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MG MGB Technical - Please, please help

I have just bought basically my favorite car, a 1979 MGB GT, it is realy nice looking and doesnt seem to be in bad condition at all, it has 38k miles on the clock and has a Weber DCOE fitted.

We drove it home the other day and have been out on drives in it, then it just wouldnt start for some reason, i know very little about cars but form what i have read there is no need for the choke? is this correct as in my car it seems to be disconnected and it just pulls out and doesnt seem to do anything engine wise, on the weber there is two big 'tubes' sticking out towards the outside of the engine. when we covered these with our hands the car tried to start a little better almost started infact, today nothing happens when we do that andit isnt even close to starting, there is petrol in the tank and i have tried other forums but no-one seems to help, i have been told to put the ignition on , wait for clicking sound, pump the pedal four times, then try again, there is no clicking sound and it just does the exact same thing as before. i have taken the battery out and tried another battery in there and the same thing no difference.

Many thanks in advance, pleasehelp and feel free to email me @

simonwalker23@yahoo.com
Simon

No clicking from the pump means there is no gas to the carburator. You seem to have a downdraft weber carburator. If you look down into the top and open and close the throttle a fwe times, you should SEE a stream of gas being shot into the carburator. You could also pour a small amount of gas down the carburator and try to start the car. Do not lean over the carburator when trying to start it as it could backfire and burn you if you are looking straight down.

On the weber, you do not need the choke to start the car. I use a lot more than four pumps to get mine started, so do not be shy about giving it a few more.

Do keep us updated as we all love to see the solution to these things!

Pete
Pete

It actually sounds liek a weber side draft carb. Covering the tubes (velocity stacks) is the same as applying the choke. Maybe try taping off 75% of the open area to get it started and go from there. Make sure the tape doesn't get sucked in. You might have some bad gas, fouled plugs, or distributor problems with weak spark. If you can at least get it to run it might clear up, but it sounds liek you need to find a weber specialist.
Jeff Schlemmer

Simon:

You may have one or more of several problems. However, if you don't hear the fuel pump ticking when the ignition is first turned on, then you should first look at the fuel pump.

Jack
J.C. Weidner

Hi Simon.

It does help to have a little mechanical knowledge when running an old car, I suggest you find a copy of the old 'AA book of the car' which describes how cars of the MGB's era work, hopefully you will find it both interesting and helpful.

The fuel pump is at the rear of the car, turn the ignition on and if it doesn't have a flurry of 'ticking' give the pump body a tap with the handle of a screwdriver, which might get things started.
Don't hit the plastic cap or get carried away and hit it violently.

Please keep us posted.. Don
Don

OK, on the odd chance that you have a fuel pump that does not click when it is running, the best thing is to remove the fuel line from the carb and then turn on the ignition. Fuel should run out the end of the line.

Go online and google up WEBER DCOE or WEBER SIDEDRAFT and see if the picture matches your application.

I also have the sidedraft and it takes about twelve pumps from the pedal for her to start, and a further 2-3 minutes of idleing to bring her to a steady state.

If you do have a sidedraft, check the rubber gasket that goes between the carb and the intake. They can cause vacum leaks.

You will also get more advice by having people post here; that way we can keep track of what you are trying.

Pete
Pete

Simon,
Suggest you first find out for sure whether or not your fuel pump is working.

Disconnect fuel line at carb and while holding it over a catch container, have a friend turn the ignition key to first position (i.e., don't crank). If gas comes out in a steady pulsating stream, your fuel pump is OK.

If no gas - let us know and we'll try to help solve your problem.

P.S.
Get an air cleaner for your carb. You don't need to be sucking dirty air into your engine.
Steve Buchina

Simon,

I knew little of cars when I bought my MGB. I didn't even understand the four stroke cycle! I can highly recommend a book called "Fundamentals of Motor Vehicle Technology" by Hillier. (http://www.amazon.co.uk/exec/obidos/ASIN/0748780823/ref=sib_rdr_dp/202-5123917-2981423?%5Fencoding=UTF8&no=266239&me=A3P5ROKL5A1OLE&st=books)
It was the best £17 I ever spent on the car! The book is aimed at people doing an NVQ in motor mechanics so goes from a very simple level to sufficiently high a level that I was happy to build an engine after reading it (and some MG specific books of course). You can see the table of contents on the Amazon site.

I also know the woman that runs the Jersey MGOC club. If you want her details let me know and I can put you in touch. Bound to be some Jersey MGB owners that would be happy to give you a hand sorting it out!

Don't have a weber myself, so I can't comment on that issue. I like the simplicity of the SU carbs!

Good luck.
Iain
I D Cameron

Oh, if the test Steve suggests does show it to be a dodgy fuel pump then tapping it with the handle of a screwdriver, as Don suggests, may be enough to get it going. If the pump is original it will have points and these can stick. Modern pumps are solid state electrics so this won't help. Often very difficult to tell from quick look whether the pump is old or newer. Anyway, my point is that when mine stuck a tap didn't help. In fact it took a few good wallops with a claw hammer to get it going! To the point I actually left a dent in the body of the pump. It then worked fine for 3 months before it sprung a leak, about the place where the dent was funnily enough!! Changing a fuel pump is not a bad little job to try yourself if you fancy doing some work yourself.

Iain
I D Cameron

WRT the DCOE, I've also left the choke disconnected on mine and even on the coldest mornings only need to pump the throttle 4 times to start. It is driven daily which invariably helps. You can operate the choke at the carb by moving the spring-loaded lever on the side that faces the engine. Hold it against the spring whilst someone attempts to start the car. That said, if you can't hear the ticking of the pump when you first switch the ignition on then it's almost certainly the pump that's stuck. If you follow the fuel line from the car you may find a clear filter which may give you a clue if it's bone dry inside. Less urgently, for road use you really want an air filter on the end of those intake tubes; if they suck in a sprinkling of sand your engine is finished.
Steve Postins

A Weber DCOE is a "sidedraft" carb - not a "downdraft".

Your carb does wear an aircleaner, yes?
If not, then get one. Yesterday.
Suggest you research K&N filters
for a Weber DCOE.

If you intend on keeping this car for a while, then
you might find it helpful to get (at least) two books:

1) "The Complete MGB" - by Robert Bentley.
I consider this one a "must have" for any MGB owner.

2) Some sort of Weber carb manual. There are
a number of books on this subject. Be sure that
the book you choose covers the DCOE series.

=====

I don't use the choke on a DCOE carb - ever.

For a cold-start, give the accelerator pedal
1-2 short pumps just prior to, or during,
spinning the starter.

In fact, the choke is so seldom used that some
tuners will tap and plug the choke enrichment
outlet ports to permanently close off the choke
circuit entirely in order to eliminate it as a
potential problem area.

=====

Offhand, it sounds like you might have a fuel feed
problem and others have addressed this.

* Check the fuel filter. Replace the filter if it appears
dirty or if brown rust powder is present inside.

* Check for fuel delivery. Disconnect the fuel feed
hose at the carb and route it into a jar or container.
Flick the ignition on for a second or two and listen
for the pump "ticking" - and see whether if fuel is
actually being pumped out of the fuel hose.

A couple of years ago, my own car was brought to
a sputtering, coughing halt (and no restart) by a
stray bit of foriegn matter (a very tiny bit!) that
had gotten itself inside the carb and had plugged
one of the idle jets.

Wear a pair of eye protector glasses, and get an
aerosol can of carburetter cleaner (get one with a
long, thin plastic tube spray nozzle).

Clean the outside body of the carb to rid it of
loose surface dirt and varnish by spraying it
with carb cleaner, and wipe with a soft cloth.

* Check the fuel screen for dirt. Unscrew the
large brass hex on top of the carb and gently
remove the bronze filter screen. Clean it with
a blast of carb cleaner spray. Reinstall.

* Check the idle and main jets for dirt. Remove
the round metal jet inspection cover on top of the
carb (it's held down with a wing nut). Unscrew and
remove the brass jet assemblies and blast them
clean with carb cleaner spray. Blast out all the jet
passages with carb cleaner, too. Reinstall all
parts.

At this point - try starting your car.

If this doesn't improve things, also try:

* Inspect the float needle valve. Remove the top
cover on the carb body. Push out the small pin that
retains the float assembly and carefully lift away
the float assembly. Remove the needle valve (it
should easily drop into your hand when the cover
is inverted). Wipe it clean and check it for wear (the
tip should be perfectly conical in shape - without
any groove worn onto it). Blow out the needle valve
seat with a spray of carb cleaner. Reassemble.
Check the float level. Make sure that the float and
needle valve are free to operate without any
hangups.

There could be other faults (ie: clogged or dirty
idle mixture screws) - but I think that the steps
I outlined above are your most likely culprits.

Removing, cleaning & reinstalling the idle mixture
screws will later involve a bit of idle tuning while
carefully listening to the engine with a trained ear;
and then finer "road" tuning and reading for
sparkplug color. Just so you know before you
wade in any deeper.

Later, if you one day feel extra adventurous, you
should remove the bottom fuel chamber cover on
the carb (it's the small square aluminum casting
underneath the carb) - and drain the fuel out along
with any accumulation of fine rust and silt. You
should do this every 2 years or so.



Daniel Wong

Hello Simon-

Just my two cents, as it sounds like a fuel supply problem.........

I have an early B now, but had a late model roadster for several years not too long ago.

One day, it just would not start. The culprit turned out to be a 5 second fix.....the fuel pump inertia switch had tripped.

Try resetting it (on US models, it is under the dash to towards the left side....don't know if it is located differently on UK spec models, however).

Julian
Julian

i would like to thank evrybody answering my questions, to update you i have bought a haynes manual and have three more books on the way, over this weekend i am going to sit there and do all of what you have suggested, again many thanks to you all

ill update after the weekend.

simon walker
Simon

This thread was discussed between 20/09/2005 and 22/09/2005

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