Grrrrrrrrrrrr. It seems to me that fuel pump relays and fuel pumps are an issue with a lot of the 850's. From what I am seeing, they are by far the #1 issue with these cars having stalling & no start problems. So, I'm wondering if a fuel pump relay that is going bad, may be the main cause of a fuel pump going out? I'm thinking, if a relay is going bad and starving a fuel pump of constant, steady, solid power, it can cause a pump to go out with all the cutting on and off and such. So, I'm thinking that these things go out at a high rate after they are 10+ years. Would it be a good idea to consider them a time change item and replace them every 10 years?

 

I think if your not going too troubleshoot any more ,yes cheapest part first.

 

Prevention is the best trouble shooting one can do, correct? We don't wait till the timing belt breaks to replace it (along with the head), a lot of people replace the water pump with absolutely nothing is wrong with it, the PCV system is suppose to be service/checked/replaced every 60,000 miles, what if this is something that simply should be added to the list of things to expect to go wrong?

 

I've never encountered a situation where the fuel pump relay would cause the pump itself to burn out.

The biggest killer of fuel pumps is running with low fuel. I always try to re-fill at 1/4 tank. The fuel actually cools the fuel pump motor.

...Lee

 

I'm so freeking broke that I rarely have more than 1/4 tank of gas in my car. I should be replacing these pumps every other week.

 

The relay is like any other relay, all it does is complete the circuit to turn the pump on.
Running low fuel tends to make the pumps die sooner because when it is submerged the gas actually cools the pump. But its not going to cut the life of the pump down bye years if you run the tank low, my original pump lasted 14 years and 350,000 mi. I remember plenty of $5 fillups just to get home.
I guess it would fall under the same category as everything else, when you do replace it go for the quality pump.

 

Ok, I think my train of thought is getting a little lost here. Lets say that the relay is like a light switch that turns the pump off an on and that switch is going bad and starts turning the pump off and on like 700 times during a 10 mile drive. Almost like a short in the wiring. Then one day the switch finally goes out. So you replace the switch but the pump has gone through the torture of the bad switch/relay flickering it off an on for several weeks or months.

Am I totally wrong or may I be on to something. And no, I don't drink, simply can't afford to. LOL

 

The fuel pump relay in the 850 isn't a simple on/off switch, it is a modulated device which when its working correctly varies the voltage to the pump. When mine went bad the car would start fine and drive normally until the engine would start to miss and then it'd die. Wait about 10 minutes and it'd start right up again. I replaced the relay and the problems went away but I have yet to change the pump.

 

rspi, today fuel pumps are dying because of the ethanol in the gas. That is a real problem here in Oregon. The siily EPA folks are planning in increasing the % to about 10-15% ethanol. This problem has also carried over to VW's and some other cars. There is rubber in the fuel pump and the ethanol is breaking down the rubber which then cause the fuel pump failire. When I replaced my pump (car just would't start, died on a return trip home 3 miles from my house. Tap on the top of the pump and would get the quick run and die) earlier this year. I also used long grappers to pick up the rubber pieces in the tank. Luckily Volvo has a trap container so the pieces don't float all over the tank.
My VW mechanic friend told me that late July VW shipped 2500 pumps to the us. They have a very similiar design to volvo. Just shows how severe this gas problem is. He also told me on the old styly VW's this gas mixture swells the fuel filter to the point of starving the flow of fuel. A real nightmare for those folks.
As a preventive measure I always run a Staybill gas treatment to try to nuetralize this issue.
Good luck with your troubleshooting.

 

@ Autoxray, thanks for the awsome information. I was under the misunderstanding that ethanol was only harmful when it sat in a car for more than 30 days. Always something.

Ok, lets say that the relay is not the cause of any fuel pump problems. However, the relays do go out often, not sure why but it's very common in these cars when they are over 12 year old. Should I replace the fuel pump relay every 10 years just to avoid having those issues? It would be like replacing old tires to avoid getting a flat or the timing belt to avoid a broken belt problem...

I say that about the fuel pump relay because that is one of the few relays that will leave you stranded on the road somewhere.

 

The two relays ran about 50 bucks each. I'd say do it just to get it off your mind as it currently is.

 

WOW!!! So much mis-information in this thread i don't know where to start!!

A relay is a HD switch; the FPR is turned on by the engine control module; the purpose of any relay is to handle heavier current than the switch (control module in this case) can handle. It most certainly does NOT modulate the voltage to the fuel pump! If it did, your fuel pump would burn up pre-maturely!

The fuel pump is indeed cooled by the fuel, but by the fuel running through it. That is why running the car completely out of gas can, and often does, damage the fuel pump. There may be some heat-sink effect of the pump being submerged in fuel but that is a secondary effect.

The fuel pumps I've seen die didn't go because they disintegrated due to rubber parts falling off them; there's a motor in there that drives vanes that pushes the fuel; the vanes wear, the motor wears, etc. That's why when they die, you can often literally bang on them and often get a few more miles before they freeze/stop completely.

As far as the fuel pump relay "flickering" like a bad light switch causing pre-mature fuel pump failure, that's actually an interesting theory, but i seriously doubt it. The pump is just a motor, you cut pwr to it, it will stop very quickly (since it's pushing fuel), and then your engine will stop also, very quickly. In other words, if it was "flickering" you would know it.

Bottom line; if you want to replace your FPR every 10 yrs, then go ahead, but why not just keep a spare (or at least a paper clip) in your glove box instead?

 

Thanks GDog. I don't think fuel pump failure is as common as relay failure, so, I'm going to do as you suggest and carry one of my spare relays in a small jar in the spare tire area. I don't like having to much stuff in the glove box.

One another note, that brings me to another sigh. It really stinks not having maintenance history on a car. The way this wagon has been cared for, it probably has had a fuel pump and relay in the past few years. I'm pretty sure it wasn't pounded on often, the motor and turbo are real strong. Also, since it was owned by an older guy, a senior, it appears that the oil was changed religiously. Now as for the orther, recommended maintenance schedule, I don't think it was followed to closely, however, I think it was taken to a good mechanic any time it blew a cel and whatever was necessary was done. So, if it had a hickup with the fuel system, it likely got a new pump. If there was a small leak in the radiator, it got a new radiator fast. If the timing belt was replaced, it likely got new rollers, tensioner and water pump as well.

On the flip side of that, the car was a little roughed up being 16 years old and 190,000 miles on it. Tear in the drivers seat, leather not conditioned, a few stains in the seats, carpet worn and soiled, and a ding here and there. Strong on the maintenance, weak on the cosmetics.

So what I think I'm going to believe on the vertic of these fuel pump relays... When they start to go, they go pretty fast. When one was acting up in my sedan, it did cause the car to spudder a few times (making me thing it was causing a flicker effect in the pump). I'm probably going to replace mine every 10th year aniversary. I'm going to assume that one has already been replaced but keep a spare with me. I have about 3 now. For some reason, I thought these relays were about $200, but I guess I somehow got that crossed with the cost of a pump.

I'm with you on the pump damage problem. I run my tank low to often for the submerge effect to be needed for cooling. I do believe that they overheat and get damaged real fast when someone runs it OUT of gas and tries over and over again to start it. The fuel going through it does the primary cooling.

As for why people don't let them get lower than 1/4 tank, there are a few myths about that. The main one being that people thinking that a low fuel level will cause and allow the system to pick up dirt from the bottom of the tank. Well, NEWS FLASH, dirt and water are heavier than gas and will alway linger around the bottom of the tank. Also, anyone that has been in a fuel tank of a Volvo knows that the fuel pick up is also at the bottom of the tanks. Therefore your car will pick this stuff up if the tank is full or empty. That is why people don't get far if they fill up at a gas station that is pumping water in their fuel. The water gets into the system real quick after a fill up. Plus the fuel pumps at the station have filters that should be replaced regularly and your car's fuel filter should pick up any dirt that gets by all that. Your fuel tank pick up unit has a screen (sock) on it as well so the likelyhood of your car getting dirt to the injectors is nill.

 

gdog - perhaps not all of my words were chosen correctly.

However - My main point was the fuel pump relay in the 850 is that it isn't a simple relay (see attached relay1.jpg), it is a CMOS Pulse Width Controlled Switch (see attached fprelay1.jpg & fprelay2.jpg), that's what all those extra bits and pieces are.

With a simple relay they works or they don't. CMOS switches can do all sorts of interesting things as they fail. I keep a spare fuel pump relay for my 850 in my garage (cause its a whole lot cheaper than keeping a spare pump).