[W126 Coupe] Wont start

[Jack Emery]

My 420 SEC 1986 refused to start when I got back in it after 1 hour parked. 
Engine spun merrily by starter motor, but not one kick. No loose wires under 
the bonnet. Plenty of fuel. Decided it was the fuel pump & had it towed to 
my mechanic. He phoned to say it ran OK & what was my complaint. When I 
explained he said it had a new fuel filter last service & there were 2 fuel 
pumps in series formation & if one failed the other would not be able to 
deliver fuel. I asked him if he could have the pumps tested & he is looking 
into that.
Any suggestions?                                           Jack OZ