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From the moment car starts to the moment engine stalls, which is about 40 - 60 seconds, fuel pressure is always above 50 psi.

Can I safely conclude stalling is not caused by fuel system problems?

I have also changed battery and alternator and the replacements did not solve the problem.

What else should I check for? Thanks.

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  • Which car is this? Is this the Merc?
    – Zaid
    Commented Oct 1, 2015 at 5:35
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    Do you know what fuel management system your Merc has? My book says that the Merc 300E of this era should have a KE5-Jetronic setup (electronic continuous injection). I don't have an entry dedicated for the Merc 300SE but I guess the difference is just in chassis, not engine. Also, 50 psi is low for a KE system. The system pressure is designed at 5.0 bar, which is 73 psi. I'm not saying that this is an answer, but if you can confirm what system you have we can hopefully infer something about your Merc's condition
    – Zaid
    Commented Oct 1, 2015 at 7:02
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    Why do you say that fuel pressure is not an issue? Could you mention your references? My source is a book that is officially sanctioned by Bosch, which says that KE systems are designed to have fuel pressure at 73 psi. If your fuel pressure is indeed lower than expected it would go a long way in explaining why your Merc is stalling once the cold-start injector has done its job.
    – Zaid
    Commented Oct 1, 2015 at 7:18
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    As much as we'd like to, we cannot generalize your Merc's problems to all vehicles. If this was a car with pulsed-injection EFI the root cause for this behavior can be quite different. Also, there is no issue with posting vehicle-specific questions. We have plenty of success stories in that regard. Here's an example
    – Zaid
    Commented Oct 1, 2015 at 7:23
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    The only way to answer your question about the fuel pressure is in the context of the fuel induction system for that car. A fuel pressure that is normal for one car may be very low for another and high for yet another. So it makes sense to be specific. Being specific also engages people who know about that car (or similar cars).
    – dlu
    Commented Jul 31, 2016 at 2:52

2 Answers 2

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As comments have mentioned, if this is a Bosch KE Jetronic system, it uses continuous injection which is very different to conventional electronic fuel injection via solenoid fuel injectors.

Bosch's system requires very high pressure (compared to EFI) and precise fuel pressure since the injectors are opened by that pressure and do not have solenoid control.

For normal EFI you could expect fuel pressure around 40 to 60 psi... (but look it up for your system)

The Bosch system is very old now, and since it's different to modern systems, there are not many people who know how to fix or tune it.

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Look at fuel filter at the first place, your car's old and i have an experience that fuel filter change in 95 perc. of cases solved all issues

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