Stromberg leaking fuel

[euan douglas]

Have just picked up a problem with the front carb on my GT6.  It has been running perfectly in the time I have had it but suddenly there is a huge amount of fuel coming out of the front carb and it is pouring down from underneath with the result that the engine runs very rough.

 

I don't know much about Strombergs, is it a simple matter to get the float chamber off if that is what is required?  Does anyone have any ideas as to the best way to proceed.

 

Thanks for any help

 

Euan

[Guest]

Hello Euan.

 

I had exactly the same problem with one of the carbs (think it was front as well) on my Vitesse.

 

My initial thought was a sticking float. I gave the carb a sharp semi-hard tap on the body a couple of times and problem sorted. It has never returned to date; so my initial suspicion was probably correct.

 

So, it is possible you may have a bit of muck in the carb affecting the float. Worth trying the above and if that does not sort it then a quick strip of the carb with a blow through & clean-up should get it operating properly.

 

I have always used a decent in-line fuel filter but goes to show that even they are not infallible; if it was a bit of muck circulating. 

 

if you look back through the fuel section on the Forum, you will note it is a topic covered from a mere tap on the side of the carb to a full overhaul of the fuel system. Hopefully your issue will be in the minor category.

 

My top tip for today: change to R9 fuel hose - it's the way forward.

 

Good luck.

 

Richard.

[Waynebaby]

Hi Euan,

 

This problem was the bane of my driving life on my GT6! The source of the problem is minute slivers of rubber which are shed by the rubber fuel hoses, usually generated after you've disturbed the metal fuel lines immediately next to the carbs - the action of pushing the metal pipework into the rubber hose shaves material from the inside of the hose which then travels to the carb and jams the float valve open. If you drop the float bowl off the offending carb you'll probably find black specks of rubber in the bottom. Unscrew the float valve, blow it through and you should be sorted. Be prepared to have do it a few times as there's probably more loose bits of rubber lurking in the pipeline.   

 

Richard's suggestion of using ethanol resistant R9 fuel hose is spot on, but if you're not careful about inserting the metal fuel lines you just end up swapping one source of float valve blockage (rotting rubber) for another (slivers of R9 rubber) I learned this the hard way.

 

Wayne

[dougbgt6]

Yes, sounds like debris stopping the valve or float from working. Slivers of rubber from the pipe or crud from the fuel tank. A filter is a good idea, I put mine in just before the fuel pump where the fuel line comes up from under. Reason being it's easier to clean the external filter than the filter in the pump.

 

You can get the bottom of the float chamber off in situ, you have to remove the air filters and possibly the side panel (if you have one!). However, the valve will be difficult to see or examine. It's easy enough to get the carbs off and if ones doing it it's likely the other will also need cleaning. Best to get a new set of gaskets as they are easily damaged and it's not recommended to reuse the old ones, although I've done it more than once!

[Pete Lewis]

Just to put a different spinnonnthis, if the fuel is coming from the float breather port which is a hole in the front airbox face then its float height or float needle problems

 

if its coming from the underside around the brass jet holder then its stuffed O rings on the big hexagon jet holder or the O ring on the adjustable Jet itself.

 

if you have the later tamper proof (top adjuster) rather than adjuster underside then the thin blanking cap needs a new O ring this is just a click fit plastic bung to cover the old style underside adjuster hole

 

so where is the leak is a need for some simple wipe clean and a wipe witha dry finger will show

the culprit zone

 

pete

[Pete Lewis]

http://www.buckeyetriumphs.org/?page_id=347

 

good site with basic clues about strombergs with good photos and text , never mind its not the same

spec or car the basics are all the same

 

Pete

[euan douglas]

_{Many thanks for all the input.  I took the K&N filter off, cleaned up round the carb and switched on the ignition.  As I have a Facet pump the fuel immediately started coming out of the carb from a hole on the filter attachment face beside the filter attachment bolt hole and possibly from the little hole at 6 o'clock in the entrance to the venture  -  a bit hard to be certain of this one as the fuel comes out pretty quickly  -  so I guess this means the needle valve in the float chamber is not seating properly?}

 

_{Anyway I will remove the float chamber and see if I can get at the needle valve   -  I really don't want to remove the carbs and upset anything.}

 

_Euan

[Guest]

Euan.

 

That's exactly where the fuel poured out from when I had the problem.  

 

Out of interest, did this happen when the car was on a gradient or on the flat ?? Mine occurred whilst on a gradient.

 

Regards.

 

Richard

[Pete Lewis]

You may need to regulate the fuel pressure , depends which facet you have but many produce above the max 2.5psi of the std mechanical pump

 

yes thats the float vent ..if its coming from there its float needle or fuel pressure has a problem

 

you need to remove the float chamber 6 screws and remove the valve to make sure behind it is clear of

debris

 

You can remove the float chamber without disturbing the jet holder or any settings its a hand push fit over an O ring on the jet holder

 

Pete

[euan douglas]

Thanks Pete, I'll have a go at that.  The original Facet pump gave up the ghost and I replaced it with an identical one from Rimmers (Rimmer part no RF4198).  There has never been a pressure regulator and everything has behaved perfectly until now, but I hear what you say.

 

Richard  -  on the flat.

 

Euan

[Pete Lewis]

Later stroms have a float with two valve operating arms, these will fit very easily with the float

upside down

 

this can upset the fuel heights the buckeye site has a shot of which way up

 

if you guess you would get it wrong, the float base must sit at an angle

 

pete

[euan douglas]

Well, I removed the float chamber and it had quite a lot of sandy deposit in it so cleaned all that out and removed the needle valve.  It had a couple of pieces of rubber behind it and one stuck in the body of the carb where the fuel comes in.  Removed all that and since the valve seemed a bit sticky even after cleaning and blowing through it I decided to order a new valve and gasket  -  better safe than sorry!

 

Hopefully that will cure everything.

 

Euan

[dougbgt6]

Like I said before, if that one's in a state, best to check the other one, also this will give you a comparison and peace of mind. 

[Pete Lewis]

Beware there ard a number of gaskets all look similar but sneaky changes in float bowl periphery means

it will leak, its down to evolution ,some kits have 6 gaskets in to cater for all changes

 

some new valves have been supplied with no fuel delivery holes in the hex base, and you get very little fuel.

 

some have a wibbly needle which allows fuel around the sides of the needle

 

but normal is two holes in the hex base.

 

slivers of rubber are a notorious problem if you can smooth the pipe ends , it helps ,

 

we were the first to introduce nylon air brake pipes and these cut slivers as the fittings were inserted

and the air fired the slivers into all the truck brake valves, that was in 1979 and the blasted things are still

breeding!!!!!!

 

pete

[euan douglas]

I ordered both the gasket and valve from Rimmers  Part nos 517453 for the valve and 513705 for the gasket so I hope they are OK!

 

Euan

[Pete Lewis]

Should be ok just check it covers all the chamber sealing face ,

 

does your carbs have the temperature compensators on the side , small plastic covered unit

 

these can gomout of spec with age , there, s plenty of techy stuff about them but in simple terms these need to be closed at normal temperatures, under the cover is a small nut turn this till the plastic plunger

remains closed in the hole at the base of the casting.

 

if its open idle mixture cannot be set correctly as this little gaget allows air to bypass the throttles

but should only do this when very!!! Hot

[euan douglas]

Yes, have got the temperature compensators though don't feel too inclined to fiddle with them as all has been running beautifully until the petrol leak, though what you say is very interesting.  I will print all these comments off for future reference because, as you say, there's a lot of stuff out there but sometimes a bit of a simple explanation is a whole lot better!

[Pete Lewis]

Yes nice simple job for a sunny day

 

my view is its best closed or deleted rather than being unknown

 

its a emmission idea to weaken mixture when getting rather hot by allowing small port to bypass air

around the closed throttles, also relies on the carb mani gasket being fitted with the said hole in the right way up.

 

in fact apart from screwing the nut down to realy close the plunger, and air leaks from the missing degraded O rings the simplest fix is to fit the gasket upside downband elliminate the little sods.

 

pete

[dougbgt6]

Buckeye Triumphs have a very good explanation of what the temperature compensators do, very useful in sunnier climes, Florida, Arizona, etc but not entirely necessary in Scotland, (although I have had some very sunny holidays up there). It is worth replacing the two fibre washers associated with the TCs, they will be in the gasket kit anyway.  No need to open up the CTs, just undo the retaining screws and replace the two washers.

[euan douglas]

As mentioned above I ordered a gasket, part no 513705, and not a gasket kit.  However I'm now wondering if this will be OK as there seem to be slight variations in gaskets  -  perhaps a kit might yet be needed but I'll wait and see what comes.  Yes, I looked at the Buckeye site and the section on Strombergs really is very good, well written and illustrated.  I'll leave the temperature compensators well alone as I don't think it gets quite as hot as Florida up here  -  unfortunately!

[Pete Lewis]

it doesnt matter what they do hot,,

 

 what you dont want........ is for them to be open when its cool or at normal running. as this messes up your idle mixture and then its wrong 

all across the range when running , hence the need to make sure they are well closed up rather than mess about with temperature measurements 

 

 

have to say all the ones ive have had to check are  when taken off   always 'open'  the plunger is well off its seating..and the  2 seals between the TC and the carb body

....dont.

 

Pete

[euan douglas]

Replaced both float valves and gaskets and so far so good  -  no more leaks.  I'll need to check both temperature compensators in the next day or two but thanks to your advice Pete, I know what to do.

 

With regard to another query I had about the tailgate light, that too is solved  -  it helps if there is a bulb in the light fitting!

 

Euan

[Pete Lewis]

Good when it all comes together

 

the missing bulb syndrome would be a good post in the Blonde Moments section Ha !!!

 

PETE