we have a 87 f250 that i am getting ready to send out to w texas to put on the bosses ranch. it must be completely reliable and be able to sit a month at a time and be depended upon to start. new parts include-fluids,brakes,u joints, tires,heater core, fuel pump, ip, batteries,glow plugs, gp relay, gp controller. the truck is still hard to start when cold. sometimes it takes 5 seconds, sometimes twenty. i ran an injector test=it came back w/in tolerance. if this problem cannot be fixed, it will have to be sold. any ideas??

 

5 seconds being your best,is too long.
so start with battery cable(s) inspection/cleaning/replacing/terminals and block cleaning,and possibly starter (though don't worry about this until last)
you want her to crank over SUPER fast before even worrying about actually starting (firing.)
if she has some miles on her,don't be afriad to check the compression.

imho,this is the order to restoring the start times (or make better than when new) for these diesels.
1.compression.if she doesn't have proper compression,there won't be much you can do.she'll need help when cold.
2.starting system.
starter/cables (3/0 down to the starter doesn't hurt fyi) /batteries (matched set with 850 CCA minimum each) all contact points cleaned,such as the starter and block,along with the terminals.
you want her to turn over so fast,it almost sounds like shes running without the diesel clatter. (but if everything is fixed latter,you don't get to hear it much lol.)
3.glow plug system.nothing besides Beru (packaged by motorcraft) glow plugs are worth putting in the 6.9/7.3l diesel.i could be paid to run another brand,but it would need to be enough to cover all repairs + labor and my effort to try them.$1,000 to even start negotiations of a 30 day test.
the glow plug system should be tested entirely for weak grounds/proper volts to each gp,and duration.
4.fuel system.once everything is up to par again,now your ready to make sure she's getting the juice to burn and ready to fire up.time to inspect ip/injectors/fuel lines/fuel selector valve,lift pump (swapping to an electric pump is not a bad idea either fyi.)

of course replacing parts last,diagnosing everything first as you go along.

my truck starts instantly the first time every time.cold (few degrees colder than she gets in west texas ) or warm unassisted (besides the glow plugs of course.)

 

thanks for the reply-however, i have done everything that you suggested already, except spring for the electric fuel pump. it does, however, have a new carter mechanical fuel pump w/ less than 1k miles, along w, the new ip. there is plenty of fuel pressure. i have ohmed out the glow plug system. battery voltage is normal. i have a 94 idi for my personal vehicle that starts easily, so i know what is lacking, just not the cause of.

 

Yeah, if the starter can't get the engine cranking fast enough, you won't get the heat needed to combust the diesel fuel on a cold soaked engine. Bad batteries, starter, or connections will effect starter performance. Also, if your charge drops too low while starting you can burn out your starter or screw the glow plug controller. I know with my '88 it is a little harder to start if it's been sitting for a few days in the cold. I usually plug in the block heater on cold mornings to make sure it'll start quickly. Otherwise, I may have to try and turn it over a couple times, but my fuel returns leak a bit so it's probably air getting in to the fuel lines or something.

 

unscrew the fuel filter to see if its full to the top after siting for many hours (at least overnight.)
how is the compression?
how many miles on ip/injectors?
does it start right up without issue using the block heater? - if so,do you read 1 ohm or less between the glow plug relay ground terminal and the negative battery post? are you getting over 10 volts to the supply? 8 volts @ the ignition terminal? what brand glow plugs? verified they are still working,by either resistance or test light/meter.all 8 gp lines are getting power when the WTS lite is on,and what are you getting for wts lite duration times @ what temps?

 

the compression check was all w/in acceptable parameters,with one cylinder being less,(270 i believe) but still well w/in the percentage of the rest. i have a brand new napa brand starter and fresh batteries. not sure of glowplug brand, purchased from napa. however, there is less than one ohm resistance at each glowplug. there is full power at the solenoid and it drops to about 10.5 volts after the resistor(normal). the ip (and all aforementioned changed parts) have less than 1k miles. i am going to check that ff level as a compromised fuel return system is the only thing that i haven't exhausted. any suggestions appreciated