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bad gas mileage

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john lewis
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bad gas mileage

Postby john lewis » 09 May 2014 10:58

I am getting about 20 miles to gallon, car works great, any idea what I should look at to see y I am getting such bad mileage, after searching I see people are getting 30 to 40 mpg, did straw trick and both carbs. seem to be rising and lowering together, thanking u in advance, john

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saabfast
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Postby saabfast » 09 May 2014 11:09

Hate to show my ignorance and ask such a question, but does Canada work on US or UK gallons?

I have never checked my mpg accurately (it is a fun car and I do not really want to know, or more importanly want the wife to know), but before I got the gauge working I used to fill up and record the mileage, baseing it on 25 mpg (UK). It seemed to gradually fill the tank between fill-ups so I would assume I was getting 25-30 mpg with mainly local running about.

(Whatever, it seems a lot more economical than my daily Saab 9-5!).

Alan
Saab 9000 Stg 1 (now passed to son for his family car)
Saab 9000 2.3 FPT Auto (now gone that others might live)
Saab 9000 2.3 LPT Auto (sold on, wish I had it back)
Saab 9-5 2.3 Vector Auto Estate
'81 TR7 DHC
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Postby Workshop Help » 09 May 2014 11:51

Dearest John, let us start by beating around the bush before diving into the engine.

First, are you carrying around 150 lbs of tools and spare parts along with an anvil in the trunk? If so, dump it. Second, inflate your tires to 30PSI. Third, do like I need to do and diet off 1/3 of your body weight. Forth, confirm the brake pads/shoes are not dragging. Fifth, don't let my boat anchor sister ride along in the car when doing a fuel mileage test.

Now the engine. Confirm each spark plug cable is reading about 5000 ohms of resistance on your ohm meter. Clean the spark plugs, the rotor, and the distributor cap contacts. Install a less restrictive K&N replacement air filter. If you have a catalytic converter, confirm it is not clogged up.

Examine each spark plug. Are they all a light tan in color? If one is black, that will be a bad spark plug cable. If two on the same carburetor are black, the inlet float needle valve is worn out, the float has developed a leak, is maladjusted, or the air metering needle is incorrectly set.

Yes, a long Saturday carburetor tuning session is in your near future.
We will appreciate the next report on your progress.

Mildred Hargis

Hasbeen
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Postby Hasbeen » 09 May 2014 13:47

Come on John, it is time to admit to yourself, [don't tell the wife], that you are just a led footed old hoon, who thrashes the daylights out of your poor little Triumph. [}:)]

Actually I doubt any are getting 40 MPG, but I did once get 37 MPG on a 150 run at a steady 60 MPH, flat road, no traffic, but only that once.

I used to regularly average 33 MPG, over many years.

Since the rebuild, with the thing going pretty well, I am just on 30, as I am using it harder. None of this is in city traffic, which would be much worse.

I would check your air filter, & change it, if it has been in there for a while. I'd also check fuel pressure & the carbs for float level & flooding.

The other possibility is leaks. Check the fuel pump bolts are tight, including the one on top, & look for any leaks in the piping.

Then have a good look at the fuel tank. I had my consumption go from 33 to 25 & finally to 22 MPG over a few months. I finally found a weep between the fuel sender fitting in the tank, & the tank.

Even when I found it, it was not dripping, but the areas around it was damp with petrol. It was evaporating off before actually dripping. I only really found it when the gauge had gone from 3/4 to 1/2 in about 5 weeks when I did not use the car.

One last possibility is the diaphragm in the fuel pump. It will still pump with a small hole or split in it, but will be passing some fuel to the sump. If that were happening badly enough to give your usage, you would be able to smell petrol on your oil dipstick.



Hasbeen

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Postby FI Spyder » 09 May 2014 14:41

In Canada we use the useless km/liter but we graduated from imperial gallons and still talk imperial when talking gallons by default. (Reminds me of the question from a university student from North Dakota I was talking to in Europe who asked me what we used for money in Canada (US dollars or British pounds)[:p]. Going to the States it makes their smaller gallon seem cheap at the gas pumps (it's still cheaper than ours, regardless how you measure it).

I have gotten a shade over 40 mpg (imp) travelling at 50 mph, tires 36 psi, 1/3 of the 10 hour trip was mountainous (up and down) the rest dead level. The car had been stored for 7 years prior to that trip but there didn't seems to be any bad effects like sticking rings or valves. The car had new plugs, wires, rotor, cap. So that is about as good as it gets.

The faster you go the lower the gas mileage almost in direct relationship that would look like a straight line edging downwards on a graph. At 60 mph it would be about 36 mpg range similar to Hasbeen's experience. My Integra (DOHC 16V)on the other hand has a sweet spot between 90 kph and 110 kph where the gas mileage is at maximum.

Any gas mileage numbers under any other conditions are meaningless as acceleration (heavy foot syndrome), coasting (hyper mileage techniques), traffic, number of stop lights, varying speeds in the roads all come into play and skew the results.



- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT
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john lewis
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Postby john lewis » 09 May 2014 18:38

noticed today a whining sound, does clutch have throw out bearing, had Toyota that made same sound and it was throw out bearing, friend thought it was a gear sound maybe in transmission, could that be reason for bad mileage,

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Postby Workshop Help » 09 May 2014 19:47

John, you're jumping all over the place like a Mexican Jumping Bean.

Yes, there is a substantial throw out or release bearing inside the bell housing and they do dry up to begin squealing when the clutch pedal is depressed.

If the gearbox is making noise at idle, it will not occur when the clutch pedal is depressed.

Mildred Hargis

HDRider
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Postby HDRider » 09 May 2014 20:38

My carb'ed TR7's usually get about 25 MPG (USA Gallon, 128oz) Highway and more like 20 MPG in the City.

They all passed SMOG so they are tuned correctly.

Edward Hamer
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Postby Workshop Help » 10 May 2014 00:04

One other point, especially for the U.S. of A. crowd. Due to the ethanol additions and various blends for different parts of the country, our anticipated EPA fuel consumption levels will not be met. The various blends have diminished the gasoline BTU ratings in favor of cleaner emissions giving poorer fuel economy. The percentage of lesser gas mileage varies from region to region which, in effect, throws a bucket of cold water on any cross country or inter-national gas mileage comparisons.

The best anyone can hope for is to tune the dickens out of your engine to achieve the highest possible efficiency from the ignition and carburetion systems. Get your engine pulling 20" of mercury on the vacuum gauge at 800 RPM idle and you're well on the road to better economy. And don't forget to rid the car of unneeded weight and air up those tires to at least 30PSI.

Mildred Hargis

john lewis
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Postby john lewis » 10 May 2014 13:24

I guess I do have a bit of a heavy foot, and that may explain for the 20mpg, I see that hdrider is about same, my whirling I referred to early when I was doing my Mexican jumping bean routine is there weather I have clutch in or out, does that sound like throw out bearing and if so, can it be greased or what is involved in fixing thanks, john

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Postby Workshop Help » 10 May 2014 15:09

No, a throw out bearing cannot be greased, it must be replaced.

As for the noise; when the clutch is pushed in, the gearbox can NOT make any noise as it is motionless. Nothing inside the gearbox is moving. But, when the clutch is pushed in, the throw out bearing is now spinning and here is when it makes a squealing noise.

If you're getting noises all the time, then both the gearbox and throw out bearing are doing it separately, or it's the engine.

Mildred Hargis

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Postby FI Spyder » 10 May 2014 15:51

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by john lewis</i>

I guess I do have a bit of a heavy foot, and that may explain for the 20mpg, I see that hdrider is about same
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

You will notice hdrider is from the US so his 25 mpg is 30 mpg to you. City driving as mentioned has little meaning. The mileage I get with my driving in Duncan and going back and forth from home to go shopping for supplies would have no relation say to my gas mileage driving home from down town Vancouver to Richmond in rush hour bumper to bumper, stop and go driving going up the Oak Street hill.

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT
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saabfast
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Postby saabfast » 10 May 2014 16:03

If the squeal is there all the time check that it is not the viscous coupling on the fan, its not good news if they let go!

Alan
Saab 9000 Stg 1 (now passed to son for his family car)
Saab 9000 2.3 FPT Auto (now gone that others might live)
Saab 9000 2.3 LPT Auto (sold on, wish I had it back)
Saab 9-5 2.3 Vector Auto Estate
'81 TR7 DHC
Image

john lewis
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Joined: 19 Jul 2009 11:04
Location: Canada
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Postby john lewis » 12 May 2014 13:34

checked today again, never heard no noise with clutch in or out, took it for a drive no squeal, checked bump stop rubber seems good, bolt is in the bottom, could not see if spacer was there or not but no noise so till I hear it again guess I will continue to enjoy it thanks again for all the help, if I need to come back to this problem I will start a new thread, john

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