It is best to have a helper so you can avoid fuel leaking all over and close the valve when pure fuel is coming out. This way you can open the bleeder on top of the filter housing and crank it over easily and bleed the new filter. While they are out I would unplug the injection pump red wire and replace the fuel filter. If you pull all 8 of your glow plugs and bench test them. I am not a mechanic by any stretch of the imagination but would like to try and fix it myself if possible. Once it starts and I drive it it starts up immediately even after it's set for 5 hours. I do this 3 or 4 times then it catches but just seems like a high idle isn't catching? This happens with temps around 55 degrees so I don't think it's a glow plug problem? After I crank it for 5 seconds I keep my foot on the accelerator but turn the key off then back on half way, the glow light goes off almost immediately then I try again. After a second or so it starts to start then a second later it doesn't fire and i get a big puff of dark smoke. I turn the key half way until my glow light goes out. It used to start almost immediately even at 0 degrees. If it were a gas engine I'd think it was a carburetor choke high idle problem. I have a starting problem on my 1986 6.2L.
