85 Fuel Rail Problem
Thread Starter
4th Gear
Joined: Apr 2016
Posts: 4
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From: Salem VA
85 Fuel Rail Problem
I have recently replaced all my fuel injectors (FI) with rebuilt FIC Bosch III in my 85 Vette. First time I've ever pulled the fuel rail (FR) myself. All seemed to go well, no leaks detected on initial installation but when starting to button up found I had to remove FR again to get clearance for left runner. At that point I seemed to have cut the o-ring on FR side of #3 injector causing a leak so off comes FR again to fix 0-ring, re-seated and found I'd cut #4 o-ring causing another leak. Seems the port edge on machined aluminum FR is very sharp, like cut your fingers sharp. Finally got FR in place, no leaks and after two weeks of driving #5 FI started to gush gas at FR o-ring. Has anyone ever beveled the edge on the FR port opening to reduce the chance of cutting an o-ring when inserting? 
Last edited by mikedubya; May 5, 2016 at 11:51 AM.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Just from memory about my 85, it seemed that there was a slight bevel for the injector into the intake manifold. Don't recall the fuel rail giving me any issues. Are you using engine oil on the "O" ring to lube it so it slides in easily?
Thread Starter
4th Gear
Joined: Apr 2016
Posts: 4
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From: Salem VA
Yes, I used oil on the o-rings.
When re-seating fuel rail after first time found I was having a hard time lining up top of FI with ports and would miss some injectors when pressing down. That's where I ran into problems I believe. An extra set of hands would have been helpful but I was working on my own. Just seems the edges of the ports are really sharp and could stand some smoothing to prevent cutting o-rings.
When re-seating fuel rail after first time found I was having a hard time lining up top of FI with ports and would miss some injectors when pressing down. That's where I ran into problems I believe. An extra set of hands would have been helpful but I was working on my own. Just seems the edges of the ports are really sharp and could stand some smoothing to prevent cutting o-rings.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
I will assume that you put the injectors into the rail first, which is what you should do. Lock them in place in the rail. Then the set of four will push into the intake manifold without issues.
Thread Starter
4th Gear
Joined: Apr 2016
Posts: 4
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From: Salem VA
Good point. However the FIC rebuilt Bosch 3's do not use the clip, the recommended mounting procedure is to insert lubed FI into manifold first then press fuel rail onto FI's. That is how I installed the FI's. But I did notice the rim of the FR port was very sharp and the two (so far) o-rings that were damaged were very cleanly sliced, not torn or warped but sliced like a knife edge cut them symmetrically on both sides. If I were installing FI that mounted into the FR (first) with clip pins I suspect I would not have experienced the problem. The manifold port does not seem to have sharp edges. Clearly caution is the order of the day in this process. I'm just curious if anyone has put a slight bevel on the edge of the FR port to avoid this problem?
Safety Car
Joined: Aug 2009
Posts: 3,751
Likes: 276
From: Melbourne, Victoria, Australia
Good point. However the FIC rebuilt Bosch 3's do not use the clip, the recommended mounting procedure is to insert lubed FI into manifold first then press fuel rail onto FI's. That is how I installed the FI's. But I did notice the rim of the FR port was very sharp and the two (so far) o-rings that were damaged were very cleanly sliced, not torn or warped but sliced like a knife edge cut them symmetrically on both sides. If I were installing FI that mounted into the FR (first) with clip pins I suspect I would not have experienced the problem. The manifold port does not seem to have sharp edges. Clearly caution is the order of the day in this process. I'm just curious if anyone has put a slight bevel on the edge of the FR port to avoid this problem?
Bosch injectors need 2 "o'' rings on the bottom of the injectors that go into the inlet manifold, the injectors are a little shorter than stock and the fuel pressure pushes the injectors down from the fuel rail.
FIC usually supply the injectors with 3 o rings one at top two at bottom, note if you twist the injectors under pressure the o ring will leak.
I use rubber grease to fit the injectors into the fuel rail, however any grease should do.
I did have success fitting the C clips on the injector/ fuel rail to hold the o ring and injector in place before I found out about the two o rings on the bottom of injectors trick.
Have not had any problem with damaging the o rings, when fitting the injectors into the fuel rail.
Last edited by gerardvg; May 9, 2016 at 09:46 PM.
