1962 Fuel Injection Problem

[Edward H.]

327/360 just totally restored, FI unit rebuilt etc. Starts easy, idles fine. Set idle to around 850RPM. Was running just fine. Last outing, when shifting, engine stalls instead of dropping to idle setting. Restarts fine. Any ideas? I didn't do anything since it was running fine except change the break-in oil. Using Sunoco 110.

[Stephen G.]

Re: 1962 Fuel Injection Problem

You might find that 850 is a little low. I run mine closer to 1k. Where are you located? What was the ambient temp at the time?

[Jim L.]

Re: 1962 Fuel Injection Problem

Set idle to around 850RPM. Was running just fine. Last outing, when shifting, engine stalls instead of dropping to idle setting. Restarts fine.

Not really enough information to make a definitive diagnosis. What you've described is consistent with any number of possible issues:

1. Your idle mixture might be too lean. Easy to adjust. Get the engine really hot and then adjust the mixture screw ("idle fuel" in FI-speak) for best idle. Then re-set idle speed to 850, if need be.

If that doesn't help.....

2. The valve that regulates nozzle fuel pressure (the "spill valve") might be sticking open.

3. A gravity operated check valve at the hub of the fuel spider could be sticking closed at the instant you release the accelerator.

4. A small, rubber splash cup under the main diaphragm might have shifted out of position causing a mechanism called the "axle and link" to not move freely.

5. Etc....

Jim

[John D.]

Re: 1962 Fuel Injection Problem

Edward, The mystery is you said it was running fine until you changed the oil.
Sounds like you may have developed a vacuum leak or signal problem.
The air meter (which today guys call the throttle body) tells the fuel meter what to do. You may have a vacuum signal problem. Check the rubber hoses also.
I have always preached that not enough time is spent on cleaning/rebuilding the air meter on FI cars.
Carbon built up in the air meter may be the culprit.
There is a 1/4" vacuum line that screws into the back side of the air meter. Take a wrench and make sure it's squeeky tight. This is the main signal line going to the brass T fitting on the fuel meter.
When '62's were brand new a lot of the FI's had a problem similiar to yours although not quite as severe.
The customer complaint was this. The car was running fine until the driver make a panic stop at a stop sign. Then the car would stall but start right up and run perfect until the next quick stop.
Rochester Products never printed a service bulletin on this problem but did come up with a fix when the FI unit was returned.
They replaced the bleed in the air meter from a .050 to a .034-.035. This solved that problem.
But since you did not have this problem until oil change I think you have something else going on.

Story: Recently I acquired a NOS 62 air meter thru an estate sell or something like that. Anyhow I checked out the bleed in the air meter bore and was surprised to see it has the updated .034-.035 size signal bleed.
One particular restorer is experimenting with the size of this bleed to solve calibration issues. The trouble with FI's is that we think one size of a bleed/restrictor fits all and it just isn't so.

Where is this bleed located you ask. Look in the Corvette Servicing Guide FI theory section and you will see it inside the air meter bore. Or look at the BB lead shot outside the air meter next to the big fat idle screw.. On the other side of this BB (exact size) shot you will see this bleed.
Make sure it's open. Use torch tip cleaner or pin gauges plus cleaners. JD

If you all want to learn the ABC's of FI's read the theory section. If you don't know the theory then you don't know FI's. Tru story.

[Edward H.]

Re: 1962 Fuel Injection Problem

Thanks John. Just occurred to me, I also changed the gas cap from a repro. vented cap to a NOS non-vented cap. Maybe my tank vent hose got crushed. I'll change caps and recheck this am.

[John D.]

Re: 1962 Fuel Injection Problem

Ed, One time long ago a local friend had a 65 FI car with problems after the FI unit was restored. We removed the gas cap-put a rag in the filler hole and took the car for a long ride. It was the rusty cap that was the problem. We still talk about that today when I see him. John