Chevy Cobalt Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
I have a 2010 Chevy Cobalt. It recently had the fuel pump replaced and ever since then the 15A fuse keeps blowing randomly. My friend who is a mechanic looked at it and gave me this diagnosis:
The Problem:
Intermittent electrical issue blowing fuse INJ which is a mini 15A fuse.
This entire circuit consists of the 4 Ignition Coils and 4 Fuel Injectors.

I attempted to diagnose the problem by unplugged each Ignition Coil and Fuel Injector and then ohming each component to see if there was an internal short/fault in the component. To no find, everything looked normal. After i connected each component back in, the car never blown the fuse again until a few days later (today 7/16/2020). Potentially a wiring fray/short or an intermittent component failure?
I was able to drive it home after he looked at it but the next day I was driving for no more than 10 minutes when it stopped being able to accelerate. I pulled over, turned the car off and could not start it again. I opened the hood and replaced the blown fuse with the spare. It wouldn’t start and the spare blew immediately. I had it towed to a shop. They were not able to find a problem and replaced the fuse and now it’s working again. Any ideas why this might be happening?
 

·
Registered
Joined
·
156 Posts
Definitely sounds like a wiring problem. They can be tricky to find, especially since a lot of shops don’t specialize in electrical faults. Most of the times electrical situations are far and few between. I see some electrical fault situations on customers cars, but not a whole lot of them to keep me busy doing mainly that. They are usually fairly expensive and time consuming to fix also.

It sounds coincidental that it happened after a fuel pump replacement. There’s not a whole lot to mess up while doing a pump. Although if they have wired a new pig tail connector to the pump, they could have screwed up and not crimped a wire correctly or used open connectors that don’t have a weather seal. Although I’ve never seen it cause an issue in the circuit for the fuel injection or ignition.

You will have to find an experienced mechanic that is highly skilled in electrical repair. When I run into electrical issues that are either going to take too long to do, as I usually try to specialize on chassis repair that is fast paced, or can’t figure it out, I’ll call my friend that mainly does these repairs. I must say that I don’t know a whole lot of mechanics that are really super good at electrical repair and diagnosis. I know a hand full really. I’m ok at it but I don’t have the patience for it.

What I would do first is test each coil and injector to see if they might have high resistance in their internal circuits. Usually you would have a crappy running engine if they did, but not always. Also, dose the car set any codes in the PCM? I’m guessing not, but worth a look. Even if they aren’t showing up as a check engine light, I’d see if there’s any stored codes. Also a wiring diagram needs to be looked at to see if there’s anything obvious that could trigger a fuse to blow in that circuit. Not sure if anything else is linked besides the injectors and coils. It could even be a bad PCM, but other things will have to be ruled out.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #3
Ok sounds good. I will talk with my friend who changed the fuel pump and tell him what you said. Thank you, I appreciate you responding.
 

·
Registered
Joined
·
156 Posts
I forgot to mention the connectors are call weather proof butt connectors. They have heat activated shrink wrap coating and contract around the wire when heat is applied. We use them for all wiring repairs that we don’t want to solder and shrink wrap. The fuel pumps I’ve installed almost always come with these connectors when a new pig tail is supplied. And almost always so on GM vehicles. I guess they have an issue with the connector burning up or melting.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #5
I forgot to mention the connectors are call weather proof butt connectors. They have heat activated shrink wrap coating and contract around the wire when heat is applied. We use them for all wiring repairs that we don’t want to solder and shrink wrap. The fuel pumps I’ve installed almost always come with these connectors when a new pig tail is supplied. And almost always so on GM vehicles. I guess they have an issue with the connector burning up or melting.
Hmm interesting I will mention that too. I went to a AAA repair shop so I have a diagnosis warranty. If the fuse blows again I will be able to take it back to them for a free diagnosis. I will give them the information you gave me and see if it helps. Thank you.
 

·
Registered
Joined
·
1,044 Posts
Agreed. Wiring can be a nightmare. I would definatly look into the fuel pump wiring if it started right after that, that could be the culprit.
 
  • Like
Reactions: ChuckJackson
1 - 6 of 6 Posts
Top