Noisy fuel pump, '93 240

So, two weeks ago my in-line fuel pump died. We replaced it with a 740 turbo spec fuel pump that had been sitting for a while. It was the only one handy and I needed to get home. After the install the pump was making a mechanical buzzing but the car seemed to do fine on the test drive. I drove the 6 hours home with no issues. The following day I started it up and the pump was still making the noise, perhaps even louder. This past weekend I replaced the in tank pump with a brand new AC pump, I replaced the filter sock, the in tank hose and the fuel sender are new as of spring 2017 and checked out fine.

Is it possible this is just a noisy pump? I'm out of ideas.

When they wear out they start to make noise. Get a multi/meter with a 10 amp test circuit and test the draw across the main pump circuit[ take out fuse and jump the two fuse contacts with the meter], start engine. If it reads high it is more than likely that the pump is bad.

check my understanding...
main pump: 740T pump
tank pump: AC Delco (?) / stock replacement

The 740T main pump is going to flow more fuel than the stock 240 main pump, so pairing that with a stock 240 tank pump, it is going to flow more than the tank pump can and cause the buzzing/cavitation.

I'd recommend getting a replacement 240 main pump and putting in a 740T tank pump (or ipd upgrade pump). With that setup the tank pump will easily keep up with the main pump and prevent cavitation.
https://www.ipdusa.com/products/5799/111016-in-tank-fuel-pump-upgrade-kit

I went through a fuel pump puzzle a few years ago and the culprit was that the tank pump was not flowing enough fuel to keep up with the main pump. The main pump should not buzz...I too thought I just had a noisy pump, but when fed with enough fuel, it is silent.

To really verify this, you need to check the flowrates.

For reference: http://forums.turbobricks.com/showthread.php?t=170882&page=2
(sorry that all the pics have all disappeared due to photobucket)

Good info old school!

oldschoolvolvo said:

check my understanding...
main pump: 740T pump
tank pump: AC Delco (?) / stock replacement

The 740T main pump is going to flow more fuel than the stock 240 main pump, so pairing that with a stock 240 tank pump, it is going to flow more than the tank pump can and cause the buzzing/cavitation.

I'd recommend getting a replacement 240 main pump and putting in a 740T tank pump (or ipd upgrade pump). With that setup the tank pump will easily keep up with the main pump and prevent cavitation.
https://www.ipdusa.com/products/5799/111016-in-tank-fuel-pump-upgrade-kit

I went through a fuel pump puzzle a few years ago and the culprit was that the tank pump was not flowing enough fuel to keep up with the main pump. The main pump should not buzz...I too thought I just had a noisy pump, but when fed with enough fuel, it is silent.

To really verify this, you need to check the flowrates.

For reference: http://forums.turbobricks.com/showthread.php?t=170882&page=2
(sorry that all the pics have all disappeared due to photobucket)

Click to expand...

Wrong. The main pump is only going to flow what the engine needs and bypass the rest back to the tank via. the pressure regulator. IOW, the amount it is pumping due to the restriction in the line is well within the range of what that in tank pump can manage. That in tank pump will easily keep up. What may be going on is the in tank pump may be wired differently. I have run into that twice now with replacement pumps. You new in tank pump may be a restriction in the system, rather than a lift pump as it is supposed to work. Take one of the leads off of the main pump and remove the fuel line from the rail and put the end into a milk jug or something like that. Cycle the key/starter several times to see if the in tank pump is actually pumping fuel. 15A just ran into this problem with a new replacement pump and so did I about 3 months ago. I think the pump I had was an AC pump.

Thanks for the responses, guys! I'm going to check some of this out this week if I have the time or this weekend. I'll report back with what I find.

283SD said:

When they wear out they start to make noise. Get a multi/meter with a 10 amp test circuit and test the draw across the main pump circuit[ take out fuse and jump the two fuse contacts with the meter], start engine. If it reads high it is more than likely that the pump is bad.

Click to expand...

Picked up a multimeter finally. Ideally what should it read here?

I checked the wiring for the in-line pump and that is good, wiring for the in-tank pump is good as well. However, I noticed a pretty consistent drip coming from the in-line pump. I don't know if it was there before, I don't think it was, but I can't be sure. So this may be the culprit? What does it take to replace the hose from the tank to the in-line pump? I searched and found a thread talking about hosing size and the recommendation was to get the original Volvo hose, but nothing about the actual work required. Is it as simple as pulling the old one off and putting the new one on?

Another datapoint...while the car was running I pulled fuse #4 and I assumed the car would sputter and stall but it didn't. I listened for the in-line pump and can still hear it buzzing, but the in-tank pump stops. What's this all about?

Thanks in advance and sorry for all the questions. This is has got me stumped.

FPR can go bad , causing main pump to be noisy

I'm having close to the same problem with my 740 turbo, after replacing the intankpump the car drove great and no special noises. A day later the inlinepump started to make noise again.
After starting the car, it will make that noise after a few minutes. Lets hope it's the FPR