Dfg22

So I have read many posts on here and have to sign up and make my own. I have a 1998 ML 320. I have a new CPS sensor new camshaft sensor new ignition coils new spark plugs new fuel injectors new fuel pump new fuel filter new mass airflow sensor. And yet I still am having trouble starting my car once in a while. The car runs fantastic when it starts no stalls no issues with acceleration. But sometimes when I try to start it cold it coughs and won’t start for a crank or two. And after it starts finally and runs for a while it gives me trouble starting back up. Almost sounds like it’s out of fuel but the fuel pressure is where it supposed to be. I honestly don’t know where my problem lies now,because it still giving me problems starting, can anyone point me in a direction to actually fix my starting issue? I have read about the ebox fan but don't think that’s my problem. Thanks

Maj. Dundee

And what is your fuel pressure reading? Are you using a fuel pressure gauge?

Dfg22

Fuel pressure is at 55 psi and i have a fuel pressure gauge, i was losing pressure before, changed the pump and filter and still lost pressure, just didnt the injectors last week, and finally have good pressure even when i turn car off, i was losing pressure before, now the pressure is constant

Maj. Dundee

So now after replacing those parts, do you still have a problem?

Dfg22

Yes, i still have a problem starting it now and then, sometimes when its cold and most times when its hot from running, and most of the time when i do have the problem sounds like a cough or a like a backfire cough when you start it.

Dfg22

I just walked out and started the ml right up, started 3 times for me with no problems , my brother pointed out that you can smell the gas when you start the car and can hear a slight rattle which I think is coming from the cat maybe. Would a bad cat give me a problem like this?

Agent-A01

If it cat is completely clogged or broken up it can cause hard starting.

But you would also get poor performance too

Dfg22

The ml performance is great when its running, thats why im kinda stumped on why its still giving me a starting problem once in a while

Maj. Dundee

More often than not it comes from the top of the fuel filter. Whenever you change the pump you must also replace the locking nut and seal.

Dfg22

I have not replaced that but i totally can order those parts and give it a try, but one question, even if my fuel pressure is stable now you would change that out?

Maj. Dundee

You previously said that you replaced the fuel pump and now you smell gas fumes. Simply look at the fuel pump and see if there is fuel on top and fumes.

Dfg22

Im not smelling gas in the car, and checked to make sure it was sealed with no leaks before i covered the pump back up, the gas smell im getting is from outside of the car, like a rich gas smell

Maj. Dundee

If you want to check the CATS, buy and Exhaust Back Pressure Gauge. Remove the front O2 sensor and install the gauge. Start the eng. and any reading above ZERO means the CAT is damaged. Then do the same to the other sensor.