have a 5.7l TPI 1990 firebird motor.

Motor oil smells off , I believe it has some gasoline in there.
Have two - three leaky injectors that I plan to swap just the O-rings ...but I suspect there is something else causing fuel to get into the crank case.

I believe I can throw parts at the motor ( new injectors, new pressure regulator, new air idle control valve ) but that costs too much. I rather do tests and determine one solution

 

Most likely cause by your leaking injectors dripping while the motor is off

 

i dont think bad orings can cause that do they?
if i not mistaken .. that would be the injector itself. but i think they are working fine. not sure

 

The external o rings go around the injector to seal them from leaking fuel out of the fuel rail and between the injector and manifold stops air leaks to the manifold. These you can replace but are not likely to be your problem. The o rings inside the injector seal fuel from going through the injector into the engine. These are likely to be your problem and getting the injectors rebuilt is relatively cheap and many places will flow balance them and give you a report on their status as they were received. You can't really do the internal rebuild on your own.

 

INJECTOR BALANCE TEST, SHOULD HAVE EXTENDED CRANK ALSO. PULL RAILS UP AND PRIME FUEL PUMP TO SEE HOW MANY ARE LEAKING.

 

so i pull the rail and prime the pump and if the injector sprays then its bad?

if they are leaking then i would need to just buy new injectors right? or at least this is the easiest fix,right?

 

Correct, but I doubt you will see them "spray".... if you do then you most likely would have also had drive-ability issues. Prime with the key on but do not start. Over time if they are faulty they will drip or seep. Even a small leak can put a lot of fuel into an engine that sits overnight. If you have one or two leak, I would replace them all as a set or have them all rebuilt as a set.

 

I have had very good luck with rebuilt injectors at a radically lower cost. Your choice though

 

thanks. i'm just going to buy new ones.
I don't really have time to rebuild them, although i'm sure its not that hard.

 

You send them out for rebuild. Takes about a week for about $20 per injector.

 

rebuilding is cheaper, never done it, dont know about the warranty they would offer. I bought a set of injectors for my truck from Five0 motorsports online. They were an upgrade over original OEM, and about a 1/4 of the cost the dealer was going to charge. Was very happy with them.

 

I got Bosch series III's from South Bay fuel injector. Very happy with how they run - they are quite loud though, and being bank fired it makes the engine sound like it has a bad lifter. They come with adaptors and all new o-rings, etc to fit the TPI rails for about $160. This is the same cost as rebuilding but no down time. South Bay is a site sponsor here as well.



Rick

 

yeah thats what i was going to do . they have bosch and i trust that brand

 

$20 * 8 thats $160 which is about approx only 30 bucks (including tax and shipping) cheaper than new injectors.