Replacing injectors - other parts
Thread Starter
Instructor
Joined: Jun 2009
Posts: 101
Likes: 1
Replacing injectors - other parts
When replacing my injectors in my '85, is it worth replacing the EGR valve, fuel regulator and maybe other parts? Or do they generally just work or break, rather than suffer from lack of performance overtime?
Drifting
Joined: Aug 2002
Posts: 1,775
Likes: 125
From: Birmingham AL
Yes, I would replace the fuel pressure regulator diaphram, egr, and all fuel rail o-rings. There have been numerous fires lately due to old o-rings on these cars. My regulator was split when I bought my car and the vacuum line was pulling fuel into the plenum.
Le Mans Master
Joined: Oct 2008
Posts: 9,758
Likes: 49
From: Houston Texas
Also, before you put the runners back on turn your key to pressurize the fuel rail. I had leaks and had to do it twice, not fun.
Before you start pull the FP fuse and let the car run until it dies. That way there is no fuel pressure when you take it apart.
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
If you're willing to spend the money. As you have to buy new upper runner gaskets every time you take the plenum off. Plus it will be easier to replace the EGR with the runners out of the way if you do remove them to do the injectors. Replacing the FPR diaphram is easier to do than the EGR. If you get an EGR, only get the AC Delco, as you want a negative back pressure EGR. Get it from autopartstomorrow.com and you will get a good price and free shipping if your order is over $50.
At the least replace the fuel rail o-rings since you are already there. You'll also want to replace the two fuel line o-rings as well since those will be off anyways to pull the fuel rail.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 413
From: WV
http://temp.corvetteforum.net/c4/vad...orremoval.html
Last edited by WW7; Dec 10, 2010 at 10:59 AM.
Pro
Joined: Mar 1999
Posts: 678
Likes: 0
From: Oslo, Norway
Hi. I have an85 too.
I changed the EGR valve as it was necessary. It is quite old if it is stock so the diafragmmay be bad. It can be checked by using a vacuum pump with a scale on and pump up and see how fast the vacuum fall. It shall hold at least 20 seconds.
But with an old valve the valve itselv is surely not optimal.
The following I woul have done:
Change the EGR valve
change the EGR sensor which is a temperature sensor near by the EGR valve
Change the Fuel pressure regulator with an adjustable (remember new membrane)
Then you have possibility to tune
Change all vacuum plastic tubes under the plenum as the are very brittle when old
When having the plenum out check the air temp sensor in the back of the plenum
I ported the plenum
I changed the EGR valve as it was necessary. It is quite old if it is stock so the diafragmmay be bad. It can be checked by using a vacuum pump with a scale on and pump up and see how fast the vacuum fall. It shall hold at least 20 seconds.
But with an old valve the valve itselv is surely not optimal.
The following I woul have done:
Change the EGR valve
change the EGR sensor which is a temperature sensor near by the EGR valve
Change the Fuel pressure regulator with an adjustable (remember new membrane)
Then you have possibility to tune
Change all vacuum plastic tubes under the plenum as the are very brittle when old
When having the plenum out check the air temp sensor in the back of the plenum
I ported the plenum
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
You don't have to remove the runners to do injectors,egr,fpr, fuel rails or o-rings. I did my injectors the way listed in the instructions below and had no problems, much easier then by the FSM. I believe the 85 has the same setup as the 89.. ..WW
http://temp.corvetteforum.net/c4/vad...orremoval.html
http://temp.corvetteforum.net/c4/vad...orremoval.html
One thing you can do if you remove the runners. Is you can check the torque on the intake bolts you are able to get to. As some of those can/tend to loosen up over time.
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
Hi. I have an85 too.
I changed the EGR valve as it was necessary. It is quite old if it is stock so the diafragmmay be bad. It can be checked by using a vacuum pump with a scale on and pump up and see how fast the vacuum fall. It shall hold at least 20 seconds.
But with an old valve the valve itselv is surely not optimal.
The following I woul have done:
Change the EGR valve
change the EGR sensor which is a temperature sensor near by the EGR valve
Change the Fuel pressure regulator with an adjustable (remember new membrane)
Then you have possibility to tune
Change all vacuum plastic tubes under the plenum as the are very brittle when old
When having the plenum out check the air temp sensor in the back of the plenum
I ported the plenum
I changed the EGR valve as it was necessary. It is quite old if it is stock so the diafragmmay be bad. It can be checked by using a vacuum pump with a scale on and pump up and see how fast the vacuum fall. It shall hold at least 20 seconds.
But with an old valve the valve itselv is surely not optimal.
The following I woul have done:
Change the EGR valve
change the EGR sensor which is a temperature sensor near by the EGR valve
Change the Fuel pressure regulator with an adjustable (remember new membrane)
Then you have possibility to tune
Change all vacuum plastic tubes under the plenum as the are very brittle when old
When having the plenum out check the air temp sensor in the back of the plenum
I ported the plenum
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 413
From: WV
Did you remove the EGR to pull the fuel rail? Sounds like a pain to have to pull the EGR and break the fuel rail down. Though, it'd be good to break down and replace the fuel rail o-rings if that hasn't been done.
One thing you can do if you remove the runners. Is you can check the torque on the intake bolts you are able to get to. As some of those can/tend to loosen up over time.
One thing you can do if you remove the runners. Is you can check the torque on the intake bolts you are able to get to. As some of those can/tend to loosen up over time.
Tip: Always use a lube on the O-rings on the injectors and fuel rails, I use Vasaline..
Last edited by WW7; Dec 10, 2010 at 12:43 PM.
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
Josh, any time you have the plenum off you should clean the egr, they has a tendency to carbon up, but you don't have to remove it to remove the rails...Also its not a good idea to just retighten the intake bolts, you should have sealer on them and if you just retighten them theres a good chance they will leak, you could pull them one at a time, reseal and retorque them as you go using the proper torque sequence..WW
Tip: Always use a lube on the O-rings on the injectors and fuel rails, I use Vasaline..
Tip: Always use a lube on the O-rings on the injectors and fuel rails, I use Vasaline..
Thread Starter
Instructor
Joined: Jun 2009
Posts: 101
Likes: 1
Where did you see leaks?
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 413
From: WV
You can have leaks at either the o-rings on the injectors or the fuel rail o-rings..If you use the method where you don't remove the runners like in the link I posted, just Pressurize the system after you get all the o-rings in to check for leaks, if there are no leaks then you can put the plenum back on...Good Luck...WW
..WW
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 413
From: WV
You can pressurize with the runner out , its just alot easiier if you don't have to reinstall the runners when your done..The secret to getting the fuel rails out without removing the runners is to take the fuel rail apart at the cross overs while its still between the runners. Sometimes the runners can be a pain to get sealed and using the method in that link lets you avoid this..Your way works fine , its just a little more work..One other thing to remember is , not to over tighten the runner bolts. Some people use the torque specs on the runners, I don't, I just tighten them down by feel..I have seen to many people strip the aluminum out using a torque wrench on them.If you tighten them down by feel and they leak, you can always tighten them down a little more but if you strip them, then you have a problem..WW
Last edited by WW7; Dec 11, 2010 at 09:01 PM.
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
I think one advantage of the Bosch III. Is I believe if you later need to replace them. Or take them out for some reason. You can just lift the rail up and pop them out vs. having to remove the rail and undo the clips.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 413
From: WV
Your right Josh, the Bosch 3s can be removed that way on a stock tpi. I have the Accel runners on mine and its to tight to do that because the fuel rail is right up against the runners.. The clips were a pain to use anyway..WW
Last edited by WW7; Dec 11, 2010 at 09:56 PM.
Thread Starter
Instructor
Joined: Jun 2009
Posts: 101
Likes: 1
Josh, any time you have the plenum off you should clean the egr, they has a tendency to carbon up, but you don't have to remove it to remove the rails...Also its not a good idea to just retighten the intake bolts, you should have sealer on them and if you just retighten them theres a good chance they will leak, you could pull them one at a time, reseal and retorque them as you go using the proper torque sequence..WW
Tip: Always use a lube on the O-rings on the injectors and fuel rails, I use Vasaline..
Tip: Always use a lube on the O-rings on the injectors and fuel rails, I use Vasaline..
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 413
From: WV
If I remember correctly its not metric. You have to take it off and clean the underside where the air moves through it, push the diaphram up and it will open the hole at the bottom so you can clean all the carbon out..Pretty easy to clean..WW