My 1990 e350 will not start without either at all it runs good once started. New glow plug relay but still needs starting fluid.

 

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What he said ^

I would start with checking if the glow plugs themselves work. The relay is only one piece of the puzzle.

 

Where are the glow plugs on this engine?

 

https://www.ford-trucks.com/forums/9...le-system.html

(pssst did you read this yet?)

 

welcome to FTE.
how long does the wait to start light stay on?

 

It does not come on I just wait for the clicking to stop.

 

Is there a way to "turn off" the glow plugs so I don't blow myself up with ether I don't think there working but I wanna feel safe.

 

the only way to turn them off is to unplug them.

 

On my negative battery cable on passenger side there is a 1 pin circular connector it was unplugged when I got the truck. What is that?

 

probably a body ground wire.

 

Would that ground affect anything? Would junkyard glow plugs be a good idea? How do I test a glow plug with a multimeter? With new relay would almost have to be glow plug. Also my dad used it one day and it was warm and he didn't wait to start just cranked while it was clicking. Started but that's where the problem started.

 

My dad cranked it while the glow plugs were cycling is when it started being a bear to start. How do I check plugs with multi meter?

 

trying to start a cold engine without the glow plugs hot will only make it harder to start, it will not do any damage.
first thing i would do is remove one of the glow plugs and see what brand they are.
if anything but motorcraft/beru ZD-9's i would not even bother trying to test them, just order a set from rock auto and replace them.
they are only $9.13 each
on a properly working glow plug system, the clicking after the wait to start light goes out is the controller doing an after heat function to help the engine warm up a little faster. what it is is the controller turning power on to the glow plugs to keep them hot after the engine starts.

 

Ok I thought clicking was glow plugs yeah the wts comes on for a second or 2 but then does the clicking. What would that mean?