General Excessive fuel consumption, HELP!!!

[JRB21]

Hi to all!

Can somebody please help me?

I recently got a '95 UNO FIRE 1100, firstly it was in a really bad condition when I got it so I did some work on it.

What I've done:

1. New Air Filter
2. New Fuel Filter
3. New Oil Filter
4. Drained and renewed engine oil.
5. Drained and renewed gearbox oil.
6. Overhauled Carburettor
7. Overhauled Master cylinder
8. Overhauled rear wheel cylinders.
9. New Spark plugs.
10. New Timing belt
11. New Fan belt/Alternator belt

I read some posts on the distributor diaphragm (vacuum advance diaphragm) and realized mine isn't working. Ordered a new one, will pick it up tomorrow.

I checked the new spark plugs (after reading another post) and they are black at the bottom. What color are they supposed to be?

My problems are:

1. My Uno misfires and is difficult to start in the morning or when it has cooled down completely.

2. It is very very very heavy on fuel. I get about 300km on my 40 liter tank, and I don't even drive it hard. (13.3 liter / 100km) OUCH!!!

A mechanic has checked the timing and says it is fine. What could be the problem, because other Uno drivers are getting about 600km on a tank.

The mixture screw (Weber TLF 32), how do you make it leaner? turning the screw in (clockwise) or out (anti-clockwise).

Any help regarding my problems would be greatly appreciated!!!

 

[waynegts]

was going to say timing but you have had that checked, maybe re check to make sure, leaking fuel tank? vacume leak?

 

[Chas Uno]

Vacuum diaphragm - if this is faulty it will put the timing out as well as causing air leaks to the carburettor. Replace!

Mixture screw - this is at the base of the carburettor (Weber 32 TLF). You screw in to weaken the mixture and screw out to richen it. However, it ONLY affects the mixture at idle. It has no effect at revs above idle.

Black spark plugs. Could be a sign of an over rich mixture, which also explains the heavy fuel consumption and difficult starting. You say that the carburettor was "overhauled" - who did this and what did they do? If they replaced gaskets and seals it's possible they didn't put something back together properly. If a new needle valve was fitted then the float height should have been checked as if improperly adjusted can cause the carburettor to flood leading to the symptoms you described.

If at all possible I'd suggest swapping on a known good carburettor. That might cure the problems or at least eliminate the carb from the equation.

Can you smell fuel when the engine is running, and does the exhaust give out BLACK smoke?

 

[JRB21]

Thanks a lot for all the pointers. Sounds like you have a lot of knowledge on uno's!!!

Checked the mixture screw, it is 9 full turns out from the stop point (fully screwed in point).

Is this too much, how much is the screw suppose to be turned out?

I will have a look at the float level. Will come back to you on that one!

I fitted a new vacuum advance diaphragm yesterday, old one was broken.

No black smoke at exhaust, but the exhaust has thick black stuff on the inside.

Will be taking the car to my mechanic on Monday to do the timing again.

There is no fuel leaks, and no smell of petrol. My rocker cover leaks oil though, but not too much.

No black smoke at exhaust, but there is thick black stuff inside exhaust

 

[thepottleflump]

Thanks a lot for all the pointers. Sounds like you have a lot of knowledge on uno's!!!

Checked the mixture screw, it is 9 full turns out from the stop point (fully screwed in point).

Is this too much, how much is the screw suppose to be turned out?

I will have a look at the float level. Will come back to you on that one!

I fitted a new vacuum advance diaphragm yesterday, old one was broken.

No black smoke at exhaust, but the exhaust has thick black stuff on the inside.

Will be taking the car to my mechanic on Monday to do the timing again.

There is no fuel leaks, and no smell of petrol. My rocker cover leaks oil though, but not too much.

No black smoke at exhaust, but there is thick black stuff inside exhaust

Check out this video for excessive fuel consumption. I'm really enjoying watching this and want to find an event in the UK

As for your mixture screw, it's not really a case of number of turns but emissions at exhaust, although 9 souns on the high side. Off top of my head you'd probably see 2.5% CO on an Uno, HC will also indicate the health of your engine high HC could mean you have a problem. Have you run a compression test to make sure your engine is in good health? All cylinders should be within 10% of one another. Black stuff in the exhaust is pretty typical, soot from the combustion process.

 

[JRB21]

Checked my float level. It was 14mm instead of 26.75 - 27.25.

I set it at 27mm.

After that I took my Uno to a garage that does timing and CO, they tuned everything in and said that it is my carburettor that's the problem.

What on the carb can make the car misfire / idle rough and use excessive fuel?

 

[Chas Uno]

Checked my float level. It was 14mm instead of 26.75 - 27.25.

I set it at 27mm.

After that I took my Uno to a garage that does timing and CO, they tuned everything in and said that it is my carburettor that's the problem.

What on the carb can make the car misfire / idle rough and use excessive fuel?

Air leaks could be the biggest culprit. Did you replace the carburettor gaskets when you set the float height? Were any of them damaged? Are all vacuum pipes and connections to the carburettor connected properly?

With the engine running try spraying some WD40 around the sealing parts of the carburettor including the base. If there is a temporary change in tickover speed then you have an air leak. Plus you might also see some puffs of smoke out of the exhaust as the WD40 gets burnt in the combustion process. Any leaks mean that the carburettor will not be functioning correctly and will affect the running of the engine.

The Weber 32TLF also uses a couple small diaphragms - one is for the accelerator pump and the other is for the anti-stall device. If these are faulty they can cause all sorts of running problems. If you overhauled the carburettor with a kit these should have come with it.

And lastly a sticking needle valve can cause flooding and in particular poor tickover and possibly misfiring. When overhauling a carburettor you have to make sure EVERYTHING is working properly and set to the correct settings else problems can occur.

When you took your Uno to the garage did they check the CO output? Was it within limits? Did they say what they thought was wrong with the carburettor? Quite often garages make a guess as to what is wrong and they are NOT always right!

First thing I'd do would be to check for air leaks. Once that has been eliminated then you can start looking elsewhere.

 

[JRB21]

Yes they did check the CO and they said that it was right.

I only got one diaphragm, the acellerator diaphragm.
I got : gaskets, seals, float needle.

I took out the jets, and blew them out with air.

This is very weird.... When looking at the carburettor from the top, you see two jets that can be screwed out. Next to them there is a little pipe kind of thing made of metal, that runs on the right hand side of the farthest right jet. When I block this, the idle is much better. WHY?????

They referred me to a company that specializes in carbs, but they ask me R1500 to overhaul the carb(that's crazy).

How would I be certain that it is the carb?

 

[Chas Uno]

If your CO is ok then it suggests that the carburettor is functioning correctly. As for this metal pipe, I can't think what it is off hand though the fact that blocking it makes it run better suggests a possible vacuum problem. Are you sure the distributor vacuum unit has been fitted correctly and is not leaking? Has the timing been set with the vacuum advance disconnected and plugged? Is the vacuum advance pipe plugged into the carburettor base?

You need to go over and double check the settings and connections. And you didn't mention if all the carburettor gaskets were changed or if they are damaged? Can you smell fuel near the carburettor?

 

[JRB21]

All the gaskets were changed, and no smell of fuel near the carb.

Do you think faulty spark plug wires would cause this problem?

 

[waynegts]

when amys mk1 uno 45s was running rough and i couldnt see anything wrong i just went to the scrapyard and got a carb off a scrap car, £10 and easier than messing about, still have a couple of carbs in my shed.
is there any near you so you could try another carb to see if that sorts it?

 

[JRB21]

Thanks, I will have a look around to see if I can find any scrapyards. I have tried everything but can't seem to cure the misfire. Maybe the best bet would be to try another carb.

 

[JRB21]

Hi, I emptied out a whole can of carb cleaner in the carb. Idle sounds much better now, not perfect but much better!

I have a few questions.

What connections is their on the fuel inlet pipe?

Mine has a small black rubber fitting (looks like a fuel filter but is not see-through), that has two wires attached to it. After this is the fuel filter and then the fuel pump.

Can anyone tell me what is this black rubber thing????

How can I test if my fuel pump is not working correctly?

When decelerating my uno makes a whining sound, I have drained and replaced gearbox oil, but the whine is still there. Any ideas?