I have a 1994 850 (non turbo). For the past few months I have been having problems with it starting and stalling. Sometimes I go to start it and it turns over but won't start. I come back later and it starts fine. This happend once in a while now at least once a week. Also in the past two weeks it began stalling while driving down the road. Same thing sometimes it will start right up and go others I have to wait a few hours and then it will go. Any suggestions. Mechanic is baffled because by the time I get it to him it runs fine!

 

Hi Lori, what has been done to the car to solve the problem? If you poked around this site, I'm sure you have seen several post about stalling 850 Volvo's.

The most likely problem is bad fuel pressure. You can start throwing parts at it or have your mechanic properly troubleshoot it. As with most post about stalling, the #1 solution is to replace the fuel pump relay. However, low fuel pressure can also cause the car not to start and stall. Fuel pressure can be checked at the fuel rail.

When your car stalls, does it act as if it is running out of gas, like it sputters to a stop? Please understand that it could be several things, but start at the most likely/common problem and work your way back.

 

Intermintant problems are very frustrating. Other than being stranded somewhere, I'd rather the car break down than act up sometimes. I recently found out that my insurance will cover a tow from anywhere except my house.

I have seen several write ups about stalling cars, a lot of the post don't have the actual remedy listed. I ask that people with experience with this problem please post solutions to help others get their cars fixed.

I stuck this thread in the sticky of the DIY.

 

Like rspi said, my 94 850NA was doing the same exact thing and it was the fuel pump relay that was bad. I have read that the cam position sensor can cause intermittent problems, as can the fuel pump. The pump relay and the pump itself would be the first place to look. My 2 cents.

 

Checking for vacuum leaks is at least cheap and it might be effective. The vacuum tree under the throttle cover is one place to look, as is the line that comes off behind the fuel rail on the passenger side of the engine.

 

Thread info from another site:
http://www.matthewsvolvosite.com/for...hp?f=1&t=44264
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You usually get trouble codes when a problem occurs before the car stalls. However, a bad fuel pump or relay usually does NOT give a code unless it causes the car to stumble for a while before it stalls. Then you get a basket full of them.

Let me first say that you can probably repair most things on your car yourself being a mechanic. The Volvo engineers has designed the cars to be pretty easy for the mechanics to work on. So, if you can turn a wrench, the first thing you need to do is get over the fear of fixing the car yourself. (Feeling free to over explain ).

Back to your problem from a few months ago... It really sounds like the place your wife to the car to decided to take the shot-gun approach to repair it and started tossing parts at it. I really don't believe a bad o2 sensor could/would cause these cars to stop running or stall. Not sure what they called the altitude sensor, but the MAF will.

As with any other combustion motor, you have fuel, air and ignition. Those 3 will enable the car to run. I have seen these cars start and stall with a torn vacuum hose, especially the one under the idle control valve. I believe your car was PRE ETC (electronic throttle control), and PRE IC (Ignition coils). If that is the case you can rule that out fast. '99 S/C/V cars has both and the ETC can cause a no start. How do you know if your car has ETC or not??? You will have a throttle cable that comes to the drivers side of the intake. Take a look at this photo:


Just above those 2 yellow circles is the throttle cable and throttle control. If you do NOT have that cable you have a ETC. Another good note on that picture is that is shows the idle control valve, between the 2 yellow circles. Now your car should have a plastic cover over the throttle control and idle control valve. You pull the 1 T25 screw out and you'll see that stuff under there.

Now, it is possible that you have a vacuum leak under that cover somewhere. I had a vacuum hose slip off of the bottom of the valve once that cause my car to stall and hard to stay running. If all of the vacuum lines there are good, move on to anther possibility. One more thing about the idle control valve, it usually buzzes when the car is ON, running or not. So when you turn on the ignition the idle control valve should be bizzing.

Now assuming that your vacuum lines are good and your idle control valve is buzzing, I would move on other possibilities. There is a good chance that you have a fuel delivery problem or your MAF is messed up. The MAF will usually toss you a code so lets assume it's good, which leaves the fuel delivery. Volvo was kind enough to give us a fuel pressure port on the end of the fuel rail. In the picture I showed you, you can see the fuel rail cover at the top of the picture. The rail actually ends, pointing at the throttle body assembly. It has a valve stem cap on it. You can pull that cap off and poke the valve to see if you have a lot of pressure there. If so, that fuel system MAY be good. The best thing to do is put a fuel pressure gauge on it and monitor it while someone starts the car and see if it falls off when the car starts or stalls. I believe the pressure should be around 45 psi. If it's 18 psi you know it's low. So, check fuel pressure. The main 2 problems with these cars and fuel pressure are: 1) Bad fuel relay; 2) Bad fuel pump; 3) Bad fuel pressure regulator; 4) Clogged fuel filter. In the order of likeliness.

The fuel pump relay is located under the fues box under the hood.


You can pull the relay and jump the fuel pump to make sure it operates. Take a jump wire or paperclip and jump 15 and 87 then try to start the car. If the car starts your fuel pump is working and you likely have a bad relay. The relay is number 103 in this picture:

Some people have actually repaired their relay. Here are the instructions:
http://www.matthewsvolvosite.com/for...pic.php?t=9681

Usually, when you try to start this car, if it fails to start, you will hear the fuel pump whine for about 3 seconds. Also, if the car stalls after you start it you may also hear the pump whine. So if you do NOT hear the fuel pump whine, there is a good chance that the relay is not working properly (or the pump is bad). So, turn the key, let it go after a second or two, and listed for the fuel pump whine.

The second thing is a bad fuel pump. The only way to know that is the problem is if you are not getting good fuel pressure or can not hear your pump running when you try to start the car or jump the relay. Someone else will have to tell you how to jump the relay, just can't remember which pins. If the fuel pump is out, there are step by step DIY instructions on this site to show you how to replace the pump.

Third thing is the pressure regulator. Being a boat mechanic/engineer, hopefully you understand that situation.

Forth, the fuel filter. That is a streatch but the filter is very easy to replace. You'll find DIY instructions here, it's located near the pass rear tire. Matter of fact, here are my instructions for that: Fuel filter replacement instructions on a 1998 Volvo S70 GLT

Another issue could be that you are not getting spark or good spark. If you have spark plugs and/or spark plug wires, how old are they? If you have coil packs, are they in good shape. The 5 cylinder motor in these cars is very smooth. Some people may NOT reconize if it's missing 1 and if it's missing 2 it probably will not start. Come to think of it, if you have NO code, you are likly getting spark because these cars will trigger a CEL for missing real quick. The difference between coil packs and spark plug wires and distributor is as follows: If you have a distributor behind the throttle body area (rear intake cam) you do NOT have coil packs. A good thing about these cars that I never seen on other (maybe I just didn't notice it) is that they have date stamps on the wires. So if you are running original spark plug wires, you will see a date stap that says something like 29/98, which means the wires were made the 29th week of the year in 1998. Hopefully you have newer wires in that car. Spark plugs, wires, distributor, d-cap should be changed when needed. The problem with these cars is that the computer will often compensate for weak wires and plugs, etc. until they totally fail. So your car CAN and often WILL run smooth with plugs that are old, 50,000+ miles on them. Not good but they will work. Change them every 30k and the wires and everything else every 90k.

Although I don't think this is the case because you should have gotten a CEL if it were, is that you may have a bad MAF. If so, you can start the car and unplug the MAF. If the car smoothes out, there is a good chance that the MAF is dirty or going bad. If you pull the plug on the MAF with the car running, you WILL get a CEL that will NOT go away intill you get it reset with a scanner.