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MG Midget and Sprite Technical - Water in Carbs?

Has anyone had the issue of water in the float chambers? Does anyone have problems with their petrol cap sealing? or water getting in elsewhere? Or does anyone know if the petrol at Sainsbury's garage has water in it?

I don't know if this is really my problem - but its possible that its giving me grief.

So is their an easy way of emptying the float bowls without taking the whole carbs apart?
C L Carter

If there was water in the carbs, then as petrol floats on water it would accumulate at the bottom of the float chamber. The easy way to clear it would be to undo the small brass compression nut at the bottom of the float chamber that holds the flexible tube connecting to the jet. Pull the tube out, let the petrol drain through and then reconnect. Don't overtighten the nut.

Alternatively, you could empty the carb with a syringe and dry/ clean it out with a tissue.

Water is most unlikely to have got into the system anywhere, unless the fuel supply was contaminated. I think that it is unlikely. And if there were small amounts of water, then the SU carb design is pretty good at clearing itself.

You may OTOH, have some dirt in the jet tube. That is a more common problem.
Guy Weller

Cleaning the jet is not a job I fancy right now! If i have to do that then I think I will completly strip and clean and service the entire carbs.

Thanks guy
C L Carter

Cleaning the jets is extremely simple! You remove the small screw that attaches the choke pull-down lever to the jet, and pull the jet down away from the carb. You don't even need to undo the jet tube. Just invert the jet, let some fuel run through it and then put it back into place and reconnect the small screw (which you will drop and loose at this stage, rendering your car unusable!)
Guy Weller

So you don't need to remove the jet from the carb to clean it?

how does one invert it - if you haven't removed it? and how does one remove it if you don't remove the jet tube?
C L Carter

Sorry, I am assuming that you have SU carbs?

If so, then the jet is a 2" brass tube that inserts into the bottom of the carb. The only thing that physicaly holds it in position is a small cross-headed screw through the choke mechanism lever. Undo that and the jet will pull down and can be detached away from the main body of the carb. It will still be connected to the bottom of the float chamber by the flexible jet fuel tube. Ideally, you would undo that as well, by slackening the brass compression nut. But you don't have to, there is usually enough flexibility in the tube to allow the jet to be turned sideways to drain out any debris that may be lodged in there.

Personally, I doubt that your problem is either water or debris in the jet as they are generally quite good at flushing themselves clear. But it is a simple procedure and may be worth the 5 minutes that it takes to check and clear each one.
Guy Weller

Thanks Guy - My plan is to see if the electronic ignition conversion fixes things.

Then I'm going to check if the fuel pump is working..

Then I will do what you have suggested re water and debris

If there is still a problem then I will need to have a big rethink.

Thanks for the advice
C L Carter

I use a syring and suck it out... you can also use an old bath towel and just sop it out

to avoid water... drive it... its the ethoniol fuel going off, here it takes about 3-6 weeks and its bad fuel time

if its going to be sitting long...add "stabil" to the gas or some variation...it will help to hold the fuel togather and keep it from attracting moisture

prop
Prop and the Blackhole Midget

I am using it everyday at the moment - commuting 25miles.... it was fine the night before...

I had only just filled up the night before... and it was a damp night...

As you can see I'm very paranoid!
C L Carter

We use this stuff when theres water in the tank "Isopropyl alcohol" they call it "dry gas".

Do you guys use it over there?

I think in this case props right, What ever mix of gas they cooked up over here... it goes bad real quick.

Ive tried driving through a tank of water contaminated gas that was aged a little ... Very unpleasent.

Theres always has a lack of power and sounds sputtery, It hates to idle under those conditions.

It so much easier to just drain the tank and put some fresh gas in! Yes its a pain to do... I just do it..
Steven Devine

yif you just purchased gas and got water in the tank...its nothing you did... its bad right out of.the pump...pump it out and take.it.back to them.and ask for a refund with your reciept...

if they refuse.. call wieghts and measures and issue a complaint

that sounds petty... but if im not mistaken you guys pay around $50 to $ 75 usa money to fill a midget gas tank in the uk...thats not chump change in my book

prop
Prop and the Blackhole Midget

the way the easist way to drain the tank is to disconnect the fuel hose at the carb add another 3-4 feet of hose stick.the open end in the cintainer and turn the key to the onew postion...about 10 minutes the tank is empty

way safer and taste better then sucking it out like straw with a garden hose thur the fuel cap

prop
Prop and the Blackhole Midget

hey steven

just a note... if you look around at the pumps... look for premium that says on the pump "Ethinol free or contains no ethinal" ....its rare and hard to find...we only have 3 stations in all of central Mo. that sells it... but if you have a car.that sits fairly often... it well worth it...

its real gas

its only primuim and it must say its free of ethinol on the pump its self....other wise its an ethoniol blend

prop



Prop and the Blackhole Midget

I've held back as long as a I can

Christian have you been through any more floods recently :D




. . . or is that a stupid question :D




on a serious note you do seem to be jumping about looking for possible causes rather than continuing a diagnostic path
Nigel Atkins

hey nigel

he said it started after his last fill up..
Prop and the Blackhole Midget

Im not sure if the ethanol is in the gas or not, Ill have to look next time. I do know I have to buy premium all the time. The way my car is timed the advance is far forward as I can go. If I get bad gas... I loose the performane and I get all sorts of pinking.
I dont want to loose a piston so I listen carefully
to avoid the problem.
I kinda like the way these old cars will talk to you.. if you listen to them.
Fun to Drive!
Steven Devine

I think Christian is awash with different ideas to the cause :D
Nigel Atkins

I haven't seen any description of the symptoms yet, so not only are their many solutions, there are also an infinite number of problems!

I was just offering suggestions on how to empty the float bowls, since that was Christian's question.
Guy Weller

A little trick if you do have water in the tank is to add some methylated spirits. I have a 1995 Jaguar XJR and the drain hole by the filler cap is notorious for getting blocked and then filling with rain and contaminating the fuel. This worked for me anyways.

I found this explanation of why it works

Many countries now have up to 10% ethanol (Brazil has 25%!) mixed into fuel for a variety of reasons such as the reduction of carbon emissions or to increase the octane rating of the fuel. Ethyl alcohols are hydroscopic and can easily absorb the moisture in air humidity and therefore increase the water content of the fuel.

This trick exploits the hydroscopic properties of the alcohol so that water is absorbed into the alcohol and can ignite in the engine. However it is important to note that the alcohol will become saturated if there is more water in the tank than it can bind with.

HTH

David
D Prince

Ethanol does not create or collect free water in the fuel, it dissolves it, until it is saturated. Water comes from outside or condensation. More alcohol will dissolve more water, as several have suggested.


You do not have to take the carbs apart to clear a bit of water from carbs, if the car will run at all. Remove the air filters, hold the throttle linkage to about 4000rpm, and choke each carb solidly with your hand; remove hand before engine dies, let it recover speed. Do the other carb, repeat a few times. This will suck any water or most dirt right through the jets (anything that will pass the filter screens in the pump will go through the jet). Generally works on fixed jet carbs too. Routine emergency procedure.

FRM
FR Millmore

Im looking at what you wrote...Nigel

I read it once, then twice, then three times..

Whats he saying?

Im confused "why would he say it like that?"

Awash....

THEN, WHAM! FRYING PAN IN THE FACE! Duh!

Slow on the uptake!

I just got it! Ha ha ha
Steven Devine

there's a second meaning Steven but it's just a wind-up for C L (see my previous to last post - but don't ask about it as youngsters can get techy :) )
Nigel Atkins

I've just been doing lots of diagnostic checks nigel and I think I've sorted out current electrics so I've moved on to fuel.

On fuel I think it might be water in carbs, so i asked the question, and got an answer - which I am now going to try.

C L Carter

OK, if you think you're on the right track good luck with it

a bit more information like if you've fitted the igniter head and the misfire is still present might help Guy and others help you

I'll keep out of it, I'm not the one with the misfire
Nigel Atkins

Nigel Atkins,

I think Christian is awash with different ideas to the cause :D


and now christian is a float with new thoughts for repair

hahaha

okay ... who stole my coat

prop
Prop and the Blackhole Midget

Well I'm stumped now.

All day fitting new electronic ignition.

New dizzy cap
New ht leads
new plugs

Beautiful bluey purple spark

to carbs apart. blue air through jet - emptied float bowls

She just won't start... she fires once and won't go... the bendix jumps out and spins round as usual.

Tried playing with static timing - no help

Other than the starter motor needing a refurbing (doubtful) as I put a replacement one in when I rebuilt the engine 2000 miles ago, and the bendix looked fine. Also, thats not how she failed.

Tomorrow I may try push starting her, we are on a nice hill for it - but if (when) she doesn't start I then have to get her back up the hill somehow!

any ideas? ? any?

C L Carter

Is it a 1500?
Guy Weller

yes and so has Guy

Guy yes it's a 1500
Nigel Atkins

OK,
Christian you have made quite a lot of changes without identifying the problem. It is possible that the problem that you now have is not the same as you had originally, or is additional to it. Don't assume that there is only one thing wrong!

If it is now firing, but just once and not then running it could be due to the way the coil is now connected. If you check the wiring diagram in your Handbook you will see that there should be 2 wires (WLG) feeding to the positive side of the coil. One is from the ignition switch and is live all the time the ignition is switched on. The other is from a terminal on the starter solenoid and is only live so long as the starter is being spun.

If in making the various changes that you have made to the ignition system, you have only reconnected the wire from the starter solenoid than it will fire when you spin the engine, but it will not then continue to run.

Just a theory, but it could explain what is now happening. It may not explain whatever the other symptoms were, but that may be a different fault.
Guy Weller

if the engine is spining on the starter and still wont start DONT PUSH START IT DOWN THE HILL, cause it still wont start

you said you now have a bright blue spark at the plugs

try this last test...

run a jumper wire from the positive side of the coil to the positive side of the battry try starting it

if it starts... then the problem is in the ignition system between the key and the coil

if it dosnt start... check the engine.ground is clean tight and not worn or missing

then ...look at your firing order

1342 dissy rotates counter clockwise

if thats correct... then check your valve clearance...if thats.correct then look at carberation

prop

Prop and the Blackhole Midget

Thanks for your comments.

Guy.
I haven't ruled out that there is a new problem. It more than likely thats what the issue is.

Have bypassed the wires you are talking of. Have fitted a new coil closer to 3 ohms, so have cut out the ballast resistor... and run postive straight from the ignition bank on the fusebox. (was also testing it straight from +ve on the battery)

Prop,

Its not 'spinning' the engine. its popping out and freely spinning.

Have already tried coil direct from battery

firing order is right

(going to try static timing it today)

Will check valve clearances today

Will also do a compression test

-

have looked at carbs - i'm no expert on carbs but i think they're fine. I've cleaned out the jets, and emptied the float bowls, have tried starting her on Lynx Africa... I don't think its the fuel anymore.

Any other carb ideas i can try?

C L Carter

to test if its carbs try this... warning crude and dangerious

pull the coil wire so it cant start then turn the engine over continuiously for 3-5 min or so

pull a spark plug... and ( this the dangerous part ) use a long fire place match or a long BBQ beutan lighter ... light it and stick it into the spark plug hole...

if you get a "WooOH BAMB" explosion out of the spark plug hole and all the hair on your hand and arm is synged off... then your carberation and fuel system is good to go...no problem there

if this works and your now hairless burnt and you have a bright blue spark at the spark plug resting on the engine block... and the engine still wont start and run for longer then 3-5 secounds

then your down to 3 issues left

1. bad compression...blown HG or warped cly. head, ect. ect.

2. the valves are adjust wrong and they are closed

3. your doing a classic prop mistake... and belive your ignition timing is set correctly ... and your backwards wrong
apperantly... this is fairly common with people that think they should know better...and whats tough, I couldnt be convinced otherwise... it took a fresh set of eyes to see it.

but I certianly belived I was right until I realised I was wrong...hahaha

btw... its not dissy timming... unless you have a radical build the engine with fire for at least 3-5 seconds if you adjust the dissy in the middle of its range... this is one area the engine is very forgiving

prop
Prop and the Blackhole Midget

opps...wrong!!!

By ignition timming on point #3 in my above posting .... I mean your spark plug firring order is wrong

sorry for the confusion

prop
Prop and the Blackhole Midget

I think I saw that diagnoses on HEE-HAW!

Yes, with ElleMay.. The beutan lighter scene... it was the one when Granpa Jones.....Waaabambed it across the...


Ooooh... Never mind.

Wheres my coat?
Steven Devine

haha...hey its one of those little tricks I learned...by thinking "hmmm I wounder if..." you put enough amomized fuel in there... it will not only turn the crankshaft.. it.makes for a cool redneck cig lighter with a 2 foot flame out the spark plug hole

it wont tell you if the carbs are set properly...only that the cly are getting fuel...

is it safe, sure....if your a redneck used to doing stupid stuff on a regular basis


"Fire on the mountains, run boys run, satens In the house with the risen sun...."

prop
Prop and the Blackhole Midget

You really need to approach this properly Christian, Nigel is right, be organised in your approach

I know you have fitted the new ignition and set the timimg properly

But

We have seen it before here, with electronic timing. When you have it right and it doesnt work try turning the dizzy body some more.

Mark it with Tippex for where you think the setting is then rotate the body, hmm, how about clockwise 15º first then maybe 30º back or even more

Try cranking it as you turn it too, even a few degrees at a time

These electronic units can alter the timing quite a lot, there have been several cases of this kind of problem on here

A secret I discoved in manymanymany years of roadside breakdowns

Fuel problems are almost always electrical...

Most frequently ignition based...

Bill1

Agree with Bill fitting electronic can put the timing position of the dizzi out a lot.
Both Ignitors I've fitted to my Midget and a B altered the setting many degrees - on the B it only just started and was very rough until I strobe'd it.

Is it coughing and throwing the bendix out ?

R.
richard boobier

Not even coughing... its just firing once cylinder once.... and then spitting bendix out.

I have tried the timing in manymany various combinations. I'm pretty damn sure its not timing anymore...
C L Carter

Sure you have the leads fitted correctly to cap and on car - sounds familiar !

R.
richard boobier

well ... lets take an inventory

you have a bright blue spark at the plugs resting on the engine block and grounds are fine ©

the ignition wires all check out because you tested with jumper wires bypass ©

the dissy postision is fine ©

you have the plug timing set to1342 ©

so whats left???

1.compression test....to test for low compression, like blown HG or a warped head...compression test should.be done with wide open throttle...not closed

2 ...valves are closed and need adjusting

3. carberation issue... do what I mentioned above with a long match....if no fire explosion and woh-whap sound out of the spark plug hole... its not getting fuel

its one one of these 3 issues...your 1/2 way there...dont get discouraged now...keep going....you will have it running in no time


prop
Prop and the Blackhole Midget

I am going to do the compression test... but I really don't suspect that to be an issue.

I will check valve clearances too

- Carbs... I have a thought on the carbs, but have been unable to test as the car is at my Girlfriends some 12 miles away.

I have an inkling that the back carb that serves 3 and 4 may have a blocked overflow and a worn/broken needle valve - there are lots of indicators that point to this and it all adds up... so i'm thinking that the back 2 cylinders are flooding and therefore not firing. I have about 6 or 7 ideas on this which all add up, so I am going to have a look at that at the weekend and see if its the issue.

1. When the initial failure happened, she started in the morning but was really lumpy and so i revved to keep her going and she cut out (I imagine she was running on 2 most of the time and revving pulled in all the extra fuel and flooded her more)

2. when I first took out the plugs, 3 and 4 were black and 1 and 2 nice and brown... I thought nothing of it, just assumed i had my mixture set wrong and would sort that out when she got running again.

3. I had condensor issues a few weeks back and thought it was carbs, so I drained the float bowls and that bowl had a red coloured fuel which i didn't understand, I'm thinking this could be due to rust from the tank? or because the needle valve is broken?

4. The inlet to the carbs were wet with fuel (can't be sure this isn't because i had been cranking her over for numerous attempts to start)

5. Plugs were wet (again can't be sure that isn't a numerous start attempt thing)

6. when we push started her down the hill, she wouldn't start but would fire stop fire stop and when she did, exhaust had black smoke come out of it...

So I'm thinking that when I turn her over, cylinder 1 or 2 is catching and then cylinder 3 or 4 isn't cos its way too flooded.

C L Carter

This thread was discussed between 21/02/2013 and 27/02/2013

MG Midget and Sprite Technical index

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