Hard start after battery cable upgrade?

gosborne

gosborne

TJ Enthusiast
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Nov 22, 2020
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204
Location
Columbia Falls, Montana
99 jeep Tj 4.0L Kind of wierd what is taking place. My jeep has always been a good started. I turn the key once til i heard the fuel pump kick in and then it would fire right up. Yesterday after upgrading the battery cables with a set of jeepcables big 7. I went to start it up the same as above. Everything turned on like it should and it cranked over but wouldn't fire. I checked every connection (i did use dielectric grease) Everything seemed fine. Tried it again and it fired up. (after it set for a bit) Test drive went great and every start up after that.. This morning I went out and turned the key on, heard the fuel pump and did it one more time. Wouldn't fire again. Tried it a few times. Under the hood I could smell fuel,like it was flooded. Let in sit about 10 minutes and it fired right up. Never had any issues before. Any ideas? I'm baffled
 
JKP said:
Dielectric grease is an insulator. You don't use it on connections that you want to conduct electricity.
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That is not true, yes dielectric grease is an insulator but that is why you can use it on electric connections. The dielectric grease will not conduct electricity itself and cause short circuits where you don't want it. Dielectric grease will not interfere with conduction across a good metal to metal connection. The main use for dielectric grease is to seal out moisture from an electrical connection and prevent it from corroding.
 
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gosborne said:
dielectric grease is made for electrical connections. Thanks for reply tho.
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It is but as above, it is still an insulator. I spent 50 years in the electronics and electrical industries and some overdo the use of dielectric grease. Overdone it can cause problems. Some people mistakenly think it improves connections. It only helps protect them from corrosion if not used excessively.
 
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rasband said:
^^ if this all just started after the main wiring changes I'd start tracing everything you touched. Firewall, block, starter, alternator and battery connections.
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Yep you need to clean and recheck every connection you made. Yes cables are simple but it only takes one not getting a good bite to mess things up.

You all need to save the dielectric grease for your spark plug boots and use something like this https://www.truck-lite.com/97944.html and apply it after you make the connection. It is inexpensive compared to dielectric grease but do not use it on plug boots as it will eat them up.
 
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Thanks for all the replies. I'll pull it in the shop today and take some contact cleaner and clean up all my connections. I'll leave off the grease. You guys all must be on the right track. I'll post a update on the results. Thanks again !!!
 
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UPDATE : This morning early around 6AM. 7 deg. out. The jeep fired right up. Pulled it in the shop and pulled every wire connection I replaced when doing the Big 7 cable upgrade. Cleaned with contact cleaner and remove all dielectric grease. Took my time reconnecting it all. Jumped in and wouldn't start. Same thing... finally fired up after sitting a bit. Spit and sputtered for a few seconds and then purred like a kitten. Drove around a bit and the thing starts up Great. So here is what I found out. (after talking to a guy at local shop) Each time I took the wires off the PDC & grounds. It caused the ECM/PCM to get out of wack. After getting it started it had to relearn and reset. Since it controls the engine timing and fuel air ratio it makes sense. Thanks guys for all your replies.
 
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