1990 420sel won't start!
 

:silly: long trip and a stop at MB dealer just wasn't rewarding. The dealer ship reset the fuel and it ran well for ten miles,then began to run rough and stall,when we spent some time on the side of the road it restarted long enough to get us home.Now it will start four ten or fifteen seconds,and stall then you can crank on it all you wish,But it isn't going to start,Any thoughts?
Im thinking in electrical problems.
just-n-time

How is the fuel filter/accumulaor/pump? I would guess one of those will cause your problem but not %100. When you turn the key all the way before you start the car, do you hear a faint "hissing noise"? If you do not then check your fuel pump or all relays and fuses

you need
1. fuel
2. spark
3. air

check the basics.... if one is missing, concentrate on that system.

:eek: the fuel pump's are new,as per MB. The fuel filter is too per myself,
THe fuel distrabution unit is new per MB.this car sat for a couple years,varnish got to it. I am trying to trace down problems in relays as we speek. thanks for the input. just-n-time;)

What yr. is your 420-SEL ?

Is the fuel pump relay new?

fuel pump relay
 

The car is a 1990 420sel and yes the relay was the fourth item r/r-d, j-n-t

It would seem a lot of fuel delivery items have been changed.

If the car sat idle for a long time, I suppose I'd suspect the injectors.

Personally, I'd find a legitimate independent tech and explain what's been done and pay him an hrs. labor or so for some diagnostic work.

My 2 cents.

My paroblem was with "hot" start. It would take a lot of cranking and holding down the gas pedal and then sputter and cough but finally would start. Turned oaut to be the fuel accumulator.

Thanks mike,I live in central Louisiana, New Orleans is 250 miles away for the good shops,or at least those reported on,havent found any close in.
just-n-time

ovp
 

have one on the way from phill, need to get her up to idel so I can check the rest of the item's to be inspected.:silly: just-n-time

:mad: Maybe I can get the car up,soon.Miss Debbie and I enjoy our little rides in this great car. Thank you all for any help, just-n-time:D

ovp
 

well gang the ovp,has arrived,after uncovering the car I quickly plugged it in and I was listening to that beautifull per,then it began that ever so slight dip in the rpm,so I am sure of a vacuum leak,thought I would travel to the highway and ride a few miles,well its 1 mile to the highway went maybe another mile and it quit. The temp was at 80c and I had a flashing ABS, after some 30 min. It started and home we came,only I kept my foot on the gas to keep the rpm's up,and got a check Eng lite for my efforts. NEED MORE THOUGHT'S. just-n-time:dizzy2:

parts listing
 

:rolleyes:
Well now this may take a while, 1990 420sel fuel system parts that are new,
Fuel gauge sender
both fuel pumps
fuel filter
fuel relay
fuel distrbution block
fuel spray nozels
ovp, oxygen sensor The car now will start and idel just fine,untill it reaches 80c then it starts to serge I am leaning towards a vacuum leak for this problem. so I will look for info on the vacuum system,Eng,and probably emissions.:pirate: I know I am asking a lot:wacko: just-n-time:)

Fuel Accumulator
 

:confused: What dose the fuel accumulator do? :rolleyes: I looked it up but Im not shure about it!:dizzy2:

Idel controll unit
 

Can the Idel controll unit cause speratic proublems and cut the engine to quit?:silly:

Try unpluging the O2 sensor and see how far you can drive it.

It sounds like it is not having 'the real problem' until it has warmed up.

If it stalls again, try unplugging the EHA to see if the computer is 'fouling things up.'

Not sure about the idle control unit but the Ignition control module will definitely cause engine to quit and bog down and stutter if it is going south.

Did the dealer drain the gas tank and clean or replace the filter screen at the bottom of the gas tank? These will get "coked-up" with fuel deposits if the fuel sits for a long time and cause all kinds of problems. Also, I have found that the fuel mixture (duty cycle) may need to be reset several times to get it right due to varying mixtures of old gas and fresh gas and the removal of varnish/gas deposits over time. When the car stalls does it emit black smoke from the exhaust or smell heavily of unburnt fuel? If so, you might want to try tweaking the 3mm adjustment screw 1/8 of a turn CCW to lean the mixture. If this improves matters, the mixture is too rich. If it is worse, try 1/4 of a turn CW (which results in a 1/8 turn rich from your original starting position) to see if matters improve. Once you find you are going in the correct direction, adjust in 1/16 turn increments to obtain a decent idle. Once you get to where the engine will run decently you can then check other posts to adjust the duty cycle properly. Mark

clean tank
 

NOT REPORTED to me so I must say no! they did brag about how much was done but I replaced the fuel filter so I am shure they did not clean the tank or the screen,how hard a job is this to do?:silly:

I cant believe that people are telling you to do this to your car, unplug this unplug that. WTF!!! I know now how some of the cars come into my shop all Fu.. I wont continue that word. Look, buddy, you need to go find an independent reputable shop that knows what they are doing with a Mercedes. FYI, if you are so into fixing the car yourself, change the reference sensor.

Reference sensor?
 

OK I know that this unit has position sensors crank shaft cam shaft, throttle and so on help me out here?:silly:

420 is alive
 

Well just a short update,the 420 is at the point that you can start it and it runs all that we have left is to replace some of the idle air lines and reset the on/off,will keep you all posted,just-n-time.:silly:

Yes...especially if the vacuum hoses leading to it and away from it are hard and brittle and cracked...

420sel
 

your problem is the pickup on the flywheel that runs to the ignition unit david poole e. p. dallas tx. 2149567007

420sel
 

your problem is the flywheel pickup going to the ignition unit in left fenderwell.these parts have been considered almost bulletproof until now.they are going out because of years not use.the failure always seems to be temp related and they are nice enough to give you some warning so that you dont get completely stranded. david poole european performance dallas tx 2149567007.

420sel
 

your problem is the flywheel pickup going to the ignition unit in left fenderwell.these parts have been considered almost bulletproof until now.they are going out because of years not use.the failure always seems to be temp related and they are nice enough to give you some warning so that you dont get completely stranded. david poole european performance dallas tx 2149567007.

Fly wheel pick up
 

Thank you for the info on a problem like this,you must have had to change a few recently?But first I will replace the idle air dist. lines.and go on from there. thank you for your response,j-n-t:silly:

RPM sensor
 

Replaced the rpm sensor car fired and ran though not smooth,so I put my little allen wrench into the slot for adjustment of the fuel,drove into town washed the car and drove home,the ABS light would flash and soon after the check Eng.light would come on pulling into our drive it stalled and it will not relight,PS we have great spark at the coil post,top of distributor.:behead:

Voltage problem perhaps?
 

Have you checked the voltage while the engine is running at operating temperature? Some of your symptoms rang a bell with previous problems that I have had. Voltage regulator is cheap and easy to inspect as are tightening ground connections and cleaning battery teminals and connections. If you have any built up crud/oxidation on you battery connections, check out the cheap and easy stuff first.

Patrick

Eha
 

Marty, started the car this morning it fired with out hesitation, it began to roll after Short time not long enough time for a complete warm up,I unplugged the EHA it smoothed out like a well tuned machine at around 700 RPM,soon as I plugged up the EHA she stalled but re-lit with no hesitation,retried the same test and got the same results,just-n-time:behead:

1990,420sel Up Date
 

Well after a week of delays or more,I got back to the 420,Though this time I could not get the car to light up,I unplugged the EHA,but it would not start,this has been areal challenge.I intend to pull the screen from the tank just to look!Maybe it is not getting full fuel flow?I don't know.Any one have more input?j-n-t:behead:

Start up
 

Well just another spot to up date our 420sel,After the smoke test and rebuilding of the intake system,we are now able to start the car on demand.check other sites of mine for pics of the air duct housing and the way the fuel linkage had to be adjusted to make it run,not cool.
Problem now is that we are in stall mode it runs fine then it will lose fuel and stall.you can slip it into neutral as it coast and restart,relights with out hesitation.looking in to the new situation,any words of wisdom?
Thanks just-n-time:behead:

How is your fuel pump relay? Try jumpering the terminals with a paperclip and drive around to see if the loss of fuel is remedied.

Terminals
 

Have any Idea as to the terminals to be jumped,j-n-t:silly:

pins-7&8
 

Ok, I will make that job #2 for tomorrow.
I worked on the idle today just trying to smooth it out,as I adjusted the linkage and tested the throttle position switch,(checked ok) I continued to look for vacuum leeks,tomorrow I will plug the main vacuum line to the break booster to see how that reacts on the Idle,I noticed that when I pushed down on the break peddle the boost gauge rose to about one quarter of the gauge and the Idle was even rougher,may have a leek in the power booster.
Idle control valve is in the pot being soaked and cleaned to see if that will make any difference, well enough for now. Thanks for all the input j-n-t:silly:

Idle cont. valve
 

Continued on the inspection and trouble shooting of the 420 today,after cleaning the ICV,and reinstalling it,I found that the Idle was even more erratic than before.
The fuel pumps are holding well and not lousing power so we are OK at this point with the pumps and relay.
Resistance in the plug wires are of course to high,I found #5&#8 to stand at 0 ohms I suppose when they go they go just six months ago I checked all that and they read 3 ohms tried another meter just to be sure.
Well I will continue as the work progresses,by the way another ICV is on the way.:silly:

News update 420sel
 

Well, it is time for the update of work, done to the 420sel. EHA was in need of being set and was done,then the duty cycle was set at Idle and 2500,this is at 60.2% the EHA is at -0.0 to + 0 to 0.01 threw 2500 to idle. The eng.runs well but for a start up roughness, then smooths out. the last peace of the puzzle is the potentiometer,it has failed all test given and one is on the way. all in all it has been ten months but well worth the time spent on a classic ride and those enjoyable trips. Other sights in my name will show a more details of the journey.jnt.

potetiometer
 

The new unit arrived and I took the ohm reading, It was 57.2, The old unit had a 94.7, I did not reset the new pot. to match the old, though I did get the pin two and one reading of .67. For giggles I am going to go back and reset the pot ohm to what the original was set at, just to see if I have any difference in the Idle.
The idle was some smother though not entirely what I expected, the low end search was better but not complete,I still have ever so slight of a waver when you lift from a snap rev. though it dose not stall as it would do at times, like when coming to a stop sign,or in slow traffic. The RPM is just at 550 to 600 in gear I was thinking 650 would have been better. I guess you get what you can?OR more like Another ICV. well let you all know of future developments.jnt:silly: