I have a 1994 2.6l 4cyl auto carby model, sometimes it's hard to start, hot or cold, and when it does black smoke comes out the exhaust indicating it's running way too rich. I need to almost floor it for 20 seconds to clear out the fuel before it runs sort of smoothly again. I know I have to put the carby off to overhaul it but has anyone had this type of problem before? This would help me know where to look when I strip the carby down. I'm guessing it's something like the float arm has broken or a jet valve isn't closing. Any advice most appreciated.

Yes, a common problem with the carby Magnas. It's the auto choke not coming off quickly enough, due to age or poor water flow through the choke body. Could also be a thermostrat stuck open and not allowing coolant to get up to temperature quickly enough.
Choke is adjustable on the car, but you need to know what you are doing. (TRANSLATION: read the manual)

If that doesn't fix it, then you can look at the float level.

Hi magna 2_6,
Looks like yr first post. Hope you get sorted.
Can I suggest you look also in the first gen section cos there's heaps of carby auto magna Q and A there.
I can relate to your problem where you say "rich / I need to floor it for 20 secs / heaps of black smoke /".
I cant relate to the 'difficult to start' bit.
When cold, it should start OK, but after starting it may run rich if the auto choke dont function well or the float/ needle doesnt function well.
I had problems with a similar complaint to yours, and you should check:
auto choke setting ; in particular the adjustment screw position.
needle and seat; there may be a sticking problem with the needle in the housing.
manual; there is a manual available on this site; download it and READ it; ( see madmax remarks about rtfm)
Float level; this is hard to judge cos once the carby is opened for business, you have no idea where the float level is. The float comes out with the top cover when you take the thing apart.

I have concluded that the float level has to be set by estimation based on how easy it is to get the fuel to flow out through the primary jet. The manuals will tell you that the float level is NOT adjustable so this means if you dont want to guess it, you buy a new needle and seat. Float level can be altered by judicious bending of the float shaft.

You might want to look at the posts by Coldamus and rumpfy in the gen 1 section and good luck.

On my old TP Magna, it was really easy to check the choke. Start the engine, run it for however long it takes to show richness, pull to top off the air cleaner, and see if the choke is still partly closed. If so, open the choke butterfly manually, and see if the idle improves. There is a screw on the choke, winding it in leans it out. Trial and error to get it to do the right thing, too lean and the car stalls when you put your foot down when it is all cold. I ended up taking the locking screw off that adjusting screw to be able to screw it in further.
This might be possible on the second gen 2.6L carby engine too.

Having a working thermostat in the cooling system and working preheat for the air intake were important on the TP as well. And water flow through the choke body.

Hi magna 2_6,
Looks like yr first post. Hope you get sorted.
Can I suggest you look also in the first gen section cos there's heaps of carby auto magna Q and A there.
I can relate to your problem where you say "rich / I need to floor it for 20 secs / heaps of black smoke /".
I cant relate to the 'difficult to start' bit.
When cold, it should start OK, but after starting it may run rich if the auto choke dont function well or the float/ needle doesnt function well.
I had problems with a similar complaint to yours, and you should check:
auto choke setting ; in particular the adjustment screw position.
needle and seat; there may be a sticking problem with the needle in the housing.
manual; there is a manual available on this site; download it and READ it; ( see madmax remarks about rtfm)
Float level; this is hard to judge cos once the carby is opened for business, you have no idea where the float level is. The float comes out with the top cover when you take the thing apart.

I have concluded that the float level has to be set by estimation based on how easy it is to get the fuel to flow out through the primary jet. The manuals will tell you that the float level is NOT adjustable so this means if you dont want to guess it, you buy a new needle and seat. Float level can be altered by judicious bending of the float shaft.

You might want to look at the posts by Coldamus and rumpfy in the gen 1 section and good luck.

Do you have a link to the service manual please? I did a search of this forum but couldn't find anything.

I got the link from one of Coldamus posts. The manual is on this site somewhere. I just had a look but cant easily find it. Ask Coldamus for the reference. Its a Mitsubishi manual for the TR/TS and is about 140 mbyte in size. Pretty big file but worth it.
I didnt say before hand, but my problem with my carby came about because there was some kind of maladjustment of the 'choke set screw'.
This screw presses against the body of the carby and my guess is that there is a shoe/slipper/pressure plate between the end of the screw and the carby body. Without this 'plate' the screw would press on the relatively soft diecast carby body and wear it away so that the carby adjustment would not be stable in service. When this plate fell out of my carby, the choke set lever deranged the whole of the choke system such that the choke was always on. Until I sorted the problem, I kept a clothes peg in the glovebox so that I could keep the butterfly open while getting the car started.
Without this plate the screw was not long enough to set the choke lever. To correct the problem I made up apiece of shet metal 1 mm thick; bent it double and had a 3 mm hole on one side so that it was captive around the screw. This fixed that problem.
regards,
rumpfy.

OK; found the reference.
S'no wonder u couldnt find it!!

http://depositfiles.com/files/cen9su9k9

When u get to the site, dont worry about 'gold plating'

I found the ref from posts by BiDDo88 and others. Thanks to them.
rumpfy.