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MG Midget and Sprite Technical - It won't start.............again.

Ever wanted to kill your car? Well, I'm certainly in that zone.

Having carried out a series of work on my 1500 recently I was finally looking forward to actually driving it.

New fuel pump fitted and it had started up so all was looking good.

Next thing I noticed was what I thought oil drops on the drive so I tucked him away for the evening before returning this afternoon to investigate which I had (wrongly) assumed was the newly fitted alloy rocker cover.

Nope, turns out the braided hose to the fuel float chamber on the front carb was letting petrol pour out.

I had managed to start the midge but it kinda dropped on revs slowly and didn't pick up leading to the discovery.

My only concern now is even though the hose is leaking (and the clip or connector on the end of the pipe is missing?) the chamber is still full of fuel so surely it should still ignite and tick over for a while?

I couldn't start it again? This is a big concern.

Should it start with a full chamber of fuel irrespective of the hose leak issue?

The new pump must be working as there's fuel delivery to the carbs so I cannot understand why it won't ignite? Is it flooded perhaps?

Thanks.
L Huggins

Dual hs 4 im guessing

Just so we are clear.... the fuel is shooting out the vent tube on top of the float chamber and not the fuel line .... is that correct ?

If thats correct... it would indicate a sticking float needle or some debrie around the float needle.

Would it fire or run with some starter spray down the carbs throats

Prop
Prop

The fuel is spurting out of the end of the fuel hose that connects with the float chamber.

I have changed over the hose tonight with a 7.5mm new replacement and it fired up.

Trouble was, once it turned over the fuel started to spurt out again?

The hose didn't move off the tube as the jubilee clip I used was tight on. Thing is it still leaked?

I think that I perhaps need to select a smalled dia. hose as a replacement to achieve a snug fit maybe?

Is there any other way to effectively seal the end of the hose where it joins the tube?

Thanks.

L Huggins

Where abouts are you in Somerset ?

I'm in North Somerset - Clevedon.

R.

richard boobier

The front carb on a 1500 has two hose connections. One is the feed from the pump, which comes via the rear carb. The other is the overflow and should be connected by a short flexible hose to a rigid pipe to discharge excess fuel somewhere down below the carbs where you cannot see it, usually onto the hot exhaust pipe! If the overflow pipe is pouring petrol out, then the needle valve in the float chamber lid is not sealing properly. It may be won, or just have dirt in it.

If the pipes themselves ate leaking, despite being fastened with the proper clips, then you probably are using the wrong sized pipes.
Guy

Isn't the fuel hose normally 1/4" - 6mm?

I'm typing whilst someone is is posting as normal but my post still stands - for a change
Nigel Atkins

Cheers Fellas - Nigel I think you're right. I have 7.5mm which I would believe is too large. I'll look to get my hands on a 6mm tomorrow which hopefully should do the trick. I can then take it out which will be the first time in 4 weeks. The MOT runs out next week!

Richard - I'm in Brent Knoll so not a million miles from you.
L Huggins

If still a problem I'm around for some of this weekend and may be able to assist.

01275 872585.

R.
richard boobier

I rather think you are connected to the overflow connection on that carb. If you were then fuel would spill everywhere regardless I think of how tight the hose was.

Also connection onto the overflow hose would seriously flood those 2 carbs and prevent starting.

Equally a stuck needle valve would have the same effect.
Bob Turbo Midget England

L,
if you think the connections might be wrong then a good quality photo posted here of the carbs and hoses in situ would help
Nigel Atkins

Boy is this frustrating.

So, changed over to a 6mm hose and fitted a minute ago.

Turned it over and it sparked up straight away.

It ran for no more than 10 secs when I started to notice 'spits' of fuel.

I tried to let it idle but without the foot on the gas it lost power?

I then couldn't start it again (flooded?).

This seems to be what has happended since changing over the fuel pump and after the original hose started leaking?

I have take a photo which is uploaded as below.

I had thought that I have simply changed over the hose so the connections are 'as were' but I may be mistaken?

Anyway, all help greatly received !

Thanks.

Regards.


L Huggins

I. See a float chamber... but what am i looking at

I hate to keep beating a dead horse but....

It just appears to be a float needle issue... it could be worn, dirty and just plane sticking.... maybe the floats need adjustment...or have suffered a leak.... also is the vent holes blocked by the gasket /airfilter....they are at 10 oclock on the front ane 2 oxlock on the rear
Prop

In the photo... the ( L ) shaped hose we can clearly see...is that going to vent... or is that for incoming fuel... from what i can tell that shuold be fuel

It appears there is a hose hooked up to the other float connection but hidden almost from view. If that hidden hose is connected to the vent or emissions.... dis connect it and see if it runs. If that vent cant breathe you will have issues for sure.

Prop
Prop

In the photo... is that the front carb on a uk spec 1500 ?

Your are running HS 4s is that correct ? Just my personal opinion but the float looks like an HS 2.... ive always thought that The fuel/vent where in parrella to each other on the HS 4s and the fuel to vent was prependicular to each other on the HS 2s.



Prop
Prop

Just curious....

are the floats all plastic incluiding where the float needle rides up and down... or are just the floats them selfs plastic and the part that the needle rides on is brass... sorta rivited/glued on to the plasitic float
Prop

Yep, as suspected, the fuel supply hose connected wrongly.

The carb lid, attached with 3 screws, needs to be moved around by 120 degrees anticlockwise. The outlet (overflow) connection will then align with the little notched cut-out that you can see in the heat shield. And should have a rigid pipe extending downwards to stop any excess fuel spraying on to the hot exhaust. Moving the lid around will then bring the other (input) connection in line with your fuel supply pipe.

Either that, or it is a possibility that you may have muddled the float chamber tops between the front and rear carbs at some stage.

Guy
Guy

Guy...

Good eye.... ive been looking at that photo for like 20 minutes trying to figure out why it didnt look right. The float lid is off by 2/3s

Congrats to robert and guy... fuel line hooked up to the vent.

Some times You just got to know how to blow in order to suck peoperly

Prop
Prop

Guy,

The pic looks just like page 125 of Horler to me !

i.e as original.

Maybe a pic of the rear carb also would help ?

R.

richard boobier

Ahh, Richard. Maybe I am wrong with that then - in which case apologies all round!

I don't have a Horler to check that page, and it is now over 10 years since I sold my 1500, so cannot readily check that either!. But I do recall that the overflow pipe aligns with the notch in the heat shield that you can see in Lance's photo, which would suggest that the float chamber top is on in the wrong orientation.

Guy
Guy

Guy,

Horler pic does not show the notch - so maybe different routings for different years.

Sold the wifes 1500 years ago so can't check that either.

Just to high jack the thread - if you speak to Mark can you ask about when he's intending to move the Dalek.

Must meet up @ M50.

R.
richard boobier

Guy...

I really think your on the corret yellow brick road... if you notice the hose we can clearly see is is connected to the air flter box... looking at my hs 4 carbs... that should be the fuel line


Also on the HS 2 set up... which is the same float lid he is using ..the fuel line goes between the carb and the engine.... not in front of the carb.


Give me another moment and ill go back to the shop and snap another photo...1 st ones didnt take to welll... raining like a bangey and vary lttle light.

But your correct the float lids are not put on correcttly...

Prop
Prop

this is my HS2 set up for a 1275 1971 usa spec... but it appears to be the same float lid ... like I said above... I know the HS 4 has a paralle vent to fuel line ... but im not sure if the HS 4 has the "T" vent to fuel line like the HS2 aka what L. is showing in his photo

i looked in my das hammel books but couldnt really find to much.

anyway here is the photo... fuel line comes in to the front carb for referance... obviously "L" carbs will be on the oppisite side of the engine... for the 1500


Prop

agian sorry for the poor photo quality... the brass vent pipes run perpendicular to the fuel pipe... its hard to see... but thats about as good as im going to get today with this weather

prop
Prop

i have 1500 midget this is how my carbs look hope it helps


m barfoot

OK, forget that idea, looks like I was wrong.

Please delete my earlier comments and substitute silence.
Guy

Guy,

Just checked the parts book and pre '78 1500 had a baffle in lieu of piped drains, 78 on had the overflow pipes.

Not sure what reg this one is or if carbs / shield is original.
A closer pic of the top of the float chamber would help identify - but sounds like it may be a blocked needle valve causing the leak.

R.
richard boobier

Looks like my neck is on the block also...

it does make good common scense to put the fuel line on the front of the carbs instead of behind them, where heat likes to party.

But i still think the issue is float needle related....

No such thing as half way pregnant.
Prop

richard my carbs are 76 reg
m barfoot

"L".... you said this started when you replaced the fuel pump....

Did you upgrade from the mechanical pump to an electronic...if so what pump did you use and how many psi of fuel pressure is it putting out ?

It well could be the pressure is to high and its bowing over the needle... but you would have alot of fuel shoutingdown the carb throat.... id think.

Prop
Prop

MB
Thanks - that confirms the parts book, I was refering to the dead car, but it helps identify carb tops.

R.
richard boobier

So, my excuse is mine was a late '78 model.
Had pipes.

But why then, does Lawrence's have that notch in the heat shield?
Guy

L ?

Why did the pump need replacing ? lack of fuel to carbs ? was the old one tested as U/S ?

Have you taken the top off the float chamber and checked the bottom is not full of crud - if you do this, check the needle valve seat at the same time - it may be worn or have dirt stuck underneath the seat.

R.
richard boobier

Gents,

I changed the pump with an exact replacement, i.e a mechanical.

Following this I started noticing the fuel escaping hence the need to change the hose (to no avail).

I've taken another photo of both carbs. See below.

Little confused now as to what I'm supposed to be doing?

Can't really understand why it's playing up when it was a straight swap over?

Just started it up again and it ran for approx a minute. This time after revvin up for say 60 secs there was a rattling noise and smoke? I turned it off naturally.

Have I go the fuel pump in correctly?






L Huggins

And another pic with air filters removed.


L Huggins

And a further pic (close up of float chamber lid).




L Huggins

And finally, link to a video of the carbs:

http://www.youtube.com/watch?v=Oktelii6HoE

L Huggins

L,

I think this is a two person job one looking in the engine bay and one starting and keeping the engine running from the cabin

second person watching engine bay for safety if nothing else

I would suggest starting at the basics again, is the fuel leaving the pump?

Is it getting to the carbs?

There might be a secondary problem that is confusing the issue also
Nigel Atkins

Gents,

Thanks very much for your imput.

I have finally managed today to resolve the issue.

To be honest I replaced the lid of the float chamber, air filters and the stub hose to the chamber again.

I also increased idle speed.

It sparked up again, idled perfectly and no spill of fuel from the hose.

I would think that it was struggling with power as the idle speed was too low and the reason for the leak from the hose was because I hadn't fitted it properly.

Took it out for a spin and it runs smoothly and effectively, better than normal!

First ride out in weeks so worth the wait.

Again, thanks for all of your input.

Cheers.

L Huggins

well done

sometimes when these things get you going best thing is to stand back or go away and return

I'll claim the >>There might be a secondary problem that is confusing the issue also<< obviously meant the idle, yeah, . . . sure

keep it vague and you can't be too far wrong (or right)
Nigel Atkins

This thread was discussed between 17/05/2011 and 22/05/2011

MG Midget and Sprite Technical index

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