1991 740 I4: I bought this car for my mom and her local (small town) handy man has concluded the fuel pump(s) are out. I am curious why we have a in tank and top mounted fuel pump on this vehicle? This seems to be a very difficult service. There also seem to be several options for parts and my mom says there aren't any names stamped on either pump. 1) How do I know which pump(s) to order? 2) It seems I need a sending unit (is this the interior pump?), exterior pump and a pump housing (which I cannot find on any web site)? 3) Has anyone simply bypassed this mess and installed a engine compartment fuel pump or am I missing something? Suggestions and ideas would be greatly helpful!

I recently had a fuel pump problem with my 91 740. Mine is a Belgium Volvo and has the Regina system with one pump. First I would check the relay, take it out and jumper back to the relay box. Then, take the relay cover off and turn the ignition to start. You should see and hear the relay actuate. If it doesn't, you need to replace it. If it does work, time to check the pump. I have never seen a base model 91 740 with the Bosch system(with two pumps), so I can't help there. Two ways to tell the difference, check the ignition coil on the driver's side strut well, if it is square and looks like a transformer, then you have a Regina system. The other way is to look underneath the car, under the driver's seat. There should be a brace/shield with fuel lines running to it. Underneath this should be a big fuel filter(Regina) or a smaller filter and pump (Bosch). If you have the Regina system with one pump, the pump could simply be clogged or the filter sock on it's suction clogged. If the sock is clogged the pump has no NPSH and therefore will not actuate, because it will create a vacuum. The pump could be clogged also, by trash or gunk. I simply removed the pump and sending unit, wired the pump up straight to the battery and ran it(AFTER THE FUMES AND GAS EVAPORATED). The pump would not run, I wired it in reverse, removed the sock, and ran it, viola, worked perfect. I ran it for about 30 seconds in reverse, rewired it forward and operated, worked fine. I wouldn't run the pump dry for more than 30-45 seconds, it could damage it. These pumps are tough though and should outlive your engine. The cool thing about the Volvo is the access port in the boot, just pull up the boot liner, and the port is on the driver's side. You have to be very careful, gas fumes are abundant,don't spark, and have plenty of ventilation. Removal of the pump is straight forward, just take your time. Also, don't cut any hoses unless you have replacements.
Hope this helps,
G.W. (I love run-on sentences and improper structure about as much as I love Volvos)

What do you mean when you say "top mounted fuel pump"? If you have a two pump system, there should be one in the tank and one under the car about where the driver sits. (The filter should also be located near this second pump.)

As others have mentioned, the relay is more likely to fail than the pump(s) itself/themselves.

Also, you mentioned something about a sending unit problem. Is the guage acting up? It's possible that the sending unit problem and the pump problem are related, like a wiring problem in the tank or going TO the tank.

Small town handyman eh?? Can we assume that he checked your fuel pump relay?? In the 700/900 series cars this relay is located just behind the ashtray (ashtray comes out). I'm not sure which relay it is in there but if you check the FAQ in the "Features" menu, there may be a picture.

These relays are known to fail, the solder that holds the components on the circuit board tends to crack. If yours is bad then it can likely be resoldered...or you can get one from a local pick&pull (junkyard)...and even buy a new one ($$).

If it's not the relay then I agree with porkface, one pump may have overworked itself while the other lay dieing.

I would highly recommend you find yourself a mechanic who knows import cars, even better would be Volvo specific. These cars have their typical problems which anyone who knows Volvos can figure out in a heartbeat. If they charge more than your lifelong mechanic then so be it, they'll find the problem faster and fix it right the first time.

For parts I highly recommend using any one of the Brickboard advertisers. They are all top notch businesses. I personally use FCP Groton, based in Groton, CT. Check out their web page fcpgroton.com

Good luck with your car. My money is on the fuel pump relay.
Bean
--
'80 242GT 92k, '94 945T 123k

if it's a bosch car, it has 2 pumps. there is no cheating by substituing another setup. all that does is bring on other problems. have someone who speaks volvo check it out. it may very well need both pumps. if the 1 in the tank dies, the main pump works harder-and dies faster-to make the car run. good luck, chuck.

"if it's a bosch car, it has two pumps." The other option is the Rex/Regina fuel management system. Both systems were used around that time, I believe. I know of a Canadian built normally aspirated '90 745 with Rex/Regina.

They are easy to tell apart. If Bosch, the ignition coil is a conventional looking "can". If Rex/Regina, the ignition coil will be a square block. (It looks like a conventional transformer if that helps.)

The Rex/Regina system uses only one fuel pump and it is located in the fuel tank.