most fuel problems are ignition, and most ignition problems are the condensor.
All modern ones are useless, you just need to carry several spares.

[Dave B]

All modern ones are useless, you just need to carry several spares.

Or just fit & forget electrnic ignition. I can only speak as I find.

[sahtuning2000]

Thanks chaps,all these ideas have been passed onto my Dad,who only today has fitted an electronic ignition that he bought recently,he hasn,t tried starting it yet as he is going through all the checks,but has confirmed that the pump is working as it should,and fuel is fine to the carbs,he has checked all the pipes and rubber connection hoses all fine,but found the dizzy was loose on the baseclamp and had moved,so he has replaced this with a new unit and fingers crossed tomorrow it will run fine,will let you know.

[sahtuning2000]

Thanks chaps,all these ideas have been passed onto my Dad,who only today has fitted an electronic ignition that he bought recently,he hasn,t tried starting it yet as he is going through all the checks,but has confirmed that the pump is working as it should,and fuel is fine to the carbs,he has checked all the pipes and rubber connection hoses all fine,but found the dizzy was loose on the baseclamp and had moved,so he has replaced this with a new unit and fingers crossed tomorrow it will run fine,will let you know.

[sahtuning2000]

O.k latest update is it still will not start!
My Dad has gone through lots of checks,but what he hasn,t checked are the carb diaphrams and he is trying to start it with no air filter box on it?So he is looking at the diaphrams today and refitting the air box,there is a strong spark and the plugs are getting wet with fuel.
He said he has even compression across all cylinders and has checked all the valve clearances
so....
It has fuel,all lines checked and pump diaphragm replaced,pump is sucking and blowing,fuel getting to carbs and is clean,filling up pump and carbs,plugs are wet with fuel.
Has brand new electronic dizzy(had the same issue with points/condenser)cap is new,leads are correct way and strong spark at plugs.
Valve clearances checked and fine,compression check done and was even.
He is now talking about removing the head,but I think this is a little drastic???

[Clifford Pope]

Are the strong sparks coming at the right time, or has the distributor been moved? Is the electronic kit timed correctly?

A couple of years ago I tried to fit a Petronix conversion. It was supposed to be a straight fit, but the engine wouldn't run. The sparks were not coinciding with cap segments, but about half way between. Clearly there was something wrong with the way the mounting plate fitted to the distributor, eg the mounting hole in the wrong place. I never did resolve the problem so went back to points, which of course have their own problems.