Poor Fuel Economy

[Green Maestro Man]

Hi all -

I'm new to this group and new to owning a Maestro - was given one by a friend who wanted a newer car. It's a G Reg 1.3L model.

I've been doing some body work on it and have tackled most of the rust under doors and wheel arches. Now am concentrating on the engine.

Have not much experience with engine repairs -but do have a Haynes book and lots of enthusiasm!

I am getting very poor fuel economy with my car - about 18 MPG - and I have been told by friends I should expect upwards of 25 MPG at least (is this right?) It hasn't got many miles on the clock (78,000).

All I've done so far is added some varnish remover to the fuel (fuel additive!) and ran some through the carburator to see if that would help. Air filter looks fine.

What sort of mileage should I expect and what would be your first few "ports of call" to improving fuel mileage? Other things I am looking at are the choke cable (is it stuck open? - but seems likely as when I close it I get a rocky ride) and perhaps doing the air filter anyway just to see...

Thanks for any help

Green Maestro Man

[E_T_V]

Yikes yes you are getting poor fuel economy. Expect 35mpg upto 40 on a good run. first port of call is to tune the carb up.

Other things that can be at fault are:
Sticking choke cable
No oil in the carb damper (the black screw thing on top of the carb)
blocked air filter.

After a good run take out the plugs and take a look they should be brown/grey. If they are black (as i suspect they are) then the mixture is likely to be too rich. If you go through the haynes manual on the tuning section you'll not go far wrong.

[E_T_V]

Oh and always remember that if the engine is damaged in anyway brand new unleaded engines can be got for 100 quid.

Another thing worth checking is the igntion timing as the car was designed to run on leaded petrol.

Oops I almost forgot the most obvious thing. The vacuum pipes can cause similar problems too and are simple and easy to change/fix. Maestros have quite a few problems with them as they age but a set of new ones often helps

[G Force]

Hi there, Here's my poor fuel consumption check list.

Check engine is getting up to temp (ie. is thermostat sticking open)
Check valve clearances.
Check exhaust system not blowing or badly corroded (if it has been on ages they start to collapse inside)
Change air filter.
Check and gap or renew plugs.
Remove distributor cap and check for corrosion or cracks.
Check distributor vacuum unit is operating.
Check for air leaks or blockages in breather hoses.
Check Vacuum pipes inlet manifold gasket for leaks.
Check and set ignition timing.
Check and set carburettor settings, look for signs of carb flooding.
Top up carb damper with engine oil.

Remember things like tyre pressures, wheel alignment and brakes sticking on can all effect fuel economy.

That lot should keep you busy at the weekend. :) ;)

Cheers gary;)

[H48HPE]

the best thing to do in my oppinon would be to start by giving it a full service, haynes tells you how to do it all so I wont bother, you need to replace the air filter, change the oil and filter, spark plugs, HT leads, distributer cap and rotor arm. Once thats done you'll be in a better position to see if there are any real problems. The other thing to check during the service is the vacuum hose network. this consists of a tube that come from the top of the inlet manifold and splits off into several other tubes that run around the engine bay to the carb, distributer and air filter box. (the air filter box vaccum pipe connects to a thermostat then another pipe links from the thermostat to a switch unit on top) check all the tubes are connected up and none are split, the reason for this is that if any air leaks in through these the petrol mixture will be weak). Make sure the carb dashpot is full of oil, this means unscrewing the black plastic cap on top of the carb, pulling the plunger out and filling the hollow tube in the middle to the top with oil, then put the plunger and cap back in and screw up).

Dont touch the carb mixture screw and idle settings till you've serviced it, you might not need to do it at all and if you do it before servicing it'll only be tuned wrong.

once it has been serviced drive it round for a week or so and check that it never runs on when you switch it off (running on is when the engine tries to keep going after its switched off) if you dont get run on, the engine is in good tune and you dont need to mess with the carb or timing, if you get run on every time there's somthing wrong and adjustments may be required. if it doesnt run on and you try to adjust it then you'll find you make it worse. best thing to do would be conduct this test and if you think adjustments are required post another post about how you do it.

As a rule I tend to fill my 1.3 up to the top and run it to and from work which has a mix of driving conditions, if I reset the milage and drive round from a full tank, I get it to about 200 miles by the time the gauge says 1 quarter left. when i calculate the MPG I get about 36 but I have had nearly 50 on a long run.

Its easy to think you are running low MPG when your actually not, I thought I was getting low MPG when I first got my car but I wasnt.

My final piece of advice is not to mess with the carb unless your confident.

Andy

[talkingcars]

As a guide I get about 230 miles from a tankful in my 2.0i, mostly motorway driving.

James

[MGTurbo]

Originally posted by talkingcars
As a guide I get about 230 miles from a tankful in my 2.0i, mostly motorway driving.

James

Used to get that in my Turbo. Get 550 miles from a tank in the Monty and filling it up shows two gallons still left in the tank :cool:

Gareth

[talkingcars]

I used to get in the region of 345 miles to the tank in my estate, a 2.0i, of course the larger tank helps.

James

[Landcrab1800]

Got to ask, is about 30 mpg on motorways (70-80) normal for the montego NG ?

[MGTurbo]

Originally posted by Landcrab1800
Got to ask, is about 30 mpg on motorways (70-80) normal for the montego NG ?

I could get up to 40mpg from my Efi but it had the 4-star ECU, later models with unleaded ECU or MEMS dont seem to go much above 35-38 mpg.

Gareth

[nate]

Originally posted by E_T_V
Oh and always remember that if the engine is damaged in anyway brand new unleaded engines can be got for 100 quid.

Another thing worth checking is the igntion timing as the car was designed to run on leaded petrol.

Oops I almost forgot the most obvious thing. The vacuum pipes can cause similar problems too and are simple and easy to change/fix. Maestros have quite a few problems with them as they age but a set of new ones often helps

where can ya get a new engine for £100?

[Beaker]

Ledbury, do a search on this site for Ledbury and it should bring lots of information up about the place.

[talkingcars]

Parkway Service Station (New RHD Maestros) - Ledbury, Herefordshire. (01531) 636252.

[E_T_V]

Run on isn't necessarily assiciated with the carb being in a bad state of tune. Mine used to run on and was tuned perfectly. It can be caused by a number of things such as coke build up in the engine, too high a tick over speed (the most common cause) and incorrect spark plugs.

I'd check out the vacuum tubing as if it is leaking it will make the mixture a little weak but it'll totally mess up the ignition timing which is the major effect. Also note that some cars have different vacuum tubing layout to others so just because it doesn't look teh same as in the haynes manual doesn't mean it is wrong.

[H48HPE]

Run on isn't necessarily assiciated with the carb being in a bad state of tune. Mine used to run on and was tuned perfectly. It can be caused by a number of things such as coke build up in the engine, too high a tick over speed (the most common cause) and incorrect spark plugs.

thats quite right, but if theres no run on, i would then go on to assume that the engine is in a good state of tune. and not needing to be tuned thus the carb can be steered clear of

Andy

[E_T_V]

Maybe but there are exceptions like when we got our first maestro. No run on, ran fine, quite well infact, but when it was MOT'd it went off of the scale for HC's at over 2000, and a CO of 6.5%. So I woudn't use run on as a guide to how well it is tuned, the colour of the plugs after a good run is a far better guide.