Well, my '88 7.3 won't start. Again.

Some recent history...

Three weeks ago, all glow plugs replaced. Immediately afterward, it developed a significant fuel leak which was traced back to return lines that were disturbed during glow plug replacement. One week ago, all new return lines/caps/o-rings were installed. Fuel leak gone.

Truck started right up Monday morning, went to work. Snowed Monday. Monday night, went to start truck to go home. No go. It cranked normally, but it wouldn't even catch.

Put more fuel in the tank. No go.
Glow plugs still working.
Cracked injector line, verified fuel delivery. Also, blowing white smoke. Still, no start, not even catching.

Suspecting maybe a weak starter/batteries, we tried to roll start it (the beauty of a manual). Still, no go. It was just rolling along in 3rd gear, blowing white smoke, still not even attempting to catch.

The only other thing I can think of is that we simply weren't going fast enough on the roll start. But we were going as fast as I've ever gone before starting it this way.

What else could be causing this? What did I miss?

I need this truck on the road, and trustworthy...

 

being a big v8 with 21:1 compression .. your starting system has to do alot to get that motor moving and fired up .. there needs to be a start assist to get the fuel burning ..

the glow plug system on the idi is pretty pathetic .. and it's largest liability .. the motors run 'forever' but many people have trouble getting them going when there is some problem ..

i cannot specifly say what's going on there but here are a few things to look for ..

charged/good condition batteries
decent cables
good connections at the starter and ground
good glow plugs [check] [[hopefully]]
working glow plug relay
working glow plug controller
fuel shutoff on ip getting 12v
air intrusion
block heater when cold soaked

sounds like you already checked the air intrusion as you pushed the shreader and got fuel instead of air..

if you have a block heater plug it in 4hrs and see if it starts, if it does then it's your glow plug system.

when you turn the key you should hear a click on and off from the glow plug relay, if you don't it's your controler or relay ..

if no clicky then run a hot wire from the + on the batt to the small wire drivers side on the glow plug relay .. just touch it a couple times briefly it should click when activated ..

if it doesn't then it's that relay. if it does click off the wire, but not on key then it's the controler ..

if the controller fails usually it fails on and burns the plugs ..

batteries .. put a charger on start to assist and turn it fast ..

if the batts are hot and plus charger and the connections are good .. and it turns slow .. then it's the starter, it could be damage from diesel runoff burning out the windings in the starter.

first thing first plug it in, and charge the batteries, check for 12v at the fuel shut off on ip.. then listen for the clicking .. then hit the key and if all is well it should spin fast .. if not it's a starter.

i totally dislike the glow plug system , after a stuck controller i used a push button to work the last half of the plugs that hadn't burned out, finally after a few years, i decided to completly disconnect that junk and use starter fluid to start.

don't ever use gp plus ether, but ether is safe to start as long as you dont spray a whole bunch .. most big fleet start them all on ether and i've seen a whole lot sprayed to start a big motor. but idi's need only 1 spirt , as short as you can press the button on the can , it's not much .

i used to burn up starters cranking forever and hard on batts.

but now i have only 1 group 31 and it fires right up saving batts and starters, and it starts every time .. i connected up spray can straws together with shrink tubing and drilled a 1/8 hole in the air cleaner assembly .. i press the button breifly and key .. it starts .. if it's cold out and it doesnt' catch first try, i stop and 1 more tiny spirt .. and it always starts #2 time.

if it's deep deep cold then you need a block heater but mine starts on ether ..

just saying but you can fix the glow plug system but i would use a push button instead of a controller.

if you do ever use ether disconnect the glow plugs first or you will dislodge your pre cups ..

 

Quick test - disconnect one of the small wires on the glow plug relay to disable it, and use a 1/2 second shot of ether into the air cleaner.
It should fire up in about 5-10 seconds of cranking, when the ether finally hits the cylinders.

If so, it's obviously glow plugs.

 

The above is good to investigate reasons it's not starting via the starter. But it should fire up pull-starting it easily IF it's getting fuel. White smoke tells me its getting at least some fuel. Does the smoke smell like raw fuel?

How cold was it when you were push-starting it?

As Leroy said you drained the fuel filter of air right?
Try the block heater. Should fire up without glows if the heater is working.

 

White smoke indicates fuel, and cracked injector lines showed the same. I don't know what the smoke smelled like, as I was in the cab at the time. A friend was watching from the side and noted the white smoke.

It was fairly cold, maybe 20 degrees.

I don't know how to "drain the fuel filter of air".

I'll give the block heater a shot. I've never actually had to use it, so I don't know if it's in working condition or not.

 

Make sure you do this before trying to start via the block heater:
There is a shraeder valve on the fuel filter head. Just like a bike tire. Press the little pin in the middle in while cranking and it will either spray out air or fuel. Lots of air means it's air locked. Just hold till it sprays fuel. An arguably less messy approach is to just remove the fuel filter and see how full it is. If it's full great, 3/4 is still ok but much under that indicates you have a bunch of air and are feeding the IP air.

It'll catch even at 20* with enough inertia. My favorite is to grab a long strap and have another vehicle tow you at 20mph. Then dump it in 3rd gear. It will always start this way if the fuel filter is full and it's otherwise in good mechanical condition.
Actually my favorite is to park on the top of a good hill but I doubt that's currently an option.

 

did you add a glow plug light/led to the output of the glow plug relay?
the wait to start light may be coming on, but the glow plugs may not be getting power due to a bad glow plug relay.

 

At 20* I'd make sure I have anti gel in fuel...just saying.

 

That's a good call

 

Well, another baffling update. I let the truck sit all week, didn't even mess with it. Went tonight to try and get it fired up. I know it has an air intrusion so I expected it to fire, and then die, and then I'd have to crank and crank and crank to get it going again.

I was half right. It did fire up and run for a few seconds, and then crapped out. I hooked up the jumper cables, let her sit, and tried several more times to get it started, to no avail.

Also, today was close to twenty degrees colder than when it first failed to start on Monday.

I don't understand this. I really don't.

I towed the truck home, hopefully I can get it running here and sell it.

 

That's the classic return line drain-back situation. The fuel is displaced out of the filter by the faulty return check valve. If you delete that line and make sure you have a full fuel filter then it shouldn't happen again, unless you run it too low on fuel and suck up air.
Or replace the check valve, Ford has them for around $25 I think.

 

I'm aware of the problem, I've known that this truck does that since I bought it.

The part I can't figure out is why it is suddenly not starting intermittently. It started up fine Sunday night, Monday morning, dead Monday night. Sat all week, fired up fine Sunday evening, died, won't start again.

There's something more at play than the drain-back issue. I've dealt with that many times, and it has almost always started back up after the first round of cranking. Occasionally, the second. Never have I experienced 5-6 cranking episodes without so much as a cough, after having only sat for 8 hours.

 

Could be something more or the same problem, but worse. The check valve gets worse over time and maybe it's just letting in more and more air.

Also a tired IP will not purge itself very well and it only gets worse with time.
I had a crappy rebuild from Pensacola Diesel for years that never purged out air very well from itself, and when it started getting really tired, it was almost impossible to re-prime the system via the starter. And I have good batts, cables, starter.
Once I got it rebuilt properly through Russ(typ4), it'll re start *easily* after running out of fuel or whatever. The difference is huge. So maybe that's the other issue?

Either way fix that check valve and it should help.
I just found the part on eBay, ordered it over the weekend.

Edit: P/N F2TZ-9K061-A

 

Y'know, I ran into a guy today who had the drainback problem. He found that if he parked facing downhill, it would work just fine. Park facing uphill and he'd need to crank and crank etc.
It makes sense, as the fuel won't flow uphill, but I'm not sure if that might contribute to your intermittent failure.

 

I've experienced the same thing re: parking downhill. However, I don't believe that's a factor in this scenario because my parking spots haven't changed in months, and yet suddenly it won't run.