[W126 Coupe] Hard start

[plustech at optonline.net]

Make sure the cold start injector is working. Mine did not and was easy to start in summer/when warm. As sson as it got cold, it would take a good 10 seconds of cranking to get it started. Note: If it (injector) is not working, check the control wiring and ECU output. In my case the injector was good, but my ECU was bad. The motor will still run with a partially working ECU. Typically symptoms of a bad ECU (that I have had) include: hard starting when cold, hesitation when cold (due to lack of enrichment), and lacking power (due to running too lean). 

If the ECU is working otherwise, but you can't track down the Injector control failure here is what I have done. I hate to admit it because it is crude, but it works excellent. Cut the injector wires. Buy a thermo switch (avaialbe from Mc Master Carr for about $60) and connect it in series with the starter. Mount the thermo switch to the intake manifold - where it can sense the temp, and adjust it to open when temp is above 60F +/- (adjust for best performance). Done. The switch will close when temp drops and will open the injector when cranking the starter. When warm, the switch opens and the motor cranks without the additional fuel injected.

It works flawlessly on mine (I put in a remote starter). Never cranks more than 1 turn and starts instantly.

Good Luck!

----- Original Message -----
From: Gary Peck 
Date: Tuesday, November 14, 2006 6:38 am
Subject: Re: [W126 Coupe] Hard start
To: Mercedes Coupes Mailing Lists 


> Hovsep

> 

> Two things come to mind

> 

> 1. The EHA regulator on the side of the fuel distributer, may be 

> leaking through the 2 o-rings, after you first start up, check 

> for fuel odor and see if there is fuel dripping out, if you 

> replace the o-rings be carefull when seating them that they 

> don't get pinched. If this corrects the problem great!, other 

> wise you may have to replace the whole unit along with a second 

> set of o-rings.

> 

> 2. Swap out the OVP regulator.

> 

> MBGary

> ----- Original Message ----- 

> From: Hovsep Dovlatian 

> To: MBCOUPES at mbcoupes.com 

> Sent: Monday, November 13, 2006 2:26 PM

> Subject: [W126 Coupe] Hard start

> 

> 

> My car has been having a problem with hard starting. Ive 

> checked the fuel presure and its there. Ive checked the spark 

> and the wires they're all good. So I just wanted to know is 

> there anythiong else I should check??? 

> 

> Thank You,

> Hovsep

> 

> 

> 

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