VP37 ESP: Hot Start Lock - Is There a Solution?

'Does anyone have knowledge about the maximum operating temperature of Bosch ESPs, specifically I'm interested in the VP37?'
I'm specifically interested in whether there are any watchdog mechanisms that, if a temperature threshold is exceeded, for example, reduce performance or prevent the engine from starting.
Is such a regulation integrated into the ELAB system? This would, for example, explain why some TDIs that have been run hot can only be started after a cooling-down period.

morti850tdi wrote:

Is such a regulation integrated into the ELAB? This would, for example, explain why some heavily stressed TDIs can only be started after a cooling-down period.

The ELAB itself is just a simple electromagnet.

However, the resistance of its copper winding increases with temperature, meaning that the hotter the pump, the lower the current and the smaller the opening force of the valve.
While this certainly won't intentionally create a hot-start lock, if significant voltage drops occur due to worn cables/connectors, etc., it could very well happen that the valve no longer opens above a temperature X.

Okay, so ELAB is definitely out of the running.
'In my opinion, the only remaining possibility is the fuel temperature sensor, which might be reporting an excessively high temperature to the control unit, causing it to prevent the engine from starting (perhaps by not activating the ELAB?). Are such control loops common?'

morti850tdi wrote:

Are such feedback loops known?

If you mention that some high-performance TDIs only start after a cooling-down period, then there is certainly something else behind these "regular" problems (see, for example, technical articles about starting problems).
If there were a constructive hot start lock, it would presumably

Quote:

affect all (type-identical) TDIs once certain limits are exceeded.

From your response, I understand that there is no constructive hot-start lock.
That's also my opinion, I just wanted to get another perspective.
I actually experienced the same problem with the engine not starting when it was hot. Cleaning the ELAB (Electronic Load Amplifier) resolved the issue; it seems that it tends to stick slightly at a certain temperature, which blocks the fuel flow.

Does anyone have knowledge about the maximum operating temperature of Bosch ESPs? I'm specifically interested in the VP37.

Ambient temperature: -20°C to +125°C.

Maximum fuel temperature for continuous operation: <= +95°C.

The EDC reduces the maximum load. Warm-up and hot-start problems have already been extensively described and resolved in this context. Regardless of this, electrical problems can of course occur, such as contact issues in hot environments, etc.
ELABs or signal boxes can also seize up when they are hot. The ELAB in this location has caused problems on several occasions.

rinderwahnsinn wrote:

ELAB devices or signal boxes can also seize up when they are hot. The ELAB has caused problems here on several occasions.

Is there a way to narrow down the susceptibility to these types of issues based on technical articles (e.g., year of manufacture, engine code, mileage, etc.)?

Okay, so my ESP was manufactured in 1996 and it started having problems, but the first time was in 2004.
However, I believe that the issues with the ELAB clamps are less likely to be caused by manufacturing defects and more likely to be caused by contamination.