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-   -   7.3 idi wont start. (https://www.dieselbombers.com/ford-83-94-6-9-7-3l-general/40968-7-3-idi-wont-start.html)

NMB2 01-17-2010 01:41 PM

7.3 idi wont start.
 
as this being my first post i would like to say thanks for such a good forum. I did search for my issue and i found a few people with similar sounding issues but their solutions did not/will not remedy mine. I recently bought a 91 F350 and am now trying to get it running, here is where i at. motor has compression and turns over fine, I have replaced fuel pump w/ electric, fuel filter and oil. i have the fuel system bled all the way to the hard lines going into the injectors, i even hardwired the fuel cutoff n the top of the pump. The truck wont start and here is where it gets even weirder.... we tried giving it a little jump start with ether, I actually ended up feeding it a crap load of ether and it wouldnt even vapor lock the motor. I am getting a little bit of white smoke out of the exhaust and i could faintly smell the ether from the exhaust. Also while cranking it over i covered the intake with my hand as best i could and noticed it even blows back a little bit during its cycle. I heard that these motors use a full hydro roller valvetrain system. this motor has been sitting approx 1-1.5 yrs since it was last used and along with moisture buildup and what not being its enemy with starting right now, if the oil bled down from the lifters, can that cause it to not be opening the valves hence the blowback and refusal to vapor lock?

Please help, I am a very experienced mechanic so you dont have to dummy everything down for me, but I am a very inexperieced DIESEL mechanic. I get the concept but this is all chinese for me.
Thanks in advance!

forgot to ask, if the valvetrain does function as described to me, is there a way to prime it without just turning the motor over? like on the HPOP's the powerstrokes use?

12vcummins96 01-17-2010 01:53 PM

no its going to be a spin over contest also use some wd 40 to help fire it off

tltruckparts 01-17-2010 03:34 PM

all those chemicals will destroy your glow plugs though just for your info.

DieselCrawler 01-17-2010 10:00 PM

yea, disable the glow plugs over at the pass fender. unhook wire goin to solinoid if using ether.

they lifters are full hydro, and possibly causing the pressures not to release from cyls.

cranking is only way to get lifters built up. remove glowplugs so there is no restrictions, unhook wire to injection pump so fuel isnt going in and crank. dont crank for anything longer then 20 seconds or starter will get hot.

NMB2 01-17-2010 11:41 PM

well i cranked and cranked and cranked today and no dice. I purged fuel to get new diesel in there and that didnt help anything. Im very concerned that the starter fluid isnt vapor locking it... what does that mean? I'm going to check injection pump timing next to make sure its on, but would that effect the motor not kicking on ether?

DieselCrawler 01-18-2010 05:11 AM

u said u have compression. what numbers did u get? also were they wet or dry numbers?

Victor 7.3 IDI 01-06-2011 05:21 PM

i have got exactly the same problem with my 1990 7.3 IDI.

very frustrated.

have you found out the cause?

86fordf250 01-20-2011 06:20 PM

i have a 86 ford f250 with a 6.9L IH that i had the same problem with and i changed the lift pump , injector pump,and glow plugs and got it to start u have to have all of them workin for it to fire since it has been sittin for awhile and u need to becareful ether can make them exploed if it hits them good luck :tu::tu:

Bigred7.3 01-20-2011 08:14 PM

my last 7.3 did the same thing i slaped a new rebuilt injection pump in her and she fired right up.

91f350idi 09-21-2011 10:42 AM

Ive got a 91 7.3 idi. wont start with ether. I dont like using it but it seemed to fire a little better. ive changed my injector pump all the lines. It has sit for 9 months and i wanted to get it running again. i need some advice.


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