Replaced original fuel pump with new Bosch pump.New Bosch buzzed loudly and after driving 20 minutes I would lose acceleration.Installed new sending unit and in tank pump and replaced new Bosch pump #1 with another new Bosch pump #2.Bosch pump #2 has low buzz.So far I have a new: Bosch main pump,in-tank pump and sending unit (made in Germany).After 10 minutes I lose acceleration @ 20-40 mph but if I take my foot off the gas and then accelerate it's fine. Could the in-tank pump be lagging? Do I need a stronger in-tank pump? Could the problem be the fuel pump relay (it does get very hot)?
Thanks for any suggestions!

 

Did you replace the filter when replacing the pump?

 

Also, you might double check country of origin for the Bosch fuel pump(s). Bosch built pumps are made in the Czech Republic. If the box or pump says made in Germany, they are low quality Chinese knock offs. Lots of 'em around. If the filter doesn't help, pull the trouble codes for any info. The fpr should get warm, but not uncomfortably so. Might also check fuel pressure at the rail.

 

Here's an update:
- I replaced the fuel filter when I had the first Bosch pump installed.
- The fuel pump regulator is A-OK,
- The on board computer was read and shows nothing wrong.
- The first new Bosch pump was made in Germany-didn't get to see the box from Bosch pump #2.
It still has so much lag from 20-40 mph even with Bosch pump #2,new AC/Delco in-tank pump and new sending unit (made in Germany).
Also I noticed that the Bosch pump #2 started buzzing when my gas tank was half full so I filled it to 3/4 and the buzzing stopped (the in-tank pump was checked when Bosch pump #2+ sending unit was installed...could the NEW in-tank pump be defective???).
I've ordered a hi-flow Air-Tex in-tank pump from IPD,should receive it next week.
Don't know what else to do unless there's an electric wiring short :-(
Thanks for everyone's help
Will give an update next week unless I give up and sink my 240 in the nearest South Florida canal ;-)