Could my leaking fuel pump be causing awful mpg?

colnerov said:
Don't assume because something is new that it is perfect...
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Quite right Colin, but in the process of elimination you put that stuff to the bottom of the list and concentrate on the more likely suspects first.

chrisyork said:
...it's time to order a full rebuild kit and new needles for the carbs."
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Perhaps, but perhaps also I should take it to the Rover Club guy next week and see what he says first? Or have a chat to Larry at Swift? He disassembled the damned things in 2010 and reckoned they were OK, and I'm sure he would have been very happy to sell me rebuild kits had they been needed.

About now I'm expecting Graeme to chime in and tell me to install an Edelbrock manifold and Weber... :wink:
 
Sounds like you are having a tough time with it Warren - sorry my instructions didnt help more! :oops:

My vote for next step would be the cheapest one - perhaps speak to the Rover guy first if his advice is free?

Good luck with it - you will get it sorted I am sure...

And before Graeme says Weber I will say EFI! :LOL: :D :roll: :roll:
 
Your instructions did more than you think, Quagmire. They helped me understand a little more about what is going on, and made me more confident about twiddling the carburettors myself.
 
My thoughts would be to buy the tune kit balancer etc and do a complete overhaul, if there is still something not right then look at other items like timing gears and cam.

A slightly left field thought occurred to me is that the possibility of a clogged air filter due to a: to much sand blasting and or b: Christchurch liquefaction dust, I had this occur on 3 cars since the earthquakes.

Graeme
 
Air filter's good, Graeme. And remember, the car has done very little mileage since previously achieving good consumption. It rules out, for now, things like timing gear and camshafts. The carburettors however, have been repeatedly messed with, and quite possibly messed up. Add to this the fact they're 40 years old and have never had anything replaced... I can see where this is going...
 
Another grasping at straws thought would be the reserve tap leaking, I know its just been sorted with a new O-Ring however as with all things in the life the last thing touched is usually the culprit for cause of current fault.

Graeme
 
If as you say, the carbs have never been touched, then you may as well bite
the bullet and do them, if for nothing else, to eliminate them as a culprit and
to have them all tickety-boo.
 
Going on the basis that Larry @ Swift Automotive decreed the carburettors to be in good shape in 2010 (only hundreds, not thousands, of miles covered since), I've taken a punt on a proper tune-up and dropped Brown Rover with the Canterbury Rover Car Club's recommended mechanic. Pat is semi-retired but operates from a beautiful purpose-built garage on his lovely rural property. There was already an MG Midget in residence, having a tune-up and some other minor work performed. All the gear, gas analysers, balancers, etc. I gave him a potted history of my carburettors and left him to it, coming home in his loan car. Will probably pick up Brown Rover tomorrow.

On the pleasant drive through the countryside to get there, made all the more pleasant by the absence of squabbling children, Brown Rover drove beautifully. The ZF shifted imperceptibly, lockup held the revs steady, the engine throbbed away (I love that subtle V8 noise pervading the car as you cruise along) and the new wheels and tyres made the ride smooth and steady. I could have just kept on going but for the knowledge that the fuel tank was being rapidly sucked dry... :(
 
Hopefully all soon sorted, would hate to think that the ZF conversion was a retrograde step.
A long held tried and true belief of mine is that engines operate at best fuel efficiency at that rpm point at the peak of the torque curve which in the case of the ZF box maybe 4th puts cruising and around town rpm at the wrong point. If this was the case however just leaving the stick in 3rd should see the same result as the BW box.
Once the retune is done there wont be much else to blame other than the brakes or some binding problem in the box.

Graeme
 
You're barking at the wrong moon, Graeme! I don't expect the ZF to make any difference around town, and to wit I haven't even bothered to measure the urban mileage. It's at highway speeds that the ZF should make a difference, and it's out there in the countryside that I've recorded the poor fuel consumption. If, at highway speeds, locking the car in third was to improve fuel consumption compared with an overdriven top and locked torque converter then: a) the world would never have moved to gearboxes with more and higher ratios; b) I might as well lock the car in low to test the theory further... :twisted:

Anyway, the difference in refinement at 100 kph between locked 4th and the old 3rd is so large that the ZF is still a grand improvement, even were fuel consumption not to benefit (and the latter was never my goal).

Tested the brakes etc for binding before delivering the car to Pat. All wheels spinning freely. Fingers crossed.
 
CASE CLOSED!!

Blessed relief! I picked up Brown Rover from Pat this morning and embarked on a trip to the countryside with the family on board for a picnic. A mixed drive (for those familiar with this part of the world the destination was Ashley Gorge via Oxford, and Loburn on the return) with some urban, some straight open road cruising, and some B-road up and down returned 25.3 mpg! In fact it was probably slightly better than that, because I filled the tank slightly more than usual* at the end-of-trip top-up. I did notice a slight drop in power from before, with the car labouring just a little up inclines, so I've had a chat to Pat. He said he'd set it towards the lean side of things, and I could just mark the mixture screws with twink and then tweak them a quarter turn each to richen things slightly, then see how it goes. I've decided to leave it for now; at least until I've got through a couple of tanks and had a proper chance to see how the mileage goes.

*Normally I fill it until the bowser handle clicks off for the first time. In my experience this gives a pretty consistent fill for calculating the mileage. However this time I didn't think enough had gone in and the car was playing the ol' P6 fill-up tricks on me, so I forced it to take a bit more. As much as a couple of litres extra were squeezed in before I noticed the fuel was almost right up to the cap. This will have artificially lowered my mpg figure slightly, so things are looking good.
 
Sounding good, as you say a bit of mixed driving going to the Ashley Gorge. perhaps you should sign up to Fuelly very handy for seeing how the overal MPG (or litres per 100KM ) is going.
A few more fuel ups before you tweak the mixture slightly richer should give a good baseline between frugality and power.

Graeme
 
That's the plan. There's a sufficiency of power around town, but it seemed to me the car was taking a bit too long to get to 100kph. A couple of overtaking manoeuvres showed plenty of go around the mid-3000s, but you can feel a bit of a lull in proceedings lower down compared with the richer settings I had after carrying out Quagmire's basic setup. As you say, Graeme, a bit more mileage to see how things go and then I'll tweak slightly for a personal compromise between economy and power.

A couple of things learned from this experience: a) my carburettors are in good shape and don't need rebuilding (two trustworthy opinions concur on this now); b) use of the lift pins is only a rough guide to determining the mixture setting.

Flicking through the mileage records noted down in Brown Rover's bible, the best I might have previously expected on a trip like today's was about 23mpg. To achieve 25.3, and maybe a bit more, is a good sign that the 4th gear might be helping out (and it didn't have the best of opportunities to show its mettle today). I'm now looking forward to the next decent straight flat road trip (Ashburton say) to see how things go then. That's an accelerate-to-100kph-and-stay-there trip and will really test the economy difference that 4th gear and lockup can make.
 
That is a noticeable improvement in fuel consumption Warren. Look forward to hearing how it goes over the next few hundered miles of testing.

Ron.
 
Wow! That's amazing - better than my manual (although mine has tailed off a little recently - need to investigate). Nice one! :D

Definitely get on Fuelly, i love the thrill of filling up, popping the numbers into my phone and the giddy anticipation whilst waiting to see what mpg I achieved :LOL: :LOL:








I'm serious. 8)
 
Only one run, but it was a relief! It just shows you what properly adjusted carbs will do. I may lose a little if I enrich them a little to overcome the slight loss of power, but that's still a vast improvement on the last few runs. I have a trip to Oamaru planned for the next couple of months (exact date to be confirmed). It's 250 kms each way, mostly long straights, very few hills, and I'm planning to run the car as it is on the way down, refuel, give the mixture screws a quarter turn, then see how it does on the way back.
 
I'll glad you've got this sorted Warren, now you can enjoy the rest of your summer with a car that's working really well.
 
I've always thought the mixture screws only adjust the mixture on tickover and make little difference at higher revs , that being taken care of by needle profile :?: At least that's what i've read on here . I know all the needles have the same profile over the part of them that covers the tickover range :? Educate me someone :D
 
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