Vacuum leak at injectors

[Makin-it]

Got a problem. Bought a 97 Mustang GT 2V and have been dealing with vacuum leaks on most of the injectors since having the engine rebuilt to include new injectors. They are 19 lb and bought from Late Model Restoration along with the intake. I’ve tried 3 different o-ring kits, moving the injectors to different locations, new fuel rail, placing the injector in fuel rail first then seating in intake, and vice versa. The only thing that seems to have a positive effect is backing off the tightness of the fuel rail and allowing the injectors to really just float, but still not getting a perfect seal. I’m at the point of RTV at the junction with the intake on all cylinders. I’ve used smoke to validate the leaks. Anyone else deal with this or have thoughts? Thank you.

 

[95opal]

Never had the problem but if the injector bungs have been bored to big I could see the issue. I would return the intake before I started globbing RTV in the injector bung. I would assume your intake was made on a crappy Monday morning in China.

 

[Makin-it]

Never had the problem but if the injector bungs have been bored to big I could see the issue. I would return the intake before I started globbing RTV in the injector bung. I would assume your intake was made on a crappy Monday morning in China.

Thanks for the reply. I initially thought intake too, so claimed a warranty on the new one that we put on after the rebuild and Later Model Restoration sent out a replacement. Installed it last Thursday only to have the same outcome. Come to think of it, this is the third intake. We tried a crappy Dorman from Auto Zone at first and had hella leaks with it across the board; vacuum and coolant, so opted to go higher quality, or so we thought… I know I didn’t make that very clear on initial post. Thanks again for the reply.

 

[SnakeBit!]

maybe the issue isn't the intake. after three different intakes and all doing the same thing, I'd start looking at the injectors. I saw you tried different "O" rings, but maybe something else.

 

[SnakeBit!]

do you have the old injectors to compare to the new? do the seal the same way. some injectors seal more at the top and some inside the intake and if you got California injectors for a non cali car....who knows what is happening??

 

[ttocs]

are you lubricating the orings at all before you put them in? I know mine are tight and with out a dab of oil on each one it can be really easy to tear one as you put it in.

 

[Makin-it]

do you have the old injectors to compare to the new? do the seal the same way. some injectors seal more at the top and some inside the intake and if you got California injectors for a non cali car....who knows what is happening??

I don’t have the old ones any longer, but did compare them prior to install and in a visual comparison they seemed identical. Bottom has an o-ring followed by a plastic ring and top is just an o-ring. I thought about grabbing a single injector at a local parts store to see if that rectifies the situation. Maybe there is something there. I’ll follow back on that attempt.

 

[Makin-it]

are you lubricating the orings at all before you put them in? I know mine are tight and with out a dab of oil on each one it can be really easy to tear one as you put it in.

I have not, but every time we replaced the o-rings none of them seemed damaged so didn’t bother lubing them up on any subsequent changes. I can definitely try that and see if it makes a difference. Thanks for offering that up. Is there a preferred method of placing them in the fuel rail or intake side first. I haven’t read anything on that but have tried both ways regardless. I’m stumped and really appreciate the ideas and comments.

 

[ttocs]

oh trust me it makes a hell of a difference. Rather than forcing them in they just slowly slip in, no tears. Just a dab of oil or a little spit as we all know can make all the difference.

I thought a torn oring would make for a leaky injector though, not create a vac leak? Are you sure the injector is working? I would maybe get a noid light from vatozone and see if it is getting signal, maybe try swapping them and see if the problem moves?

 

[Makin-it]

oh trust me it makes a hell of a difference. Rather than forcing them in they just slowly slip in, no tears. Just a dab of oil or a little spit as we all know can make all the difference.

I thought a torn oring would make for a leaky injector though, not create a vac leak? Are you sure the injector is working? I would maybe get a noid light from vatozone and see if it is getting signal, maybe try swapping them and see if the problem moves?

For sure, I’ll give it a try. I’ve got good indication that signal is getting to the injectors and that they are all working correctly. Kind of strange that they have a vacuum leak but not a fuel leak, but then again it’s a suction so there’s that. Gonna get yet another set of rings and will try the lube approach. Thanks.