I sent the injectors from my '91 Formula 350 to Rich at Cruzin Performance for cleaning and flow matching, and when he got them he sent me an e-mail to call him. So I talked to him, and the first two things he said about the injectors was that the best thing I could have done was find a large body of water and deposited them at the bottom of it, and that they made some good paper wieghts.
Basically his story is this. Between 85 and 88, GM used Bosch style injectors made by Rochester for the 5.7L TPI in the Corvette and F-bodies. These injectors he said were some of the best he's seen. They could take 200K miles easily. At that point, some designer at Rochester thought that because electronics in the injector get hot due to their high resistance, it'd be a good idea to flow cool fuel over them in order to keep that temperature down. Seems like a good idea, but.... In order to protect the windings from the fuel, they coated the electronics in a verithane. The only problem is that verithane doesn't hold up to gasoline very well. In fact gasoline or petroleum solvents are exactly what you use to clean verithane from furniture or paintbrushes you've used with verithane. So, as the fuel flows over the windings of the injectors, the protective coating is worn off, and eventually, the electronics short out. This problem Rich said, has given these injectors one of the highest failure rates he's ever seen in all the injectors he's serviced.
Because of this little problem, he said that he doesn't even service these types of injectors from the 89 and up L98. I guess they changed the injector type when the LT1 was designed. He told me that 3 of my 8 injectors were already shorted out and were running at 10, 9, and 6 OHMs where they should be at a minimum of 12 and normally at 16. Personally, his explanation and the consequences of my injectors electronics problems explain everything I've had a problem with in my car as far as drivability goes. And they've all seemed like phantom problems. I thought that I would never find the problem behind it. It seems like there are a lot of those hot start, rough idle, poor fuel economy problems that never get a solid answer around here.
Anyhow, I was just wondering if anyone else had heard this, because I've been hanging out on F-body message boards for the past 3 or 4 years, and have never seen this posted. So, I just wanted to get the info out there. Maybe it'll help someone figure out their problem or guide someone who is considering buying some different injectors.

 

I've not heard that particular story, but idle problems do show up as possibly being injector problems. It's a good thing he did the injector balance test, no? There are about 10 things that can cause idle/rough running problems, according to the service manuals. Injectors don't normally go bad until they get old, so it tends to be overlooked and is one of the last things that are checked, next to mechanical problems with the engine block.

When replacing injectors it's not just the lb/hr but also the fuel pressure it is rated at. Just some information to throw out there. An adjustable fuel pressure regulator would probably be a necessity when using SVO injectors. I understand they are rated at a lower pressure rate, but I'm not sure what they are. Accel are rated at 43.5, so that should pop right in.

 

I dunno. My car is 12 years old although it's only got a bit over 100K on the clock, so I guess that's plenty of time for the injectors to have problems. But the way he made it sound was that he wouldn't guarantee those injectors for more than 15 minutes.
Either way, I'm not putting those injectors back in my car, and I'm not payin $80 a piece from the dealer for new ones, even to just replace the 3 that came out bad. I've got a set of 24# FMS injectors lined up for $160 that have less than 2K on them, or a set of 24# LT1 injectors that I may be able to pick up for shipping costs or little above that. I do have a Holley AFPR I'm putting in, so adequate fuel pressure shouldn't be an issue. The only other thing I want to get is some PROM burning equipment so I can at least modify the injector constant to reflect the new 24# injectors.

 

I hear ya. I'm looking into putting together the ALDL cable for an old laptop...should I ever get off my lazy butt and make it over to fry's. It comes in handy for checking things out while you're running.

 

I've heard that same story.

 

I had a couple go bad in my '88. Rich tested them and said they held pressure fine but when they got hot they would leak (causing poor starting condition).

Anyway I ended up replacing them all with 23# Accel injectors and it has fired up like new ever since. Just another option for you to look at.

Bob

 

Wow, thanks for some insight on injector problems everyone. Though I have an '86, I think I was on the right path with my planned injector service once the weather gets a bit better (not a winter hermit, but we've got 12" of new white stuff this morning! I'm pooped from scooping it up!)

One thing I want to ask is, what exactly have been your hard starting problems when warm? Does it crank hard and perhaps take a few tries to fire? I've got the poor mileage and irratic idle when warm too, making me think it was the injectors. I'm just looking for a vote of confidence that I'm on the right track perhaps.

Checking resistance and a good pressurized cleaning (forward and reverse flow) via the home based methods I learned on this board (tire inflator nozzle on carb/brake cleaner, pressurize, then flicker 12V power to open/close the injector quickly). Hopefully, none of my injectors are failed, instead are only dirty.

 

Rich at cruzin performance is very informative and knowledgable about fuel injectors. I have called him several times for advice and sent my '87 L98 injectors to him.

You can trust everything that he says.

BTW: My L98 injectors were fine, he cleaned then and flow em for me.

 

Brad, why do you need a stock FPR? If you just need the top part I have one but not the whole unit (diaphram).
I could probably let you have it.

Bob

 

A quick goggle shows Verithane is good up to 15% NITROMETHANE levels as used in model airplanes.

Varathane is for wood based product use.

Almost sounds like an easy error to mistake Verithane for Varathane.

Some of the garbage the refineries are passing off for gas I would suspect eat thru about anything given time.

A mistake as bad as picking the WRONG insulation, would I'm sure get the eye of lots of folks, ie the EPA.

 

Interesting about the Varathane/Verithane. They seem like they sound the same, so I don't know what he was talking about. But whatever it was didn't work so well I guess.

My hot start problem was a real mystery. The car would start fine when it had been sitting overnight, or if I had only had it turned off a couple minutes. But if it was warm, and I had let it sit more than 5 or 10 minutes, it would have to turn over for like 5 seconds before it'd start. I finally just started trying once, then having it start on the second try. And this problem persisted after changing the coil, cap, rotor, plugs, wires, fuel filter, etc.... That's what got me to the point of narrowing it down to the FPR or injectors, especially with the high O2 sensor code, and the crappy idling I was having.

 

Top part only will do. Thanks for the offer Bob, but I may have another FPR found already state side (saves shipping). If this one falls through, I may be giving you a PM about yours. The reason I need one? Making my own adjustable unit to bump pressure. Poor man's (or in my case, just a cheap bastard's) AFPR mod.

 

Silly, many of us have experienced this same problem. I have even posted a topic on this after having that same discussion with Rich myself. You can find it here:

https://www.thirdgen.org/techbb2/sho...hreadid=123315

Hope this helps.


Eric

 

I just read that thread. The injectors I have are a very light blue color with silver at the bottom, and they're kinda wide. Not the skinny type. Are these the ones with the problem?? I've only had the car a year and a half so I dunno if they've been replaced or not.

 

Sounds like you have leaky injectors.