WillsShop

I'm trying to decide on the injector replacement. I think a new Bosch injector is probably the safest way to proceed but would like some input. In searching through possible Bosch injectors, it appears some may be shorter than the OEM and would require an adaptor. The Bosch part number from those who have successfully made the swap would be appreciated. It appears that the OEM were 22lb @ 43.5 psi and were likely made by AC Delco.

I would like to use a replacement with the same specs. If there are issues with the connectors, some input would also be helpful.

I'm also planning on replacing the fuel pressure regulator and would like suggestions on the replacement. Again, I would like to stay within OEM specs.

While I have the 1990 torn apart for the injector/FPR replacement are there any other parts I should be considering for replacement or inspection/cleaning?

I'm sure there are many owners and/or technicians who have actually replaced the injectors on the L98 as equipped on the 1990 and their replies would be greatly appreciated. In fact, there has probably been many unforeseen issues, in what started out as a simple injector replacement.

I have read a couple of dozen posts concerning the injector replacement, reviewed the fsm and done a lot of research on the internet. I'm at the point I need to make some decisions and move forward with the project.

I hope everyone has been able to stay safe during these troubling times.

ajp01

On my '89 L98 motor I have used the Bosch III Exact Fit new injectors from Fuel Injector Connection and they work extremely well. FIC also offers the rebuild kit for the fuel pressure regulator, which I also used, and it's a direct fit with no problems at all.

Current injectors received as recently as last year are black, not yellow as in the photo, but I would call them to check if that matters to you. They use the stock electrical connectors. The fit is precise and easy to install just as advertised.
https://fuelinjectorconnection.com/c...22lb-injectors

This is the fuel pressure regulator rebuild diaphragm kit.
https://fuelinjectorconnection.com/c...and-spring-kit

Replace all your fuel rail O-rings while you do the injectors and regulator. There are fuel rail O-ring kits available at Napa, Zip Corvette online, etc...plus FIC offers this gasket / O-ring kit for the L98 motors using FelPro products.
https://fuelinjectorconnection.com/c...ith-viton-seal

You should also replace the two O-rings at the front connections from the fuel rail to the fuel supply / return lines. They vary by model year, so check your research and order the two O-rings appropriate for your year car.

Good luck with it. There is plenty of research material here on this forum using the Search utility.

*89x2*

I’ve used Delphi 22lb injectors from Jon at FIC


they are perfect and look great compared to other options

https://fuelinjectorconnection.com/c...l-injector-set


I've used these now on 3 different L98 cars.

SmokinBlack

This is great info. Thanks for the links everyone.

ctmccloskey

Being on the East Coast I have been using the South Bay Injectors out of NYC. They have great prices and fast service just like the other company mentioned.

WillsShop

Thank you for the information, especially about the O rings. From most of the threads I have read, it certainly appears that the Bosch are good option. I would have probably purchased a fuel regulator locally, so I appreciate the heads up on the rebuilding. When I get the job completed, I will post some additional information. This is a very good article on C4 fuel system. C4 Fuel Injection Overview - CC Tech (corvettecentral.com)

DWAVette

Another thumbs up for Fuel Injector Connection. I replaced all of them on my 91 with rebuilt injectors from FIC. I had a question when they arrived. When I called I actually got a human technician on the phone who answered my questions.
They we’re drop in replacements to the old Multecs and fit perfectly.
I also rebuilt my entire fuel rail by cleaning the inside thoroughly with carb cleaner and replacing all the o-rings for everything -including the two for the fuel lines connecting to the front of the fuel rail. Been doing great for a year now.

I also replaced my valve cover gaskets plus a lot of other stuff to my L98 when I did this.

jts90vette

While you have the air intake system apart and the fuel rail off the intake, you would be wise to also disassemble the fuel rails and crossover tubes and replace all the o-rings. If they have never been replaced, they are 32 years old. They WILL leak! you should also consider replacing the fuel pressure regulator also. Don't forget new o-rings where the 2 fuel lines connect to the fuel rail also, do not reuse the old ones. Fuel Injector Connection has everything you need.

WillsShop

I'm going to replace all of the O rings. I called FIC and they have everything in stock except the two O rings for the fuel line connector to the rail. The O rings shouldn't be hard to find. I will get all of the parts ordered in the next couple of weeks. I really appreciate the heads up on FIC. The car has been sitting for a number of years and needs to get back on the road. I installed a new fuel pump, new clutch hydraulics and a new heater core. The heater core project made me wish I had never bought the car. This is my sixth Corvette and my first C4. Except for my 94-year-old mother's car, it has been many years since I had a corvette or one of my cars in a shop for any maintenance. However, I really made a mistake by not having a shop replace the heater core. Looking back, I would have never questioned the labor cost. I purchased an average quality heater core before I started, when I finally was able to remove the leaking core, I threw away the one I purchased and purchased the best one I could buy. I'm going to take a look at the fsm to get some ideas on what else may need some TLC while I'm replacing the injectors. It's probably going to be a two-day project and I would like to have all of the parts before I start.

DWAVette

Taking the TPI apart is tedious, but if you did the heater core, should be child’s play for you. Carefully record where each bolt goes. A few of mine were different lengths.

Any words of wisdom on heater core replacement? Lessons learned? I don’t have a problem now, but you never know.

ajp01

I know it's a b*tch of a job, but let me assure you - you didn't make a mistake. Had you let the shop do it, not only would you be out $800-1000 but they would have broken myriad dash pieces, carpet areas, HVAC controls and actuators, and probably 3 other things that would now be broken after the job. And it maybe wouldn't work right, either.

ajp01

The 2 O-rings that connect the front of the fuel rail to the fuel supply/return lines (if they are equal size like the '89) are AC Delco part #217-452 or GM part #22514722.

jts90vette

On the 1990 model they are not equal sizes. AutoZone or Napa will have them

ajp01

Thank you for verifying on the '90.

Gale Banks 80'

If Yoo buy a Fuel Regulator rebuild kit it will probably come with all the o-rings to do the Fuel Rail all the way around but not the Injector o-rings that will come with the injectors

colter

Replace the plastic clip that is inside the plastic case next to the heater core. I believe it's the clip for the blend door. But might as well replace the plastic clip while everything is apart.

ABD87

I've also used these guys and recommend them.

WillsShop

If you decide to replace the heater core, carpet and head unit, get a folding table. Put a sheet of plywood on top of a folding table. Cover the plywood with brown wrapping paper. As you take parts off of the car, lay them out and number them in the order they were removed. Make notes on the wrapping paper and keep all of the fasteners with each part. If they were mixed together, replacement would have been a b....h. If the fasteners are different, make some notes where they go. Take some pictures and draw some pictures. Depending on what you have decided to replace, you may need more than one table. I was amazed at the number of parts and fasteners that needed to be removed to replace the carpet, head unit and the heater core.

Like Colter stated, while you have access, replace some of the plastic connectors that have become very brittle. If you get organized, reassemble is not a daunting project but if you mix everything up, you might never get it back together because there is not much reference material to help you out.

The AC Delco OEM o-rings for the fuel line to rail appear to be made of vulcanized rubber. I would like to replace them with Viton o-rings. The OEM o-rings lasted 30 years so maybe I can by-pass the idea. Maybe someone bought the o-rings and they turned out to be Viton and they have a source. I only found one reference to the size 7.35mm x 1.66mm but I will not know for sure until I take it apart. You don't want to compress an o-ring by much more than 20- 25% and the ID should be slightly smaller than the tube or grove it fits over. It shouldn't be hard to get the Viton, once you know the size of the tubes. I will post the size after I measure the tubes.

MikeT 90 C4sixer

I will echo what most folks say above, as far as the injectors and fuel rails. Replace all O-rings, get the kit, and make sure they are rated for ethanol fuel. Fuel line rings are very important, change them and get the right ones. Also, for the pressure regulator, might go for an adjustable one. I got all my stuff from FIC, but the other source should be fine as well. I went with Bosch III, 24 lbs. Worked well, but I do my own PROM programming. If you dont, might suggest some exact stock replacements, such as the Delphi 22 lbs. Might not be that cheap, but a good investment for sure. Good luck!