My 940 stopped while idling last week and won't restart. I have tried all of these things to sort it out. It has spark at the coil and plugs, It has around 40 psi on the fuel rail. A vacuum on the FPR does reduce the pressure a few psi. It retains fuel pressure on the rail overnight (20 psi). I checked the timing belt and all the marks line up. The compression is around 170 on all cylinders. The injectors all seem to spray, When I pulled the injectors out and turn the crank manually they pulse fuel. The plugs were black and wet with fuel so I have replaced them. There are no codes set, although the battery was discharged and I think I might have held the button down too long when checking codes the first time and accidentally cleared them. I also checked the resistance of the CTS and it was 3900 ohms. It was idling a bit rough for a few days before it died. I am thinking that the oxygen sensor doesn't com into play until a minute or so after start. I haven't tried ether yet. Any ideas?

VICTORY!!
It was the distributor cap/rotor. Even though I was getting enough "spark" at each plug wire to trip my timing light pickup I was losing voltage though the cap. Thanks to all of your advice. I bought one of those spark checkers from Harbor freight and hooked it up. Since I was working by myself I set up my video camera on my phone to watch it as I cranked. Very pathetic spark. Thanks Again to all.
Eric

Update, It finally got warm enough to work on it today. I replaced the ignition control module. (lifetime warranty from Autozone, cheap test) Still no start

I have A spark at each cylinder but I don't know how hot it is. I suppose it should get a higher primary voltage while cranking. Does anyone know what voltage that is?
It did fire a few times while cranking but never started.

The injectors are spraying. The fuel pressure is at 40 psi,

The IAC doesn't seem clogged but how would it act if it were messed up. I tried opening the throttle to different positions while cranking and that is when it fired a few times. I have seen IACs replaced with a PVC ball valve. (this is KY)
Would that be a good way to test it?

While cranking, how advanced is the spark from TDC, what vacuum reading should I see and what should the fuel pressure be?

It does seem to be getting plenty of fuel, It blew up the muffler when I lit the tailpipe.(joke)

I think I will next try another coil. Does any one vote to eliminate any of the components that have been nominated? I believe my crank sensor is good, suppression relay seems good, Ignition module good.

Another question, when the cam sprocket is lined up with the mark, should the crank pulley be at the TDC mark on the belt cover used for ignition setting?

thanks y'all

Seriously. check the Radio Supression Relay. Easy test. Check the FAQ.
Rule it out if you haven't already.

The RSR grounds the injection system. When it fails you get no fuel.

If you get fuel, put a $2 in-line spark tester from Harbor Freight on #1 and have a friend crank the ignition. Determine if you are getting spark to your plugs.

After cranking, pull a plug and smell for unburnt fuel on the plugs.

The system only works if you have Fuel, Fire, and Compression.

duplicate post - disregard.

Nobody seems to have mentioned it. My 1990 740 with Rex Regina suffered the intermittent -and eventually permanent- failure of the RSR.

Seems the RSR kills the ground side of the injection circuit and mechanics find it hard to properly diagnose.

The test-fix is easy. Switch the RSR for the Cooling Fan Relay and see if the car starts.

Everything seems OK in your outline above and responses below. Maybe the following sequence will help locate the problem. I've eliminated the Bosch elements to hopefully simplify it for Rex-Regina consideration. It assumes that basic timing and compression are correct.
Hope this helps.

REX-Regina Start-Run Sequence

1) During starter cranking, the Crank Position Sensor sends timing pulses to the REX Ignition Control Unit.

2-a) The ICU uses these CPS pulses to trigger the Power Stage (aka Ignition Amplifier), which initiates spark from the coil.

2-b) At the same time, The ICU also propagates the pulses to the Regina FI ECU, to allow FI operation (no ICU pulses means no FI operation).

3-a) The Fuel Injection (System*) relay (previously energized at Key On) powers the IAC valve, ECU, Radio suppression Relay (supplies Injector voltage), and Fuel (pump) relay coil + side.
* The System relay is in the white case with the Fuel relay.

3-b) When ICU pulses are received by the FI ECU, it "energizes" the Fuel relay by grounding the relay coil (– side) to run the fuel pumps.

When all these things work, the engine runs until the Ignition is switched off, which in turn shuts down the FI system.

Determining whether or not there is spark at the plugs (2a) — and whether or not the plugs are getting gas (3b) — makes a good no-start "starting" point.

For example, if 2a fails due to a bad Power Stage/Amplifier, there will be a no-start with gas-wet plugs. If 2b fails (practically never) symptoms will be Fuel-related: a no-start with spark at the plugs, but plugs remain dry.

--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Dear lucid,

Hope you're well. If this clear analysis is not in the FAQs, it should be.

Yours faithfully,

Spook

Just a possible if you run out of other ideas.

I've had the IAC controller kill my engine before if it jams and it doesn't help if you have a flooded engine, I'm pretty sure it would be low down on other board users lists as the culprit but that problem idling in the preceding days is a probable indicator of whatever the fault is.

My volvo was an absolute swine to get going last time I flooded it and I wished I'd taken all the plugs out and vented it to clear the excess (although I noted you had changed the plugs)

regards
pierso

I cleaned the connections on the coil. The primary resistance was about 2 ohms and the secondary was about 6k. Does that seem normal?

hi,
the IAC as I remember would jam in any position and would work for a few miles before letting you down. Its favourite trick was to kill the engine as you came up to red traffic lights as the revs were coming down just when you needed the brakes. Put a new one in and it was fine though the tick over was never as smooth with the new one (as it wasn't a volvo one i expect). Tried the old one again after a good clean up and proved itself as erratic as ever. Probably something had flaked off inside and was intermittently jamming it.

regards
pierso

I had this mysterious occurrence happen to 93 245 (Bosch system) and it turned out that I had installed the Crank Position Sensor a few degrees off. Check that it is OK and the wiring is intact.
Good luck,
el raidman
AKA el profe GLo

Dear raidman,

Hope you're well. The Crank Position Sensor (CPS) is secured by a 10mm hex head bolt. There's a mounting hole in the CPS, through which the bolt passes and a hole in the transmission bell housing, into which the bolt goes. I don't think it is possible to mis-align the CPS. Do you refer perhaps to the throttle position sensor?

Yours faithfully,

Spook

If your getting fuel, and everything else is as good as you say, I too would suspect that the spark (firing in open air) may not be as healthy as you think. Just taking it off the amplifier heat sink to clean the 2 contact pins may help. Rex failures are few and far between. [And who can say the 1 or 2 coil "fixes" we've heard of here might merely be due to the burnishing of the terminals when replacing a "bad" coil?]

I don't know how good the >$40± RockAuto' replacement coils are, but the best OE price for PN 1367438 is at Tasca Volvo — about $103, which includes the amplifier that's integral to the heat sink. List price is about $160.

Rex coil-amplifier-heatsink


P.S. If the cylinders have received a lot of unburned fuel, the rings and bore may have been "washed down" to where a loss of compression will prevent starting, even with spark restored (assuming that's the problem). If the dipstick smells gassy you should probably change the oil, once he starting is fixed.


--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

I've squirted 2 cycle oil in cylinders that I suspected may have washed down. Seemed to work as far as getting compression. When the problem was fixed,,, Oh yeah changed out that gassy oil
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/

I suspect the coil. You can try removing it from the vehicle, separating the two halves and cleaning the contacts between the two. Then clean the contacts directly on vehicle and reinstall. Or you can get a new one at Rock Auto for >$40.
I wont say its a common problem on Regina's as that gets some peeps panties in twist, but it solved a similar sounding problem I had on my 740 Regina a couple years back and another board member who I cant recall at the moment at the least.