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So I changed my injectors to the Bosch 3s on my 85 corvette a month or so ago and fuel just started shooting out of the top of the left rear injector. Any idea why? Or the best way to fix it? I’d rather not have to do it all over again but if I have to I have to.
why? most likely you have an O-ring problem. I know it's a pain, but don't take chances here - drop back ten and get things right. inspect the O-rings, especially the leaker. not sure how you installed the boschIII's, but I always installed them in the fuel rail first, then lower the rail/injector assembly down and fit the injectors, one by one, into the manifold - gently and with kid gloves. as the injectors slide into the manifold, work the fuel rail into position, and finish up by hand tightening the fuel rail bolts. when everything is secure, positioned, and you're satisfied, torque to spec. make sure you use plenty of lube on the O-rings and don't force anything.
What kind of lube do you use on the O-rings? Petroleum products break down rubber so never sure what to use, etc. I was thinking silicon spray like I use on belts and wipers, etc.
What kind of lube do you use on the O-rings? Petroleum products break down rubber so never sure what to use, etc. I was thinking silicon spray like I use on belts and wipers, etc.
fuel system O-rings are usually resistant to petroleum based products. injector O-rings are typically viton. a little engine oil should suffice -
why? most likely you have an O-ring problem. I know it's a pain, but don't take chances here - drop back ten and get things right. inspect the O-rings, especially the leaker. not sure how you installed the boschIII's, but I always installed them in the fuel rail first, then lower the rail/injector assembly down and fit the injectors, one by one, into the manifold - gently and with kid gloves. as the injectors slide into the manifold, work the fuel rail into position, and finish up by hand tightening the fuel rail bolts. when everything is secure, positioned, and you're satisfied, torque to spec. make sure you use plenty of lube on the O-rings and don't force anything.
Alright thanks, do I need all new gaskets and o-rings? I’m guessing I do but figured I’d ask.
So I changed my injectors to the Bosch 3s on my 85 corvette a month or so ago and fuel just started shooting out of the top of the left rear injector. Any idea why? Or the best way to fix it? I’d rather not have to do it all over again but if I have to I have to.
Hi
the Bosch 111 injectors are shorter than the original injectors, they can slide down into the inlet manifold injector recess.
The original injectors larger body hits the manifold preventing the injector from popping out of the fuel rail if a retainer clip breaks.
You need 2x o rings at the bottom one at the top
(one above the normal lower o ring recess) the second "top" o ring will look bigger outer diameter when fitted but stops the injector being forced down by the fuel pressure. It works trust me I have been using Bosch 111 injectors for around 8 years, no leaks.
^Excellent point about the injector length. gerardvg is right. Good call.
- hopefully, the OP bought his boschIII's from FIC - they would have been supplied the injectors with the second o-ring. what I like about the (manifold end) two o-ring design, is, not only does the upper o-ring limit the depth the within the intake manifold, as a bonus, it also functions as a secondary seal, keeping dirt and debris from the primary or lower o-ring seal.
again, since the OP indicated a leak from the upper part, or fuel rail end of the injector, note that the fuel rail injector ports have very sharp edges - exercise care when inserting the injectors into the rails.
That's odd. Mine were the exact same length and only needed one o-ring on the bottom. I think mine was an early 85 build so maybe they are different? They bottomed out perfectly when the rail was pushed down.
That's odd. Mine were the exact same length and only needed one o-ring on the bottom. I think mine was an early 85 build so maybe they are different? They bottomed out perfectly when the rail was pushed down.
that is odd - got pics?
the yellow injectors is what i'm assuming everyone is referring to as boxchIII's. note, there are different configurations - applications, unknown. do you recall what design you have? my boschIII's all came with a secondary bottom o-ring. that upper-bottom o-ring fits nicely in the injector port chamfered edge in the intake manifold.
this is typical how my boschIII's fit to the intake --
I wasn't smart enough to take pics of both sets. Mine are blue (not sure if that means anything) and are the 24lb variety. I think that changed to 22lb in 87? I will take a pic of what they look like in the manifold to see if it looks any different. I also remember seeing pictures of Multec injectors and thinking mine didn't look quite like those. They looked like the ones on the far left in the bottom photo. Mine certainly looked original to the car and based on what I know about it's history I would suspect they were.
My memory is older and certainly more worn out than my Vette. I could be way off.
Last edited by Silver85; Oct 11, 2017 at 10:25 AM.
I wasn't smart enough to take pics of both sets. Mine are blue (not sure if that means anything) and are the 24lb variety. I think that changed to 22lb in 87? I will take a pic of what they look like in the manifold to see if it looks any different. I also remember seeing pictures of Multec injectors and thinking mine didn't look quite like those. They looked like the ones on the far left in the bottom photo. Mine certainly looked original to the car and based on what I know about it's history I would suspect they were.
My memory is older and certainly more worn out than my Vette. I could be way off.
yes, 24-pounders are blue. as a matter fo fact, that what I have in my 85, but they still had the double o-ring on the manifold side. fit the same at the yellow 22 lb version.
as for your originals, they most likely were first generation bosch, and for the time period, very good injectors.
- hopefully, the OP bought his boschIII's from FIC - they would have been supplied the injectors with the second o-ring. what I like about the (manifold end) two o-ring design, is, not only does the upper o-ring limit the depth the within the intake manifold, as a bonus, it also functions as a secondary seal, keeping dirt and debris from the primary or lower o-ring seal.
again, since the OP indicated a leak from the upper part, or fuel rail end of the injector, note that the fuel rail injector ports have very sharp edges - exercise care when inserting the injectors into the rails.
Joe C - 5X boschIII/FIC customer -
I did buy them from FIC but my injectors are gray not yellow
the yellow injectors is what i'm assuming everyone is referring to as boxchIII's. note, there are different configurations - applications, unknown. do you recall what design you have? my boschIII's all came with a secondary bottom o-ring. that upper-bottom o-ring fits nicely in the injector port chamfered edge in the intake manifold.
this is typical how my boschIII's fit to the intake --
Did you install your injectors with the injector clips to hold them into the fuel rail? The instructions told me not to use the clips for the Bosch 3s but can’t they pop out if you don’t use the clips?
Hi
the Bosch 111 injectors are shorter than the original injectors, they can slide down into the inlet manifold injector recess.
The original injectors larger body hits the manifold preventing the injector from popping out of the fuel rail if a retainer clip breaks.
You need 2x o rings at the bottom one at the top
(one above the normal lower o ring recess) the second "top" o ring will look bigger outer diameter when fitted but stops the injector being forced down by the fuel pressure. It works trust me I have been using Bosch 111 injectors for around 8 years, no leaks.
Are these the correct injectors? I noticed that I can’t fit the retainer clip which it sounds like you’re saying is normal. So do you have any tips to make sure they seat right and don’t get unseated?
Did you install your injectors with the injector clips to hold them into the fuel rail? The instructions told me not to use the clips for the Bosch 3s but can’t they pop out if you don’t use the clips?
How would it pop out? It is being held down by the fuel rail. Unless it is too short and the rail doesn't hold it down.
Leaky injector
- hopefully, the OP bought his boschIII's from FIC - they would have been supplied the injectors with the second o-ring. what I like about the (manifold end) two o-ring design, is, not only does the upper o-ring limit the depth the within the intake manifold, as a bonus, it also functions as a secondary seal, keeping dirt and debris from the primary or lower o-ring seal. 
