I live a long way from a Volvo Dealer or mechanic that specializes in Volvo, so I use diagnostic tips from IPD and a Volvo book by Hayes, then have a local mechanic do any work that I'm not able to do.

The problem is;
My main fuel pump is making a horrendous growling noise. This all started with my belief that my in tank pre-pump had failed. I had my mechanic replace the pre-pump with a replacement from IPD. Unfortunately he didn't replace the rubber connecting hose, he said the original one seemed fine(he should have just replaced it anyway). He installed a new fuel filter as well as the pre-pump sock.

On my way home my main pump started to make an intermittent growling noise so I returned to the mechanics shop. He identified the main pump as the source and we could feel intermittent vibration in relation to the sound. We figured the main pump must be worn. I had to leave for the Vancouver the next day and decided to chance it and get a new pump there. (I live at 1700 ft altitude, Vancouver at sea level) At sea level the pump didn't seem as noisy but I had a Volvo shop replace the main pump with a new Bosch. For the month that I spent in Vancouver the pump was nice and quiet and the car ran well.

On my way back home the main pump started to growl more and more as my altitude increased. My mechanic here took the pump off and I shipped it back to the shop in Vancouver and they replaced it with another brand new one. When the new one was installed it made the exact same sound.
Also on hot days sometimes when I press the gas pedal the car will buck and lurch a few times then run fine after that(this didn't happen before).

In doing some tests this morning;

-we can here that the in-tank pump is running and a pressure gauge put on the line that supplies the main pump shows about 7 pounds pressure

-a multimeter on the contacts for the main pump at the fuse strip shows about 16 amps draw(it sometimes blows the fuse)

-the fuel pressure taken at the cold start injector is 70 pounds

Any suggestions?
Thanks.

I just went through the same problem on my '86 245. My main pump had always been noisy - I was told my more than one person that this was common for rebuilt pumps. After having an intermittent problem with my car dying when the fuel got below 1/2 tank, I replaced the in-tank pump. Life got better for a little while, until the dying problem came back with a vengeance. It quit on the way home from work, and my only option was to limp it to a small Volvo shop that I use for things that require the car to be put on a lift. After putting a known good used pump on the car, it pumped out a molasses-like goo. It turns out my tank was full of crud, some it so fine it would pass through the filter and into the system. A new pump and $300 later, the car has a good clean fuel tank and a quiet pump. The only problem I have is on cold-starting, I believe the used fuel pump they put on has a weak relief valve. I would recommend checking your tank out. The guy at the shop tells me 240's are hard on fuel tanks, and he literally has to go through 10 cars to find 1 good fuel tank.

Lance
near Memphis, TN

I don't have FI, but

"-we can here that the in-tank pump is running and a pressure gauge put on the line that supplies the main pump shows about 7 pounds pressure"

only 7psi from the in-tank? I thought those pushed more.

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'80..245..M46...b21a..SU carb..

They are there to supply volume not pressure, 5-7psi is what they are suposed to put out.
The main pump provides the fuel pressure.
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My 85 760Ti, and her name is Veronica...

This is a tough one. I think the main pump should only draw 5-6 Amps. However, I don't believe the pump could be the problem when you replaced it twice. You say you measured the current at the fuse. Fuse 7 carries the power for both pumps. The relay output has two wires, one to the main pump and the other goes back through fuse 5 and then to the prepump. I believe there are separate connectors for each pump under the rear seat (inside the car), drivers side. This may be a better place to measure current to each pump. The noise may be a separate problem. I had a main pump make noise because the mechanical contacts inside the pump relay were burnt and arcing thus causing a fluctuating current to the pump and it also occasionally blew fuse 7. In addition to rechecking the current you could jumper the pins in the relay's harness socket, pins 30 to 87 (not 87b), to see if bypassing the relay makes a difference. You won't need the engine running or even the key on. The injectors won't spray either because the air meter will be in the closed position. The pump will just be pressurizing the system.