How to Diagnose Foxbody Mustang Wiring Problems 

Thanks for your kind feedback. I'm doing my best to release something every week.

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Thanks! This channel is almost as old as RU-vid but I decided to change direction and make some more personal contributions to it and I have been pleasantly surprised at the reception it has gotten. Positive comments like this are what make the intrusion of the cameras into my workflow worthwhile!

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Thanks for your positive feedback! Subscribe and watch my back catalog for lots more technical content.

I think the customer likes this car now that we have it running well, but unlike some of the other cars I have featured on here I don't think he is married to it, so you might be able to pry it away from him with the right offer! I have more videos related to this car that I will be editing and releasing in the not too distant future if you want to see more of it.

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@@tecmotiondyno anytime, got a question should. I update all my wiring for my 89 I put The key in and it don't stop trying to turn on. Even if I pull the key

It is a distinct possibility.

The car appeared to be either down a cylinder or running poorly on the driver’s bank based on logged fuel trims. It is a 347 that someone slapped together to sell and needed an injector upgrade anyway. I also pulled the valve covers to check the valvetrain setup and fixed one adjustable guide plate alignment problem. A possible issue was a fuel injector circuit issue and the time to check it is when you have it apart this far. The “one tab” injector connectors and the bunched weather seal may have been factors so I fixed those. When I got it back together, it was running right.

@@tecmotiondyno thanks for the reply! I actually found you from a podcast I listened to @kaslcustoms. I love old school Foxbody guys passing knowledge down to others. Really appreciate it!👍🏻

@@krisf5247 Thanks for your support of my channel!

I don’t see why not, though the harnesses are a little different on virtually every year of EFI foxbody mustang. The engines themselves are pretty interchangeable but of course the 86 5.0’s have a funny piston and head combination. That should not stop it from running with an 89 harness though.

Good question. Your problems sound like something that needs to be looked at in person. Maybe some of my other subscribers have an idea of who you could trust in New York or some adjacent state. Did you go through the checklists in my videos "what's broken on your foxbody" and "mistakes foxbody builders make"? Those are all common issues but sometimes overlooked, and they might be a starting point. You can DM me on instagram @tecmotiondyno if you need more help and I will see if I can find anyone there who might be trustworthy enough to take a look for you.

@@tecmotiondyno YES ALL OF THEM and many other channels too ......after talking to some old school mechanics and their thoughts (ford guys but not mustang guys) on fuel return lines and injectors firing with a Noid light (other creative solutions) all checked out fine BUT all wasn't fine. months of switching parts and basically giving up i was ready to bring it somewhere anywhere and again the old school guys had knowledge but wouldnt look at it as it was a headache, they didnt want as they can make 2 0r 3 time more money now switching out brake pad or exhaust work on something other than tracing issues on my 87GT ...I GET IT but still i was stuck with a non-running car .... i let a few weeks go by and did nothing was going to give up and put a used motor out of anything else i knew ran and seen personally it run. hit facebook up and started looking and for that good motor ($800 to $1200 used ) ... well i didnt need to put a used motor in where the new ($3500) motor was as glory B a 1998 Moutaineer came in my local pull a part yard ...took the upper and lower with the injectors and used a sn95 GT rail switched it over to my set up and first fire i could tell it was finally right ... now i can drive and enjoy my 87 GT ttop car ... i think the old stock 19lb injectors was firing right (they were check and new filters installed on them) but were staying open flooding the cylinder or cylinders with too much fuel creating some sorta flooding /black tail pipe smoke and non-running issue. what a pain and there is not many real people of knowledge out there now they just want to plug it in and "see what the code is"... i feel for the somethings wrong with my mustang people its a hard road for them...

@@AwakeDude911 thanks for the update. If you were in my area I would have taken your car on, but I know that lots of guys wouldn’t. Injectors don’t last forever and are susceptible to having debris flushed into them or gumming up, which is why I always suggest that guys use new injectors on a project rather than someone’s used ones that were a “good deal”. I’m glad to hear that it’s working again. I sure hate to see guys give up on these cars!

Well, if you can get it to Calgary I am sure I could do it for you. Wiring is one of those things that takes time and care or you end up with hard to find problems, and I realize that it isn't for everybody.