Technical Uno Racer Not Idling

randomspeedfreak · May 20, 2009

hi all,

ive recently set the timing up on the uno racer.

we have got it to be fine down to about 1700 rpm. below this it will spit, missfire and try to stall.

can anyone give me some possible causes other than the ones below:

1)ive bent the centrifugal advance weight springs - they are now giving it too little advance low down in the rev range causing it to misfire.

2) the missfiring that occoured before the timing was set up has changed or broken something inside the carb

3) the dirty fuel that clogged the fuel filter (which has now been cleaned flushed and replaced) has somehow got through the filter into the carb and clogged something in the carb - causing crap running

any help much appreciated - i need to get a move on if im going to get it finished before summer!

CLXCraig · May 20, 2009

For the dirty carb. remove it and have it cleaned. you can get carb cleaners, some better than others like all things, but if you get a, or have use of an ultrasonic bath. they work brilliantly.

Alternatively, a new recond carb could be an easier option if you only have a standard carb fitted.

Hurry up and get it fixed, want to see it on the local roads!

Ucof · May 20, 2009

Reddex (fuel line cleaner) straight into the carb. Remove the air filter and manually pull the throttle cable to stop the engine from stalling.

You can find Reddex in Tesco petrol stations, as well as Halfrauds and many other garages.

It explicitly says it IS safe for use with catalytic convertors.

stick a bottle in and see how it goes.

CLXCraig · May 20, 2009

How would you put it in the carb bfore the injector? Sorry don't know much about carbs. Surely the purpose of Reddex is to flush threw with the fuel?

Yazza54 · May 20, 2009

being a racer is it cammed up to its eyeballs and is the carb jetted to match?

Sorum91 · May 20, 2009

well, it's not an easy one to figure out, but it's probably not a complicated thing. have you checked the elektrical side? it's a simple rule that when a car is not running properly it's either petrol, air or the elektrics thet is the problem. biut I think I would check the distributor cap and the parts inside it. (sinse I am from norway, I don't know the english name of way to many parts

)

I'll think more abaut the problems, and ask aroud a bit, and see what comes up, so to speech

-Sorum91

Ucof · May 21, 2009

With regards to the reddex, whip off the air filter and pour it in the hole in the top whilst the engine is running. If it starts to stall, yank the throttle cable and it will splutter into life.

Doing this will clean the carb out of carbon deposits.

randomspeedfreak · May 21, 2009

Ucof said:
With regards to the reddex, whip off the air filter and pour it in the hole in the top whilst the engine is running. If it starts to stall, yank the throttle cable and it will splutter into life.

Doing this will clean the carb out of carbon deposits.

ok ill give this a go, but, i dont really understand how this will clean anything but the inner walls of the carb, and the inlet manifold?

wouldnt it just come into contact with the end of the jets, the 'throat' of the carb, and the inlet manifold before being burnt off by the engine? none of it would actually clean the internals of the carb?

Sorum91 said:
well, it's not an easy one to figure out, but it's probably not a complicated thing. have you checked the elektrical side? it's a simple rule that when a car is not running properly it's either petrol, air or the elektrics thet is the problem. biut I think I would check the distributor cap and the parts inside it. (sinse I am from norway, I don't know the english name of way to many parts)

I'll think more abaut the problems, and ask aroud a bit, and see what comes up, so to speech

-Sorum91

ok thanks,
i work with that principle too.

I did the timing recently and all sparks are big and consistantly on time, timed to the best of my abillities (i cant account for the centrifugal advance springs as i dont have a timing strobe - hence problem idea number 1 above)

Yazza54 said:
being a racer is it cammed up to its eyeballs and is the carb jetted to match?

a good question, from what ive seen its not that far removed from the standard engine, it is only making 30 maybe 40 bhp more at most (when it runs lol

)

The main reason i dont think it is this is becasue it was idling totally fine a few months ago, before it decided to throw a strop

- i have changed nothing since then....unless the jets have changed themselves? (problem idea 2 above)

CLXCraig said:
How would you put it in the carb bfore the injector? Sorry don't know much about carbs. Surely the purpose of Reddex is to flush threw with the fuel?

thats what i was thinking Ucof ^

Ucof said:
Reddex (fuel line cleaner) straight into the carb. Remove the air filter and manually pull the throttle cable to stop the engine from stalling.

You can find Reddex in Tesco petrol stations, as well as Halfrauds and many other garages.

It explicitly says it IS safe for use with catalytic convertors.

stick a bottle in and see how it goes.

ok im lucky in that i have no cat.

i will give this a try asap

(ive got an exam this pm, then im straight off to france for a week, so ill report back in 10 days or so)

Thanks very much everyone for your thoughts so far

randomspeedfreak · May 21, 2009

oh and while im gone, if your interested the car in question is the one in this thread:
https://www.fiatforum.com/uno/178182-rsf-uno-roadracer-project.html

seems pretty quiet there - just me and craig atm!

was it something i said?

cheers guys

Ucof · May 21, 2009

Good luck with the Exam, and have a great time in France (if possible

).

Have faith in the Reddex for it awesome stuff is.

Red it is too

You can put it in the fuel tank to flush through the fuel lines and pumps (basically wherever fuel goes) but you can also pour it straight into the carburettor to give that a clean out too. It made my lil' Uno very happy and better running (about 70k miles with no Reddex at all) and was one of the first things I did when I got it

alexGS · May 21, 2009

randomspeedfreak said:
seems pretty quiet there - just me and craig atm!

was it something i said?

Sorry

It's a bit like the news media - a story makes a splash, then is quietly forgotten, even though there may be interesting developments. Also, you seemed to be having a great old chat and maybe no-one had anything to add

-Alex

Yazza54 · May 21, 2009

On a naturally aspirated engine another 30 - 4o is a hell of alot extra power. the only way you could make that power is high up in the rev range burning a lot more fuel and air using higher lift/duration cams.

if its turbo'd then this aint the reason.

But if its n/a then sounds like its cammed up too much to idle and in that state it will never idle

Chas Uno · May 21, 2009

Yazza54 said:
On a naturally aspirated engine another 30 - 4o is a hell of alot extra power. the only way you could make that power is high up in the rev range burning a lot more fuel and air using higher lift/duration cams.

if its turbo'd then this aint the reason.

But if its n/a then sounds like its cammed up too much to idle and in that state it will never idle

All very valid points, but it WAS idling fine up until recently. Something has happend/ changed that's caused an idle fault.

I'm still wondering if the Luminition system is part of the problem. Did it idle properly AFTER you repaired it Matt? If not, it could still be the problem.

The other thing to check is the vacuum advance unit on the distributor. If this is faulty then it will be allowing air leaks as well as affecting the ignition advance. Also, when you checked the timing did you disconnect the vacuum advance unit and plug the vacuum pipe whilst doing this? What degrees did you set the timing to and which timing mark did you use (crank pulley or flywheel)? If I remember it should be about 10 degrees. Did you check the timing at a low idle i.e. below 1000 rpm?

It does sound like it could be ignition related, especially as you describe spitting (backfiring?), misfiring and attempting to stall. These are all symptoms of incorrect ignition timing so it could well be that.

Let us know how you get on as it will be great to see this little racer back on the road

Chas Uno · May 21, 2009

randomspeedfreak said:
I did the timing recently and all sparks are big and consistantly on time, timed to the best of my abillities (i cant account for the centrifugal advance springs as i dont have a timing strobe - hence problem idea number 1 above)

Just caught this in your post Matt. Did you set the timing WITHOUT a strobe? Setting it via crank/ cam/ flywheel marks is only a rough guide and could well be why you are having problems. These engines should have their ignition timing set dynamically with a strobe, so before you do anything else then get this checked/ reset with a suitable timing light.

Also it's worth bearing in mind that the advance bob weights don't have a lot of effect until higher revs, where the centrifugal forces try and pull them away from the springs. I don't think you slightly bending one will affect the idle much (hopefully!)

Keep us posted with how you get on

Sorum91 · May 22, 2009

1986Uno45S said:
Just caught this in your post Matt. Did you set the timing WITHOUT a strobe? Setting it via crank/ cam/ flywheel marks is only a rough guide and could well be why you are having problems. These engines should have their ignition timing set dynamically with a strobe, so before you do anything else then get this checked/ reset with a suitable timing light.

couldn't agree more.

You should get a strobe and get it completly right, I think it will fix your problem, you probably set it to early. I don't think it's too late because then you woluld have trouble getting revs. you'll probably get a bit more power too

good luck on your exam, and have a nice time in france

Sorum91

Yazza54 · May 22, 2009

1986Uno45S said:
All very valid points, but it WAS idling fine up until recently. Something has happend/ changed that's caused an idle fault.

I'm still wondering if the Luminition system is part of the problem. Did it idle properly AFTER you repaired it Matt? If not, it could still be the problem.

The other thing to check is the vacuum advance unit on the distributor. If this is faulty then it will be allowing air leaks as well as affecting the ignition advance. Also, when you checked the timing did you disconnect the vacuum advance unit and plug the vacuum pipe whilst doing this? What degrees did you set the timing to and which timing mark did you use (crank pulley or flywheel)? If I remember it should be about 10 degrees. Did you check the timing at a low idle i.e. below 1000 rpm?

It does sound like it could be ignition related, especially as you describe spitting (backfiring?), misfiring and attempting to stall. These are all symptoms of incorrect ignition timing so it could well be that.

Let us know how you get on as it will be great to see this little racer back on the road

In that case id check the timing isnt out incase a belt has slipped or a sensor isnt picking up properly.
Thing is aswell with carbs is that you get a bit of dirt in there and the thing will flood and only pick up when you open the throttle and give it some air.

Take the carb apart and give it a good clean. The floats might not be working properly if theres muck in there or some air ways /jets could be blocked.

Carbs can be a nightmare tbh. But if it used to idle and doesnt now it really is one of these things i wouldve thought..

either bad timing

incorrect fuel/air mixture

poor spark

could even be sucking air from somewhere if a manifold gasket has failed

randomspeedfreak · May 22, 2009

1986Uno45S said:
All very valid points, but it WAS idling fine up until recently. Something has happend/ changed that's caused an idle fault.

I'm still wondering if the Luminition system is part of the problem. Did it idle properly AFTER you repaired it Matt? If not, it could still be the problem.

The other thing to check is the vacuum advance unit on the distributor. If this is faulty then it will be allowing air leaks as well as affecting the ignition advance. Also, when you checked the timing did you disconnect the vacuum advance unit and plug the vacuum pipe whilst doing this? What degrees did you set the timing to and which timing mark did you use (crank pulley or flywheel)? If I remember it should be about 10 degrees. Did you check the timing at a low idle i.e. below 1000 rpm?

It does sound like it could be ignition related, especially as you describe spitting (backfiring?), misfiring and attempting to stall. These are all symptoms of incorrect ignition timing so it could well be that.

Let us know how you get on as it will be great to see this little racer back on the road

It hasnt worked properly since it broke that sensor on the luminition that i replaced.

i checked the vacum advance i think its fine....i was setting the timing up as per this manual : http://www.bccp.nl/techdocs/PMA50ins.pdf
page 4 is where your looking, but its not that boring to read all of it just so you know whats going on (if you have the time that is!

)

thanks man yeah im pretty desperate to get it sorted - i havent driven in like 8 months!

1986Uno45S said:
Just caught this in your post Matt. Did you set the timing WITHOUT a strobe? Setting it via crank/ cam/ flywheel marks is only a rough guide and could well be why you are having problems. These engines should have their ignition timing set dynamically with a strobe, so before you do anything else then get this checked/ reset with a suitable timing light.

Also it's worth bearing in mind that the advance bob weights don't have a lot of effect until higher revs, where the centrifugal forces try and pull them away from the springs. I don't think you slightly bending one will affect the idle much (hopefully!)

Keep us posted with how you get on

i set it up as per the manual - http://www.bccp.nl/techdocs/PMA50ins.pdf
at the bottom of page 4 is static timing using a voltmeter - this is how i did it. i was under the impression this was accurate?

oh and i used cylinder number 4 - not 1 as it says.

after we had done this we found the idle would get a bit better if we advanced the ignition a little bit (like, really little) (steps of 0.5degrees or less per time!) until we got to teh point where we are now where it would get a bit worse if we went further...

Sorum91 said:
(quote: chas, above)

couldn't agree more.

You should get a strobe and get it completly right, I think it will fix your problem, you probably set it to early. I don't think it's too late because then you woluld have trouble getting revs. you'll probably get a bit more power too

good luck on your exam, and have a nice time in france

Sorum91

ok. i just find it weird that its only at low revs - if it was too early surely it would get worse at higher revs? maybe ive got it backwards?
ive been up since 4am

so im a bit iffy lol

thaks sorum - i think i did terrible in the exam

.....France is nice and hot though!

Yazza54 said:
In that case id check the timing isnt out incase a belt has slipped or a sensor isnt picking up properly.
Thing is aswell with carbs is that you get a bit of dirt in there and the thing will flood and only pick up when you open the throttle and give it some air.

Take the carb apart and give it a good clean. The floats might not be working properly if theres muck in there or some air ways /jets could be blocked.

Carbs can be a nightmare tbh. But if it used to idle and doesnt now it really is one of these things i wouldve thought..

either bad timing

incorrect fuel/air mixture

poor spark

could even be sucking air from somewhere if a manifold gasket has failed

i agree with all of the above.

will do as soon as i get back. thanks for your input

thankyou everyone for your help - ill be updating with progress asap

Sorum91 · May 22, 2009

no, I don't think so, how did you check the vacum advance?
because what the vacum device does is adjust the timing earlier when you rev the engine, so if the device or a vacum lead is faulty the ignition would be right at higher revs, but wrong at low revs and when the engine is ideling

you'll see that if you use a strobe and rev the engine, the ignition mark will move earlier and earlier the higer you rev the engine. that is if your vacum advance is working properly

I'm sure you'll get a good result on your exam

and have fun in france

Sorum91

randomspeedfreak · May 23, 2009

Sorum91 said:
no, I don't think so, how did you check the vacum advance?
because what the vacum device does is adjust the timing earlier when you rev the engine, so if the device or a vacum lead is faulty the ignition would be right at higher revs, but wrong at low revs and when the engine is ideling

you'll see that if you use a strobe and rev the engine, the ignition mark will move earlier and earlier the higer you rev the engine. that is if your vacum advance is working properly

I'm sure you'll get a good result on your exam
and have fun in france

Sorum91

i got the pipe going into tha vacum advance and blew and sucked on it (oh er) to see if it was making a seal.
i see where your coming from - my problem does sound very much like vacum advance - i should double check it when i get back

ill see if i have enough money to get a strobe for when i get back

i dont know about teh results...i only need 3 D's to get into uni tho so im

very sunny here

anyone know where i could get a gasket kit....would fiat do one?
cheers

Sorum91 · May 23, 2009

randomspeedfreak said:
i got the pipe going into tha vacum advance and blew and sucked on it (oh er) to see if it was making a seal.
i see where your coming from - my problem does sound very much like vacum advance - i should double check it when i get back

ill see if i have enough money to get a strobe for when i get back

i dont know about teh results...i only need 3 D's to get into uni tho so im

very sunny here

anyone know where i could get a gasket kit....would fiat do one?
cheers

well, it's the right way to check the vacum advance

It could be a good idea

maybe you could borrow one from a friend or maybe a garage will lend you one, it's not that much work to just check it

I'm sure you'll get in easyly

I wish I was in france

sorry, don't know about the UK mate

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