Under Hood E350 fuse block removal
 

I am trying to solve a crank with NO start on my 1992 Ford E350 cutaway Champion RV. We required a Coach Net Hauls back home when at 70 mph the RV responded as having run out of gas. I decided that it must be the fuel pump, so yard mechanic I lowered the tank and installed a new fuel pump... NO JOY.... The 7.5 liter 460 cubic inch engine will spring to life after filling the intake with starting fluid and continue for about 10 seconds before quitting. Indicating there is no ignition problem. Trouble-shooting has indicated the wiring harness female connecter under the fuelpump relay tray besides the drive side battery shelf has at least one female connector pushed out of its socket. Crappy engineering by ford located this tray under the dual brake steel lines exiting under the master cylinder. The fuze/relay box must be separated from the hard mounted black plastic docking tray to allow me to reinstall the female wire terminal

Does anyone here know how to engage the releases on the exterior black plastic boxes to get access. There appears to be three such side mounted clips; in addition to the end clips that hold down the lid. Your assisrtancis appreciated greatly.... https://cimg0.ibsrv.net/gimg/www.for...a8754569a9.jpg
https://cimg8.ibsrv.net/gimg/www.for...0a5f236326.jpg
https://cimg9.ibsrv.net/gimg/www.for...0f58890929.jpg
https://cimg3.ibsrv.net/gimg/www.for...f11e25357d.jpg
If anyone has a link for visual access showing the process, it would excellent help. Please phone seven0six three five 6,,,, eight0 eight 7 to discuss. Thanks so much in advance.
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If you cannot get the entire answer you want , might consider the following,
Remove battery ground cable from battery, then look for where harness or wiring is secured and whether you want to undo them so you can move panel to gain access.

Be careful not to attempt to stretch harness too far. After you do what you want to do, carefully reinstall securing pieces , could be Zip ties or clamps.

If you find you cannot gain the access you seek, maybe you can consider changing why you need to go there.