# Ford 7.3L Diesel won't start



## mikewhite85 (Aug 13, 2010)

My 89 Superduty started right up as it always but after going about 25 ft it suddenly died on me.

I'm guessing it has something to do with the glow plugs because the Wait to Start light isn't coming on. It's not the fuel pump because I loosened the bolt on the fuel filter and diesel came right out. I also checked the fuses and they seem to be good. My tank is full as well. Help???


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## mdavlee (Aug 13, 2010)

Might be the relay to the glow plugs.


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## mikewhite85 (Aug 13, 2010)

mdavlee said:


> Might be the relay to the glow plugs.



I am not the most mechanical person but if the relay is shot, will the glowplugs then burn out? How do I find the relay? Know of any diagrams?


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## mdavlee (Aug 13, 2010)

The relay may be sticking and keeping them on the whole time. Google will be your friend for that. I don't know the wiring on the fords. On the dodge/cummins I could really help you out.


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## Biker Dude (Aug 14, 2010)

If it ran fine and you drove 25 feet before it died then the glow plug system had nothing to do with the problem. An 89 would be mechanical injection so the first thing to do is check for power at the fuel shutoff solenoid on top of the injection pump. There should be power there with the key on. No power = no fuel, no start. You can test the glow plugs by hooking your test light to battery + and touching the end of each plug. If the light lights up then the glow plug is fine. Usually glow plug relays burn open, not short but if it is shorted then there will be a fusible link that is fried and that link could also power the fuel shutoff solenoid so check your fusible links too. All a 7.3 indirect needs to run is compression, fuel, and power at the fuel shutoff solenoid. Chances are that the compression didn't disappear suddenly so the problem has to be fuel or electrical. I would replace the fuel filter if it hasn't been done lately, just for good measure.


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## PARTSWOODCHUCK (Aug 14, 2010)

On the newer 7.3's the valve cover gasket has the injector wiring attached to the glow plug wiring, so when the glow plug shorts out it takes the injector plug with it. May not be the case but I have a buddy who has this problem from time to time. Good luck


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## mikewhite85 (Aug 14, 2010)

Thanks guys.

I finally just got it started. The problem was some of the wires going from the relay to the glowplugs and shut off over the fuel pump had been disconnected. Whew! Glad it wasn't something worse.


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## mdavlee (Aug 14, 2010)

Glad it was an easy fix. I couldn't remember if that relay did the shutoff or not. My friend had a 7.3 like yours about 4-5 years ago.


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## Biker Dude (Aug 17, 2010)

PARTSWOODCHUCK said:


> On the newer 7.3's the valve cover gasket has the injector wiring attached to the glow plug wiring, so when the glow plug shorts out it takes the injector plug with it. May not be the case but I have a buddy who has this problem from time to time. Good luck


That would be the powerstroke that has that issue and it is common for older powerstrokes. 1993 and older 7.3 motors were a lot simpler and more trouble free. I'm glad it was an easy fix for the OP, the non-powerstroke 7.3s were pretty reliable.


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## cat-face timber (Aug 17, 2010)

Im glad you fixed it!!

Every once and a while on my 88 7.3 L, I will get absoultly nothing when I try to crank her up, nothing at all. I learned to disconnect both batteries and count to 30, reconnect them and she starts great.
I do not know why this happens?


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