Diesel starts hard

[6670charger]

have a buddy with a 95 Diesel wagon who is having a starting problem. car has a new engine. turn the key, cycle the glow plugs, and crank. motor cranks for about 15-20 seconds and won't start. repeat this 2 or 3 more times and then the motor acts like it wants to start or briefly feels like it catches, but immediately dies. then try again and this time hold foot on the "gas" pedal and it fires up.

the more times it starts during the day, the less the problem becomes; for example; when running errands all day long on a day off, the problem sometimes goes away and it fires up on the 1st turn of the key.

sounds to me like a fuel feed problem? poor fuel pressure or lines not staying pressurized? fuel pump or lines?

thanks.

[genphreak]

Sounds like fuel pressure to me. Check that, but also check anything else that has been fiddled with in the last 3 months to see if it was done right. (plugs, etc.) but i don'treallly know diesels so maybe someone else will give u something specific.

[whiskychaser]

There is a known issue with the tank pump on diesel E34s. AFIK they dont really have much to do until the tank is down to about 1/4 full but below that they can drag in air. There is an easy fix around somewhere though. You may find helpful:
United Diesel UK – Diesel Engine Smoke Explained (http://www.uniteddiesel.co.uk/diesel-engine-smoke.php)

[Tiger]

Diesel engine is quite simple to diagnose... first check glow plugs... make sure they are good by checking the resistance. Then check fuel line... make sure there is no leak... prime system if available... not sure about BMW diesel engine but knows alot about MB diesel.

If there is air in diesel line... you need to purge the system. Owner's manual will tell you how. On MB, full throttle until and after engine starts up and engine smooths out. Then let go slowly on throttle until it idles good.

[Bill R.]

Typically its the pre supply pump thats in the fuel tank thats not working. The injection pump on the engine will draw fuel eventually but if the pre pump is working it supplies fuel to the high pressure injection pump on the engine. When the pre pump fails you have to usually crank and crank before it will start.