Engine cranks but no start

[SWISS MIKE]

Hello 500E family,

Hope somebody can help me get my 1992 500E running.
Car was in storage for the last couple of years as a nonoperation, I would drive the car once/twice a year for a couple of miles.
Now I am ready to put the car back on the road. I replaced the front brakes, brake fluid flush, engine oil and filter change and replaced the brake light switch due to ABS code.
Engine cranks but doesn't start. Battery is good, fuel pressure at 3.5 bar, added 7 gallons of fresh gas. I get spark on the plugs, removed both distributors and spark plugs. Everything is looking good. Performed compression test, all 8 cylinders are between 180 to 195 PSI. With starter fluid, engine almost starts...
Any idea what to check next? Could a new (faulty) brake light switch cause a no start?

 

[gsxr]

Faulty brake light switch will NOT cause a no start condition.

If you squirt starting fluid down the MAF and it still doesn't start, it's not fuel supply either.

So, it's probably not getting spark. Not sure how you are testing for spark. Any fault codes? All fuses good including the ones in BM/GM (CAN box)? Do you have access to SDS / HHT-Win?

 

[SWISS MIKE]

GSXR,

I used a cheap in-line ignition spark tester. I check two different cylinders, one on each bank. I get spark on both sides.
All the fuses are good, including the once inside the BM/GM box.
I don't have access to SDS anymore. I worked for the Mercedes Dealer for 10+ years, but that was a while ago.
All I have is the blink code tester.

 

[190EVAN]

You need to absolutely verify the routing of your spark plug wires if they have ever been touched. Mismatched routing will lead to a no-start or extreme misfiring.

Have you inspected the wiring harness for insulation damage or if it’s ever been replaced?

You may also want to consider building a simple noid/pulse tester that you can install in place of one of your injectors to verify the ECU is actuating them. If you have good fuel pressure and the injectors are pulsing, your problem is probably ignition related. If you have no injector pulse, I would start looking into sensors that are inputs to the ECU for controlling injection.

Crank sensor, MAF, Coolant temp sensor (unlikely but possible if it thinks the car is running wildly hot) and finally the ETA (Electronic throttle actuator/Throttle Body).

The ETA has an internal throttle position sensor and they can fail internally or the wiring harness coming out of them can suffer from insulation problems. I would check this last as it’s buried in there pretty good!

 

[frall]

are there signals form the Crankshaft sensor?

 

[SWISS MIKE]

You need to absolutely verify the routing of your spark plug wires if they have ever been touched. Mismatched routing will lead to a no-start or extreme misfiring.

Have you inspected the wiring harness for insulation damage or if it’s ever been replaced?

You may also want to consider building a simple noid/pulse tester that you can install in place of one of your injectors to verify the ECU is actuating them. If you have good fuel pressure and the injectors are pulsing, your problem is probably ignition related. If you have no injector pulse, I would start looking into sensors that are inputs to the ECU for controlling injection.

Crank sensor, MAF, Coolant temp sensor (unlikely but possible if it thinks the car is running wildly hot) and finally the ETA (Electronic throttle actuator/Throttle Body).

The ETA has an internal throttle position sensor and they can fail internally or the wiring harness coming out of them can suffer from insulation problems. I would check this last as it’s buried in there pretty good!

Evan, thank you so much for reaching out. After all the testing listed above, I decided to remove both valve covers to make sure the chain didn't jump. At 45 degrees above TDC all camshafts pin perfectly. The spark plug wires are not mismatched, I double checked and compared with other posts on this forum. I noticed that the wire from ignition coil to distributor on the left side has a too high resistance. Since the spark plug wires look original, I installed a new Beru Kit with new spark plugs. Still... engine cranks but does not start!
The upper wiring harness is fairly new; I replaced it couple years ago.
I checked injector pulse on 1 injector, seems to be okay.

How can I check the crank sensor, MAF and coolant temp sensor without WIS? With the blink code reader, I'm not getting any codes.

Thank you for your help, much appreciated!

 

[SWISS MIKE]

are there signals form the Crankshaft sensor?

What's the best way to check the signal from the crankshaft sensor?

 

[190EVAN]

If you need access to Legacy data (Wiring diagrams for older mercs), I have access and can share the PDF with you that you can you to reference.

If the crank sensor had failed, and you have access to a blink code reader, you would have seen a code for a missing crankshaft signal, also you would not have a injector pulse, without a crank signal the ECU would not know when to fire the injector, thus ruling out the crank sensor.

Are you familiar with using the blink code tester beyond its standard general use, for example attaching the blink signal wire to alternate pins to read a particular control unit. In this case you will want to read directly from the LH-control unit which I believe is Pin 4, refer to the link below for details.

Thread 'Read Trouble Codes on a 1993 400E'

Dec 4, 2014

I tried to read the trouble codes on my 93 400e from the 38 pin connector with a blink code reader , but I only get a response ( a single blink , or a counted code ) from pins 31 ,32 , and 33 this is done straight into the 38 pin connector not using a 38 pin break out box , is a breakout box needed ? Am I doing this the wrong way ? The 400e idles low at times .

• Berlin
• Replies: 7
• Forum: 400E / E420 Discussions

If you have no codes there, you can proceed with testing actual values/sensor readings with the help of a wiring diagram.

Please verify you have checked the LH control units specific codes and if there are none I can assist with wiring diagrams and potentially reference values for each sensor you need to test.

Also if you did want to test the crank sensor, which I don’t recommend as I believe it’s functioning properly, you would need to hook up an oscilloscope to read the TN signal. On early M119’s it’s at the 9 pin diagnostic connector near the EZL, on a 1993 car I can’t recall without looking at a diagram if there is a 9 pin or if it’s integrated into the 38-pin diagnostic port.

If you don’t have access to HHT-Win, I doubt you’re yearning to bust out an oscilloscope haha.

Let me know about the codes and if there are none we can more forward with getting you some testing values/diagrams.

 

[190EVAN]

Also, how did you check for the injector pulse?

You would need to set up a noid light tester unless you own one already.

Sorry but I need to know for certain that there is an actual pulse (ECU grounding the injector) and not just power to the injector, what was your testing method for that?

 

[gsxr]

If you squirt starting fluid down the MAF and it still doesn't start, it's not fuel supply either.

Have you done this yet? ^^^

This is a simple, easy, cheap test to figure out if the problem is fuel or spark. Start here before wasting hours of diagnostics...

 

[SWISS MIKE]

Have you done this yet? ^^^

This is a simple, easy, cheap test to figure out if the problem is fuel or spark. Start here before wasting hours of diagnostics...

With starter fluid, the engine starts up and shuts off immediately.
Fuel pressure @ 3.5 bar. Removed the fuel pressure line to the fuel rail. Plenty of fuel coming out. I added 7 Gallons of fresh gas.
Checked for codes again on Pin#4 with blink-code reader, no codes. All the fuses are good, including the one on the GM module.
Checked injector pulse on cylinder#7, and I get a pulse. Not sure if that pulse is sufficient and correct.
I will try to upload a video.
I was reading in several posts that the resistors inside the LH module are known to go bad. Could that cause my no start?
How would I know the resistors are bad?

 

[SWISS MIKE]

Also, how did you check for the injector pulse?

You would need to set up a noid light tester unless you own one already.

Sorry but I need to know for certain that there is an actual pulse (ECU grounding the injector) and not just power to the injector, what was your testing method for that?

That's the test light I'm using to check the injector pulse.

 

[gsxr]

This is progress! You have ignition, and fuel pressure at the rail, but the injection system is not injecting. Bad capacitors inside the LH won't cause this problem, they usually cause the fuel pump relay to click with the engine at idle RPM. However, if you could swap in a different LH module for testing (any M119 V8 LH module will work) that would be an easy test. I generally recommend any long-term owners invest in a set of spare modules for the CAN box for testing purposes like this (don't need to be exact part numbers as original, just need to be functional equivalents, test & put on the shelf for when needed).

Since the car was stored for multiple years, it's also possible that the injectors have gummed up, especially if the old fuel was an ethanol blend (E10). Unfortunately that's a lot of work for a bit of a gamble.

 

[190EVAN]

Now I am not positive without checking a function description on LH but I know on a lot of injections systems you will get a single test pulse with the ignition on. When cranking the engine you should be seeing repeated pulses, not just one, indicating that the ECU has good inputs in regard to determining injection timing.

Do you have a repeated pulse or just one single pulse, a video of the pulse would really help confirm if this is in fact the ECU limiting injection or if it is trying to pulse but your injectors are clogged up.

 

[Eno]

I didn’t read all the feedback above but I would recommend to:
1. Make sure the small cable at the battery is tight.
2. Check the green fuel pump relay behind right passenger seat is ok and tightly in.
3. Check if there the fuel pumps have voltage.
4. Check if all three magnets on the flywheel are in place.
5. Check/replace the crankshaft flywheel sensor.

 

[SWISS MIKE]

Now I am not positive without checking a function description on LH but I know on a lot of injections systems you will get a single test pulse with the ignition on. When cranking the engine you should be seeing repeated pulses, not just one, indicating that the ECU has good inputs in regard to determining injection timing.

Do you have a repeated pulse or just one single pulse, a video of the pulse would really help confirm if this is in fact the ECU limiting injection or if it is trying to pulse but your injectors are clogged up.

Yes, I am getting a repeated pulse while cranking, but the pulse is not too consistent. I made a video, but I am not able to upload the video.
Over the weekend, I will remove the fuel rail and inspect the injectors. Since I don't have access to try out another LH module.

 

[Alphasud40]

Bet you have clogged injectors or stuck pintles from old fuel and lack of running. Pull the injectors and have them professionally cleaned.

 

[Alphasud40]

Also I would do the sniff test on the fuel. You might get by adding good fuel on top of bad fuel but generally if it’s bad the best practice is to remove the fuel, replace the filter and refill with new. Storing a car should only be done with ethanol free fuel and no more than a couple years.

 

[SWISS MIKE]

500E experts I need your advice again.

I removed all the fuel injectors and tested them with a cheap fuel injector tester from Amazon. Please see picture below.
None of the injectors has a pulse. I thought the tester was defective and ordered a replacement. Same thing, no pulse! Tested with two known good batteries. Since I am getting spark, fuel rail pressure and the signal to the injectors, defective fuel injectors make sense why the engine doesn't start.
But what would cause all 8 injectors to go bad???? I'm worried to order all new injectors install them and I fry them!!!!
FCP has a clearance for $143 each.

All the removed injectors have part#000 07 87 823

 

[190EVAN]

I find it extremely hard to believe that all of your injectors have failed, I would put money on a cheap Amazon tester that is not designed for the injectors you are trying to test. Have you considered just hooking the injectors up to power directly (momentarily) and seeing if you can hear the injector open? Also is it possible that you hooked up the injectors to the tester with reverse polarity? They will not work if polarity is reversed.

If you supply the injector with 12V and ground from a car battery directly, to the correct terminals on the injector, you should be able to hear an audible pulse/click. Remember to only power the injector momentarily as to not burn the injector up.

 

[gsxr]

DO NOT spend $1200 on new injectors!

190EVAN is correct. Seems very unlikely all of your injectors would fail simultaneously. It appears the Amazon tester just applied the 12V pulse more easily than rigging up your own wires, and you are just listening for a "click" when energized - correct? No click, no fuel. It wouldn't hurt to try testing one injector directly off the vehicle battery, again just a brief time energized... should click when voltage is applied. Make sure the polarity is correct as noted above.

If for some reason you do need replacement injectors, you could either send yours in for cleaning / testing as described here, or buy a set of GB Reman injectors for ~$300/set. The only thing I can think of is that you had ethanol-blend fuel go stale while in storage which gummed up the old injectors, but this seems unlikely... I've had ethanol fuel in cars that sat for years and never had a problem (not that I recommend trying this at home, kids).

 

[SWISS MIKE]

Tested all the injectors directly off the vehicle battery for just a brief second. Injector is labeled with the positive pin, therefore I'm sure the polarity is correct.
Injectors are dead, no click or pulse! Changed polarity and still nothing. Ebay is selling remanufactured Injectors Bosch#280155217 for $159 for the set. I will probably order them and if the engine starts, I will send out my original injectors for repair.
Does anybody have any experience with those injectors?

 

[190EVAN]

Well that is wild

I hope for your sake that is the case because honestly that is a much easier repair than the ETA if it had failed lol.

I have used EBay Bosch EV1 injectors in the past with poor results, although if you were not intending on keeping them in there, it wouldn’t hurt as a diagnostic measure. While I do not like making trips to the junkyard, I would probably just rip some out of an M119 in a yard and throw them in rather than shelf out $160 for what are basically paperweights.

I tried eBay injectors on my Jaguar XJS V12 and they were pretty much duds out of the box with incorrect impedance, this is scary because if the impedance is not the same as factory (especially lower than factory) it will draw excessive current through the harness and can also fry the injector drivers located inside the ECU. I learned my lesson and pretty much never resort to aftermarket parts when it comes to things as detrimental as fuel injectors, engine sensors or anything that could potentially damage the motor.

If they are indeed remanufactured, and not an aftermarket injector, then you may be fine. Usually remanufactured EV1 injectors just have the inlet filters, pintle caps and o rings replaced. They don’t usually open the injectors and replace the solenoids inside.

Also verify the part number on the listing (280155217) is the same as the number listed on your 5.0L injectors. I can’t remember if the 4.2L uses the same injectors or if they are slightly different. If you supply me with a VIN, I can compare the injectors listed for your car to my S420 in the shop and confirm.

Just let me know!

 

[gsxr]

If they are indeed remanufactured, and not an aftermarket injector, then you may be fine. Usually remanufactured EV1 injectors just have the inlet filters, pintle caps and o rings replaced. They don’t usually open the injectors and replace the solenoids inside.

Correct. It's unpossible to open the injectors. They are cleaned in an ultrasonic bath and flow tested, with new caps & O-rings.

Also verify the part number on the listing (280155217) is the same as the number listed on your 5.0L injectors. I can’t remember if the 4.2L uses the same injectors or if they are slightly different. If you supply me with a VIN, I can compare the injectors listed for your car to my S420 in the shop and confirm.

There are 4-5 different part numbers used during M119 production... 3-4 Bosch plus 1 Siemens. All are interchangeable, and are used on all displacements from 4.2L to 6.4L.

 

[R129 UK]

Assuming your car has caused all 8 injectors to fail simultaneously (or over a very short period of time) and you haven't addressed the root cause, you will likely use the next set as a "fuse" and destroy them too.

 

[gsxr]

I'm thinking the injectors are gummed up internally after sitting for years in stale fuel.

You can also measure the resistance of the coil on the old injectors for grins.

 

[190EVAN]

Assuming your car has caused all 8 injectors to fail simultaneously (or over a very short period of time) and you haven't addressed the root cause, you will likely use the next set as a "fuse" and destroy them too.

Bingo, I’d at the very least collect a sample of the fuel from your fuel feed line in the engine bay into a container and see what it looks like. If your injectors look like that, the likelihood of your fuel pump package/tank being gummed up is high too.

One of the R129’s in my shop had a tank with fuel in it that was the consistency of molasses, Granted it sat for 5+ years in a warm warehouse.

 

[SWISS MIKE]

I'm thinking the injectors are gummed up internally after sitting for years in stale fuel.

You can also measure the resistance of the coil on the old injectors for grins.

The resistance of the injectors is around 14 ohms.
Big mistake letting the car sit for so long. Thank you for all your help.

 

[SWISS MIKE]

Bingo, I’d at the very least collect a sample of the fuel from your fuel feed line in the engine bay into a container and see what it looks like. If your injectors look like that, the likelihood of your fuel pump package/tank being gummed up is high too.

One of the R129’s in my shop had a tank with fuel in it that was the consistency of molasses, Granted it sat for 5+ years in a warm warehouse.

When I first removed the supply line to the fuel rail, the fuel that came out had a blueish color and smelled really bad.
I should have drained all the fuel from the tank before starting the car. I had roughly 1/3 of gas in the tank. Then I added 7 gallons of fresh fuel; now the tank is almost full. I will drain the whole tank and inspect the inside of the tank with a borescope and, of course, replace the fuel filter.
Not sure how to dispose of the old fuel???

Thank you so much for helping me out and for all your advice.

 

[gsxr]

Old fuel can usually be burned in your yard equipment (lawn mower, etc) assuming the fuel isn't TOTALLY stale. Try some in your mower and if it runs normally, it should be fine. I did this years ago with something like 10 gallons of old, stale fuel. The exhaust smelled pretty bad from the riding mower but it ran fine. Otherwise, try evaporation for disposal...

 

[gsxr]

The resistance of the injectors is around 14 ohms.

14 ohms is normal, so that's good.

Any chance you have an ultrasonic cleaner? if they are gooped up internally, ultrasonic cleaning might get them going again.

 

[emerydc8]

You might want to inspect the fuel pressure regulator in case it’s gummed up too.

 

[SWISS MIKE]

Update on the no start.
Installed all new injectors, drained the whole fuel tank, and replaced the fuel filter.
The engine starts and runs great! Lesson learned: don't let your car sit for too long.

Thank you for all the help!

 

[LE BLAY]

Hello 500E family,

Hope somebody can help me get my 1992 500E running.
Car was in storage for the last couple of years as a nonoperation, I would drive the car once/twice a year for a couple of miles.
Now I am ready to put the car back on the road. I replaced the front brakes, brake fluid flush, engine oil and filter change and replaced the brake light switch due to ABS code.
Engine cranks but doesn't start. Battery is good, fuel pressure at 3.5 bar, added 7 gallons of fresh gas. I get spark on the plugs, removed both distributors and spark plugs. Everything is looking good. Performed compression test, all 8 cylinders are between 180 to 195 PSI. With starter fluid, engine almost starts...
Any idea what to check next? Could a new (faulty) brake light switch cause a no start?

As-tu vérifié ta pompe à essence ? Et elle pas grippée. Cela arrive lorsque tu ne roules pas pendant plusieurs mois

Google translation:
Have you checked your fuel pump? And is it seized? This happens when you don't drive for several months.