1991 Volvo 850 Starting problem solution found

[TheJoynter]

Hello there,
it's my first post, and first thing I want to thank Matt for this wonderful site, and everyone for the company.
This is another post on the Volvo 850 starting problems, as I had them on my very recently bought, veteran October 1991 850 GLT (75,000 km, Germany).

The car had start problems with cold engine. It would turn but not ignite on the first attempt, but only on the second or third. It would usually restart without problems e.g. after a shop stop, etc – but not always.
Replaced spark plugs, battery (it died), jumped the relay. Fuel pump turns 2 seconds when turning the key, fuel pressure goes away as soon as the car is turned off (meaning, immediately).

I was already set to replace the pump, BUT…

Turns out it was an electric problem, at least till now. However, fuel pressure still worries me, I am not sure I have enough. Here the facts:

1) Problems started when I took out the radio (to look for the code, ehm) and did not put it back for 3 weeks. I understood it only in hindsight.
2) With the radio out, I had much more probability of igniting with headlights on (yes, urban legend, but true in this case - which killed my battery, though). More probability, not certainty.
3) Suspecting an electrical problem, I put the radio back and…
a. If the radio is OFF when I turn the key, the problem happily remains
b. If the radio is ON, it ignites perfectly the 1st time, 100% of the time.

It took me more than one month to figure this out: obviously I only have max 3 attempts a day with reasonably cold engine, did not want to "pollute" the results by trying too frequently, and of course had lots of trials and errors.

At present I am happy with that – why replace something if it still works - and first of all wish to share it: maybe some other can benefit. Then the question: would anyone have an idea of the actual reason? Wire contacts expanding, energy drain and so on? I read there are similar problems reported with the glove drawer light, etc.
Note that I am a complete newbie for what concerns electricity – barely understand 220v vs 380v.

Many thanks to everyone!

Kind regards,
Matteo - TJ

[abscate]

That's a strange problem,,,will be interesting to see thoughts here!

[Ozark Lee]

Has the wiring harness behind the radio been tampered with? I have seen some real hack jobs when people try to replace the head unit with an aftermarket radio. If it has be chopped up and spliced that is where I would start looking for shorted wires or wires that have come apart. It could be that the ignition ground or the ignition voltage is being back fed through the radio.

Good luck, electrical problems are usually easily repaired - once the problem is found.

...Lee

[abscate]

It could be that the ignition ground or the ignition voltage is being back fed through the radio.

Nice Lee - I bet that is either the problem or related to the root cause.

[TheJoynter]

Thanks for the suggestion, but there are no aftermarket things with re-wiring.
The radio is a Volvo original one, cassette, probably the one installed by the factory (the previous owner has written the code on the car manual, and there is no trace of previous codes).
It's a very old model, the one fitting only half of the emplacement, and in my opinion I've been the first one taking it off - or so.

After some more time, unfortunately, I need to report that the problem still lurks - although much less frequently.
I will go on trying and, if I realize that things go worse and worse, I will probably modify the header of the post.

My (little) money remains on the electrical, though. When I bought it, the climate fan (sorry I don't know its name - I have no conditioning, it's manual) and the emergency lights did not work and the retailer fixed them very quickly.

Another piece of info: the car has done 45,000 km from 1991 to 1996, and 30,000 km from 1996 to 2013, and the last oil change was in 2003. The previous owner is (was?) class 1922, and cared for it a lot - but understandably, I think he left it sitting for more than a while, lately.

Kind regards

[TheJoynter]

After temporary patches which seemed to work, involving doing more and more arcane gestures and fiddling with any electrical button and switch, it definitely kicked the bucket.

It was just the fuel pump relay. Replaced and working like a charm.

Many thanks to all of you for the help - and making me think that nearly always the solution is one somebody else has already found.

I am going now to look at how to replace the rear view mirror, I snapped it this morning with my attaché case.
Ciao
Matteo

[TheJoynter]

Dear All,
After long time, I had OTHER, different, many, many cases of starting problems and anomalies in the battery drainage…And figured out how to read the fault codes in the pre-OBDII ECU, it seems that I have found out the solution to the worst one to date.

In the last months, my car developed the nasty behavior of

1) starting pretty well when cold, but just refusing to start when hot. In the last weeks, I had to refuel with a jerry can and to leave the car running when stopping at a convenience store. No, I don't use the car that much, fortunately.

2) This, in conjunction with an idle prone to stalling and coughing up again.
Other symptoms I had were:

3) car tending to "cough" when flooring the 2nd and 3rd gear…Sorry if I don't know the correct term, basically it did not deliver power smoothly;

4) a couple of times, when flooring in 3rd gear to overtake, I had a worrying loss of power, and in one of these 2 cases the check engine light came out and I came back home sputtering – I had really low and somewhat erratic RPMs…An extreme version of point 3).

After reading several threads, here and elsewhere (especially for 1 and 2), the likely culprit seemed either the temp sensor or the RPM sensor. I changed the temp sensor and the thermostat (as I was there), but that did nothing for the problem at hand. It solved the - till then unnoticed - problem of insufficient heating from the blower, though.

Then, after the discovery of the diagnostic codes, which I had tried but failing to use the correct socket (sorry, sorry, sorry), in fact I found both ones related to the RPM sensor (both erratic signal and NO signal). I tried cleaning the contacts with electric contact spray, and this alone worked like magic. There was some gunk in them, and at the same time I cleaned the ones of the crankshaft sensor.
For the time being, I have completely solved 1) and 3); 2) is still marginally present, and luckily I have not experienced 4) anymore.

The codes, however, are still present despite my several attempts to reset them. I have already ordered a new RPM sensor, which I will install asap. For the less than perfect idle, first thing I'll try cleaning all the contacts I see (IAC valve itself already cleaned), checking the vacuum hoses and reassess.

This pretty long message was to update you for future references, and especially to thank you all for the volume of high-quality info in this forum. Also a small bit of shame, because I've been convinced for one year that I did not have any fault codes. As a partial excuse, strangely enough, I only had the check engine on once, for a few seconds only.

…I hope it will not become a wikipaedia of all the starting problems that this tank can have, because I feel I am running out of the easy ones. The battery drainage thing was probably due to savage attempts at restarting.

Of course, should you have any other suggestion, they are more than welcome.

All the best,
Matt

[theobviousfaker]

My '96 850 has had the same problem 1), 2) 3). Could not check for 4). It was after the car was parked about 3 weeks. It had a torn CV-joint-cover, so I didn't want to drive too much, lest I damage the joint itself.
The first start after 3 weeks standstill was perfect. I drove the car a couple of miles, because I wanted to fully warm up the engine. Stopped at a gas station to check tire pressure. And then - car does'nt start, just couges a little and then nothing. Some more tries - not even coughing, just plain dead.
I tried to call some buddies, a couple of minutes passed. Tried again - engine started, idling very rough. Lightly pressed the gas pedal, engine died immediately! Second try, engine starts, has the problems 1) 2) 3). Drove the car a little longer then, to REALLY warm it up, and the problem gradually disappeared.
Runs perfectly smooth again.

The engine had the same problem when I bought the car, with the same chronology. That is: The car started well after unknown time of not being moved. Got it home for some basic checkup, and then basically everything from above followed. We checked lots of things, but the problem simply disappeared by itself.

Since my engine is generally in a very good condition, I don't fear too much. I blame the way too long standstill. There might be condensation water or some other gas/fluid in some electrical component or messing with a sensor, maybe air bubbles in the fuel line (or rust/dirt), condensation water in the distributor cap, etc etc.

I have seen a post here, where somebody changed his distributor cap and found the old one to still be the original one, after roughly 20 years! I will check mine soon, it is an original Bosch one, so it might also be 20 years old. Also a bad mass connection (electrical mass, that is) might cause spark loss.

The IAC is a viable culprit, too. That is the first thing we checked when we had the problems right after I bought it. It worked perfectly, we tested it with another battery. Deliberately sprayed it with WD40 anyway, just to be sure. Maybe it is some wiring or some sensor signals controlling the IAC that make it behave strangely. The MAF could be reporting high mass wrongly, suffocating the engine.
For me, IAC and MAF are out of the game - IAC runs well, and I checked MAF by disconnecting it, with no change.

Unfortunately a hard problem to work on. Maybe its a german 850 problem (Grüße aus Frankfurt!)