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Read alot of posts but nothing exactly like this so I'm hoping somebody might throw me some clues. LH 2.4. Have had an intermittant no start and both recent times the same sequence got it started. Happened this morning. First verified no power was at fuse 4 with the key on. Then swapped in what I think is a good FPRelay. Still no start. Then here's the same sequence that happened both times: I upplugged the AMM and it started and ran in the terrible limp mode. Turned it off plugged the AMM back in and it started right up like nothing happened. Turned off a few times and all times started up. So what's going on? I burnished the male side of the contacts on the AMM side - didn't mess with the female on the plug side yet. Is this consistent with a bad AMM? I have 2 on the shelf that are probably good but because of the intermittant nature it might take a while to know. Any ideas out there?
Robb McC
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Was "lucky" enough to have it happen again to give me time to troubleshoot. During cranking both relays in the FPR are energized (thanks Bruce/Lucid for the education on that), there is power at fuse 4, power at Pin 5 AMM, power at the IAC valve and I didn't check pin 9 at the ECU but assumed it was ok since the AMM and IAC had power. During the process there was an occasional sputtering kind of start and then it stalled. Unplugged the AMM and it started in limp mode. Plugged the AMM back in, cleared the ECU by removing fuse 6 for a while then tried again - again no start. Now the puzzeling part - swapped in my spare AMM (again removing fuse 6 to clear) and it started right up. But wait the "spare" AMM was the same one I swapped out 2 weeks ago with the same results. It starts and runs for a couple of weeks and then does it again. Anybody ever heard of AMM's failing in a way that takes a week or more to manifest? I could have 2 AMMs with the same problem? So puzzling. The AMM is the most mysterious part on the whole car if you ask me. Any thoughts appreciated.
Robb McC
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On the vein of simplest explanations often being correct, could it simply be that the wiring or connector to the AMM is still making poor connection?
I haven't re-read all the posts, but I think these are the facts: the problem arises intermittently, with either AMM, but fiddling with the connector by unplugging or swapping units, usually allows the car to start and run normally, correct?
In my mind, there's a very high probability that the culprit is still the connector or wiring.
Edit: looking back through the posts, I see that you had what might be a seperate problem while it was raining hard - does this problem seem to occur more often in rain or very humid weather? Have you checked thoroughly behind the glove box area for signs that water might be getting in?
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No sign of water anywhere in the dash and it was just that one time it happened in the rain so I don't think that's it. I agree about the connector idea. I got the AMM connector under a magnifying glass - spring contacts on both sides of each position seem good and pressed together and aligned correctly. I glued some 400 grit to my smallest exact knife and burnished up both sides of each contact making sure I hadn't sprung any of them afterwards. The wiring is all virginly encased in the factory vinyl sheathing as far as I can trace - hate to start digging into that. Time will tell. I can't see what else I can do with the connector or wiring.
Robb McC
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All,
This is interesting. I discovered (and barely remembered) that I had this problem back in 2009:
http://www.brickboard.com/RWD/volvo/1387142/220/240/260/280/intermitant_cutout_start_advanced_class.html
I was determined to find out then if I had spark during the no start times and that's why I made the dash spark gauge. Then the problem went away for 4 years. Now it is back and I know I have spark (Yeah). So what to do next in the brief 10 or 15 minutes of no start? The fact that it won't start if unswitched power is applied to either side of fuse 4 is a real stumper? Do fuel pumps intermittantly stop working for 15 minuites?? Also the business about power for fuel and spark going thru the ignition switch - is it 1 or 2 circuits, ie, does the fact that I have spark eliminate the ignition switch? This diagnosis make take me a record breaking 5 years...
Robb McC
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"The fact that it won't start if unswitched power is applied to either side of fuse 4 is a real stumper?"
1) What is the unswitched power source?
2) Can you hear both pumps?
Even if you hear the pumps, there's another relay in that white case called the "System" relay. You should hear/feel that one "pick" as soon as the key is ON. Without it there's no power to:
AMM pin 5
ECU pin 9
IAC valve
Injectors
• Beside those major players, the System relay also powers the pump relay coil
If your System relay could be suspect, I'd start with fuse 6, which feeds it's coil. I think some one recently had one with a "micro crack" in the fuse metal, making for an intermittent "open" (and maybe thermally sensitive?).
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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What I am seeking is what data I need get next during my meager 10-15 minutes of no-start the next time? I know it has spark, power both sides of fuse 6, jumping power to fuse 4 no effect and won't start even in limp mode. So what do I need to find out next? It's not much time for diagnosing.
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"Are you saying that jumping power to fuse 4 does not bypass the system relay?"
Right. Normally the power to fuse 4 comes from the Fuel pump relay. The voltage path then splits at the fuse 4 input:
a) a lead-off straight to the Main pump and,
b) thru fuse 4 to the Tank pump.
Forcing the pumps to run being futile is what makes me lean toward the System relay, or it's feeder Fuse 6. With no System relay power, you'd be pumping fuel to dead injectors, along with a dead AMM and ECU.
I suggest taking the cover off the "pump" relay so you can easily see the System relay armature, and activate it manually if necessary. More to the point, you can watch the 2 relays when things are OK, so you know what to look for.
For example, watch the so-called "Prime" cycle where both relays should "pick" at KPII, then the pump relay drops out a second (±) later while the System relay stays energized as long as the Key is ON.
The photo below has the pump relay armature held closed with a piece of hose, and the de-energized System relay above it.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Thanks Bruce - I have taken apart one of my spare FPR's and observed the actions of the 2 relays (just as you described) and will know what to look for now the next time. I've cleaned the 2 fuse holders (4 and 6) in questions again and put in new copper fuses (again) and will see - it sometimes is weeks between occurances so stay tuned- I'll post when it happens again. but what you are getting at here is that all 3 of my spare FPR's have bad system side relays?? Seems inplausible to me.
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...but what you are getting at here is that all 3 of my spare FPR's have bad system side relays?? Seems implausible to me."
I agree, but the power from Fuse 6 to the relay is a constant. And my focus is on the relay because it's observable (with cover off) and the most likely suspect as I understand the situation: Spark OK and jumpered pumps but no combustion.
Have you cleaned the actual wire connections at fuse 6 by taking them on and off a few times to burnish the push-on terminals? I think someone here once found a bad wire that way.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Bruce - no start this morning. I could see the spark gauge lighting so same problem. This afternoon I will verify operation of that system relay part of the FPR at KPII and if is activating correctly I will then verify power at each of the points it supplies:
AMM pin 5
ECU pin 9
IAC valve
Injectors
Oh I guess the other thing is to verify that fuse 4 is hot during cranking and the there is power at the pump. I think I am getting closer. Will post back.
Robb
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thanks Bruce - ok I've cleaned the actual wire connections to the fuse block at fuse 6 - time will tell because it seems to only happen every couple of weeks but I will post back to this thread. Went ahead and cleaned all the fuses while I had the power off. You know for a 240 owner cleaning fuses is a reflectful task, kind of like counting prayer beads. You are reminded to have humility because even the most skilled troubleshooter can be tripped up by some little pieces of copper and ceramic and their micro corrosion. Even though I walk thru the valley of oxides ...
Robb McC
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It's probably disturbing now much time I've spent on those 2 fuses over the past month. I've examined and cleaned from all angles however I have never pulled the wires off and looked at those connections - will do that tonite. Also I have to order some parts and I'm going to throw in a new FPR just to have because now I am questioning my spares. Thanks again for your great suggestions so far....
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thanks for responding. Fuse 6 was the source for the jumper onto fuse 4 and both sides of 6 lite the test light during this recent no start incident (and it's brand new fuse). Pretty sure I can hear the pumps going with the key in pos II - even without the jumper. Are you saying that jumping power to fuse 4 does not bypass the system relay? This morning I did swap in a "thought to be good" FPRelay with no effect so system relay problem seems unlikely.
Robb McC
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Yes jumper left side of 4 and 6 to bypass or check system relay.
Do you feel or hear 2 clicks as you turn the key?
Pull a plug and see if it is wet with gas, if so power stage/ ignition amplifier has failed or pins pushed back in connector.
Dan
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Dan - remember I have my home made spark gauge telling me there is spark in wire one - did you not see that or is my gauge fallible, ie, there could be spark enought to light my light but not enough to fire the plug? This is in response to your power stage comment. Thanks for taking the time to respond
Robb McC
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No don't remember, CRS!
Dab
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All,
Well I spoke too soon on this one - happened again this morning. The no start period seems to last a specific period of time - today about 15 minutes. During that time I tried to start twice in limp mode and this time it would not even do that. No power at all at fuse 4 (either side) with the key in pos II. Also there was definitely spark during the whole period (I could tell with the nifty spark guage I built into an empty slot next to the lighter based on coiled wire around number 1 spark wire firing a little xenon bulb). I jumped 4 to 6 and thought I could hear the pumps firing (pouring down rain so hard to hear) but still no start. Swapped out the FPRelay - no dice. Finally getting ready to call a tow and it started right up 15 minutes later. The CEL is on but it drove home and I'll collect the code tonite. The last time it also triggered a code which was "no signal from the TPS" so I swapped that out with a new one but I think this is a red herring code. Any thoughts? If the ECU was not getting signal from the CPS there would be no spark- correct? I did swap out the AMM last time so I can't believe both AMM spares would have the same problem of intermittant no start every 2 weeks. Most frustrating. Now that it won't start in limp mode I'm getting uneasy about driving it far. Any input appreciated
Robb Mc
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Hi All,
A recent post on the mysteries of the AMM reminded me I needed to go back and post that this problem has been resolved. Recap: 2 no-starts over a few days where I unplugged the AMM, started it in limp mode, then plugged AMM back in and problem went away for a day or 2. So my solution that has been working since early last week is I cleaned both sides of the AMM connector and I also swapped in a known good AMM from the shelf. For sake of the scientific method I wish I had only done one at time... I was just tired of having to fool with it every couple of days. I will go back and test the old AMM though because I need to get it off the shelf if is bad...
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Swap it back in and see. I exchanged AMM's with my daughter because I suspected a problem with hers and knew mine was fine. So far her's is just fine and I know she has a good one in her car.
Dan
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Uncle robbmcc,
Welp, first, to start the diagnosis process well before you take stuff apart, check the OBD-1 for set fault codes in both the Bosch LH-Jetronic and the Bosch EZK 1xxk Ignition system.
If you do not have power at fuse #4 with the ignition key set to dentente II (dash lights are on), this could suggest a problem with the ignition switch. Do you carry a bunch of keys or weight on the keychain? You should limit the keychain weight to as little as possible or risk damaging the cylinder lock. Though somehow a heavy keychain seems to shorten the fragile foil contacts in the ignition switch. I use a key, with a Volvo fob, when driving the 240 about.
See the FAQ here (http://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm).
Also, the (#1) Bentley Volvo 240 Bible, the (#1 if you are well practiced at automobile electromechnicals) Volvo OEM Factory Green Service manual, the (#98) Haynes, and I think the (#9999) Chilton manual. #1=best and on downward.
Perform the OBD-1 test again until you have recorded all codes from both systems (sockets #2 and #6).
Also, if you believe the issue is in or around the AMM, is it hot where you are in Maryland? Inside, as you know, the air filter box is that pesky air flap valve that closes and open depending on ambient air temperature. If it is hot, and you or a prior owner have never futz with replacing the thermostat that controls the in-air box flap valve, you may want to disconnect that silver accordion hose from the heat shroud on the exhaust manifold.
Have you resolved the ignition works fine under the distributor cap? Cap and rotor problems can be a little heat dependent. There exists no sensor on the ignition HT side from the power stage amplifier onward to the coil and to the distributor rotor.
The fuel rail pressure regulator is not leaking fuel into the air intake port (manifold)?
I think that does it.
Post back with your results so we can further help you.
Hope that helps.
Spooky MacDuffy's Tavern.
--
Peanut butter and hunny sandwich and a glass of buttermilk.
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Thank you for taking time to respond! My keychain is fairly light so I don't know about that. I did forget to mention during this last no-start period I did run the fuel and ignition codes and got only the 1-1-1 all clear from both. I removed the airbox thermostat and silver accordian tube, hmm, probably in the last century if you can believe that. I believe my ignition tune up parts are in very good condition. I do have the Bentley's and have been studying. It seems the next time it happens (who knows maybe it just was that crude on the AMM connectors) my first priority needs to be to determine if there is spark. No power to fuel pump fuse And no spark is classic "ecu shutting everything down" for a specific reason like for instance no signal from the CPS. I will post if any more develops or best case it never happens again I'll post that too in a couple weeks.
Thanks again,
Robb McC
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Spray connector with contact cleaner.
Wiggle the wire on the crank position sensor to see if it starts, look at insulation at the sensor. Replace if the insulation is cracked and or missing.
Dan
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OK - I've cleaned the female side of the AMM connector - looked like some 20 year old crusty dielectric grease on there. And the TPS... don't see how unnplugging the AMM and then plugging it in could affect that but I did check and wiring looks pretty darn pristine. Also according my book I replaced that with new in 09 about 30k miles ago so I'm not leaning towards that. Time will tell. I also swapped in one of my other AMM's and will drive it now and see what happens. If it happens again I will rule out AMM now I think.
Robb McC
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I am talking about the crank or RPM sensor, are you?
Dan
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Oh sorry Dan - I knew what you meant and mistakenly typed TPS instead of what I meant which is CPS which is the one I replaced 4 years ago. Sorry about that,
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4 years is enough time for the insulation to go bad, it is worth a look. Next time it won't start wiggle the wire and see if it helps.
Check fuses 4 and 6 make sure they are corrosion free and tight in the holder.
Do you have the fuses mounted on the battery?
Dan
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thanks Dan - my fuses are flawless copper and cleaned every few months - no worries there. Nope this does not have that late 93 fuse holder addition by the battery. You may be on to something with the wiggle. Each time it happened I started it in limp mode which means alot of vibration and "wiggling" and after that it started... you never know. That CPS is only $49 at FCP, it may be worth it to premptively replace it. I'm thinking... If there is no spark the next time it happens I will definitely go that way.
Thanks again.
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If the insulation one the CPS is cracked or missing it is worth replacing.
Check the Cap on the dizzy, I had one this weekend I discovered had the center contact was broken off.
Dan
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Look at the insulation first, unless it is cracked the CPS should be OK.
Cap, rotor and plug wires need to be Bosch and Bougicord quality. PLugs copper NGK.
Jumper fuses 4 and 6 to test for intermittent fuel relay.
Dan
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