Fuel starvation

[Stokiestag]

Having a problem with missing fuel in the engine bay filter ?.Starts first time ,runs great till it gets warm and then seems to be lacking fuel.Dont switch engine off but open bonnet and you can't see any fuel in filter ( 3/4 full before starting) engine idles ok and you can hear pump ticking intermittently.Had a garage check it last week. Pressure stayed constant and no petrol leaks.Mechanic suggested crap in the tank maybe blocking pipe occasionally.Took the tank out last Thursday and you could hear bits swilling about so brought a kit and cleaned it and coated it as required.Out came 5 lumps of lead and bits of rusting mesh !!.Tried it today but no different.Should air be pressurised in the system ? Cheers for any suggestions.
Mark

[Lingen]

Mark. That is perfectly normal.The fuel filter will only fill completely if you mount it vertically with the inlet at the bottom. Vapour collects in there as the fuel warms up, when it is mounted horizontally, but this has no effect on the supply of fuel to the carburettors.
Mike.

[Stokiestag]

Cheers mike, after 15 mins of sitting with bonnet open, the filter was empty, turned ignition on and rapid pump noise and the filter filled to 3/4 in about 3seconds . Any idea why I keep getting the “missing “ especially going upbank?

[Phil S]

Could be the points sticking in the fuel pump. Not sure if the stag has a condenser fitted but we used to fit one to mini and moggies to stop this.
check the points and give me a clean if needed.
symptoms are the same as when the pump works all is well, then under high demand they stick.
Phil

[Stokiestag]

Changed the pump 2 weeks ago but no different, could it be carburettor?

[Alanmax]

Had the same with mine. Fitted a filter king, cleaned out the float bowls ,( full of crap) set the floats to correct hight and fitted new float valves. now all is well.

[Stokiestag]

Hi Alan, what’s the best kit I need to buy ?, will definitely be doing that next. Is there a write up on how to do it
cheers Mark

[Alanmax]

I don't think they do a kit, I bought a filter king from ebay new float valves from J P,+ you will need a new pedestal O ring when you take the Carbs off. I don't think there's a write up, just follow the work shop manual on how to remove the carbs and float bowls. + how to set the float hight, the valves just unscrew and new one's screw straight in. All the best Alan

[barkerwilliams]

The fuel pump draws fuel up from the tank before sending it off to the engine. Ensure the gasket on the tank side of the pump is a perfect seal. Any air getting past the gasket into the pump breaks the vacuum needed to raise the fuel to the pump and the volume of fuel pumped to the engine is reduced.

Alan

[Stokiestag]

Changed the air valves,set the floats,changed the filter ( for a normal one ), still getting the " missing " when starting after a run out ?. Filter is still empty and it takes about 1/2 mile and then it clears itself !!.When you start from cold the filter fills straight away to 3/4 full but after a run it stays empty.Any thoughts what next to try?, how can the air be released from the system to allow the pump to pressurise fuel and not air ?.There are no air bleed valves on the side of my carbs , should there be.Runs great otherwise.

[Guest]

Hi Mark
I can very much sympathise with you as my Stag didn't perform very well for almost 1 1/2 years. This is not a recommendation but I list the process I went through based on bad advice from local German workshops ( cost me a lot of money wiht the car sometimes returning even worse than before) and better ones from this place (cost money as well! but more to the point). In the end a chap from the forum helped me to sort things out for good.
Maybe something jogs your mind you want to try or things you may want to avoid.
It all started after I changed the fuel filter in late summer last year. I only had the car for a couple of years and no record of a fuel filter change for the 15 yrs before that, it was opaques so I thought it a good idea to change it for a clear see through version.
Soon after that the car sometimes stopped in mid drive which became more persistent over time and in the end I hardly could get it our of the garage to limp back on half a cylinder bank probably only half a cylinder.
Of course I thought the filter change was to blame and I found what I think were rust particles in the old filter. With the new filter sometimes empty I banked on a new fuel pump and filter before the pump thinking I could perform a fuel tank restoration during the winter. But the original success was soon dampened again.
I invested in a 2nd pump as my German workshop advised me the 1st one must be dead runing it with rust in the tank. Which wasn't the case, I have 2 pumps now.
Restored the tank which wasn't rusty at all. checked all plugs and leads.
I then replaced the diaphragms in the carbs, new rotor arm in the distributor and new coil.
In the end my friend found 2 tiny particles the size of a sand grain in the carb inlet valves made of plastic. I blame the old filter. Mabe collapsing inside due to the new fuel types.
He also discovered that theres was a tiny pin hole on 1 of the floats which made it run full and fuel coming in.
I was also advised on replacing the fuel line from back to front as this can collapse with the new fuel as well. Was on my list next.

There are now bleed valves and I don't think filter Kings are required.

I hope you may find this a liitls helpfull.

cheers Hans

[Stokiestag]

Cheers Hans, I've virtually done everything you have listed and was thinking about doing the fuel pipes.Think I will leave that now, like I've said,I've done the tank,filter, float valves ( very clean inside),changed pump,but still no joy ?. I have got a spare set of carbs in the shed ( condition unknown but very clean) so I might just try em to see what happens.I don't understand why the filter is empty of fuel while running, where does the vapour/ air go after restarting ?, straight into the float chambers ?,is this why it is being starved of fuel for a short while ?, very confused
Mark

[Guest]

Well if you pump is working the cause must be the regulatory item in the carbs demanding the amount of fuel necessary for the state of speed you are going.
Has that not to do with the diaphragms? Have you changed them? There are tiny holes in them when they are damaged or even torn.

[Stokiestag]

You’ve guessed it Hans, changed the diaphragms Monday, no holes in the old ones though.
Baffling eh !

[Stagdad]

Are you getting a tank vacuum? Have you done a flow test?