I suspect fuel pump issues, please validate. I'm driving a 1989 300E with an in-line 6 3.0L block, which has been having a difficult time starting when cold for the last few months (60ºF or 21ºF outside, no real difference). I've found that turning the key several times from off to on(while hearing the fuel pump work... a barely auduble uumm*thump) will make the car more likely to start up. Even then though, the first couple times that it starts, it idles at 400RPM and will die if I try to give it more gas. Once I let it idle for 2-3 minutes, it is a little laggy, but will rev up on command; after 3-4 minutes, it is wonderfully responsive.

Once the block is warmed up (or perhaps because there is still fuel in the lines), it'll start without a problem, idling at about 1000RPM. I'm not sure if it is a block-temp issue or if it is just that when the block is warm, the fuel lines are full from being recently run.

Today, I went out to start her and there was no mmmmm*thump* (but the car had power) so I suspect that my fuel pump is not pumping at all.

Here is my plan of action; I'd like to know if I'm attacking it from the right angle. This is my daily driver and she's stuck across town and my budget is low at the moment. I'll be doing the work myself.

1) Get to fuel pump and test electrical to make sure it is getting power. I don't think that this is the issue because I've been having problems when the pump was obviously getting power when i was having related issues.

2) If it is getting electrical power, feel it while it should be working to see if there is any motion.

3) If Fuel pump is inactive but is getting electrical power, replace it. I've found replacement pumps for as low as $135, but if you have a better connection (or if you sell it for $150, I'd rather buy from you to appreciate your feedback.


Thank you for your feedback.