Hi all. New Volvo owner (a 1990 740GL sedan) and new member. I've been experiencing that "vapor lock" problem. Ran fine till the weather turned hot and I'm tired of waiting by the side of the road till she cools down so she'll restart. Is the fuel pump relay the large white one on the far left side of the second row? I had to take out the ashtray and the little storage cubby above that to actually get to it. I see three rows of relays. The car was a one owner and currently has 60k miles. Bought it last Nov for one dollar! No problems with it except for this fuel problem. Please advise. Thanks.

 

That's the one. Costs about $50.

 

Thanks. I've read the other replys concerning this problem and others quote about $25. Just wanted to be sure I was about to yank out the correct unit. Thanks again.

 

there's cheaper and more expensive replacement relays. me, I prefer to use the better ones, KAE or Stibel brand.

your problem might be with the fuel pump itself, you probably have two pumps, one in the gas tank and the main pressure pump under the car. we just had to replace the main pump (and fuel filter) on my daughter's 240, the symptoms were occasional no-start when hot, then finally it got so it wouldn't start at all.

 

Pierce, I'm quite sure I have 2 fuel pumps as I have 2 fuses, #1 (fuel pump) and #11 (intank fuel pump). Now that leads me to another couple of questions: since the F.I. system is pressurized, shouldn't I hear a hiss when I loosen the gas cap to fill the tank? (I don't hear a hiss as I used to on my American cars). Second: I've read the discussions about jumpering between these fuses to power up the pumps thus bypassing the relay. I'm guessing I have to pull the fuse block and/or the relay block out and attach the clips on the underside. Correct? or is there an easier way? As I said, I didn't have this problem until the weather turned hot, and it reminded me of the vapor lock on older (carburetor) cars. So far it will start and be driveable after letting it sit for 20-30 minutes, the motor and manifold still quite hot and temp gauge needle about midway to the red zone (where it was when shut off). Sometimes I can go another couple of miles and sometimes 10 miles or more. I just got back from a trip to Salt Lake City for a relay this morning when the temps were cooler. A round-trip distance of almost 100 miles and no problems. But this afternoon would be iffy.

 

the pressurized part of the fuel system is from the main pump to the fuel pressure regulator on the fuel rail. the tank isn't pressurized, although its supposed to develop a slight vacuum after fuel has been consumed.

the full fuel path is like this...

tank -> intank low pressure 'primer' pump -> main pump -> fuel filter -> injector rail -> fuel pressure regulator -> tank return

 

oh, to jumper the fuel pump, you have a couple choices. you can remove the fuses, and clip to the springs that hold the fuses, or you can jumper at the fuel pump relay pins (but, remember, that relay has TWO relays in it, one controls the power to the whole system, and the other controls the power to the fuel pumps, so you have to jump both of these)

 

Hey Pierce, I have a stupid question. I know a little about electronics (I'm always chasing some electrical gremlin in my motorcycle) but I'm a little confused about jumpering these fuses. Current goes from negative to positive, and jumpering from one side of a fuse to the other is moot as that would simply put a wire in place of a fuse. My fuses are fine. So if I remove these fuses and stick one side of my jumper in place of Fuse #1, where do I clip the other end? Same goes for Fuse #11. Since I don't have electrical schematics to look at I thought I'd ask you. Also, yesterday it was over 100 degrees and the car died on me 4 times on the way home. I switched the fuel pump relay when it died the first time but it would not start. Had to wait about 30 minutes, then only got another 5 miles before it died again. Had to wait an hour, then got another 4 miles. I had 3/4 of a tank of gas in case you were wondering. Anybody want to but a Volvo? I can't deal with this much longer.

 

actually, what I was talking about doing was jumping from another fuse that's always hot to fuse 11 (I think) which is on the other side of the fuel pump relay.

your symptoms sound something like what happened on my daughter's high mileage 240, it took changing the main fuel pump and filter to fix it.

 

I am leaning that direction (replacing the pump) but I'm unemployed and money is tighter than bark on a tree. Also, the car may 22 years old but only has 60000 miles. The previous owners (the daughter of the original owner) hardly drove it. It mostly just took up space in the garage. Also the fuse 11 is for the intank pump according to the fuse block label.

 

yes, fuse 11 is for the intank pump, but its downstream (electrically) from the fuel pump relay... so jumpering from fuse 1 to fuse 11 will power both pumps even with the fuel pump relay unplugged. you would only do this to test the relays...

this is hte pump I'd use (assuming your car is a non-turbo, with LH2.4 injection)
Main Fuel Pump

and this fuel filter
Fuel Filter with Copper Sealing Washers

 

Pull the relay and jumper from lower left socket to middle right socket. Use a decent gauge wire; 14awg at least. If you have a 90 GL, 99% guaranty it is a RexRegina system, not a Bosch. Regina cars ahve only an intank pump. Other distinguishing characteristics include a squarish coil and a map sensor rather than an amm. Looks like this engine...

By 90, most if not all GL's were Regina, turbo cars were all LH2.4 Bosch as were the GLE's with the B234.
Jumper the relay socket; if the relay is bad, jumpering will cause the fuel pump to run non stop until the jumper is removed. The car will start and run using the jumper...IF all that is wrong is the relay.

 

Thanks guys. The car is a 1990 740GL sedan without turbo. I assume it has two pumps, at least it has 2 fuses. I haven't crawled under it to look for the main pump yet. Looks like a project for this afternoon.

 

I wouldn't trust the fuses to be an accurate indication of whether its a dual or single fuel pump system.

look under the hood. find the distributor, and follow the center lead back to the ignition coil. if it has a conventional round ignition coil, its Bosch, if it has a square module thing as is seen on the near strut tower in the above photo, then its Regina/Rex.

look under the car, the gas tank is forward of the rear axle, and forward of the gas tank, on the passenger side of the drive axle, the main pump of a dual pump system sits above a tray/guard, along with the fuel filter.. if its a single pump system, I think the fuel filter is there but there's no pump next to it.

if there's a 'main' fuel pump, then the in-tank pump is just a booster/transfer pump, the car will run without it if its got more than 1/4 tank of gas, but it might not be happy at high speeds. if there is no external main pump, then the in-tank pump IS the main high pressure pump, and its all or nothing.

 

Finally jacked the car up, set the jack stands (safety first!) and crawled under to look. I found the main pump and the fuel filter, protected by a guard of sorts, so it is a two pump system. Doesn't look too difficult of a job to replace. By the way, it has a round ignition coil. Thanks for that tip, Pierce.

 

Hello all, especially Pierce (if you are still here and reading). This will be the third summer living with this fuel pump relay problem. To review: when the temps get very warm, maybe above 80, the car stalls, resembling "vapor lock" of days gone by (before EFI). The car is a 1990 740GL non-turbo with a Bosch ignition coil and two fuel pumps, one in-tank and main one under the car and the fuel filter next to it. I replaced the main pump and the filter and carry a spare relay. The new pump is a Carter, made in US, but ever since I installed it, it has made an obnoxious whining noise that stays at a constant pitch (doesn't vary with RPM). The old pump, most likely an original, made no noise. When the car stalls, I switch pump relays but that doesn't seem to be the problem as I can drive only a few miles, if the car starts at all. I haven't dropped the tank to inspect the other fuel pump. I'm reluctant to drive more than 10 miles at a time and with summer coming and my job being 15 miles away I've got to find the real problem and get it fixed once and for all. Ideas and suggestions, other than getting another car, would be most welcome.

 

the intank pump is accessed from a panel under the floor behind the back seat. on a sedan, just remove the carpet, and you'll see the black panel, a couple screws to remove. on the wagon, fold the back seats forward, lift the front edge of the hinged floor panel immediately behind them, and that gives you access to a couple screws then you can remove those floor panels and gain access to said black panel described above.

here's the procedures, on a sedan. Volvo Fuel Tank Pump/Sender Replacement

 

Thank you Pierce. The Swedes got another thing right - an access panel rather than having to drop the tank! Guess tomorrow might be spent in the trunk, at least to take a good look at things. Can't afford a new pump right now. Are these units available at a parts store or do I need to drive 80 miles round trip to the dealer? There is a NAPA parts store within walking distance.

 

i order most of my parts from Genuine & OEM European Car Parts | BMW Volvo Audi VW Mercedes Saab or TascaParts.com (the latter is a real volvo dealer selling discount parts online, but you need to know the part numbers).

stuff you get from auto parts chains tends to be chinese knockoff parts, not something I'd put on a vehicle I was planning to keep a long time.

 

remove the f/p relay and take of the plastic cover. Cut off a piece of a pencil eraser (or something similarly nonconducting) and wedge it in the relay so both relays are closed ( sorry haven't figured out how to post pictures yet). when you put it back in the socket it will start up the fuel pumps.
Remove the gas cap and put your ear to the filler or put a n appropriately sized hose just inside the filler neck and listen for the whine of the transfer pump. If you are in doubt remove and replace the appropriate fuses and note the difference in the sound you hear at the neck.
Keep your tank above half full so it will assist in gravity feeding.
The main pump is cooled and lubed by the gas going through it.
Just to make your day. I foresee a trip to a pick-a-part in your future for a newer main pump, as it is being stressed out by the lack of a transfer pump.
when you get to the replacing the pump part write back and I have links to other sites whee i have found some really nicely detailed examples for doing intake pump replacements