Hard start after cooling off

Trikebent

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1988 7.3 IDI, 1st gen Banks, manual transmission. Electric lift pump.
Truck is slightly hard to start when cold. Usually takes 2 sessions with manual glow plug at 10-12 sec 1st time then 4-5 the second time. I'll see white smoke out the tail pipe when cranking. I've replaced all of the Injector return lines, but need to recheck for leaks as I have a wet lifter valley cover.

After that it will fire immediately if you crank within 30-40 minutes of shut down.

If it sets for 1-3 hours in cool temps, 40°F-60°F, it is very hard to start. No smoke of any color out the tail pipe. Long cranks of 15 sec, pausing to let the starter cool. New geared starter, good cranking RPM. I checked the FSS, it has power, the advance solenoid is off (no power)

Possibly related, when I drove it yesterday, When i pulled in at home after a short drive, 2-3 miles, I noticed the Engine light was on and the Temp gauge was pegged when I pulled in at home. It had been 5 minuted since I remember checking the gauges and it was fine then. No external sign of overheating, boiling ect. It did not look/sound smell like it was overheating. 1.5 hours later in 50°F temp it would not start like above and the temp gauge pegged on hot as I was cranking. I'm suspecting the sending unit(s) is bad. Is there a safety switch in the temperature sense system?
 

Nero

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I had something similar happen on my dad's 88, the two yellow/black wires that run from the starter solenoid over to the gp module, at the black connector they were highly corroded and slightly melted. Bypassed the connector, and worked fine after that.
 

Cubey

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It could be a combination of air intrusion and weak glow plugs?

And sometimes these things can be fussy for a few months then be fine again for no obvious reason.

My RV was acting like it had air intrusion now and then around Nov 2020-Mar 2021, then was fine again, until around July/Aug 2021 a few times, and has since been fine again. I didn't touch anything to try to fix it.
 

IDIBRONCO

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Is there a safety switch in the temperature sense system?
There's no safety switch on these engines. Air intrusion wouldn't do this. With air intrusion, your engine won't run right. It will usually act like it gains power for a bit and then loses it again. If it's fuel related, it's fuel drain back. That's where fuel drains back toward the tank after you shut off the engine. First you should make sure that your glow plug system is up to par.
 

Big Bart

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Your advance and high idle should both get power when the engine is less than ~120 *. That will help with starting if your engine is timed.

I would do a quick check of the glow plugs via a ohm meter when they are unplugged. Open is a dead plug.

If you are still getting diesel on the valley pan you have a leak, that will allow air in and drain back to happen. Could be a few things but likely your return line kit is leaking at a o-ring or a injector line is loose or cracked.
 
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Trikebent

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OK, Checked the glow plugs. all 8 read 1.2-1.5 ohms.
Tightened the "Olives" on the hard lines. After a short test drive the Diesel smell is much less. Tomorrow i'll try a cooldown test. Too late tonight.
 

Trikebent

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Turn out it was air intrusion. Put clear hose on Filter head to #1 injector return line and had an air leak. Also put clear hose on the Injection pump return line an found a leak there. Truck on starts after sitting for 2-3 hours.
 

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