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Author Topic: Idle speed erratic and dies away  (Read 484 times)
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andyps
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« on: 04 January, 2021, 02:31:42 PM »

Looking for some advice. I've had my Fulvia S2 started and running a few times recently after it had stood for a long time. I rebuilt the carbs (standard Solex) to get all the jets cleaned up but haven't done anything about the float levels. I bought the guide to set up from Omicron which I have followed and am reasonably happy that they are balanced - not perfect but it runs OK and revs smoothly. However, the idle speed is a little erratic and if I leave it it seems to idle for a while and then gradually slows down and stops if I don't do anything. Also, it isn't easy to start - when cold it takes a while and when it has got warm it sometimes needs a little choke to start it, immediately then running without choke.

Once the car is on the road I'm happy to take it to someone to get it set up properly (I'm in Yorkshire) but would like to get it a little better than it is if possible before that stage so any advice welcome.

Almost ready for a first drive, I was aiming for 2020 but the roads at home were covered in ice for the last few days so I didn't bother rushing to get it out of the garage!
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andyps
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« Reply #1 on: 04 January, 2021, 02:32:17 PM »

And just realised I forgot to say Happy New Year everyone!
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peteracs
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« Reply #2 on: 04 January, 2021, 08:20:03 PM »

Hi

First question is how old is the petrol you are using?

If stood for a while will not help the situation.

Peter
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Beta Spyder S2 pre F/L 1600
Saab 9-3 1.9Tid Cabrio
lancialulu
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« Reply #3 on: 04 January, 2021, 10:21:17 PM »

Very hard to diagnose from a distance. Statement of the obvious is to go through everything , valve tappet clearance, compression when hot, ignition timing 8 deg static, float levels (easier than you think), fuel pump pressure when idling, clogged fuel supply line etc etc.
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Its not the winning but taking part! or is it taking apart?
1955 Aurelia B12
1967 Flavia Vignale iniezione
1967 Fulvia 1.3HFR
1972 Fulvia 1600HF
1972 Fulvia 1600HF
1972 1600 Fulvia Sport
1979 2500 Gamma Coupe
1988 Delta 1.6GTi
1998 Zeta
davidwheeler
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« Reply #4 on: 04 January, 2021, 10:56:38 PM »

I had endless trouble with mine until I cleaned the earth on the (electronic) ignition.     It is always worth checking earths!
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David Wheeler.  Lambdas, Aprilia, Fulvia Sport.(formerly Appia and Thema as well).
jus
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Posts: 33



« Reply #5 on: 04 January, 2021, 11:45:44 PM »

Could be an air leak. Try spraying some carb cleaner carefully at different areas of the carbs (spindles and mounting rubber for example) and see if the idle changes. If you have a brake servo or ignition advance hose - check for vacuum leaks there as well.
Do you have a mechanical or electronic fuel pump?
Do you hear an equalising pressure change when you open the fuel cap?
Do you have an inline fuel filter that could be a bit clogged up?
« Last Edit: 06 January, 2021, 02:00:59 PM by jus » Logged

1982 Beta Spyder
1969 S1 Fulvia 1.6HF Rallye
1971 Works Fulvia 1.6HF
1972 S2 Fulvia 1.6HF Lusso
1982 037 Rally
andyps
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Posts: 192


« Reply #6 on: 06 January, 2021, 11:42:36 AM »

Thanks for the replies, been a busy few days back at work so I hadn't had chance to look at them until now.

Petrol is fresh so shouldn't be an issue hopefully it's a couple of months old at the most but probably less than that.

I've done all of the valve clearances, haven't checked compressions, sorted the timing as far as I can tell, fuel pump (both electric and mechanical) are new and I've cleaned through the lines. Sounds like I should check compression which I'll try next time it is hot.

All earths have been cleaned with additional earthing added as I couldn't get it to run at all at one point.

I'll try the carb cleaner for air leaks, it doesn't sound to have any but may be a small leak somewhere. The brake servo hose is something I have intended to replace as it is the only old hose left.

Some ideas for this weekend, I'll let you know how I get on.
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lancialulu
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« Reply #7 on: 06 January, 2021, 05:01:21 PM »

Normally an air leak (manifold or servo pipe) leads to a rising (>2000rpm generally) tick over.... I can vouch for this as it was a problem I had when recently installing a pair of solexes on a 1600.

Sound more like the mix is too rich and when it warms up the air/fuel is too low  for the engine to tick over comfortably. When it starts to drop tweak the no1 mix screw in and see if the revs slightly rise. If so do this to all until it is stable.....
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Its not the winning but taking part! or is it taking apart?
1955 Aurelia B12
1967 Flavia Vignale iniezione
1967 Fulvia 1.3HFR
1972 Fulvia 1600HF
1972 Fulvia 1600HF
1972 1600 Fulvia Sport
1979 2500 Gamma Coupe
1988 Delta 1.6GTi
1998 Zeta
andyps
Senior Member
*****
Posts: 192


« Reply #8 on: 06 January, 2021, 05:52:03 PM »

Thanks Tim, I've been trying adjusting the carb screws but this is my first car with Solex carbs so I am learning about them! If it had SUs I'd understand what I'm doing a lot better. It is running a lot more smoothly than it was, just not as well as it should be, if it would sit at idle without assistance I'd be happy enough for the moment.
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nistri
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Posts: 341


« Reply #9 on: 07 January, 2021, 08:34:16 AM »

worth checking the needle valves: their opening and closing can become erratic. Assuming that their needle washers are correct for size and thickness, the valves often respond positively to soaking in carb cleaner for a few hours. Andrea
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Andrea Nistri

Ardea S2
Appia S2
Fulvia GTE
Fulvia Sport 1.3 S
Fulvia Montecarlo
Fulvia Coupe 1.3 S
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