Why Do The Fuel Pump Relays Fail So Often?

jacob_coulter · Post by **jacob_coulter** » 20 Dec 2008, 20:44

Just like the title says, why do the fuel pump relays on the Volvo 240 have so many failures?

I recently purchased a 1991 Volvo 240, and the same day I purchased it, after filling it up with gas, it wouldn't restart. After reading that this failure was common, I replaced the relay (it was a Volvo brand relay) it has been working great ever since.

Were Volvo brand relays just poor quality? Is it the way the system is wired?

I looked around a lot to try and find a Bosch brand relay, since they have an excellent reputation, but it doesn't seem they make one for this application. I ended up buying one at Napa.

It seems to me the last brand of relay you would want to buy are the OEM Volvo relays from a dealer, since they have so many failures.

wojeepster · Post by **wojeepster** » 21 Dec 2008, 08:37

the fuel pump relay isn't really only the fuel pump relay...if you look at a wiring diagram it is actually the main relay (two relays in one) there was some poor soldering on some of the relays to begin with....As long as you know about this and KEEP A SPARE it is not really much of a problem. I have had two relay failures in a little over 500,000 miles (one in my 240 and one in my 740). As relays get old and crusty the resistance of the contacts increases, this leads to more heat and eventual failure. Just figure it as a wear item. I buy replacements from fcpgroton for $20. Most other cars are scrap heap by the time you have to replace relay....I think this common failure and easy fix is endearing. On my 2000 miata I had to replace two ENGINES because of factory thrust bearing problem. There was nothing endearing about that and I will never buy a mazda ever again.

Kmaniac in California USA · Post by **Kmaniac in California USA** » 21 Dec 2008, 08:38

Quite frankly, I don't think the fuel pump relays fail as often as people claim to replace them. I have read many posts on this forum and it seems to me that whenever a fuel pump starts to act flakey, the first thing people replace is the relay, assuming the relay is the problem, when, in actuality, the problem is a pump going bad. Remember, fuel pumps don't always fail by stopping altogether. Sometimes they mysteriously run intermittently and this symptom can mimic a failing relay. Some people have mistakenly replaced good relays over and over before the pump finally gives it up for good. Mechanics make money selling parts and fuel relays are a high mark up item. My 740 has the original fuel pump relay installed. I know, because I have inspected it and know the date code. Now, I have had fuel pump issues in the past (you can read my posts in this forum), but I never "just assumed" that the relay was the problem.

jacob_coulter · Post by **jacob_coulter** » 21 Dec 2008, 14:25

I do think there's more to it than just people mistakenly replacing fuel pump relays, it seems to happen to an awful lot of people. At the end of the day, it's a small, easy repair.

In my situation, I looked at the meticulous records the previous owner had kept, and the fuel pump had been replaced just a short time before I purchased it. In the repair records, the car was having the same "no start" symptoms I had. I found no record of the fuel pump relay ever being replaced, and when I pulled it, it looked like it was an older Volvo brand relay.

My guess is the car never really needed a new fuel pump, and it could have been fixed with a simple relay swap, but the mechanic wanted to make a bigger sale, so they swapped out the pump. Oh well, I haven't had a problem since replacing the relay.

My point is, I've never heard of any other cars where it's advised you keep a spare fuel pump relay with you at all times. I was just curious to see if there was a confirmed defect in the Volvo-made relays, or if the car is wired in a way that it eats through these relays. I also wanted to see if anyone knew of a "beefier" relay that might hold up better.

Post by **MadeInJapan** » 21 Dec 2008, 15:45

Not necessarily a beefier relay but routinely we have been taking the fuel pump relays apart for the FWD Volvo's and resoldering the joints and replacing capacitors...seems that solder joints go after awhile as do the small parts inside (easily replaced, and cheaply so by parts from Radio Shack). You might check the repair database about this- there's a write-up concerning it. Your relay might not be much different you may be able to do essentially the same upgrade to your old relay and keep it as a spare, rather than throw it away.

volvoman1980 · Post by **volvoman1980** » 22 Feb 2009, 02:56

Hey, with regards to the actual fuel pump, in my opinion if you have the bosch 2 pump setup(in-tank and main under drivers seat), That perticular setup is extremely robust and long lived. I have well over 250,000 miles on the original pumps(both) far as i know. I did replace the main pump with a used one(thought it was a fuel pump when it was indeed a borg warner timing tensoner that busted apart to blame-ill never buy them again nasty on the phone to me),The replacement main pump had near 300,000 miles when installed give or take. Like mentioned, try resoldering the fuel pump relay(theres actually 2 relays in the white box), Alot of the relays(bosch branded 1980s era) have solder issues, Possibly as a result of poor wave soldering techniques at the time. Whatever the case however, It is best to check and if necessary, Resolder ALL bosch branded relays(fuel pump,overdrive in perticular) as its not usually component failure. The relays, As with most bosh components have a tendancy to keep going almost indefinately.
hope this helps a bit