My 92 240 is a no start. It started to run poorly, missing shaking and no throttle response. It threw a 1 2 1 code indicating an AMM problem. Compression is good and even across all 4 cylinders, there is spark at the plugs. So far I have changed the AMM, ECU,and the pressure control valve from another running Volvo. The engine coolant sensor resistance is within specs. If I remove the spark plugs,dry them off and re intall, the car will start and run for a few seconds and then flood and stall. kWhat have I missed? Any suggestions would be appreciated.

Your problem sounds very simimilar to the one I have with my 93. I have tested/swapped all of the things you described and not found the problem. On cold starts the car runs rich and rough like one cylinder is not firing. The problem gets worse at lower temperatures and is occasionally fowls the plugs.

Someone on the board suggested that failing ignition power stages don't work at low temps, so I am going to pick up a spare and try that.

Sounds like a fuel pressure regulator gone bad - esp. your comment about "flooding". Withe th engine OFF, pull the vacuum line off the FPR and sniff it. If you get a raw fuel odor, then there's a likelihood your FPR is shot. FWIW, the FPR is cheap enough ($50 or so) to replace every 100K miles as a PM measure.
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Thank goodness we don't get all the government we pay for. -- Wiley Post

A 1992 should have five fuel injectors. It sounds like one of them is not closing, and my money is on the fifth one (cold start injector).

If it is the fifth injector, most likely, the problem is electrical. Start by unplugging it and see if the problem disappears. If it does, leave it unplugged and forget about it unless you live where it is REALLY cold. My '91 started and ran just fine at 10F in Iowa on only four injectors.

I do live in the Great White North where is sometimes gets really cold, but the fuel rail on this car only has 4 injectors. I guess the next step is to pull those injectors out and see if they are leaking.

The fifth injector is not on the fuel rail, it is beneath the throttle body. A bit hard to get at. As I recall, it is tough to release the spring clip to get the electrical connector off that injector. My spring clip is somewhere in the parking lot of a truckstop in Wyoming.

Hi,

That sounds about right to me too, if it does have the fifth injector. I know we lost it in 92 or 93 with the phase in of the -951 ecu, which does not have the driver for the cold start valve, but I can't say for certain by year. And if it was one of the other four, the plugs would tell the tale.
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Art Benstein near Baltimore

The man who fell into an upholstery machine is fully recovered.

"The man who fell into an upholstery machine is fully recovered."

Hanging is to good for a man who makes bad puns...
....he should be drawn and quoted.

Doesn't seem to me you've missed anything - in the way of easy-swap parts.

In light of the 121, I'd examine the harness connector for the AMM carefully, but that isn't known to flood a car, more like starve it. Could be the ECU has the injectors on all the time - rare, but known to occur. Is your spare compatible? Run the fuel pumps without the motor by jumper 4-6 fuse. Squeeze the return hose briefly to be sure it isn't blocked.

Go through the mode 3 diags on your OBD - make sure the ECU can click the injectors, CS valve if you have one, etc. Make sure you fully reset the ECU - lift fuse 6 for a second, and double check those suspect parts (AMM and FPR) in your swap car. Ox sensor shouldn't get involved in starting problems, but you might want to be sure it isn't shorted to the heater by disconnecting it temporarily, or putting a meter on it.

I have checked the fuel return line and it is clear. I double checked the ECU,AMM,FPC by trying each one on my 1990 245, so I am sure that each component is in working order. I checked the O2 sensor for a possible short, disconnected the leads and tried to start the vehicle. The flooding condition persists. Puzzling.

I see that in my haste I missed your ECU swap. There was more in my post than that suggestion though - stuff that is fairly easy to do and doesn't amount to parts swapping.

I see your response to Farm Boy about having only four injectors on the rail. All of the B230s have only 4 injectors on the rail; the 5th injector is about as off-rail as one can be - located in the manifold. If yours doesn't have the CSV, and you can't tell one plug from another for flooding, maybe you could check the service injector pulse with a noid light, tell us what codes have been set, which model ECU was in the 92 and which in the 90, and one of us will respond with a "yeah, that happened to me too".

-K

I took your advice from a previous post and ran the level 3 diagnostics. The ECU is clicking the injectors and the IAC but I did not hear any other diagnostic sounds. When you mention resetting the ECU, is that to be done after performing the diagnostics? The ECU in both the 90 and 92 is the 561 model. The 90 has a cold start valve but the 92 does not. When I mentioned that the 92 only had 4 injectors on the rail, what I should have said that there were only 4 taps for injectors in the rail. I do not own a noid light, but if need be I could probably track one down... You can,t have too many tools! The puzzling part for me is that all the cylinders are loading up with fuel, not just one or two.

Did you check the FPR yet?
--
Thank goodness we don't get all the government we pay for. -- Wiley Post

Yes, I changed the FPR from another 240 which is running well.

Hi,

It sounds like you've stumped us so far. If I had swapped the parts you had with the results you had, I would be staring in disbelief for a few moments before I dragged out my line tap for fuel pressure gauge and oscilloscope to measure injection duration. I'd trust these two tools to tell me how much fuel the ECU thinks is being delivered, and if yet incongruous, I'd have no choice but to pull all the injectors, and either swap them wholesale, or find a way to pressurize them with mineral spirits to be sure they shut off.

I noticed in another post you did the OBD checks for the system outputs. You don't mention any codes seen by the ECU, but each time you swapped it, the codes were cleared by that action.

Are all the plugs wet after just a bit of cranking? You wouldn't have ingested something to totally close off fresh air intake, right? Hard to imagine that leading an owner to concluding the motor is flooding.

Well I finally found the problem. It turns out that the crankshaft position sensor was working well enough to fool the OBD but not well enough to supply adequate spark. When tested it was way below specs. I changed the CPS and installed a brand new ECS for good measure and the old girl roared back to life. I am not sure that I completely understand how the CPS affects the quality of spark. Checking for spark was one of the 1st things that I did. In hindsight, perhaps if I had paid closer attention to the spark intensity I might have saved myself a lot of aggravation. Thanks to all for your support.

I took a wild guess and figure he calls the FPR the "pressure control valve" in his first post, if you are referring to the Fuel Pressure Regulator. The SAE definition of the FPR abbreviation is Fuel Pump Relay, so there is some ambiguity in our Brickboard slang.

If the 92 has no cold start valve, the 561 ECU is not its original. But that's not the problem, because, if anything, that would make it would be too lean in the cold.

But you're right, this has all the smell of a fuel pressure regulator despite the attempt to rule it out, like, first thing he did. I think.

-K

Could be slipped ot stripped T belt teeth at crank sprocket, or sheared sprocket key as postet here recently. You have the right stuff but maybe at the wrong time.

Check for coincidence of crank and cam 0 degree marks and rotor pointing at #1 wire.

As part of this process the timing belt was replaced along with coil, plugs,rotor,cap and wires. However, I did recheck the timing, just in case, and it is correct. The elimination list grows shorter!

I've had this problem too with my '91. Have you cleaned the throttle body & Idle Air Control Valve? That might help it...good luck.
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1991 Volvo 240 Sedan 115000