"Injector" fuse blowing...need help ASAP!

[turbov6joe]

For whatever reason I keep blowing the injector fuse??? I took the new Supra pump out of the picture, I've disconnected the ECM and hotwire kit, even hooked up the old working Walbro pump and have checked all grounds. Just as soon as I turn the key on it pops a new injector fuse...with or without anything hooked up to it on the other end. I've used all amp fuses from 10-30 and that doesn't make a difference...does anyone have any idea WTF is going on here

 

[azcode3gn]

Have you checked the wiring to make sure there aren't any cuts in the wiring insulation and metal contact causing a short in that circuit? Could possibly be the cause.

 

[turbov6joe]

From what I have checked thus far no cuts. What else other than the fuel pump runs off this fuse? Think it might be a bad fuel pump relay??

 

[GNVenom]

Check the wiring that goes to the oil pressure switch, near the oil pump. If you added an aftermarket oil pressure gauge and have disconnected the original switch connector, chances are it hit the header and melted thru..causing a short.
VERY common for this to happen.

Also, check the injector harness for burn-thru near the EGR. Another common cause for the FP INJ fuse to open.

Your failure will likely be one of these two possibilities.

 

[turbov6joe]

Check the wiring that goes to the oil pressure switch, near the oil pump. If you added an aftermarket oil pressure gauge and have disconnected the original switch connector, chances are it hit the header and melted thru..causing a short.
VERY common for this to happen.

Also, check the injector harness for burn-thru near the EGR. Another common cause for the FP INJ fuse to open.

Your failure will likely be one of these two possibilities.

John,
I just got done looking at the service manual and noticed that the electrical link goes to the 2 things you mentioned as well as the pump. I will check those things you mentioned...thanks!

PS...I did indeed unhook the factory oil pressure sensor, it is just hanging there...very good possibility it touched something it shouldn't have. I did have an injector wire get pinched by a bolt at one time and exposed some bare wire, I will take a close look at this as well.

 

[gbsean]

+1 on oil pressure wire...been there and done that....2x...

 

[turbov6joe]

I could not wait to tommorow to take a look, so I went back out to the shop and started tracing wires. What I found was an injector wire that was under the coil pack mounting plate on the DS that looked kinda flat/pinched. SO.. I removed the coil pack and low and behold....bare injector wire touching that plate!
I moved the wire out of the way, put a new fuse in the panel and gave her another try....pump cycled like it should!! A big thanks to all that responded and gave advice. You would think that after 19 years of mucking with these cars I could have seen what was right under my nose...prime example of K.I.S.S (keep it simple stupid).

 

[turbov6joe]

+1 on oil pressure wire...been there and done that....2x...

I WILL have this wire secured out of the way before the car moves again.

 

[gbsean]

I WILL have this wire secured out of the way before the car moves again.

... the first time it took me 2 days to trace the short when I replaced the stock pressure sender....the last time 10 years ago as it was being loaded on flat bed...a light bulb went off...I checked it....replaced fuse and it started right up.. as wife was already there...had car taken back....I then clipped the wire shorter....and wire tied it....

 

[salvageV6]

A good first test, that's probably in the search feature archives somewhere, for that FP/INJ fuse, which separates the circuits roughly in half in terms of checking the wiring, is to disconnect the Injector harness at the plug under the coil pack.

If the fuse doesn't blow it's in the harness for the injectors, if it still pops quickly it's usually in the FP wiring circuit end of the wiring.

That test doesn't work as well if it's an intermittant however that needs to be troubleshot when it's running etc.

 

[87GNSteve]

I had this happen when my fuel pump test lead got put away wrong (by me) and made contact with the hot header

 

[bison]

Check the wiring that goes to the oil pressure switch, near the oil pump. If you added an aftermarket oil pressure gauge and have disconnected the original switch connector, chances are it hit the header and melted thru..causing a short.
VERY common for this to happen.

Also, check the injector harness for burn-thru near the EGR. Another common cause for the FP INJ fuse to open.

Your failure will likely be one of these two possibilities.

Ive had it short to ground through the factory sender when everything looked ok. Try unplugging it if its still connected.

 

[gbsean]

A good first test, that's probably in the search feature archives somewhere, for that FP/INJ fuse, which separates the circuits roughly in half in terms of checking the wiring, is to disconnect the Injector harness at the plug under the coil pack.

If the fuse doesn't blow it's in the harness for the injectors, if it still pops quickly it's usually in the FP wiring circuit end of the wiring.

That test doesn't work as well if it's an intermittant however that needs to be troubleshot when it's running etc.

first time it happend was back in 1996....I was not on the net yet....had to use shop manual...outside in the winter....