# 84 Ford 6.9 diesel starting issue



## epicklein22

I have a buddy with a 84 ford 6.9 diesel truck that just will not start w/o either cold. New glow plugs, new glow plug relays, and another part for the glow plugs, but it will still not start cold. A shot of starting fluid and it fires right up and will be good to go the rest of the day if warm. So, any ideas what the problem can be? My friend bought it in this condition, so he doesn't know when this started to happen. Even though he used diesel specific starting fluid, He is thinking that the rings are washed. Thoughts?

(I know there are diesel forums, just checking here first)


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## stihlbro

This is what I would check. Are the batteries good and strong? what shape are the cables in? Just because the glow plugs are new does not mean they are working. Easy to check though. Take a test light and connect lead to positive post of battery. Make sure it works by touching neg terminal and verify test light lights. Unplug all glow plugs and touch test light to tip of glow plug. If it lights it is good. Next there is a cold start advance solenoid on top of inj pump. Single wire on top. It should have battery voltage if coolant temperature is cold enough. You can follow that wire back to the switch on the water outlet and verify voltage there too. Glow plugs should cycle for 10 to 15 second. If 2 or more glow plugs are not working it affects the cycle time of the glow plugs heating up. Good luck and I will check back.


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## Rookie1

Real quick,useing ether with glow plugs is a nono. It almost sounds like they arent working as stated already. Id doublecheck glowplug system. Does it run ok when running?


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## epicklein22

As far as I know, glow plugs have juice to them. I will have to have him read this forum and see/check with what he has done so far. 

Ross, truck runs great after it is started. So, glow plugs and starting fluid are a no-no? Why is that?


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## Biker Dude

Glow plugs and starting fluid are a no-no because when the glow plug activates it glows (go figure) because it gets really hot. If ether is in the pre-chamber at the time it can detonate and shatter the glow plug or blow the pre-chamber out of the head or crack the head itself. It's really easy to test the glow plugs. Just hook your 12V test lite up to the + terminal of the battery and touch the pointy end to the connector end of the glow plug. If the glow plug is good, the light will light up. Same for the controller except you want to be hooked to the - terminal of the battery and the pointy end to the big post on the controller that goes to the glow plugs. Key on, the test light should light up and tell you current is flowing to the glow plugs. Lastly, if you use ether to start a diesel repeatedly it can destroy the piston rings and make the engine incapable of starting cold without ether. If you suspect ring damage you can do a compression check by using a diesel compression gauge that can be had on feebay for $30 or so. If you already have a compression tester that can read up to 500 psi then you just need to get an adapter that screws into the glow plug hole for about $10. 

You can get more info here


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## treeclimber101

I have a 1990 7.3 with a similiar problem , the issue was with the ground on the glow plugs the wire was burnt and the cycle was too quick to properly heat the plugs


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