Asking for a friend. He has a 2007 ML 3.2L diesel manual.
Quite often, more so under load eg towing caravan, he will lose power and has to stop and bleed the system with the lift pump.
This has been going on for a couple years, he has tried many remedies, new pump housing, replaced lines etc. Replaced the diaphram, new seals.
He is at a loss where to look next, even considering changing to an electric pump system.
The strange thing is, a neighbour with virtually the same car is having the same problem so theirs cannot be isolated incidents, someone else must have had the problem.
HELP!