I bought a set of Bosch injectors (from FIVE-O Motorsports) that match the characteristics of my '89 stock ones, and a friend put them in. Now I have two problems!

First, it doesn't start as well as before. It used to fire immediately, then run smooth and strong. Now it turns over longer before it catches, and it is not as smooth. Our suspicion is that the injector sequence is out of order. Since they come to their location in pairs, we tried switching them around and listening. We have it as close as we could get by listening, but are not sure if it is right. Can anyone suggest anything to verify the injector sequence???

Second, we now have a fuel rail clicking/hammering sound. It sounds a little like a valve noise, but (using the usual listening devices) is very clearly loudest at the fuel rail, not the injectors or the heads. This noise is not changed as the injectors are each individually disconnected and reconnected. Does anyone know about this or have a cure?

Thanks!

 

I purchased a set from Five O Motorsports for my 90 coupe. They have worked great. It sounds like you may have got ahold of a bad one that is leaking maybe. I would hook up a pressure gauge to the fuel rail and click the key to the first position and make sure after the pump shuts off (approx 2 seconds) that it holds fuel pressure. Sound like either one of them is leaking on you or maybe your fuel pressure pump check valve went bad also. That is what turned out to be the problem in mine. I also have a procedure I used that worked well to check that if you have determine that it is not holding pressure. My experience with Five O Motorsports was excellent. Let me know if you keep getting stuck and maybe I can give you a couple of ideas. As far as the injectors not being matched or put in the correct order that doesn't sound like the problem to me but I've been wrong on alot of things! Al

 

I didn't think the injectors had a firing order, I thought it was just batch fire where it would fire all the injectors on one side, then the other side.

 

Get back to Bruce (5-0 Motorsports) and explain the situation.
I had problems with my "pink ones": vacuum leaks and noisy operation when I put them in my '89. He offered me a refund which I used towards a set of rebuilt Multec's and put those in. Been about a year now; no problems.
I know a lot of people blast the Multec's as being "the worst injectors...", but hey, the original ones lasted 120k. This time, I'll skip adding injector cleaner to my tank.

 

Really? :o I thought they fired sequentially??!

If the noise is just fuel rail hammering from a sharp injection termination, does anyone have any idea why it is not as quick to start now??

Thanks!

 

Well, I have a thought and your post helps confirm it....

The reason I haven't gotten a new set of injectors yet is because of the things I've heard like your post, westifier.

First, my Corvette mechanic (Frank at FranknVette, Costa Mesa, CA) says that if the stock injectors are in good shape they're are good to 500HP with an AFPR and so is the fuel pump. He says Corvette's aren't like Fords. Fords have smaller engines and are built on the conservative side as far as injectors are concerned. They respond well with a larger injector install. But L98's don't necessarily. They need more air rather than fuel since the C4 TPI assembly was designed for a 305 C.I. engine. Many C4 owners make the mistake of putting larger injectors on a "air-choaked" engine and it just makes the situation worse.

And second (this is something I have researched on my own) new fuel injectors are made to flow within certain parameters and as long as they are within those parameters, they are given the same part number. But one injector could be on the low side of flow and the other on the high-side wit the same part number. And I believe it's possible to have a set of new injectors that flow so differently that they can cause rough idle, excessive fuel consumption and not deliver the performance they should.

I have pretty much made up my mind to have my spare set of '87 injectors remanufactured and flow matched. The cost is about the same as brand new injectors, $230 with shipping but they are guaranted to performance as new and come with all the necessary gaskets, O-rings whatever for a clean install.

Best of all they are flow matched as a set. Plus they will remanufacture them to any size you ask for. if yours can't be made as big as you want they will take a set from their stock in exchange. The people I'm taking about are in Florida, call SunCoast Carb and Fuel Injectors, abbreviated www.suncarb.com on their website.

I've talked on the phone with one of their techies and they have been doing what they do for over 20 years and they have a few testimonials on their site statng smoother running, more power, etc. Which is what I would think are the benefits of a flow-matched set.

I'm sorry I can't help you with your fuel rail noise. I've got fuel delivery probs of my own. I listened to someone on this site telling how to bypass the VATS. This person said to ground the purple wire in the #963 circuit (among other things) which was absolutely WRONG! Now I have spent $750 so far to get an intermittant electrical problem diagnosed and it's still in the shop as I type this.

What I'm getting to is, before you blindly follow anyone's free advice you don't know, get a second opinion from a professional. This instance is the third time I have used advice found on this forum that have cost me money or extra time because it was wrong.

FWIW,
BIG JIM

 

I think that is good advice. Some specific things that work for one system will not necessarilly work on another due to variations in the years and small design changes. So verifying ideas before deploying sounds good to me.

That being said, I still need to solve this. I tried to reach 5-O Motorsports but only got a machine, so I will try tomorrow again. If I can return them, I will get another set, maybe rebuilt, maybe new... Big Jim liked the sounds of Suncarb - does anyone else have some suggestions?

And if the injectors ar big enough, but more air is better, what has been successful for intake mods?

I am all ears!