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No spark on 7MGE engine

Attempted to fire up a newly rebuilt 7MGE and seem to have no spark. I pulled the coil lead and duct taped it so the contact is in close proximity to a nut on top of the shock tower, cranked the engine in a dark garage with my head outside the car watching and no spark visible. Going under the assumption that the spark should be discernible from that vantage - i.e. a few feet away. Nuthin'.

The car was running okay other than a breached head gasket a couple of months ago - which is why I took it out to begin with. I haven't been able to locate anything that isn't hooked up. All ground wires are in place, no connectors that haven't been reconnected AFAIK.

Another thing that's going on is some buzzer on the passenger side under/behind the glove compartment whenever the battery is hooked up. No idea if it's related to the no spark condition. I also see the temp guage is pinned to the top, obviously a false reading since the engine is stone cold.

Thoughts, suggestions? Can a coil go bad just sitting like that? There are other components right next to the coil that I confess ignorance of. One is a rectangular, finned aluminum piece with some small brown unit attached to it. I'll pore through my shop manual to see if I can determine what these are.

Thanks for all input.

Reply to
Doc
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If you stick a plug in the coil wire, do you get spark going _into_ the distributor?

Do you have voltage at the coil?

Coils don't go bad much at all. Ignition modules go bad more often.

--scott

Reply to
Scott Dorsey

In this case, because of the work that was done, a connection problem or broken wire (internally) would also be a strong possibility. I mean if it works, then you pull out a wire, put it back in, and it doesn't work, chances are it is the wire or the connection that is bad. In this case, there are a bunch of wires and connections that might have failed.

Jeff

Reply to
Jeff

For the assumed lack of a scope and understanding of magnetic reluctor operation in the distributor, I would suggest that you carefully inspect the 4 wire harness at the distributor for breaks, pinching, heat damage, etc. Maybe double verify lack of spark with a second person cranking while you ensure that your test gap is correct and to a proper ground. Systematic testing would be easier than looking for what you "left off" at this point; you might eventually need to pull out a DVOM in the least.

That raises a red flag that the temp sender wire is pinched to ground or the end is loose and touching ground. Either way it would indicate that not all wires have been connected and routed properly as you assume.

That's your ignition module. On this engine it needs to be grounded by it's metal bracket. Look for a missing ground wire that *may* supposed to be attached under one of the coil/module bracket bolts. Otherwise, make sure the module is grounded well before going any further. Run a redundant ground straight to the neg battery post, then attempt to start the engine as a quick test. I've never seen a coil failure on that engine, but have diagnosed quite a few bad modules, and they are pricey.

Toyota MDT in MO

Reply to
Comboverfish

And don't forget to check the stupid connector at the coil.

Right. Or, if some short occured, they could be melded together within the wire jacket.

I've had to replace the coil only once in 300k miles. Obviously, no spark was the issue. It wasn't cheap either. :)

Reply to
Gary L. Burnore

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