When driving for more then 10-15 miles the car will stall and shutdown. After waiting for an hour it will start right back up again and go that same 10-15 miles and do the same thing. I've seen this happen 5-6 times in a row. The fuel filter was just replaced and the fuel filter relay is running fine (I can still here the buzz after it's died). The vacuum hose on the fuel pressure regulator was loose and has since been replaced as well. This has become quite a nuisance as you can imagine. I can seem to figure out what else is causing the problem other then the things I've already checked. Any input would be appreciated.

I'm able to get the engine to go into its failure mode easily now in the garage, instead of by driving it out on the street.If I run the engine for 12 minutes plus or minus a couple of minutes, it will die out every time.

This time I attempted to check for spark by hooking up my inductive timing light to the #1 plug wire and had enough wire to reach the drivers seat so I could trigger the light and hold the key at the same time. When I turned the car over to try and start it the light flashed evenly, but the engine wouldn't fire. I'm assuming at this point it means I have spark. The plugs are stuck on this car and I'd rather not risk further damage trying to get them out for troubleshooting if I can avoid it right now.

After about 1 1/2 hours of cool-down time the car will start, and run for another 12 minutes before dying. I've repeated this four times, in the garage, in the direct sun, hood up, hood down. No difference.

I think I should probably check fuel pressure when it dies but I don't have a fuel pressure gauge yet. I did replace the fuel filter, and a very loose vacuum hose on the fuel pressure regulator but these two things have not made a difference. I spotted the crank position sensor after a lot of searching, behind the engine as was posted. Is there one bolt, or two holding it? I could only see one but I need to let the engine cool completely before trying to get my hand stuck back there. This stalling out is so regular I'm beginning to think its likely the ECU, ideally it would be nice to swap this one into another running car or vice verse to test it.

UPDATE:

Fuel pump does not prime when key turned on..

Does the ECU alone control the function where the fuel pumps are activated for a moment when the key is turned on, before the starter is energized?

Swapped ECUs with another pink label 561, also swapped fuel pump relays. Both parts unknown quality, from friends parts car.

First time with other ECU and relay it ran and then died after 12 minutes just like before.

After fiddling with cable connections to crank position sensor ( to investigate how hard it would be to remove) AND hot wiring fuel pumps on at fuse block ( wanted to prime fuel rail before starting ) the car idled for an hour with no issues, until I shut it off. Halfway through this period I removed jumper from +12 to fuel pumps, engine continued to run. After I shut it off it would re-start but a little difficult because fuel pump not priming. Fuel rail not holding pressure either I noticed, slow bleed down . Glad its no longer cutting out after 12 minutes but I need to do more testing with the 2 ECUs and F.P. relays. Hard to believe just unplugging and plugging crank position sensor would make a difference. I need to see if old ECU goers back to previous failure mode where it would die after 12 minutes. I now have two flakey ECUs? Intermittant crank position sensor sensitive to pulling on cable?

I'd definitely think it's some electrical thing getting hot... really need to check for spark.

My first guess (not knowing about newer cars/ignition amplifiers..etc.) would be the coil.

--
-Matt I ♥ my ♂

I couldn't remove the spark plug because they were in there so tight and didn't want to strip them while in the housing. So I tested them for spark with another plug and they seemed to getting it. Only problem is I don't know if they are receiving enough. I might try some different techniques to getting them out without ruining the threading.

On mine it ends up being the spark/ignition module. Is is located beside the battery on the fender. If it fells very hot like mine did and the coil measures 5-6 volts on the white wire with red stripe (2 of them tied to left terminal of coil. You will need a repacement. Got mine on E-bay and it came with new metal heat sink. Also make sure the ground wires on the fuel rail are clean and secure, they are black wires on thw 2 main mounting bolts. 1 of them is the ground wire for that module. The coil is not usually the problem. Volvos were known for this part failing. It's actually a time issue not mileage.

Is this the same as the power stage (spark/ignition module)?

What year 240 is this?

I have a 1983 with a simular problem.
My 83 does not have a power stage / ignition amplifier.
What if any part on my 83 does the power stage / ignition amplifier
replace?

Thanks,
Joseph

It's a 1991

The power stage / ignition amplifier may be bad or need a new coat of thermal heat sink paste. When is quits see you have spark or not at a spark plug. Remove a spark plug and see if it is wet or dry. If the plug is wet and you have no spark the power stage is bad.
Dan

Hi Dan,
What is "a new coat of thermal heat sink paste"?

I am having a simular issue, but only on HOT days/drives.

Thanks,
Joseph in New Mexico

Go to a radio shack and ask for thermal dielectric heart sink paste. It gives a better heat dissipating connection between the heat sink and the ignition amplifier / power stage.

http://www.radioshack.com/product/index.jsp?productId=2102858

Dan

So I would apply some to where the amplifier attaches to the car?
Thanks,
Joseph

Yes on the back surface of the power stage where it attaches to the heat sink.
Dan

I have a 1983 with a simular problem.
My 83 does not have a power stage / ignition amplifier.
What if any part on my 83 does the power stage / ignition amplifier
replace?

Thanks,
Joseph

Post a new thread, I am not familiar with the older 240's.
Dan

Thanks, I will check this and get back to you.

I believe on older cars it is handled by distributor underneath rotor button. Can someone confirm this?