View Full Version : diesel not starting

02-05-2011, 02:08 AM
does anyone know if the mechanical fuel pump on the side of the block (1986 6.9 i.d.i diesel) will pump air if its gone bad? my brothers tank if full and the truck just does not want to start i seen that he had a bunch of air in his fuel filter and leaky return lines so i replaced them all and the trucks filter seems to be still filling with air

it started with the truck just being harder to start then it started to stall now it just wont start i ran a electric fuel pump into a gerry can and it seemed like it wanted to start but just was not quite doing it

02-05-2011, 10:31 AM
If its a standard , tow it around for a bit.
I had the same thing with a old 6.9 and towed it and it started , seemed to work the air out.

02-05-2011, 11:54 AM
i towed the crap out of it! it started for a little bit then died now it seems like it is not starting at all and i have cracked the lines etc.. the filter just seems to be still filling with air and now that the return lines are done i dont know where the air would be coming from both fuel tanks have the same result to so all i can think is lift pump because i dont see the injection pump filling the filter with air that seems backwards to me

02-05-2011, 06:38 PM
when cranking the engine, crack the the injector lines at the injectors untill you see constant fuel spilling out, do it one at a time and make sure you have a good charge and boost ready for your battery. Make sure you get constant dribble out of all your injector lines at the injectors before you tighten them back up (remember to do this one at a time) give er a little shot of ether to get it started when they are all tightened back up, let it run for a few minutes to get the rest of the air out and keep it running. If you still get air in your system, shoot ether around all of your fuel system connections including around the fuel filter and housing, if the engine revvs up when doing this you have found your vacuum leak. Good luck.

02-05-2011, 08:30 PM
ya i have cracked all the lines etc but the fuel filter seems to be filling with air so i was wondering if a weak lift pump would cause air

02-05-2011, 08:33 PM
sucks because i have had my diesel for 2 years and have replaced everything! and always have got it back up and running like a champ! just his truck seems to have stumped me to bad my brother is a quitter lol now he just wants to send it to a shop ... o well his money lol

FU Toolbag
02-06-2011, 12:27 AM
A cracked pump would do that. Also, is it actually air, or is it a vacume? have you replaced the lift pump yet? the fords injector pumps don't suck enough to sustain their prime, so if you do all the right stuff, you'll just have to do it again. That pump is only about $30 so probably the cheapest thing to fix on that motor. Also try and look or feel the lobe, can't remember if you can or not, but make sure it's still there. Or just plum in an electric and bypass it perminantly.

02-06-2011, 12:43 AM
and ya its not vacuum it blows out and not suck in and ya i got the mechanical pump for my 7.3 for 60-70 bucks ended up taking it back and installing a electric pump myself

but thanks for all the input guys! im still going to try and talk him into replacing the lift pump before he takes it to a shop is sure is tight i there to get at it and i will probably be the one doing it so i may just let him take it to the shop lol