Technical weber carb mixture far too rich 1990 tipo 1.4 running very rough

[yaztaz]

very long time since last post!

1990 carb tipo 1.4 - spark plugs black - very rich mixture (not burning oil) seems like engine running on full choke and then some.. but no its nothing to do with the choke for sure. for some reason not getting enough air? if its misfiring then probably when plugs get overloaded with carbon deposits.

the only way i can get it to tickover without stalling is to wind throttle stop screw to absolute max position. its just about driveable but very juddery even when 'cruising' at 50mph but.. when 2nd barrel of the weber comes in under hard acceleration engine pulls well and smoothly too. so some kind of blockage on the primary barrel side of things?

this problem persisted for couple weeks but on a 9 mile journey the problem cleared after filling up with petrol, then went great for the rest of trip of about 40 mile, including 2 stops and starting again after half hour just fine. then a 3 hour park up and started fine after that too. left car undisturbed at home for 4 days and when started the problem was back. curses !! before starting on that day i did check the plugs and found perfect beige-brown appearance indicating had been correct fuel mixture during the approx 50 mile run.

i have a weber TLDE carb rebuild kit and am all set to remove carb and dismantle but i wonder if anything will be found to be blocked, as there is no obvious signs down the primary barrel of gumming up at all which i am told can happen with 'modern' petrol (all unleaded or some recent formula?) i have sprayed a fair amount of carb cleaner into primary barrel with engine revving some, but with zero effect.

i also have a spare 1.4 tipo carb but some difference in how the accelerator and choke levers are configured so cannot just swap over. haynes manual says there are two types fitted to 1.4 tipo before single point injection systems took over, and looks like my spare one is the other type.

pretty sure after checks that theres nothing wrong with ignition system. would the line filters (there are two - one of which has 3 connections - not present in the haynes diagrams or pictures) be causing this kind of problem, or some kind of float level problem?

BEAR IN MIND THE PROBLEM DID CLEAR ITSELF JUST THE ONCE AND RAN PERFECTLY FOR MANY MILES AND SEVERAL STOP STARTS BEFORE ITS PERSISTENT RETURN AFTER NOT BEING DRIVEN FOR A FURTHER 4 DAYS.

hoping for some help with this - thanks :|

 

[ZaphodB]

i have sprayed a fair amount of carb cleaner into primary barrel with engine revving some, but with zero effect.

That will have zero effect

The carb cleaner needs to be in the fuel passages before it enters the barrel, (i.e. in the various fuel passages) - the fuel is already mixed/mixing with air at the barrel/intake, so you'll need to carefully strip it, (meticulously recording stuff as you go) and fit your rebuild kit

 

[jackwhoo]

If it has a full throttle enrichment jet that is opened by a diaphragm.......If the diaphragm gets old/perished , holed or split neat fuel is drawn through the diaphragm straight into inlet manifold.

 

[jackwhoo]

Sometimes the full throttle enrichment is not used but the diaphragm is still fitted and still causes hugely rich symptoms. Split diaphragm allows neat fuel through vacuum side of diaphragm straight to engine.

Again I'm not sure this applies to your exact Webber.

 

[bugsymike]

Re idle setting , have you checked the small idle jet on outside of carb if fitted?
Around that year cars were going from carbs to injection and catalysts and lots of issues/compromises.
Some had a volume screw rather than an idle screw, this controlled air flow through the carb jets etc. so the more you screwed it in the slower the engine, it still had a mixture screw so it all needed balancing up.
Many Webers had emulsion tubes inside when you took the top off and the could be pulled out with a match stick after removing the small jet above them, often if tapped on a hard surface lots of water and dirt would drop out.

 

[varesecrazy]

Most of my tipo experience was TD's

But my previous cars were 2 x Regata petrol

Both of them had Weber carb related running issues,

So I think a THOROUGH strip and clean would make sense as a 1st step

 

[yaztaz]

many thanks for the many replies, i didnt expect such a lot and so quickly too!

so, the throttle enrichment diaphragm seems to be most likely cause and could explain massive fuel consumption before filling up on the day in question.

but if diaphragm is split then how could the problem clear itself for that remaining 40 mile covered on the same day? and why would the old problem return after standing for 4 days. but thanks very much @jackwhoo for that one.

and thanks everyone else for the morale support to dismantle weber systematically, clean out and use all new parts in the kit.

no main jets in the kit though, so im wondering (if) they were supplied; have they been used by previous owner of the kit. perhaps the main jets dont wear on a weber and dont therefore need replacing, hmmm. . . thanks again all, i wont forget to report back.

 

[yaztaz]

If it has a full throttle enrichment jet that is opened by a diaphragm.......If the diaphragm gets old/perished , holed or split neat fuel is drawn through the diaphragm straight into inlet manifold.

thanks much for the replies, i didnt expect as many and so quickly too!

so, the throttle enrichment diaphragm seems to be most likely cause and could explain massive fuel consumption before filling up on the day in question.

but if diaphragm is split then how could the problem clear itself for that remaining 40 mile covered on the same day? and why would the old problem return after standing for 4 days. but thanks very much for that one.

and thanks everyone else for the morale support to dismantle weber systematically, clean out and use all new parts in the kit.

no main jets in the kit though, so im wondering (if) they were supplied; have they been used by previous owner of the kit. perhaps the main jets dont wear on a weber and dont therefore need replacing, hmmm. .

thanks again all, i wont forget to report back.

 

[jackwhoo]

Jets don't wear unless someone pushes anything through them or carb has metering needle(yours does not)

Have you considered carb flooding? Bad float or float valve.

 

[jackwhoo]

Carb diaphragms can degrade in petrol with ethanol , do not use e85 petrol

 

[bugsymike]

Carb diaphragms can degrade in petrol with ethanol , do not use e85 petrol

E10 ?

 

[jackwhoo]

E10 ?

I advise premium only with garden equipment using 2 stroke motors and 4 stroke motors using a combined tank/carb assembly (Briggs and stratton) which is a hybrid "pulse" carb.
So anything with diaphragms I suggest only premium fuel max e5

 

[jackwhoo]

@Pugglt Auld Jock

Hi Jock, do I recall you enjoyed a fair bit of landscaping machinery with carbs?

Please share your wisdom regarding fuel.

Best wishes
Jack

 

[Pugglt Auld Jock]

@Pugglt Auld Jock

Hi Jock, do I recall you enjoyed a fair bit of landscaping machinery with carbs?

Please share your wisdom regarding fuel.

Best wishes
Jack

Oh absolutely! It's a minefield though because some say they can handle it in their newer machines. I'd guess American machines are maybe able to as they've had methanol fuels for a long time. The problem is that, as you say, unless specifically designed to use it, the high methanol fuels will not only destroy diaphragms but it can also actually corrode some of the metals. I don't have the answer as to how you are supposed to find out for sure which are which so I just run everything on E5 "premium grade" which at worst is going to have only a very small percentage or maybe, from reports I've read, non at all. I think it likely that if you buy a new machine it'll be Ok, but I'd read the manual just to be sure. The older machines I'm interested in I wouldn't even consider it. By the way, the effects are non reversible so, as soon as you put a high ethanol fuel -E10 - in the tank and run the engine the damage starts to accumulate. This can't be reversed by subsequently running some low ethanol - E5 - through it, Once the damage is done, it's done! Many small engine shops stock fuel conditioners which claim to cope with ethanol problems, but I think it's better just not to risk it. Of course, in older engines there can also be the problem of valve recession brought on by unleaded fuels allowing the seats and valve faces to be eaten away. Luckily this isn't such a problem with air cooled engines because they tend to have quite hard valves and seats due to the fact they run hotter than water cooled engines. I don't get any valve and seat problems with my engines, but I do use them with sympathy! By the way, I've found a straight 30 weight oil works best in these small air cooled engines, where multigrade oils tend to break down due to the heat - Local "hot spots" are quite a problem in air cooled engines which are not encountered in water cooled ones. I run pretty much all the small engines on SAE30 or maybe SAE40 in very hot weather or where I've an old engine which burns a bit of oil and I want to get another season out of it. Don't think though that I'm recommending using these oils in your car engine - unless perhaps, you're running around in an old air cooled VW Beetle, DAF twin cylinder or maybe a 2CV/Dyane etc.

Edit, @jackwhoo Does that help? do ask more if anything occurs to you.

 

[Pugglt Auld Jock]

Oh absolutely! It's a minefield though because some say they can handle it in their newer machines. I'd guess American machines are maybe able to as they've had methanol fuels for a long time. The problem is that, as you say, unless specifically designed to use it, the high methanol fuels will not only destroy diaphragms but it can also actually corrode some of the metals. I don't have the answer as to how you are supposed to find out for sure which are which so I just run everything on E5 "premium grade" which at worst is going to have only a very small percentage or maybe, from reports I've read, non at all. I think it likely that if you buy a new machine it'll be Ok, but I'd read the manual just to be sure. The older machines I'm interested in I wouldn't even consider it. By the way, the effects are non reversible so, as soon as you put a high ethanol fuel -E10 - in the tank and run the engine the damage starts to accumulate. This can't be reversed by subsequently running some low ethanol - E5 - through it, Once the damage is done, it's done! Many small engine shops stock fuel conditioners which claim to cope with ethanol problems, but I think it's better just not to risk it. Of course, in older engines there can also be the problem of valve recession brought on by unleaded fuels allowing the seats and valve faces to be eaten away. Luckily this isn't such a problem with air cooled engines because they tend to have quite hard valves and seats due to the fact they run hotter than water cooled engines. I don't get any valve and seat problems with my engines, but I do use them with sympathy! By the way, I've found a straight 30 weight oil works best in these small air cooled engines, where multigrade oils tend to break down due to the heat - Local "hot spots" are quite a problem in air cooled engines which are not encountered in water cooled ones. I run pretty much all the small engines on SAE30 or maybe SAE40 in very hot weather or where I've an old engine which burns a bit of oil and I want to get another season out of it. Don't think though that I'm recommending using these oils in your car engine - unless perhaps, you're running around in an old air cooled VW Beetle, DAF twin cylinder or maybe a 2CV/Dyane etc.

Edit, @jackwhoo Does that help? do ask more if anything occurs to you.

By the way. The problems with E10 apply to some older cars too. If you - that is anyone reading this - runs an older car you can check if it's Ok to run E10 in it. Check here: https://www.gov.uk/check-vehicle-e10-petrol. The effects of running E10 in a vehicle that can't cope with it can be quite slow and insidious, Might take many months or even a year or so to become a really big problem. Once it does get a hold though it can be very costly to sort out the many parts which have been affected, especially if it's a fuel injected system.

Here's just one of many articles posted on the web that you can read regarding using petrol in horticultural machines: https://ripongroundcare.com/blogs/lawnmower-help/is-my-engine-compatible-with-e10-fuel#:~:text=Can I use E10 petrol,shared advice around E10 fuel.
Fuel stabilisers are very popular in the States but I think that's often due to the higher temperatures which evaporate the fuel's lighter elements and, maybe, because you come across even higher ethanol content over there? Maybe @Cheest could enlighten us? I don't know any professional gardeners over here who use them. I buy just 5 litres of E5 at any one time, some of which immediately gets mixed with 2 stroke in a separate container for the smaller machines. Both containers are properly sealed type. So I'm buying fuel at about 2 monthly intervals - even less at the height of summer. It's a really good idea to drain your fuel tank over the winter though and run the engine 'till it stops which will pull most of the residual fuel out of the carb and pipes. Do an oil change just before you do this and the new oil, with all it's nice corrosion inhibitors, will get to all parts of the engine as you run the old fuel through so give added protection to the engine while it lies dormant until the next spring.

 

[Cheest]

I felt a disturbance in the force.

On this side of the pond E10 is pretty much the norm, especially if one lives in a corn growing state(raises hand)like, Illannoy or Iowa. We also have E88(12%) and E85(15%). Those two I won't run as the vehicles fuel system must be designed for it. There will be an emblem on the vehicle stating 'Flex Fuel' to run those two.

As far as older vehicles running E10, I've never had an issue. My Dad would occasionally run an octane booster in the DeSoto but quit when studies showed that years of running leaded fuels pretty much protected the valve seats against issues with E10. Also, Chrysler was already using hardened valve seats in their engines in the 30s. The real issues with the fuel systems were the rubber parts deteriorating due to the ethanol. Newer replacement parts are designed for the ethanol fuels. One reason why I won't buy NOS repair kits with rubber parts. There can be corrosion of certain metal parts but I haven't experienced myself.

I do use Sta-Bil Marine fuel stabilizer. It's in the mower, bikes, and DeSoto in the winter months. The snowblower gets it in the warmer months. I use the blue Marine stuff because it's surprisingly humid here. I dump the required amount in the fuel tanks and run each about five minutes, then forget about them during the season.

 

[bugsymike]

I felt a disturbance in the force.

On this side of the pond E10 is pretty much the norm, especially if one lives in a corn growing state(raises hand)like, Illannoy or Iowa. We also have E88(12%) and E85(15%). Those two I won't run as the vehicles fuel system must be designed for it. There will be an emblem on the vehicle stating 'Flex Fuel' to run those two.

As far as older vehicles running E10, I've never had an issue. My Dad would occasionally run an octane booster in the DeSoto but quit when studies showed that years of running leaded fuels pretty much protected the valve seats against issues with E10. Also, Chrysler was already using hardened valve seats in their engines in the 30s. The real issues with the fuel systems were the rubber parts deteriorating due to the ethanol. Newer replacement parts are designed for the ethanol fuels. One reason why I won't buy NOS repair kits with rubber parts. There can be corrosion of certain metal parts but I haven't experienced myself.

I do use Sta-Bil Marine fuel stabilizer. It's in the mower, bikes, and DeSoto in the winter months. The snowblower gets it in the warmer months. I use the blue Marine stuff because it's surprisingly humid here. I dump the required amount in the fuel tanks and run each about five minutes, then forget about them during the season.

I had never heard of E88 and E85, around here all they sell is E5 and E10, so stick with E5 for my older petrol machinery.