1989 420 SEL cranks but no start

[Cigar Havana]

This is a 1989 420 SEL, 275K KM, the engine cranks but does not start after about 6 attempts. Car has been sitting in an unheated garage for about 1 week, and today it is -7c. On first attempt, there was a loud buzzing sound coming from the front passenger foot well. So I replaced the idle control module, which is located there. No more buzzing on start attempts. Then replaced fuel pump relay (used) , OVP(new). Still cranks but no start.

Car had been idling at little too high for about 3 months, and 3K KM prior to this no start situation. At first when the high idle appeared, it was only on a warm engine, but most recently the high idle would be at both cold and hot engine in park or neutral. It was around 800 to 1000 RPM in park. Sometimes it would settle down to the desired 650 in park but at the next stop it would back up to 900 or 1000 rpm in neutral. Most recently, on cold start it would be at about 800 RPM in park when outside temperature was about 3C.

Here is repair history, most recent repairs first. Only listing ignition and fuel, vacuum repairs vacuum here.

Trying to solve high idle which was present prior to the current no start condition, replaced Idle control valve (ICV), distributor cap and rotor, which had no effect a week ago. It started well, after these parts were replaced and only driven about 30 KM afterwards.

The climate control unit was replaced with brand new one, about 1,000 KM ago. Battery replaced at 270,000 KM.

Valve job was done at 250,000 KM, 2 years ago, included new chain guides, chain tensioner, cold start valve, intake manifold 'o' rings, injector seals, new plugs, belts, new head bolts and washers, etc.

About 4 years ago, air tubes leading to injectors and ICV were replaced, along with fuel pumps, fuel accumulator, fuel valves (attached to the pumps), and injectors, and the black vacuum valve near the ICV. Fuel filter was replaced about 3 years ago, at 242,000 KM.

All vacuum tubes and rubber connectors in the engine compartment were replaced about 5 years ago.

[Xsbank]

Do you have a spark? At the coil lead? At the plugs?
Is it getting fuel?
Can you warm the garage up? Ice, water in the fuel?

High idle might be the coolant sensor that keeps the idle up until it warms up.
Battery voltage? Does it turn over fast?

Gotta be something simple if it just happened.

[Robert Squires]

* CH, you're actually better off now than before when you just had the idle rpm problem. This should be pretty straightforward. Xsbank's advise is spot on. Find out whether you're missing spark or missing fuel.
* Given all the parts and serevice you've done to this car, when you've got the engine running again, and you're back to the high idle problem, you might want to check the oil temp switch (on the block, next to the oil filter). It's responsible for raising the idle rpm when the engine (oil) is cold (colder than the switch point).

[Cigar Havana]

Charged battery 4 hours at 2 amps. Checked battery voltage, it is 12.82 volts after 5 min. off the charger. Cracked open the fuel line at the cold start injector, fuel poured out, ignition is off. Disconnected spark plug wire 8, connected it to a spark plug and grounded the plug threads, cranked engine and saw blue sparks.

Temperature is now down to -13c, no chance of heating garage.

Checked resistance on that blue 2 pin temperature sensor on the top pipe leading to radiator. 21.82 kohms between pins.

Fuel dististributor was replaced with a rebuilt one about 3 years ago.

Next steps?

[Cigar Havana]

After sitting 12 hours at -12c, battery reads 12.7 volts. Battery became fully charged in 20 minutes. Then I tried 3 long cranks, it still won't start. Pulled 7 plugs and they all looked black and a little wet. I guess the cylinders are getting fuel.

Could it be a weak coil? Coil was replaced about 4 years ago?

Could some wire be broken that causes a no start but allows cranking?

Come to think of it, after replacing the ICV, cap and rotor, it started a little rougher.

Any recommendations? I guess it will have to go to the shop tomorrow.

[Xsbank]

Have another look for a spark. If you had one, you'd likely be getting something. Any exhaust smoke? Got a spark from the coil lead?