7.3 wont start unless pluged in

[JLDickmon]

Just my two cents, the guys saying compression are probably headed downthe right path, but I'm still curious about plugs and relays.

Have you jumped your relay (just run a jumper between both posts) to see if it starts easier afterwards? I've bought bad parts from the auto parts guys before, and this is a really easy test.

However, if it is strggling to start at 80, I still think compression is a big issue.

x2

mainly because of the UVC harness issues...
which is also easy enough to check... just ohm it from connector to ground..

valve covers have gotta come off and the glow plugs have to come out to do a compression test, so it's a good time to check everything...

 

[Potentialbuyer]

You will need a Rotunda 014-00761 test kit that includes a gage that reads inches of water and a crankcase orifice restrictor. You hook up the crankcase orifice restrictor to the right valve cover, connect it to the gage, and plug off the breather at the left valve cover. With the engine at operating temperature, run it WOT (3400 rpm) for 30 seconds until the reading stabilizes. You should have less than 4" of water for an engine without blow by. The CAT test you describe sounds exactly like the Ford test.

 

[Zookie400]

You will need a Rotunda 014-00761 test kit that includes a gage that reads inches of water and a crankcase orifice restrictor. You hook up the crankcase orifice restrictor to the right valve cover, connect it to the gage, and plug off the breather at the left valve cover. With the engine at operating temperature, run it WOT (3400 rpm) for 30 seconds until the reading stabilizes. You should have less than 4" of water for an engine without blow by. The CAT test you describe sounds exactly like the Ford test.

thanks for the part number....do you own or have access to this kit? if i could find out how big the orifice is i could make my own restrictor.

 

[Potentialbuyer]

I will have to check. I teach auto body at a state college in NY currently. I used to teach for Ford. The 7.3 and 6.0 were included along with the other courses I taught before I switched to auto body. I will have to go into my old classroom and look in the tool room.