Fuel problem, fault find strategy help please.

[jellypig]

Hi,

First off, I havent had my car very long. (Late S2, FHC, LHD, Ex-USA)

On arrival it had blocked float chamber valves - stripped, cleaned, replaced.
It had a 2nd fuel pump (aftermarket) in the engine bay - removed. (clearly a sticking plaster)
The pipe from filter to carbs was then too short - replaced.
The filter bowl was filthy - removed, cleaned, new filter, replaced.

I have no idea why there was that second pump.
I have not seen the OEM pump, but can hear it , and when the engine's running the pump is giving nice loud clicks.
With a few squirts of easy start into the carbs, the engine fires and runs sweetly. (OK, the throttle pedal, and linkage are both way off, but thats a job for another day)


But.. when left overnight all the fuel runs back into the tank - or more precisely the fuel level in the glass bowl filter drops to about 10mm up from the bottom, I don't know if its run out of the floats too.

I haven't attempted any form of repair yet only thinking about what to do.

When I now turn the key, the OEM pump clicks 4 or so times and recharges the bowl, but not enough to allow the car to start without a manual squirt into the carbs.

Obviously one potential source of trouble would be the original pump. Dont' they have a non-return valve?

I guess there is further evidence that it has "issues" because the former keeper added a second electrical pump in the engine bay. I've not actually looked at the pump, only felt and heard it. I'd read they can be a bit awkward to get out, so I thought I'd leave well alone unless I had to.


But.. what would be your diagnostic fault find on the whole system?
I thought of removing the pipe to the carbs and bagging it over - meaning zero change of an airleak at the carb end, but then realised that didnt tell me that much so havent done that yet, and thought the whole job needed a proper think given that I need to leave it a few hours between stages to see if it worked.

Any ideas?


Thanks.

[cactusman]

The su pump you have should tick to fill the float chambers. Once the float chambers are full the float valves shut and pressure in the fuel line rises. The pump has a pressure switch built in that stops the pump once the line is pressurised. So on initial switch on you should hear a few clicks as the system is filled and pressurised. If there is a leak the pump will tick endlessly. No tick equals dead pump.
So from your description the pump is OK. There will probably be some air in the filter bowl. I would not worry unduely. However to be sure the pump is OK remove the pipe from the carb inlet and pop into a jar. Switch on and you should get a good flow?
From your description though I would suspect a carburetion issue. Is the choke functioning? If it starts from hot but not cold then chance is a choke issue. I would fix the issue rather than use eazystart as it is for dire emergency and is not good for the engine!.

[mgcjag]

Hi You dont mention your name.....the pump has a check valve built in that prevents the fuel running back...sounds like a fault there....the pumps are awkward to get out but quite a simple job...small hands help....if you do replace it go for tbe electronic replacement..looks exactly the same and you still hear the pump ticking.. Steve

[BRM]

Hi, as above . . . If the pump ticks a few times and then stops and at that time the float chambers are full, and it runs fine once started that sounds quite normal. It seems that your only real issue is starting when the car has been standing. As Julian said check that the choke linkage is operating all carbs equally and that the cable adjustment is giving you maximum movement of the jets. It seems that E types need all the choke they can get for cold starting.

Also you mention fitting new float needles. Did you check the float levels while you were at it. If the fuel level is a bit low it won't help.

As Steve said removing the pump is not difficult. I recently changed mine for an electronic one as a precaution before a long trip and carry the original as a spare. Remove the oval access panel on the right hand side and remove the spare wheel so you can get at it from underneath. It's a bit fiddly but not difficult unless you've got sausages for fingers and a bad back.

[jellypig]

Thanks Chaps.

Thats all really very useful.

I can follow your logic, and agree with it - specifically chokes. I've no doubt that my carbs are badly adjusted. Working in a single garage with a driveway that has quite a pronounced slope, "Acceptable" at this stage in proceedings would be , starting well enough to facilitate jiggling at home, and I hope soon, taking it for its MOT. Performance, clean and more optimum running can wait. (probably for tuning and balancing by others)


Ok, so when I got the car, the front choke cable wasnt even connected, but it is now. But I'll check again following the "all it can get" comment, I'll look again at how far they operate, and I'll hold open the lever (pressure from the cables pulls it back to half way if released) , when I try and start the car tomorrow. So should the lever fully up equate to the chokes open to the stops? And should it stay at the top of its own accord or should I have to hold it there?


And yes, the pump does exactly as described, a few clicks when I turn the key and then stops, with the occasional click when running.

Float levels? You've got me there. I changed the float valves. I changed the gasket. I changed the floats themselves (I think they were ?10 - piece of mind) . But how do I set the chamber level? (Stromberg carb) I don't remember there being any form of adjustment on the floats or valve, but am happy to be guided.



As for "luck" , its not going tremendously well if I'm honest, when I thought I'd crack on with a few other jobs whilst I thought about "fuelling" and :

1) Have changed the front pads and flexible hoses, but "willing (bleeding) assistants" are suddenly in short supply. Job halted. Pads probably didnt need it for wear, but I dont' know how old they were. Flexi hoses arent in bad shape, but again its a risk so I changed them...

2) I appear to have developed a coolant leak that's only manifested itself now the front end of the car is in the air. Can't see exactly where its coming from yet. Water pump area I think. But am puzzled that its only started since I raised the front end up to do 1)

3) Changed the plugs and coil, which was painless, but I don't own a spanner large enough to crank the engine to check/set the points. Annoying. I did consider cranking the engine hoping to get lucky, but decided that was daft, there will other reasons to crank the engine, so I aught to get the socket. I didnt want to appeal for assistance with fuel until I knew "spark" was fully sorted.

4) The cooling fan's have been behaving randomly, and although am sure its probably a dirty electrical connection somewhere, I thought I'd change the Otter Switch - just from a safety perspective. One nut was fine. One had previously sheared off leaving very little thread and no nut, and I've just sheared the third one off. (despite being very steady, and using lots of penetrating oil) Am guessing it wont tighten back with only 1 1/2 out of 3 nuts, so I'll have to replace 2 of the studs or rotate 60degs and retap 3 holes? Radiator out or Bonnet off?


And so am feeling a bit tested if I'm honest.
But I'll get there.


Thanks for your help, chaps

Matt

[BRM]

Sorry, I was assuming SU carbs. Perhaps I should have guessed you had Strombergs being a USA car. I have no experience of them so someone else will have to advise you.

[jellypig]

Sorry, I was assuming SU carbs. Perhaps I should have guessed you had Strombergs being a USA car. I have no experience of them so someone else will have to advise you.

That's OK. Thanks though.

Have more thinking time on the fuel thing now... broke a stud on the otter switch, and so the radiator is now sitting leant up against the wall of the garage.

[rolando38]

. for the fuel: you assume some fuel goes back to the tank but have you checked it does'nt drip below the carbs ?
. for the otter swithc I also broke one of the 3 studs; it seems ok to run with only 2; still, access is OK with the bonnet only fully bent forward (and car lifted on front), I wouldn't try to remove the rad at this stage; tell me if you manage to remove studs and retap

[jellypig]

. for the fuel: you assume some fuel goes back to the tank but have you checked it does'nt drip below the carbs ?
. for the otter swithc I also broke one of the 3 studs; it seems ok to run with only 2; still, access is OK with the bonnet only fully bent forward (and car lifted on front), I wouldn't try to remove the rad at this stage; tell me if you manage to remove studs and retap

Fuel - it did used to weap a little

but its dry now.
Have done not further work on fuel today.. been fighting the radiator.

Radiator - is already out of the car. Bit of a struggle to remove it on my own, especially being a US car and having the work round the AC condensor and the Alternator up high. But with it out of the car, I can detail the front of the engine, clean everything up and have a look at the water pump. Plus its a great time to change the thermostat and coolant.

[nefematic]

The choke lever should stay on its own, i believe. Mine had pretty much the same issues. After cleaning the choke mechanisms, and a bit of oil on the mechanism and the lines, your choke lever might stay where you put it.

Martin

[andrewh]

This may be off the wall, but if your fuel tank is not venting perhaps you are getting a vacuum in the tank which pulls the fuel back into the tank when the pump stops? Clearly the non return valve in the pump may well be the culprit as well. Perhaps worth checking the vent pipe is clear.

Edit. Of course the vacuum in the tank if indeed there is one may well be overriding the valve in the fuel pump but you would expect the engine to starve of fuel after a while.

[cactusman]

Sorry. I have SU carbs so can't say much about Stromberg's. However if the carbs are miles out the car will be a pig to start. Check the needle location VERY carefully. On my SU's one needle was 2mm too far up in the piston. Made a HUGE difference when all three were correct. Good luck with the radiator. Remember to apply cooper grease to every bolt as you refit. Makes removal later a doddle. Non original I know but if you can use stainless steel nuts and bolts (not in suspension or steering or brakes) to refit things like radiators and engine ancillaries. 20 years later they will be like new. Ahhh the joys of classic car ownership. It will be worth all the strife, grazed knuckes, oil and bits when she does run like she should! Good luck. Julian

[jellypig]

Again, thanks all.


Tank vent - I don't know if that works or not, but I get the same issue if I leave the filler cap off. So I suspect it does

Carb Setup - maybe it just "off" a bit , I'll certainly have a better look next time I;m working in that parish. And I'll definitely take you chap's guidance on chokes , its many years since I last dabbled in the black arts of carburettors, I was brave young and foolish, and I had hoped/assumed that if I could just get these running "good enough" I'd be able to employ a guru to fine tune, sounds like I need get a lot nearer than "good enough" from the offing.


And although I set off today with a mission of improving the starting and ending up with no progress on that, and now a broken stud on the radiator and it out of the car, I'm calling it a positive day. (and when I thaw out I might even smile. Maybe.)

I can fix the radiator, and whilst its off, refurb a load of the fittings around it.
I can get to a load of electrical connectors and clean all their contacts and terminations enhancing their reliability long term.
I can get to have a good look at my water pump and some of the about a million jubilee clips and pipes on the cooling system.
I've already made a start on removing the thermostat for replacement, and I'll definitely know the coolant is brand new, because now I've got to replace it.
I'll probably also change the alternator belt too whilst I'm at it, because its 90% off now to make room for the rad.
So.. although I've added a week to the programme, I'll end up with a better car, eventually.

[rolando38]

please take pictures and give details on replacement of broken studs

[jellypig]

please take pictures and give details on replacement of broken studs

Sorry its a really rubbish photo


The one just past 12 O'Clock only has about 3 or 4 turns of thread and is not long enough, broken before I started.

The the one at 4 O'Clock is intact.

The one at about 8 O'Clock is sheered off almost flush with surface.

Because the Otter Switch is a Reuleaux triangle (a word I just found on the internet. https://en.wikipedia.org/wiki/Reuleaux_triangle) I think I can rotate it 60degrees drill and retap leaving those 3 as is.
But its been really cold today and I didnt offer it up to try, because I was cold.

[PeterCrespin]

You said:
But.. when left overnight all the fuel runs back into the tank - or more precisely the fuel level in the glass bowl filter drops to about 10mm up from the bottom, I don't know if its run out of the floats too.

This is impossible unless you have a cracked glass bowl. Fuel can't leak through glass and gravity stops it climbing over the sides. I suspect the bowl was never full rather than the petrol escapes from a fuel proof housing. If it's parked on a very steep slope and the bowl gasket is naff it can seep and drop a bit but winding up with only 10mm of fuel from full, overnight, makes it sounds highly improbable that it was ever much higher?

The in/out connections are above fuel level so no run-back is possible from bowl to tank.

If you've just replaced the filter it's not an issue but most modern elements keep the dirt inside instead of in the bowl so it can be blocked but look OK.

The American S2.has no fuel cap vent, but you've eliminated that anyway.

Strangleberg carbs are a bit fussier in the choke department than SU. Plus they have temperature compensators and variable vacuum connections. Have you got a manual?

[JagWaugh]

please take pictures and give details on replacement of broken studs

Sorry its a really rubbish photo

One way to get those broken studs out (if they are Ferrous) is to boil them out. Center drill them to reduce the mass of Fe, then arrange a tank of Alum & Water and heat to a boil. The Alum will dissolve the steel (Even a bolt extractor) but not touch the non ferrous metals. It will take a while (24 hours or more depending on how much steel needs dissolving), but it will dissolve the screw, leaving the threaded hole perfectly intact.

I did this on an intake rail from a saloon a couple of years ago - it worked quite well. See http://www.jag-lovers.org/v.htm?id=1380816154 for details.

Andrew

[rolando38]

Because the Otter Switch is a Reuleaux triangle (a word I just found on the internet. https://en.wikipedia.org/wiki/Reuleaux_triangle) I think I can rotate it 60degrees drill and retap leaving those 3 as is.

didn't know the term either
actually you can turn it any nb of degrees, as most convenient
you wil have to eliminate the remaining studs flush, I think
I'm not sure what result you get when drilling aside from existing studs, there might not be enough material
Finally, why not re-drill and tap faulty studs holes at a slightly bigger diameter ?
did you find suitable studs ?

[jellypig]

Wow... lots of stuff to reply to.

Fuel - there was a definite tide mark in the glass bowl, fuel had gone somewhere. I suspected, because it fitted the data, air leak somewhere, tank lower than the filter, adequately venting tank, hence air entering and allowing the fuel to flow .

But, you are right - the "in" and "out" of the filter is above the glass. So am doubting myself now!
:D

But honestly, I was sure of it. Tide Mark. Turn key, many clicks from the pump, no tide mark. Maybe I was seeing the bottom of the glass? Maybe I am going daft (er).
When I get the car back in almost one piece I'll look seriously at the chokes. Thank you all.


Studs. - I've done nothing with it all yet. I landed it on the garage floor, took that photo and retired to the house to thaw out. So am not sure if those existing studs are tapped in, welded in - but i do know that the material ring round where the otter switch goes felt the same thickness all the way round so I'm confident I can fix that.

Am hoping to get some "garage time" later, but domestic things are beckoning.

[jellypig]

I did this on an intake rail from a saloon a couple of years ago - it worked quite well. See http://www.jag-lovers.org/v.htm?id=1380816154 for details.

Andrew

Wow. The boiling out with Alum is really cool. I hope I don't need to do that, but it sounds exciting!.