'98 E300 engine start requirements - PeachParts Mercedes-Benz Forum

torsionbar · #1 07-18-2017, 05:03 PM

Trying to diagnose an intermittent no-start on '98 E300. It just began doing this earlier this week.

Background: The following stuff has been replaced in 2017 all are Genuine MB parts. Fuel is visible in the clear fuel lines, and no bubbles, even after being parked facing up hill for a week.

- all six clear fuel lines
- shut off valve and o-ring
- fuel filter and o-rings
- pre-filter and o-ring
- fuel thermostat and gasket

Current state: Yesterday engine cranks and cranks but no start, does not fire at all, not even a little bit. No fuel smell or smoke from the exhaust either. So sounds like it isn't getting fuel. Tried cranking some more, on and off for 15 seconds at a time until battery got real low.

Today went out and tried it again, engine cranked really slow from low battery, but it fired right up! Started immediately, less than 1 sec of cranking. Went for a spirited drive and it runs great, loads of power, everything feels really great.

I didn't touch anything between yesterday and today. No start yesterday. Start today. Weather and temperature outside same both days.

It almost sounds like the SOV wasn't opening, because yesterday, it wouldn't fire at all, not even a little stumble. But the SOV is a brand new Genuine MB part. Could it be at fault here?

I'm trying to figure out what else, if anything, is required for the car to start. Is there anything other than fuel supply and SOV that could prevent the engine from starting? I know the '98 E300 is heavy on the electronics and sensors and such, but I don't know how much of that is needed just to start the engine? The problem sounds like it almost has to be electrical. Either the SOV, or some other electronic component.

engatwork · #2 07-18-2017, 05:45 PM

How many miles are on it? Is fuel pump original? How old is the battery? It is my experience that a battery on its last leg will cause issues similar to what you are describing. Oh yea, if it is hot in Va then that kinda brings things to a head regarding if the battery is any good or not.

torsionbar · #3 07-18-2017, 05:59 PM

155k miles. The IP is original to the car, the lift pump was recently replaced (Genuine MB). Battery is Bosch Platinum AGM battery brand new February 2017, and goes on a Battery Tender when not driven for more than a few days. K40 relay replaced Feb 2017 (Genuine MB) and alternator also replaced Feb 2017 (Bosch).

Everything working beautifully until yesterday's no-start.

engatwork · #4 07-18-2017, 06:05 PM

I have seen a new MB fuel shut off not work before. Check the connector to the SOV and make sure it is not wet.

torsionbar · #5 07-18-2017, 11:10 PM

Quote:

Originally Posted by engatwork

I have seen a new MB fuel shut off not work before. Check the connector to the SOV and make sure it is not wet.

Hmm ok I'll wrenching on it this weekend, and will check it out. I just don't know what else could have caused this, besides the SOV.

KarTek · #6 07-19-2017, 02:53 PM

Part of the normal noises from the engine preparing to start is a "click" from the SOV and a sort of "tok" sound from the fuel rack cycling and releasing.

These sounds may be almost simultaneous but they can be heard if you have the window or door open. I would listen for these sounds each try at starting and if any are absent, you can start to determine why.

Once cranking, the ECU will advance the rack forward slowly until the engine catches and then the rack moves back to an idle position where it's regulated by the ECU. This can be observed if the side cover is removed from the IP.

pimpernell · #7 07-19-2017, 03:35 PM

Quote:

Originally Posted by torsionbar

Trying to diagnose an intermittent no-start on '98 E300. It just began doing this earlier this week.

Background: The following stuff has been replaced in 2017 all are Genuine MB parts. Fuel is visible in the clear fuel lines, and no bubbles, even after being parked facing up hill for a week.

- all six clear fuel lines
- shut off valve and o-ring
- fuel filter and o-rings
- pre-filter and o-ring
- fuel thermostat and gasket

Current state: Yesterday engine cranks and cranks but no start, does not fire at all, not even a little bit. No fuel smell or smoke from the exhaust either. So sounds like it isn't getting fuel. Tried cranking some more, on and off for 15 seconds at a time until battery got real low.

Today went out and tried it again, engine cranked really slow from low battery, but it fired right up! Started immediately, less than 1 sec of cranking. Went for a spirited drive and it runs great, loads of power, everything feels really great.

I didn't touch anything between yesterday and today. No start yesterday. Start today. Weather and temperature outside same both days.

It almost sounds like the SOV wasn't opening, because yesterday, it wouldn't fire at all, not even a little stumble. But the SOV is a brand new Genuine MB part. Could it be at fault here?

I'm trying to figure out what else, if anything, is required for the car to start. Is there anything other than fuel supply and SOV that could prevent the engine from starting? I know the '98 E300 is heavy on the electronics and sensors and such, but I don't know how much of that is needed just to start the engine? The problem sounds like it almost has to be electrical. Either the SOV, or some other electronic component.

There are numerous posts regarding the same problem as yours, and it turned out to be the k40. It is not an expensive fix, and that would be the first thing I would be inclined to replace. Good Luck!!!

torsionbar · #8 07-19-2017, 03:43 PM

Quote:

Originally Posted by KarTek

Part of the normal noises from the engine preparing to start is a "click" from the SOV and a sort of "tok" sound from the fuel rack cycling and releasing.

These sounds may be almost simultaneous but they can be heard if you have the window or door open. I would listen for these sounds each try at starting and if any are absent, you can start to determine why.

Once cranking, the ECU will advance the rack forward slowly until the engine catches and then the rack moves back to an idle position where it's regulated by the ECU. This can be observed if the side cover is removed from the IP.

Familiar noises, now I know what they mean, awesome!

Thank you I'll keep an ear out for them. Always wondered what that loud tok sound was...

Quote:

Originally Posted by pimpernell

There are numerous posts regarding the same problem as yours, and it turned out to be the k40. It is not an expensive fix, and that would be the first thing I would be inclined to replace. Good Luck!!!

Replaced a few months ago as stated, Genuine MB part, I doubt it has failed so quickly.

pimpernell · #9 07-20-2017, 09:00 AM

Quote:

Originally Posted by torsionbar

Familiar noises, now I know what they mean, awesome!

Thank you I'll keep an ear out for them. Always wondered what that loud tok sound was...

Replaced a few months ago as stated, Genuine MB part, I doubt it has failed so quickly.

You might want to check out these posts regarding the CPS sensor:

e300d crankcase position sensor

tjts1 · #10 07-20-2017, 11:32 AM

+1 very likely crank sensor.

torsionbar · #11 07-20-2017, 02:54 PM

I'll investigate this sensor, however my symptoms are not the same as in the linked thread. I've experienced no stalling, no rough running, no hesitation. It either starts immediately and runs perfect, or it doesn't start at all.

torsionbar · #12 07-24-2017, 10:37 PM

Spent some time over the weekend troubleshooting. Practically everything related to starting the engine is new on this car, so I figured it had to be a defective new part somewhere. Key to position 2 I was not hearing the click and tok sounds. Likelihood of two unrelated components failing at once is pretty slim, so next thing to check was the battery...

Turns out the battery had a bad cell. Its a new battery Feb 2017, so the store replaced it under warranty thankfully. Running the glow plugs in key position 2 must have been pulling the voltage down low enough that it couldn't operate the SOV and fuel rack.

New battery installed... turn key, click, tok, vrooom!

engatwork · #13 07-25-2017, 06:00 AM

Quote:

It is my experience that a battery on its last leg will cause issues similar to what you are describing.

torsionbar · #14 07-25-2017, 10:07 AM

Yes you called it Jim. The one confounding variable was that the battery was new. I've never had a brand new battery fail internally like this one did. But at least it was under warranty!