A friend's 89 240 began hard starting eg. crank and crank and crank until it finally caught; then it ran rough until warmed up. I asked him to notice
- Temp related - harder to start when cold air/engine temp?
- Fuel-level related - worse when tank low? (in-tank pump hose)
- Unplug the MAS/AMM - did it start more easily?

The answer to all 3 was "yes" but they turned out to be false clues*.

After he got it to my house it would barely run; then wouldn't start at all. I suspected CPS (although new), MAS, hole in air hose after the MAS, bad intake-manifold gasket, bad fuel-filter and/or main fuel pump, power stage, coil, ...

It would fire, sometimes run a few seconds, die. Smelled gas, plugs were damp. Disconnected coil wire at distributor cap and grounded it. Faint spark once when the key was turned on and once more on the 1st engine turn; sometimes when the key was released. Pulled the battery to clean the power-stage plug contacts & noticed it was slightly loose. And had fresh grease so perhaps I'd even done the deed when I worked on it ~1 year ago.

Tightened the 2 screws, got good and consistent spark; it started right up. Could still be problems, we'll see.

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*Reminding us, as psychologists finally admitted in the 1990s, that it's easy to plant false memories and associations.
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240 drivers / parts cars - JH, Ohio

Mounting the PS firmly with a good coating of thermal paste is a good idea but this is not likely the cause of the no start. They will work fine unmounted to the heat sink.

Problem might have been bad electrical connection with the PS.

Good quality Bosch cap, rotor, plug wires, and plugs are very important.
Dan

Dan, you mentioned tn a thread to someone else that you'd fixed a hard start with a new distributor cap. This car had a new Bosch cap a few months ago but it didn't look great (scratches inside) so I replaced it with a NIB not-Bosch cap I had around.

So far it's made the difference: it consistently starts cold and runs without stalling. We'll see how it goes with some more driving.

When I have rough running - or the existing cap looks bad - I replace it. I get that it would improve starting and running but not sure why it would eliminate the 2-3 stalls that were typical to this car. Unless it's just the general case of trying to start car with some miles on it.

Thanks again.
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240 drivers / parts cars - JH, Ohio

Yes I had a no start many years ago that was a cap or rotor not sure which because I replaced both at the same time. There have been several other people who have reported the same thing over the years.

If you didn't replace the rotor I would do it as well as spark plug wires and plugs if they are of unknown quality and age. I always use Bosch, Bougicord and NKG.

Dan

Thanks Dan.

I had replaced cap, rotor, wires, plugs, IDK, last year sometime. Bosch cap, good wires.

This time I just replaced the cap so I could see what made the difference. I also replaced the O2 sensor but starting seemed the same on a couple of test starts. And that really shouldn't affect starting unless eg. it was running so rich that it flooded the plugs when you turned it off every time.

I'll drive it through a few cycles and we'll see.

It's just not a cause I'd seen before. This car ran strong after a 5-minute warm up. No missing under load. Smooth idle.
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240 drivers / parts cars - JH, Ohio

I agree, it shouldn't have needed the physical ground. But it didn't work loose; worked tightened; didn't work loose; now works tightened; ....

However, yes, this still could (have been) a bad wire connection at the plug as you suggest. We'll see how it runs. And I'm going to go through it again.

You wrote "Good quality Bosch cap, rotor, plug wires, and plugs are very important."

This car has all new I think. I'd say "Good quality ... are ideal" - I've logged many 240 miles in cars with aftermarket parts. Don't last as long; probably aren't as efficient - starting, power, MPG ... but sometimes that's what you have.
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240 drivers / parts cars - JH, Ohio