W123 - Trouble starting after fuel filter change

[hatecherry]

I've swapped out both fuel filters on my 83' 300D and my engine is not happy.

Initially, it was airlocked so I bled the fuel system but even so, the engine shakes, sputters and kicks out exhaust but won't properly start up. After about 30 minutes of intermittent cranking (15s max) it's now cranking very slowly until it eventually dies out. I figured I'd drained the battery so I had a neighbour come give me a jump and even with that it's still slow.

Has anyone dealt with this before? Open to any and all recommendations before I tow it to the shop.

Thanks,

[Shern]

1.) You have big time air in your injector pump.

Did you fill the secondary filter with diesel before installing it?
Did you prime until it squeaks?

2.)Your battery is drained.

Go get yourself a trickle charger and get your battery back in the game.

When you’re cranking, if you can get your nose down 10 degrees or so (or your tail up) I find that really helps get the trapped air out.
There’s a procedure for bleeding air involving cracking the hardlines that’s been described here a thousand times (search).

You’ll be firing in no time. Good luck!

[Diesel911]

Originally Posted by Shern

1.) You have big time air in your injector pump.

Did you fill the secondary filter with diesel before installing it?
Did you prime until it squeaks?

2.)Your battery is drained.

Go get yourself a trickle charger and get your battery back in the game.

When you’re cranking, if you can get your nose down 10 degrees or so (or your tail up) I find that really helps get the trapped air out.
There’s a procedure for bleeding air involving cracking the hardlines that’s been described here a thousand times (search).

You’ll be firing in no time. Good luck!

And or the starter is now no good.

[Diesel911]

There is 2 parts of the fuel system that need to be bled if air gets into it.

The fuel supply system starts and the fuel tank and goes forward through the plastic primary filter into the fuel supply/lift pump.

The fuel is pushed out of the fuel supply/lift pump through the secondary/spin on fuel filter. From there the fuel is pushed into the fuel injection pump body and from there out of the fuel pressure relief/overflow valve and back to the fuel tank. You do that with the hand primer. (If the hand primer is leaking fuel as you use it that means it can also be a source of getting air into the system.)

Inside of the fuel injection pump housing is the high-pressure part of the fuel system. That takes in the fuel supply or if there is air in there take in air. The problem with taking in air is that the fuel injectors are spring loaded valves. When there is air between the fuel injecting pup and the injectors the air compresses a lot but moves very little. And you can end up killing your batter and or starter by cranking the engine trying to get the air out that way.

As was mentioned you loosen the connection nuts on the fuel injection (steel) hard lines at the injectors. That way when you crank the engine the air has some place to move/escape out of. When you are getting fuel to the injectors you can tighten the injector line nuts and attempt to start.

[hatecherry]

Thanks both! I got a trickle charger and the starter is sounding good again. It smokes and shakes, but doesn't start.

I gave the primer pump a good 50+ hits and cracked the injectors to release air; they're all trickling but not squirting out fuel the way I've seen in videos online.

Is it possible the washers need to be replaced? I'm not seeing fuel leaking anywhere but as a novice, I don't know how sensitive the system is.

[hercules]

Had this same thing happen ,was the primer pump sucking air. If you have old style primer
I would suggest renewing with later style.
Try this; prime each time you crank.

[resago2000]

you can spray Pam cooking oil spray into the intake before or while cranking, if you can get the engine to run a little with the pedal to the floor, it will get the air out faster.

[Benz-76]

On my 240D i couldnt get started once after replacing the fuel filter it was because the liftpump had siezed and was no longer pumping. Ran decent before but would surge a little at stoplights. I guess it was able to run without it with no air but obviously no pumping makes it impossible to get the air out after filter replacement. Last time i changed the filter i filled it with oil and started up without a miss.

[dkr]

I had a similar issue once where the cheap plastic filter had a tiny hairline crack. You may want to change it. It's only a few bucks and a quick job.

Dkr.