740 poor running and stalling

[Beadybc]

Originally Posted by Laird Scooby

I hate Haynes for referring to K-Jetronic as CI - K is short for Kontinuierlich which means continuous. They are one and the same.

You shouldn't be able to turn the distributor cap whether the engine is running or not, it's fixed to the cam carrier and driven off the rear end of the camshaft. The EZK ignition ECU above the pedals does all the timing adjustments needed.

If your fuel tank is full, you need to empty 3/4 of the tank. You will need the full 2L of meths, not the silly little 500ml bottle as that won't do any good. The ratio is important, about 10% meths to fuel so 2L of meths to 18L of petrol which is about 4 gallons. I was going on the fuel guage reading, normally 7xx don't give a reading at all if the guage isn't working.
That's why i linked to the 2L bottle of meths and NOT the 500ml bottle!

With the extra info that it has never run right in your ownership, was sat for at least a year beforehand etc i would definitely suggest condensation in the fuel. Hence the meths. Try the things i mentioned in the order i mentioned them (unless already done like the plugs) but you need to reduce the amount of fuel in the tank to make the 2L of meths effective or increase the amount of meths to 6L which probably won't even fit in the tank if it's full.


*** EDIT *** Just had a look at your extra pics and can't see a cat, Lambda or anything else to suggest it's a KE-Jetronic so pretty safe to say it's a standard K-Jetronic

I should have the methylated spirit and the equipment to syphon out most of the fuel tomorrow but in the mean time I took off the panel under the dash to look for the Ignition ECU and that was when I remembered that I also forgot to mention that there is an old Cobra alarm system fitted so the wiring has been tampered with at some point.

I'm struggling to see an ECU with tubing to it, I have attached photos of what it looks like under there.

[Laird Scooby]

Originally Posted by Beadybc

I'm struggling to see an ECU with tubing to it, I have attached photos of what it looks like under there.

Here it is :



The ECU is outlined in blue, the green hose (other end is on the inlet manifold) is the advance and the rubber elbow/connector is in the bit where the blue and green cross to make a weird slug-shape. Make sure that elbow is on the stub at the back of the ECU, isn't split or perished and that the neutral coloured pipe/hose is also secure in it. Also worth checking on the inlet manifold end to make sure the stub on the manifold isn't blocked, if so some carb and air intake cleaner will help clear it.

[Beadybc]

Originally Posted by Laird Scooby

Here it is :



The ECU is outlined in blue, the green hose (other end is on the inlet manifold) is the advance and the rubber elbow/connector is in the bit where the blue and green cross to make a weird slug-shape. Make sure that elbow is on the stub at the back of the ECU, isn't split or perished and that the neutral coloured pipe/hose is also secure in it. Also worth checking on the inlet manifold end to make sure the stub on the manifold isn't blocked, if so some carb and air intake cleaner will help clear it.

Cheers Dave I'll check both.

[Beadybc]

So the elbow on the ECU is fine and the tubing itself is fine however the inlet manifold elbow is in poor condition, you can see this in the original photos that I uploaded with my original post (I've linked that pdf again). This was one of the first things that I wanted to replace but held off as I have no idea where to find one of these. Now that I think of it I could probably just order some non kinked tubing the same size and use that instead.

[Laird Scooby]

Originally Posted by Beadybc

So the elbow on the ECU is fine and the tubing itself is fine however the inlet manifold elbow is in poor condition, you can see this in the original photos that I uploaded with my original post (I've linked that pdf again). This was one of the first things that I wanted to replace but held off as I have no idea where to find one of these. Now that I think of it I could probably just order some non kinked tubing the same size and use that instead.

You should be able to get them in your local accessory shop, fairly sure Pearly Wot-Nots make them. Alternatively i think Volvo still have them, if not some 4mm bore vacuum tubing (again from local accessory shop) will do.

[Beadybc]

So I've checked the plug gaps and they were set to 0.8mm so I've changed them to 0.7mm. I ran the engine with the Methylated spirit, started strong but made no difference after 15 minutes of idling. Started it again about an hour later and the car stopped dropping in idle but the throttle would go up and not come down for about 10 seconds. Tried it again the day after and it was back to square one.

Here's a video:
https://youtu.be/fqS72I7ArDY

I'm gonna carry on working with the other suggestions.

[Beadybc]

Originally Posted by Laird Scooby

First of all, did it run at all before you replaced the fuel? Second, how much have you put it? Third, how long was the car stood?

Fourth, go to your local Toolstation and buy :

https://www.toolstation.com/methylated-spirit/p99550

Add the contents to the fuel tank, start the car and let it run for 5-10 minutes then see what it does.

What gap did you set the plugs to when you did them? Should be 0.65-0.7mm (0.025-0.028")

Sixth, the timing is non-adjustable on that engine.

Seventh, you only have an AAV (Auxiliary Air Valve) you don't have an AICV (Air Idle Control Valve) so the idle speed won't be maintained at 900rpm regardless. The AAV is working, you've proved that.

Eighth, inspect that rubber sock between the throttle body and the fuel distributor for splits, perishing and security - any leaks there will cause your symptoms.

Ninth, buy some Carlube ATF-U, NAPA MV or Dexron III synthetic ATF. Buy a gallon of petrol in a fuel can and add ~1/4-1/3pt (150-200ml) of the ATF to the fuel, replace the lid and give it a shake to mix it then add it to the fuel tank - don't add any more fuel at this stage. Also add about a pint (0.5L) of the ATF to the engine oil.

Start the engine and let it run for 15-20 minutes at idle - don't be tempted to blip the throttle to "test it" - once it's run like this for 15-20 minutes, gradually push down on the accelerator and see how it goes.

Tenth - remove the trim panel under the dash below the steering wheel. Look up and you should see a single ECU for the ignition - there should be a neutral coloured nylon tube ~4mm or 3/16" OD going to it with a short rubber link tube about 25-30mm long (about an inch) to connect it. Make sure this is connected.

Lastly, let us know how you get on. It sounds suspiciously like lack of use combined with condensation in the fuel, dried rubber seals and/or sticking components in the fuel distributor and possibly splits in the air sock between the fuel distributor and throttle body.

Also worth cleaning the PCV system out but that won't normally cause the problems you've got, at least not on a K-Jetronic engine which is what you have there. Just to clarify things, it doesn't have a Lambda-Sond badge on the radiator grille, a catalytic converter and Lambda sensor does it? If so that makes it a KE-Jetronic which increases the fun-factor ten-fold! (For "fun" read complications!)

Oh yeah, check the air filter is clean as well.

Noticed an exposed connection on the starter motor (attached a photo)

[Laird Scooby]

Originally Posted by Beadybc

So I've checked the plug gaps and they were set to 0.8mm so I've changed them to 0.7mm. I ran the engine with the Methylated spirit, started strong but made no difference after 15 minutes of idling. Started it again about an hour later and the car stopped dropping in idle but the throttle would go up and not come down for about 10 seconds. Tried it again the day after and it was back to square one.

Here's a video:
https://youtu.be/fqS72I7ArDY

I'm gonna carry on working with the other suggestions.

Originally Posted by Beadybc

Noticed an exposed connection on the starter motor (attached a photo)

That's idling and starting a lot better! Your dad has found a good clue and it isn't the starter motor. To wiggle the wires on the starter he'd have to have nudged the sock between the fuel distributor and the throttle body.

I'm fairly convinced that sock is either loose, perished or split or not fitted properly.

[Beadybc]

Originally Posted by Laird Scooby

That's idling and starting a lot better! Your dad has found a good clue and it isn't the starter motor. To wiggle the wires on the starter he'd have to have nudged the sock between the fuel distributor and the throttle body.

I'm fairly convinced that sock is either loose, perished or split or not fitted properly.

Yeah the top connection of the sock seems to be getting lower with every run even though the rings are attached tightly.

It has an arrow on it pointing downwards, not sure what it is indicating and I can't find any information on it as I don't know it's official name.

[griston64]

It's this https://www.skandix.de/en/spare-part...ubber/1012350/