620i won't go much above idle

My friend has a 620i and has started loosing rpm's and gets worse as it warms up. It ran fine one day and while driving it the rpm's slowly began to fall. When it starts to loose rpm's and you try to give it more throttle it looses more rpm's. You can only press the gas pedal so far then it starts to run rough and loose rpm, but it will run like nothing is wrong at idle. I'm beginning to think its the fuel pump because you can hear it whine before you start it with the key in the on position. Any ideas on how to solve this?

Check out these threads and see if one of these might resemble your problem...

https://www.johndeeregatorforum.com/f...ighlight=check

https://www.johndeeregatorforum.com/f...ighlight=check

Hope one of these links helps.

David in TX

I'm not sure if it belches out smoke when the engine starts to run rough, but give the oil a quick check. I've had lots of issues with 620s towards the 2nd half of winter where there is a lot of condensation buildup in the oil, and once it gets warm enough, it'll only go so fast before the engine dies way down and will start smoking. A quick oil change solves that issue every time.

sounds like the engine is not get up to temp. short run times hard on a lot of engines

Check the fuel tank breather hose, could possibly be plugged which will cause your problem also. Hose comes out under the floor beneath the passenger seat. Also check fuel filter. Start at the easiest things first.:Ysnd: