Help! How do I test the ICU on W114 250 ???

I am not getting spark and just replaced the coil also.Removed the ICU from under battery tray but have no clue what the test procedure is.Thank you in advance!

Reply to
CaptainW116
Loading thread data ...

PS It is a 71 with twin zenith carbs.

Reply to
CaptainW116

You just tested it. It's bad, they all are. If the engine quits, pour some cold water on the unit to cool it. Usually, the engine will then start-meaning the unit is bad.

Reply to
Chas Hurst

That's a joke right ?

Reply to
CaptainW116

No.

Reply to
Chas Hurst

Kind of like checking a PCV valve by shaking it. If it rattles, it's broken and should be replaced. If it doesn't rattle, it's gummed shut and should be replaced.

Seriously, there's not a lot to go wrong in an ignition system. If you've check your points, condensor, coil wire, primary and secondary coil windings, and the ballast resistor, and all of your connections are clean and tight, you've pretty much isolated the problem to the ICU anyway.

For $200 and about a 1/2-hour of installation work, you can ditch the ICU entirely and get a modern capacitive-discharge multi-spark ignition controller and a high-voltage coil, and be done with it. You would still be using the stock points and condenser, but you could remove the ICU entirely and bypass the ballast resistor, so that's two less parts to worry about.

Come to think of it, my '72 250C *might* still have the ICU under the battery. The previous owner replaced the stock distributor with a Mallory Unilite, and I just added an MSD ignition box and coil. I don't know if the original ICU is still there, and if it's there, I don't know if it works, but you could have it for the shipping cost.

I'll check this afternoon and get back to you.

Reply to
Scott Gardner

Thanks for the help and offer guys.

I'm going to also go out and buy a MSD spark box and etc and see if this remedies the problem all together.

Reply to
CaptainW116

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.