340 Too Rich

340_Chris · Jan 19th, 2009, 13:56

Dear All,

I have a 3-door 1985 1.4 340 GL with a very irritating problem. When I was first given it the weather was rather better than it is now and all seemed fine. When the cold snap started just before Christmas I noticed that the engine wasn't really getting hot (not even to the 'C' on the guage). At the same time I also noticed that the 'change gear' light on the dashboard was constantly lit. To combat the warmth problem I have fitted a new thermostat and that is now fine. The idle speed seems too high but I haven't got a tacho so can't say exactly what it is - I'd guestimate that it must be around the 1500-1800 mark when at normal temperature.

The main problem is that it's running rich the whole time. I thought that the replacement thermostat might sort things out but it's now started to break down on long (motorway) journeys and I'm having to literally clean the plugs before I can continue. They are getting really sooty to the point where I'm using emery paper to clean it off.
Round town and on short-ish motorway journeys it can cope with but the exhaust fumes are always 'rich' in odour and the exhaust pipe is very sooty too. Not to mention the excessive fuel consumption.

Can anyone suggest anything that I can troubleshoot to try and get this sorted as I'd like to keep hold of it for the time-being and can't really afford to hand it over to a garage to look at.

Many thanks.

Chris

Chris_C · Jan 19th, 2009, 14:59

I'm not sure what rev range the change gear light comes in on, but knowing Volvo... probably about 1800.

Check your dizzy cap, and rotor arm. These go *very* quickly, and possible that you are getting a weak spark anyway. Leads the same, check the ends arn't at all corroded. Then check that the air filter has all three bolts (I think it's 3 for a 1.4, not played with one for a while) to the carb top, and that these arn't stripped. Hand tight, no more. Mixture and idle speed can be tuned be ear, but only if you've done it before. Idle speed is a screw with a plastic nut on the end, that touches the cam with the accel linkage on. Mixture should be down a little tube from memory, but basically on the carb base at a 45 degree angle.

If you've not done it before, the process is tricky to explain, but turn the mixture until it sounds like it's running better, then back the idle speed down, then mixture again, then idle. At the end, she'll sound perfect, which in real life is half a turn to rich, so tighten the mixture in half a turn and she'll be perfect.

340_Chris · Jan 19th, 2009, 15:13

Thanks for the speedy reply.

Before I had the car all the electrical components (plugs, leads, dizzy cap and rotor arm) were replaced as it was running really sporadically - in the end it was the flywheel sensor so it's had a replacement just to get it going full stop.

I'll have a go at changing the mixture as you've suggested - so tighten to lean and loosen to enrich? Will this have any affect when it's running at speed or just at idle?

Many thanks again.

Chris

Clan · Jan 19th, 2009, 18:39

You may well find the top of the carb is loose , and also the accelerator pump jet assembly on top of the carb , take the top off the air filter and get someone to press the throttle a few times and you will probably see fuel flooding from the loose jet into the engine ...

Chris_C · Jan 20th, 2009, 10:36

Good point Clan, I forgot to mention the carb top.

Mixture will be affected all through.

340_Chris · Jan 20th, 2009, 12:33

Thanks again - I'll have a go and let you know the outcome.

340_Chris · Jan 21st, 2009, 08:54

OK. I had a look under the air filter and tried the throttle but nothing appears to be loose but I could see fuel sqirting down into the chambers - but I assume that's normal.

I've leaned off the mixture a quarter of a turn and also reduced the idle speed slightly. It's sounding a little better, however, it hesitates slightly when I blip the throttle.

Something else I noticed was that there is no metal piping between the inlet manifold and the air filter - could this be causing any of these problems as it looks like there is some sort of valve inside the air filter?

Do you think I need to take the carb off and have a proper look? Do you know if you can still get repair kits for these Weber carbs?

Chris_C · Jan 21st, 2009, 10:05

Repair kits are still available, Mac posted a few places to get them a while ago, but they may have been on V3M.

That pipe feeds warm air to the carb when it's cold. The valve you see is a heat controlled flappy paddle that switches between various mixes of hot and cold air. Yes, I'd replace it and tweak the carb so that it runs best with that in place. Having said that I've run my 1.7 the last few months without that valve, it takes longer to warm itself up, and if tuned in the summer won't like running in winter and vice versa. This isn't inconvenient for me, but may be for others!!!

Clan · Jan 21st, 2009, 17:09

Did you see fuel ONLY spraying out of the jet as a fine jet? When the jet is loose fuel floods everywhere from the base of the jet every time the throttle is pressed and gets drawn in to the engine , far too rich hence flat spot ...

340_Chris · Jan 22nd, 2009, 09:46

Yes, when the throttle was pressed the fuel came out of the jets in a thin stream - which I assume is how it's supposed to be yes?

I drove it for the first time since meddling with the mixture last night and, on the surface at least, things seem to be a little better. The idle is down to a nice speed and there's no more slight run-on when I turn the engine off. I won't know how things are until I've done a long journey but I'm confident that you've got things going in the right direction so many thanks again.

Jan 19th, 2009, 13:56	#1
340_Chris New Member Last Online: Dec 3rd, 2014 17:25 Join Date: Jan 2009 Location: Malvern	340 Too Rich Dear All, I have a 3-door 1985 1.4 340 GL with a very irritating problem. When I was first given it the weather was rather better than it is now and all seemed fine. When the cold snap started just before Christmas I noticed that the engine wasn't really getting hot (not even to the 'C' on the guage). At the same time I also noticed that the 'change gear' light on the dashboard was constantly lit. To combat the warmth problem I have fitted a new thermostat and that is now fine. The idle speed seems too high but I haven't got a tacho so can't say exactly what it is - I'd guestimate that it must be around the 1500-1800 mark when at normal temperature. The main problem is that it's running rich the whole time. I thought that the replacement thermostat might sort things out but it's now started to break down on long (motorway) journeys and I'm having to literally clean the plugs before I can continue. They are getting really sooty to the point where I'm using emery paper to clean it off. Round town and on short-ish motorway journeys it can cope with but the exhaust fumes are always 'rich' in odour and the exhaust pipe is very sooty too. Not to mention the excessive fuel consumption. Can anyone suggest anything that I can troubleshoot to try and get this sorted as I'd like to keep hold of it for the time-being and can't really afford to hand it over to a garage to look at. Many thanks. Chris

Jan 19th, 2009, 14:59	#2
Chris_C Gopher Last Online: Oct 12th, 2023 15:31 Join Date: Dec 2003 Location: Southampton or Isle of Wight View Photos By: Chris_C	I'm not sure what rev range the change gear light comes in on, but knowing Volvo... probably about 1800. Check your dizzy cap, and rotor arm. These go very quickly, and possible that you are getting a weak spark anyway. Leads the same, check the ends arn't at all corroded. Then check that the air filter has all three bolts (I think it's 3 for a 1.4, not played with one for a while) to the carb top, and that these arn't stripped. Hand tight, no more. Mixture and idle speed can be tuned be ear, but only if you've done it before. Idle speed is a screw with a plastic nut on the end, that touches the cam with the accel linkage on. Mixture should be down a little tube from memory, but basically on the carb base at a 45 degree angle. If you've not done it before, the process is tricky to explain, but turn the mixture until it sounds like it's running better, then back the idle speed down, then mixture again, then idle. At the end, she'll sound perfect, which in real life is half a turn to rich, so tighten the mixture in half a turn and she'll be perfect. __________________ 2003 S60 D5 SE 1989 340GL - Fake - Gallery Project Thread - Spare parts car turned motorsport plaything. 8 more valves, 277 more cc's Previously, a lot of various 300s

Jan 19th, 2009, 18:39	#4
Clan Experienced Member Last Online: Yesterday 22:18 Join Date: Jun 2007 Location: L/H side	You may well find the top of the carb is loose , and also the accelerator pump jet assembly on top of the carb , take the top off the air filter and get someone to press the throttle a few times and you will probably see fuel flooding from the loose jet into the engine ... __________________ My comments are only based on my opinions and vast experience .

Jan 20th, 2009, 10:36	#5
Chris_C Gopher Last Online: Oct 12th, 2023 15:31 Join Date: Dec 2003 Location: Southampton or Isle of Wight View Photos By: Chris_C	Good point Clan, I forgot to mention the carb top. Mixture will be affected all through. __________________ 2003 S60 D5 SE 1989 340GL - Fake - Gallery Project Thread - Spare parts car turned motorsport plaything. 8 more valves, 277 more cc's Previously, a lot of various 300s

Jan 21st, 2009, 08:54	#7
340_Chris New Member Last Online: Dec 3rd, 2014 17:25 Join Date: Jan 2009 Location: Malvern	OK. I had a look under the air filter and tried the throttle but nothing appears to be loose but I could see fuel sqirting down into the chambers - but I assume that's normal. I've leaned off the mixture a quarter of a turn and also reduced the idle speed slightly. It's sounding a little better, however, it hesitates slightly when I blip the throttle. Something else I noticed was that there is no metal piping between the inlet manifold and the air filter - could this be causing any of these problems as it looks like there is some sort of valve inside the air filter? Do you think I need to take the carb off and have a proper look? Do you know if you can still get repair kits for these Weber carbs? Last edited by 340_Chris; Jan 21st, 2009 at 08:58.

Jan 19th, 2009, 15:13	#3
340_Chris New Member Last Online: Dec 3rd, 2014 17:25 Join Date: Jan 2009 Location: Malvern	Thanks for the speedy reply. Before I had the car all the electrical components (plugs, leads, dizzy cap and rotor arm) were replaced as it was running really sporadically - in the end it was the flywheel sensor so it's had a replacement just to get it going full stop. I'll have a go at changing the mixture as you've suggested - so tighten to lean and loosen to enrich? Will this have any affect when it's running at speed or just at idle? Many thanks again. Chris

Jan 20th, 2009, 12:33	#6
340_Chris New Member Last Online: Dec 3rd, 2014 17:25 Join Date: Jan 2009 Location: Malvern	Thanks again - I'll have a go and let you know the outcome.

Jan 21st, 2009, 10:05	#8
Chris_C Gopher Last Online: Oct 12th, 2023 15:31 Join Date: Dec 2003 Location: Southampton or Isle of Wight View Photos By: Chris_C	Repair kits are still available, Mac posted a few places to get them a while ago, but they may have been on V3M. That pipe feeds warm air to the carb when it's cold. The valve you see is a heat controlled flappy paddle that switches between various mixes of hot and cold air. Yes, I'd replace it and tweak the carb so that it runs best with that in place. Having said that I've run my 1.7 the last few months without that valve, it takes longer to warm itself up, and if tuned in the summer won't like running in winter and vice versa. This isn't inconvenient for me, but may be for others!!! __________________ 2003 S60 D5 SE 1989 340GL - Fake - Gallery Project Thread - Spare parts car turned motorsport plaything. 8 more valves, 277 more cc's Previously, a lot of various 300s

Jan 21st, 2009, 17:09	#9
Clan Experienced Member Last Online: Yesterday 22:18 Join Date: Jun 2007 Location: L/H side	Did you see fuel ONLY spraying out of the jet as a fine jet? When the jet is loose fuel floods everywhere from the base of the jet every time the throttle is pressed and gets drawn in to the engine , far too rich hence flat spot ... __________________ My comments are only based on my opinions and vast experience .

Jan 22nd, 2009, 09:46	#10
340_Chris New Member Last Online: Dec 3rd, 2014 17:25 Join Date: Jan 2009 Location: Malvern	Yes, when the throttle was pressed the fuel came out of the jets in a thin stream - which I assume is how it's supposed to be yes? I drove it for the first time since meddling with the mixture last night and, on the surface at least, things seem to be a little better. The idle is down to a nice speed and there's no more slight run-on when I turn the engine off. I won't know how things are until I've done a long journey but I'm confident that you've got things going in the right direction so many thanks again.

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