1988 v6. 3 cylinders not working. Inj2 fuse blown. Electrical problem? (Page 2/4)
danahart SEP 09, 07:43 PM
Thanks. I found it without issue and disconnected it. I tried cranking the engine a bunch of times and couldn't get the fuse to blow. I plugged it back in and it blew with just a few 3000rpm low revs. So I guess that rules out the wiring on the battery side of that connector. My issue must be on the engine side or like carter above said, there is an issue with an injector itself. I was really hoping your idea would find the issue was just in a wire outside. I guess I need to keep looking.



quote
Originally posted by Raydar:


It is quite accessible, just looking at the top of the engine - usually between the upper intake and the thermostat cap. No need to take off any manifold/mechanical parts, unless you want to unplug the connectors from the individual injectors.
It's usually a flat connector about 1.75-2" square. One half of the connector goes to the main harness, and the other goes to a handful of wires that disappear under the upper intake and connect to the injectors.
I said "usually", because some of the 88s had a different connector that was more of a cube shape, but performed exactly the same function. It will also be in about the same place.



danahart SEP 09, 07:46 PM
Ok. I'll try unplugging the cold start injector. I assume to check each injector, you mean to take off the manifold and test each on the injector itself? Why wouldn't I want to use the higher rated fuse? Wouldn't that just likely cause the troublesome injector to fully break, identifying the problem?


quote
Originally posted by cartercarbaficionado:

sounds like the injector is having an intermittent fault. you can check it's power wire to ground to see which injector is shorted. I would actually unplug your cold start Injector if its still equipped since most 3.1 engines do have larger injectors and can easily have faulty injector ontop of them drawing just a little more power. but DO NOT replace the fuse with a higher rating whatever you do.
Patrick SEP 09, 08:13 PM

quote
Originally posted by danahart:

Why wouldn't I want to use the higher rated fuse?



Because that's a great way of possibly setting your car on fire.

There's probably a relatively simple way of determining which injector (and/or individual injector cable) has a dead short by probing the injector harness main connector (while it's still attached to all the injectors).

[This message has been edited by Patrick (edited 09-09-2024).]

cartercarbaficionado SEP 10, 01:46 AM

quote
Originally posted by Patrick:

Because that's a great way of possibly setting your car on fire.

There's probably a relatively simple way of determining which injector (and/or individual injector cable) has a dead short by probing the injector harness main connector (while it's still attached to all the injectors).



see it's not a dead short. it would just blow all the time then. it's acting like a c4 corvettes shellac coated Injectors after someone runs e20 through them. occasionally the metal inside will just touch and short temporarily. honestly the 3000 rpm specifically is quite telling because that's when they start to fully open and pulse faster
cartercarbaficionado SEP 10, 01:49 AM

quote
Originally posted by danahart:

Ok. I'll try unplugging the cold start injector. I assume to check each injector, you mean to take off the manifold and test each on the injector itself? Why wouldn't I want to use the higher rated fuse? Wouldn't that just likely cause the troublesome injector to fully break, identifying the problem?



you could but if you are going through the effort to remove the intake then why not get them all tested and take the harness covering off and make sure it's all nice and not kinked or starting to rub through and replace the crappy split loom with better stuff from a local parts store and wrap it in nice tape
please do make sure the wiring harness on the side near the firewall (back glass) is able to move freely between the Intake and valve cover and not pinched under the cover.
Patrick SEP 10, 01:58 AM

quote
Originally posted by cartercarbaficionado:

see it's not a dead short. it would just blow all the time then.



It could be a break in the insulation somewhere in the injector wiring harness, and due to the fact that the wiring harness can move, will only cause a dead short when the exposed wire happens to make direct contact with a "ground" in the engine bay.

None of us has a crystal ball at our disposal to help figure these things out. All we can do is make our best guesses based on our own experiences and the minimal info we're supplied.
danahart SEP 21, 04:00 PM
Ok. I finally had some time to start working on this problem. I took off the upper manifold so that I could get a look at the wires. Nothing looked pinched and everything looks neat and nicely taped by the previous owner. So now I'm trying to decide if I should pull all of the electrical tape off the wires, inspect, and rewrap each one. Or send out the injectors for testing. Before doing that I thought of an idea - tell me if this is sound.

Currently only 1 of the 2 fuel inj fuses is breaking, the one for the front (passenger) side injectors. If I swap the three injector connectors from the front 3 injectors with the back 3 injectors, that should tell me if it is the wiring or the injectors. If the same fuse is blowing, I know it must be the fuses. If a new fuse blows, I know that it must be wiring since the bad wires are connected to the other side now.

Is that a sound plan? Is there any order to what injector connector goes to each injector? I thought they fired all at once? Thoughts? I may not have enough wire to swap them so, if that is the case, I'll just swap the actual injectors and then see if the problem moves.





quote
Originally posted by cartercarbaficionado:

you could but if you are going through the effort to remove the intake then why not get them all tested and take the harness covering off and make sure it's all nice and not kinked or starting to rub through and replace the crappy split loom with better stuff from a local parts store and wrap it in nice tape
please do make sure the wiring harness on the side near the firewall (back glass) is able to move freely between the Intake and valve cover and not pinched under the cover.
Patrick SEP 21, 06:34 PM

quote
Originally posted by Raydar:

... if you can get an ohm meter to them, measure the individual injectors. It's possible that one of them has shorted. They should measure around 12-14 ohms. But anything "close" should be okay.



Did you test the resistance of each injector yet?
danahart SEP 22, 09:55 AM
No, I had not and thank you for the reminder. I just tested this morning and 5 read 12 Ohms and one only 3. So I guess that guy is the culprit.

New question: Can I just replace 1 injector? Does it matter if it matches the others? I ask because I'm fairly sure the ones in there are not the stock ones. Is it worth sending off the troublesome one for testing/cleaning instead of replacing?


quote
Originally posted by Patrick:

Did you test the resistance of each injector yet?

[This message has been edited by danahart (edited 09-22-2024).]

Patrick SEP 22, 04:39 PM

Someone with more experience with injectors than I will need to respond, but all I know is that it's optimal for the flow of all six injectors to be very similar. I'm not sure what your best option is... and if you go the route of replacing the whole set, whether or not a 3.1 requires different injectors than a 2.8 engine.