'90 300e ran fine- changed OVP and now won't start?
 

I had just taken my car out for a spin and it ran great. I swapped in different EHA in an effort to test one I got from eBay and my car rand great. I then swapped in a KAE OVP that I also got from eBay and it wouldn't idle properly and stalled. I put the original OVP ( a 2014 KAE) and now my car won't start. It acts like it's not getting any gas. I can hear the fuel pump kick in briefly as it always does after I turn the ignition on without activating the starter.

I didn't disconnect the battery (negative cable) when I did the OVP swapping. I check the fuses on the OVP and they are still good.

What did I do?
How do I need to do to get my car to run again?

Stumped in Folsom,

AL

Got the correct OVP right? There are two types one for CIS and one for HFM...

Yes I have the same KAE's. The one that was in the car when running fine and the exact same that I got from ebay (used) that didn't work. Plugged the original one in again and it cranks, almost starts, but never does. It always started on the first couple of cranks before I monkey around with the EHA and the OVP.

????

AL

Did you check the fuses in the top of the ovp?

Yup, I said so above. thanks anyway.

Reinstall the original EHA and check if the engine will start.

FYI - The OVP is an electrical "surge protector" which protects sensitive electronic devices on the car from a voltage surge - which could damage them. On my 420 car, the following are powered by the OVP...

CIS-E
ABS
Idle Speed Control Unit

You should get some sort of voltage at pins 1 and 2 of the round X11 diagnostic connector if the CIS-E has power.

There would also be some sort of voltage at the Idle Air Valve if that was getting power.

If the ABS is not getting power, the ABS light would be on with the engine running.

As for the EHA, that is not a "plug-and-play" device! Rather it is "analog" and quite mechanical - not "digital"! Somewhat like a Swiss watch mechanism which requires delicate adjustments so it works just right. Might want to read about it here...

(Following for a RR, but same Jetronic EHA theory of operation - See page 9)
http://rroc.org.au/wiki/images/c/cd/B_Bosch_KE2_Jetronic_Injection_Part_2.pdf

Problem solved!
 

After a careful review of what I had done, I discovered that the EHA that had previously been working fine had suddenly decided to not work as well. It was a lucky break that it decided to fail in my driveway and not as my son was on his way back to college in SoCal. I have a couple of EHA's emergency spares and each of them worked fine. The original one somehow developed an internal contact issue as the engine would not idle with it installed. It doesn't leak at all.

I went ahead and showed my son how to install a replacement EHA and new o-rings that I'll send down with him.

Why it failed during swapping with another EHA is a mystery. Chime in if you have any insight on what that might have happened. Bottom line though, all is well and running again.

Thanks,