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The subject car is a 1990 760 Turbo with about 227k on the odo.
I posted a message about this here at the Brickboard back in January when it first started happening. Back then, the car would just randomly die, but I could usually restart it almost immediately. Then it might be days or weeks before the problem re-appeared.
Knowing how next-to-impossible it is to find an intermittent problem like this, I just put up with it. Until one day, when finally it would not start. I replaced the flywheel sensor. The original unit's wiring insulation was falling off, and it looked old enough to be OEM. After replacement, the car started up immediately, and ran fine for about a month. Then one day it died suddenly, same as before.
But this time, I was not able to restart the car almost immediately. I ended up having to wait about fifteen minutes before it would restart. It has reoccurred a couple of times since then. Because the car will restart and run for days or weeks before this recurs, it leads me to think I didn't fix the original problem after all. But because the failure mode is somewhat different -- the 15 minute wait I have to deal with now -- it causes me to think that another component waa also faulty.
I checked the FAQ and found some info here about the ignition power stage amplifier:
http://www.brickboard.com/FAQ/700-900/ElectricalIgnition.htm#IgnitionAmplifer
This sounds a lot like it might be the culprit. However, none of the examples shown duplicate the symptoms my car is showing. So, I thought I'd post this message to ask brickboarders if you might have experienced something similar to what I am?
Incidentaly, I checked the condition of the ignition amplifier, and it appears to be fine visually. Tight, uncorroded screws holding it in place, and the electrical connection shows no evidence of corrosion or even light oxidation either. So, if it is the amplifier, the problem is internal.
Any way to test one of these before I have to shell out the bucks for a new one?
Best,
Michael
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You can get the ignition power stage tested at Autozone and maybe other auto parts stores. I know autozone tests them for free.
I have a 1990 740 and it began dying on me periodically while driving or while I was sitting at stop signs or traffic lights. It was very, very, very, VERY annoying and sometimes scary. After replacing about 10 things, including the ignition power stage, it turned out that my new fuel pump relay that had been replaced a year back had gone bad. Believe me, I tried EVERYTHING else I could possibly do. After about $500 in parts, I found out that I needed a new fuel pump relay. I would guess that for you, it may be the same. It's about a $50 part and takes about five minutes to change out. Good luck.
P.S. I would get one from the Volvo dealership, they're the best quality and virtually the same price as the outlet auto parts stores.
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...which gave me the same symptoms.
See pictures in THIS POST, which has a link to a my earlier thread about 940 stall and recovery symptom.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Thanks for the response re the RSR ground. I went out to my car and had a look. Unless it's buried behind the winshield water bottle or beneath the air cleaner, there is no RSR ground on the right side of this car. I did spot something similar on the left side, however. Even has the wire with the red band that has a code on it.
I tried posting an image using the "image url" link below this edit window but I get a 404 error. So, I uploaded it to my site. Here's a link to the photo:
http://michaelmcbroom.com/760electrics1.jpg
I included the power amplifier and what looks an awful lot like a ballast resistor in the photo. The RSR ground can be seen on the far right, with four wires connecting to it. It appears to be totally free from corrosion, but I guess a good scrubbing won't hurt anything. :)
How about the RSR itself? In another thread, it was mentioned that the RSR is located on one of the shock towers for a mid-80s 740. Is that still the case with a '90 760T? (I don't know what it looks like)
Best,
Michael
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"...there is no RSR ground on the right side of this car."
That's surprising. My 940 has two of those 4-pin grounding tabs, one on the left like your photo below, and one in the same relative position in the right (where my RSR ground is. I assumed that all 700/900 shared those ground tabs like so many other common or generic items. FWIW, I did have to move a wire bundle to get the picture I posted in the linked thread.
If your RSR is on the left side of the car, that ground tab you found is probably the one it uses.
Here's a picture of eEuroparts KAE brand "Noise Suppression" relay. Other brands may not have the same white markings, but the general shape should be the same.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Ah, I recognize that relay. I remember on my '88 765T, the plug for it had crumbled into dust basically. I recall having to replace the plug, but I don't remember if I replaced the relay. Probably did.
I'll have another look on the right side. I shined a light down behind the water bottle and as much around the air cleaner I could, but I'll take another look anyway.
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"I'll have another look on the right side. I shined a light down behind the water bottle and as much around the air cleaner I could, but I'll take another look anyway."
The water bottle and air cleaner are on the "right" side? As in the co pilot's side of an airplane?
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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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"The water bottle and air cleaner are on the "right" side? As in the co pilot's side of an airplane?"
Yup. This car has a turbo.
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Gremlins are hard to pin down. On my 740, it turned out to be old bad spark plug wires.
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I guess the next time it dies and doesn't start, I would check for spark. That would tell you if electrical or fuel related. My first thought was fuel pump relay or radio suppression relay.
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Post Back. That's whats makes this forum work.
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If it were fuel related, I would expect some coughing or sputtering before it finally quit. When it quits, it's as if I turned off the ignition.
Not always so easy to check for spark when this happens. Every time it has, I've been alone and on the road. It's kinda hard to hold the coil wire with one hand (or insulated pliers, preferably) to check spark while cranking the ignition with the other. :)
Best,
Michael
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