1987 6.9 IDI Diesel stalls after cranking

[Ford Guy]

I have a 1987 6.9 diesel, that if you leave sitting over night when you go to start it, it cranks and fires, and feels like it starts but after a few seconds of running stalls and dies, and then it is extremely hard to start. I am sure it is air in the lines somewhere but what i need help with is trying to figure out where it is getting air at. The return caps are slightly leaky and there appears to be diesel in the valley pan, non related leak to the return caps. any ideas where the air might be intruding at, or possibly any other ideas as to what could cause this to happen? its got me stumped and it usually only does it after the engine has cooled and sets for at least 18 hours. Its got me stumped, any help would be greatly appreciated.

 

[choppedjunk]

Any place fuel can leak out air can get in so I would start by doing a return line kit.

 

[sle2115]

These systems work on a "bell jar" principle in that the fuel in the lines remains there because of atmospheric pressure. Mel once said think of it as putting a glass into a bowl or sink full of water, open end down, the glass will remain water free inside, but as soon as you introduce a leak, the glass will fill with water, same thing happens, when or wherever there is a leak in the system, air will enter, causing what you are seeing or worse. I'd say the return line set would be a good and cost effective place to start cause if they are leaking fuel, they are leaking air too.

 

[onebadiditurbo]

Replace the fuel return lines and caps and o-ring on top of the injectors. Russ (type4) i believe sells a kit or he used to. another thing to check is the line fittings on the ip itself. if you have a leak there it will push air into the injectors. Air intrusion is a Biotch

 

[anthonyj]

The 87 model still uses the water seperator on the firewall that is prone to air leaks.