starting a cold 6.9

[acey4342]

Sorry if there was already a post on this one, but I have a few questions for you idi folks. #1 on an 86 6.9 idi will the glow plug light come and appear to work when it actually does not heat the glow plugs (is this possible) it does however come on for 8.5 seconds in temps of approx 80 degrees f.
#2 if you were going to install a check valve on the suction side of the lift pump to keepthe ip primed and prevent leakdown what kind of valve is best and where would you buy one? Thanks in advance!

 

[Full Monte]

Plug in the block heater that has a power cord in the radiator area. Let it sit overnight plugged in. If it starts in the morning, the problem is most likely the glow plugs. Replace any with Beru/Motorcraft plugs, nothing else. You can directly check glow plugs for being burned out by getting a 12v trouble light with a 50 watt 12v bulb. Attach the red clamp to the + terminal of the battery, touch the black clamp to the top of each glow plug MOMENTARILY. If the light turns on (make sure the trouble light switch is on), the glow plug has continuity (or is not burned out).

I have never heard of installing a check valve to prevent leakdown. I'd guess that since no one else has been talking about a solution like this, it's not a typical problem.

 

[82F100SWB]

On an 86 6.9, the glow plug light is powered by the terminal that powers the glows, and the controller has no way of knowing if the glows are actually working, so, yes, the light will come on even if the glows are dead.

 

[hahn_rossman]

The early style glowplug controller is a failure prone POS. It also fails in a manner where it kills the plugs. You should disable it immediately and either retrofit the later solid state system, or wire up a momentary switch. The switch has worked great for me for years now.
The fuel system will not lose it's prime or leak into the tank if everything is correct. Better than adding a check valve is to locate your air leak and fix it. The return lines and o rings are the most common, followed by bad olives, or square cross section o rings on the hard lines. The stock lift pump has been known to cause problems as well. And the stock water separator will also leak air from the drain connection. Please plug the line, except when you are using the drain or get a better version (Racor, whatever).
Good luck

 

[Mr_Roboto]

In fact, if the GP's are more than a few years old, it is very likely that one or more are burned out. I had a new (Beru) plug burn out within weeks.....