1991 7.4L 454 Starting Problems

[Brettwingfield]

First let me preface this post by saying I am new to forum and please excuse any ignorance. With that being said I have taken over a 91 Cobalt 222 with the 7.4L 454 Merc engine. I am having a thought time starting it. Once it starts it runs fine but I am always afraid to shut it off because it might not start back up.

It is hard to turn over. What I call very slow cranking. The other day I turned the key and there was nothing. No blowers worked, no horn, etc.. Only thing that worked was the electric engine compartment lift. Thought it might be it the battery so I replaced it and it started. The next day same thing, nothing worked. Let it sit about 30 minutes or so and then it started but slow cranking. I have also recently replaced spark plugs. Any thoughts greatly appreciated.

brett

 

[Docksidemarineservices]

You will have a bad connection at the batteries or oat the grounds on the engine. You will need to do a voltage drop test which requires a Digital volt ohm meter.

 

[Brettwingfield]

You will have a bad connection at the batteries or oat the grounds on the engine. You will need to do a voltage drop test which requires a Digital volt ohm meter.

Thanks Chris! Again, excuse my lack of knowledge but what is "oat the grounds on the engine" and how and where would I do that? Thanks again.

 

[Docksidemarineservices]

Thanks Chris! Again, excuse my lack of knowledge but what is "oat the grounds on the engine" and how and where would I do that? Thanks again.

Opps

or at the grounds on the engine.

 

[kghost]

When you have a fresh known good battery and a engine turns over very slowly and other accesories do not work properly, it typically is bad or weak connections.

The place to start is to look carefully at the red and black battery cables and its connections. If corroded or looking old they should be replaced.
Many times the black (ground) wire going to the engine block from the battery may be weak or loose or just bad.

Also the main engine wire harness connector (big black connector), with key off pull the connector apart and look at the pins and sockets and look for rust or oxidation. If none reconnect and make sure it is tight, if a hose clamp was in place to assure it was tight then retighten the clamp (not too tight but good and snug)

If all of this fails then it "may" be your starter.........very hard to tell from here!

 

[Brettwingfield]

Great explanation! Thanks for the comments. I will check all this and go from there. Thanks again.