Why is one of my fuel injectors shorting out all the time electrically?

LDNEEDSHELP

MEMBER
1987 CHEVROLET BLAZER
150,000 MILES

I have a tbi 220 2.8 blazer. One day one of my fuel injectors went bad so I replaced. Well a few weeks later the same injector shorted out(pouring out of the end) again. So I figured it was just a bad one or was clogged etc. Replaced again. Well a few weeks later happened again. Remember this is the same side injector not the other one or both. SO I replaced and this time switched the wires to the other injector and vice versa. Well 3 weeks or so later it happened once again but now on the other injector where I switched the wire. So now I have a short somewhere I am figuring. I am being told to drop the gas tank, change out the fuel pump, fix reground the ground, then change the fuel regulator, and if that doesnt do it, change the pcm and or o2 sensor. Man thats alot of money. How can I find out what is causing this without having to spend 800.00 first?
Please help.

5 Replies

RIVERMIKERAT

MECHANIC
6,110 POSTS

Check and fix all grounds. Make sure nothing is rubbing against the injectors. Make sure the replacement injector is replaced properly and completely seated.

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Saturday, October 8th, 2011 AT 12:58 AM

LDNEEDSHELP

MEMBER
3 POSTS

NOthing is rubbing. Replacement inj is fully seated. As far as all grounds? Do not have any clue how many, where the ones that correspond to the injectors are located.

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Saturday, October 8th, 2011 AT 1:50 AM

RIVERMIKERAT

MECHANIC
6,110 POSTS

My reference doesn't list the grounds for your vehicle. If the injector is shorting, it could be damaging the ECM. It should(per electrical theory) also be damaging the fuel injection relay. You should also probably be seeing damage to the wiring for the injector. Check the connector itself. Make sure the wires in the connector don't wiggle excessively.

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Saturday, October 8th, 2011 AT 2:44 AM

LDNEEDSHELP

MEMBER
3 POSTS

Ok NOw would the ground with the fuel pump, or the fuel pressure reg make that happen?

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Saturday, October 8th, 2011 AT 2:51 AM

RIVERMIKERAT

MECHANIC
6,110 POSTS

I doubt it would be the fuel pump. That should be a different circuit.

The pressure regulator is a diaphragm-operated relief valve with injector pressure acting on one side
and air cleaner pressure acting on the other. The pressure regulator maintains a constant pressure drop
of about 10 psi (.7 kg/cm2 ) across injector(s), throughout all engine operating conditions. The model
700 fuel pressure regulator may be disassembled and repaired.