My '86 F250 with '92 7.3 has stumped me... Now it's stumped the repair shop. Was running perfectly, then just wouldn't start. So I replaced the lift pump with electric and that didn't work. Replaced the IP and got fuel where it's supposed to be but still no joy. I get some pressure through the exhaust but also through the intake along with fuel vapor. I gave in at that point and took it to a shop with knowledge of that model/engine. Now they're saying they are stumped as well, and a complete teardown is prohibitively expensive. Anybody have ideas?