93 7.3 wont start

[payne5757]

Need help. At work we have a 93 7.3L that wont start. It seemed the batteries were weak but after charging and jumping attempts, it still wont start. After further inspection we noticed that the glow plug relay clicked initially but after 3-4seconds it starts clicking irradically. I checked the glow plugs w/ a multi metere and they are getting 9volts till the relay goes haywire. Does anyone know if this would keep it from starting? It was about 60degrees out when we were trying to start it and still it wont start. I also checked the fuses in the cab and under the hood and found no bad ones. What else should I try and check? Thanks in advance

[sea71]

Bump Bump Bump

[Clay Henry]

60 degrees isn't that cold but yes, if the glow plugs aren't working like they are supposed to, you won't start that cold diesel i don't think. Try cycliing them more that once...maybe 3 - 4 times in a row before you crank it and it "may" start.

[gbear]

Sounds like you don't have enought cranking capacity in the batteries being used. 9 volts won't get it. Read the voltage at the batteries to see if you have battery cable problems or if it's the batteries being used. Was the 9 volts being read with the starter turnning over or with out?

Jim

[djsdiesel]

9 volts to the glow plugs won't do it, if your batteries are at 12 and your 9 volts at the realy then you have a 3 volt voltage drop across the reley. Take your multimeter and attatch it to both the big terimals on the glow plug relay. with the key off it should battery volteg, when you turn the key on it should read .02 or less volts, what ever it says with key is how many volts your losing across the relay, also set your multi meter to ohms to check the glow plugs, hook one end to the negative side of the battery and the other to the each glow plug pin in the valve cover harness. it should read less than 7 ohms. Also have your batteries tested if you havent already. but it sounds like you have a voltage drop across your relay. If your glow plugs aren't working it won't start at 60 deg

[payne5757]

Thanks for all the info, Ill post back with updates.

[payne5757]

We just tried replacing the relay and that didnt work. Dont have a multimeter handy right now. Any other suggestions?

[djsdiesel]

are you getting fuel to the injectors, the IDI's are known for the fuel lines that connect each injector together or the o-rings to leak. they may not leak fuel externally but when you shut the truck off they can suck air, then allow it to suck all the fuel back into the fuel tank, thus taking alot of cranking to reprime the fuel system. Try removing the fuel filter from the engine and filling it full of fuel then reinstall the filter and crank on it.

Maybe also try plugging it in for a couple of hours. We had an IDI here at work that the motor had 310000 miles on it and was very very hard to start when it was cold unless you plugged it in.

Last I checked you could get all the o-rings and fuel line to the job for around $100. If they are leaking.

[payne5757]

I now have a multimeter, what else should i check?

[payne5757]

Went to check the fuel filter, and now I cant get that dumb cap on the bottom back on. Never worked on these IDI 7.3s before. Is there a trick? Also, the fuel smells like wood sealer or varnish. Im pretty sure its really old fuel. Would this be enough to keep it from running?