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I have a 1984 Corvette 5.7 L with Cross Fire Injection
When I first got the car I had it serviced including lube, oil, plugs and new filters. The engine seemed to be running good, but backfired once or twice in the next 500 miles.
Then I inspected the plugs and they were clean and firing. However, when I removed the air cleaner, the throttle bodies and injectors were covered with a black carbon film. I had cleaned these components before and there was no sign of carbon deposits at that time.
I referred to my Chilton manual on the emission vacuum system and found that my engine’s PVC routing was different. The topside vacuum fitting on my PVC routed to a rear manifold fitting shared by several other vacuum hoses. There is also another fitting at this location that is connected to the power brake diaphragm. This all looks stock to me except the hose from the PVC runs across the rocker cover and doesn’t look right? The port at the front of the manifold where Chilton shows where the PVC hose connects has been plugged. Where can I get a shop manual that is more detailed? I will appreciate any help.
Charlieman2
 

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Try alldata.com. The check the fuel pressure when it backfires.
 

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aka Duke of URL
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I have a 1984 Corvette 5.7 L with Cross Fire Injection

The engine seemed to be running good, but backfired once or twice in the next 500 miles.

when I removed the air cleaner, the throttle bodies and injectors were covered with a black carbon film.
This will be carbon from the backfire(s).


I referred to my Chilton manual on the emission vacuum system and found that my engine’s PVC routing was different.
What does the vacuum hose routing on the emmission decal on the hood show?

You need a CHEVROLET shop manual for your year.

It may be that the hose was changed at one time and the factory service part was not used.

CHILTON and others only use a little of the information from the factory literature. It is compressed.
 
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