I`ve got a stutter

[georgem]

Guys please help,

I`m not talking about my speech, perfectly good Aussie strine, but our car - 230SL.   For the last 18 months its been running perfectly -  starts instantly hot or cold (well hot most times) great idle smooth running etc until lately its developed a stutter - the motor misses a couple of times one after the other. The annoying thing is that it is random so I cannot nail it down to anything - it will do it while I`m accelerating - cruising fast or slow.  It feels like an electrical fault rather than fuel - as if someone has a large switch that is flicked on and off rapidly. Fuel starvation normaly is "softer" if thats any way to describe it and would last a tad longer.

So, where do I start? The only visual thing I can see is that the ceramic block is broken in two, but its been like that for a while. All other wires and plugs are firmly attached.

Any help would be greatly appreciated.

Cheers

George
Brisbane

[J. Huber]

Hi George. By no means the expert here, but I would first double confirm that all the electrical connections are snug. I would also immediately replace that cracked ballast resistor (if thats whats cracked). What coil are you using? I'd suggest red label bosch with a 1.8 ballast. And are you running standard points? If so, check the dwell. Others will add I'm sure...Good luck.

[ja17]

Hello,

Sounds like your ignition points are closing up. Check the gap.

[georgem]

Guys,

Thanks for the feed back. I have worked my way throught the distributor and now she wont fire up - no spark.  I think the problem may be where the low voltage circuit and the condensor connect to the side of the distributor.

Two questions:

Is the bolt on the distributor that the coil wire and the condensor connected to insulated from the body? There are two large fibre washers: one on the inside and one outside but i cannot see anything that stops the bolt from contacting the body of the distributor - I may have dropped it., and

Please confirm that the wire from the negative terminal on the coil goes to the distributor.

Thanks

[jacovdw]

...Is the bolt on the distributor that the coil wire and the condensor connected to insulated from the body?

Yes, otherwise you would short your ignition system to ground and hence no spark.

Lastly, the negative terminal of the coil is connected to the points in the distributor.

[georgem]

Thanks Jaco,

Actually, after I posted my questions, the more I thought about it, the more I realised that the bolt had to be insulated, so I went back and checked my work area and found a tiny plastic spacer/washer/ring that isolates the bolt where it passes through the distributor body. Put everything back together and she fired up - so I also figured that the neg from the coil must be the one. Thanks for confirming though.

Cheers

[ja17]

Hello George,

You forgot to tell us how it runs now?

One other thing to watch out for......... when your tightening down the forked terminal of the ignition contacts be careful it does not rotate off its insulated washer and ground out against the distributor.

A small rubber o-ring can be used in place of the insulated sleeve, if needed, between the two insulated warhers. 

[georgem]

Joe,

Its been a bit of a journey. The bottom line is that it now is running beautifully, but to be honest I am not completely sure why.

After my first post, I took your advice and went to the points. I had trouble setting these - to get the dwell at about 40deg, I had to close the points down to about .006in - a gap of .013in meant a dwell of about 33deg. I played around with these for a while; trying various combinations but the stutter remained. In the end I opted for the feeler guage and set the points at .013in.

I replaced the suppressor and had the coil tested which was ok, so them I started to scratch my head. I remembered threads about fuel and vaporisation if the fuel flow wasn`t accurate, both delivery and return, so I took the sender unit off the tank and checked that there was a strong swirling from the return line - seemed good. Unfortunately there was too much fuel in the tank to see the strainer.

Still, on fuel I took the fuel filter out and tipped the fuel into an ice cream container and swirled it about - black fuel with a lot of very fune black gritty sedement left in the container. Unfortunately I didn`t have a new filter so i put the old one back in.

Once I solved the last problem re the isolation of the bolt on the distributor, she fired up and ran perfectly yesterday for about 80kms.

So, what was the problem - I`m not sure but my suspicion is now fuel because of the clogged fuel filter. (I will repace the current one ASAP). The black sediment can only be coming from the tank so when the fuel gets down a but, I shall pull the bottom plug and check the filter screen.   Hmmmmmm.

BTW, I am having to eat some humble pie at the moment as the first time the stutter happened, my wife was in the can and she thought it was fuel!

Cheers

[georgem]

Well, by way of completing the loop and closing this topic off...


I drained the tank and cleaned the filter in the pump - same black grit. The fuel tank filter was pretty clear. BTW,  the fuel pump and tank drain plug are easily reached with the car on the floor - there is excellent access.

Now the trivial pursuit winning information.....

being a little anal retentive, I though I would do a check on volumes so:

From completely empty until the fuel runs out the off take line that feeds the pump; 3.3litres ( not totally scientific as it may have been siphoning)

From this point until the red fuel light goes out; 10liters.

So, in summary the tank has just over 3 litres that we can`t use, and 10litres of fuel once the warning light comes on, which will probably gives about 100km before she splutters to a stop.

Cheers

[w113dude]

So, in summary the tank has just over 3 litres that we can`t use, and 10litres of fuel once the warning light comes on, which will probably gives about 100km before she splutters to a stop.

Since most of the gas sender units don't work properly, This is a very useful bit of info!