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Discussion Starter #1 (Edited)
1990 420sel sat for approximately 18 months. Replaced FPR and now starts and idles fine. Revs up in park also with no problems. It had been close to empty when I first tried to get it running so I put 2 gallons of new gas from a can in it. It ran down the road fine(after the FPR). I then filled it with 100% gasoline from a pump and that’s when it began to stall while driving. I then replaced the fuel filter and put some water remover in. It will drive about 1/8 of a mile and stall. Fire right back up and do the same thing over and over again. Still idles fine. I did a diagnostic test on the 8 port center for the fuel system with no code. A guess would be a fuel pressure problem? I’ve searched the forum and have found suggestions for the OVP, Crank Position Sensor, EHA, etc. Maybe filling it up stirred up some sediment and clogged a port? Don’t want to throw parts at it. Any advice would be greatly appreciated...
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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Eliminate your emissions control system first and easily. Hope you are good with the multimeter. Measure your EHA current both at idle and when driving. You can pull a couple of wires in the cabin if you like for this. If your EHA current is behaving nicely (meaning fluctuating between 0 and -2 mA at idle and 3-5mA while driving (at any speed really) at operating temp then you can forget about all of the emission system. You can even check it at cold temp and we can tell you how it is supposed to behave.

There are posts here from H.D. that show you how the connection is made for the EHA current measurement. Skip the duty cycle measurement, EHA current tells you a lot more than duty cycle.

Once everything checks out there you can concentrate on the fuel system and ignition as most likely there is where the problem lies.
 

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1991 560sec. 1969 280SL
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I’d check system fuel pressure. I think it should be around 90psi iirc. You may have a primary fuel filter that is partially clogged. That filter or strainer sits in the base of the gas tank outlet. Filling the tank may have stirred up some sediment in the bottom of the tank.
 

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Discussion Starter #4
Thanks. I’ll work on checking the EHA current. As for the filter/strainer in the gas tank, I’m guessing all of the fuel needs to be out of the tank in order to change or clean that filter?
 

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Yes you will have to drain the tank. Obviously FP test should be done first and that will guide you in the right direction.
 

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I was made aware of this thread. I have no time to offer assistance in it, but I‘d like to point to a few things.

... If your EHA current is behaving nicely (meaning fluctuating between 0 and -2 mA at idle and 3-5mA while driving (at any speed really) at operating temp than you can forget about all of the emission system. ...
An EHA current behaving like ^this, is not “behaving nicely“. It is indicating a number of possible problems that should be checked.

... Skip the duty cycle measurement, EHA current tells you a lot more than duty cycle. ...
I disagree. … Neither of these measurements would be the only thing to check in this case. But, aside from the fact that the duty cycle should generally be one of the first things to check in case of engine running issues, the duty cycle measurement is in most cases the more informative separate measurement of the two, especially in case of intermittent issues.

Please don‘t take this as personal criticism, dolucasi. There are CIS-E related mistakes that you posted in another W126 forum thread a few weeks ago, which I haven‘t had time to correct yet. … I just try to keep mistakes about the KE-Jetronic out of this W126 forum. It‘s the only Benzworld sub-forum where I‘m still trying to do that. I stopped doing that in the W124, W201 & R107 forums some time ago already, because the amount of mistakes about this injection system that are continuously posted in these forums (and not corrected by anyone there !) would occupy way too much time.

H.D.
 

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Checking return flow from pressure regulator to tank would tell if there is a problem with strainer, fuel pumps or filter.
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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Sorry H.D. but we are going to have to agree to disagree on your point of view.
Duty cycle is a good tool to diagnose matters related to the emissions components, that of course is true.

Meaning the ECU maybe "trying" to tell you issues with the emissions system problems, if you have any.
An all encompassing and "continuous" EHA current measurement will not only alert one of any issues if you are measuring it at all times like your ashtray instrument tool. It will also teach forum members how how a working system is supposed to behave. I see no reason to keep these facts in the vault.

Particularly, when a car is newly acquired, when very little is known about the car, it does not make any sense in trying to check out each component, one at a time, when one can do pretty much a high level "check" before digging in and spending 2 months to check out things.

So it is all in the approach. Diagnosing systems or directing others on how to diagnose systems is what I have been doing for over 35 years. Approaches may vary......

As I said earlier, we will have to agree to disagree, and leave it at that.
 

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Sorry H.D. but we are going to have to agree to disagree on your point of view. ...

... So it is all in the approach. Diagnosing systems or directing others on how to diagnose systems is what I have been doing for over 35 years. ...
It seems that that‘s indeed what we are going to have to do, dolucasi … disagree.

I‘m currently too busy with other things to go into details. But let me quickly say that I disgree with many things you have posted here at Benzworld … especially in the W124 & W201 forum.

Having not only helped others (from several countries around here) to take care of their (mostly pristine) CIS-E cars for over 35 years but also been involved as a young engineer in MB‘s CIS-E engines before they were available ;) … I assure you that a lot of the info you have posted & post about these engines (especially in the W124 & W201 forum !) is incorrect and a lot of your diagnostic approaches are illogical. The two things I mentioned in my last post are just the two latest examples.

Sorry dolucasi, but … for the sake of help seeking CIS-E car owners worldwide … I warmly recommend you to take a closer look at how the KE-Jetronic works and ask you to try not to add more misinformation about this injection system to this forum (at least not to this W126 forum). There are a lot of things about it that you clearly don‘t know … but that are important to know for proper troubleshooting.

In general a lot of info & advice about the KE-Jetronic on the internet is incorrect. It has been my objective to make CIS-E car owners/enthusiasts aware of that and to show them how to properly take care of their cars by sharing some knowledge here on this board. Please try to avoid counteracting that, dolucasi … at least in this W126 forum.

There are many CIS-E related things left that I‘d like to post in this W126 forum when I have time … things that are very helpful for targeted troubleshooting and that can probably not be found in this or any other forum, and that are not mentioned in the FSM … unless it takes too much time to correct misinformation in this sub-forum too.

H.D.
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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Yep, agree to disagree as I mentioned. And let's just leave it at that....
Please keep helping W126 owners here at your leisure, I'll stay out of it.
Plenty of members on the W201 and W124 forums with CIS-E issues that do not necessarily prefer your approach.
I'd rather not leave them stranded if you do not mind.....
-Cheers!
 

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Plenty of members on the W201 and W124 forums with CIS-E issues that do not necessarily prefer your approach.
I know. They told me that and let me understand that my approach takes more thinking than they are willing to invest. I accepted that and stopped trying to convince them of my approach quite some time ago already.

The KE-Jetronic is an underestimated piece of engineering. It was designed with a significant dose of mental discipline … a little of which, whether you like it or not, is necessary if you want to properly maintain cars that are equipped with it. It‘s your free decision to disagree with what I have posted about this injection system here at Benzworld. If, however, you want to understand how it really works and how to properly diagnose problems with it, you might realize that it‘s a counterproductive decision.

BTW … and, again, solely for the sake of facts & help seeking CIS-E car owners … in post 8 you said that a continuous EHA current measurement will teach forum members how a working system is supposed to behave. Don‘t forget what I said in post 6 about what you call a “nicely behaving“ EHA current. … ;)

H.D.
 

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Discussion Starter #12
1990 420sel sat for approximately 18 months. Replaced FPR and now starts and idles fine. Revs up in park also with no problems. It had been close to empty when I first tried to get it running so I put 2 gallons of new gas from a can in it. It ran down the road fine(after the FPR). I then filled it with 100% gasoline from a pump and that’s when it began to stall while driving. I then replaced the fuel filter and put some water remover in. It will drive about 1/8 of a mile and stall. Fire right back up and do the same thing over and over again. Still idles fine. I did a diagnostic test on the 8 port center for the fuel system with no code. A guess would be a fuel pressure problem? I’ve searched the forum and have found suggestions for the OVP, Crank Position Sensor, EHA, etc. Maybe filling it up stirred up some sediment and clogged a port? Don’t want to throw parts at it. Any advice would be greatly appreciated...
 

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Discussion Starter #13
Update:

I drove the ‘90 420sel yesterday (2/17/2020) for about 5 miles with only two stalls, both of which occurred while slowing and making 90 degree right turns. This leads me to believe that it might be a combination of sediment in the fuel tank, water in the fuel, and possibly the fuel tank filter. About a week ago I started it and let it idle for about 30 minutes to try to see if I could get some of the water out and some of the new fuel run through it. Maybe that helped. I’m leaning towards removing the fuel tank and cleaning it out even though, from what I’ve read, it doesn’t seem like a fun job.
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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BTW … and, again, solely for the sake of facts & help seeking CIS-E car owners … in post 8 you said that a continuous EHA current measurement will teach forum members how a working system is supposed to behave. Don‘t forget what I said in post 6 about what you call a “nicely behaving“ EHA current. … ;)

H.D.
It was a generalization, as you well know H.D. . Once owners measure it continuously it will be quite obvious if their "running issues" is emissions control related as I said way back in my first post. Again, agree to disagree. Perhaps you can help the forum member going forward.
 

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It was a generalization, as you well know H.D. . Once owners measure it continuously it will be quite obvious if their "running issues" is emissions control related as I said way back in my first post.
I actually don‘t have time for this, but ... your first post is exactly what I‘m talking about. In that post you said:
... If your EHA current is behaving nicely (meaning fluctuating between 0 and -2 mA at idle and 3-5mA while driving (at any speed really) at operating temp than you can forget about all of the emission system. ...
^This does not sound like a generalization to me, dolucasi. This sounds like you think that an EHA current fluctuating in these ranges means that the “EHA current is behaving nicely“ … which is not correct and which is what I want to prevent readers in this W126 forum to believe !

Continue to disagree with me, if you want, dolucasi … but I assure you that such a suspicious EHA current behavior should definitely not lead to “forget about all of the emission system“. On the contrary, it should lead to take a close look at a number of possible problems that it points to ! … These are basics, if you will forgive my saying so. ;)

H.D.
 

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I will send a PM H.D., this post is not the correct forum to discuss all this.
 

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Checking return flow from pressure regulator to tank would tell if there is a problem with strainer, fuel pumps or filter.
 

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I will send a PM H.D., this post is not the correct forum to discuss all this.
I disagree, dolucasi … this post is exactly the right place to discuss this, because this is where you posted this incorrect information. ... Again dolucasi, one of my objectives here in this W126 forum is to keep it as free of CIS-E related mistakes as my time allows. … How are forum visiters supposed to find out about corrections of mistakes, if they take place in PM‘s !?
 

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You can correct the mistake (if there is any) and move on if you like. That would avoid all of this back and forth.
I still do not believe there is an error as you have not stated what the error is? Perhaps if you state it, we can come to a conclusion to help others.

So H.D., how is the EHA current supposed to behave when you are driving down the highway at 60 MPH?
 
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