Hot start problem 1984 Corvette
Race Director
Joined: Oct 2008
Posts: 17,982
Likes: 1,074
From: Lansing MI
Semantics. Useless talking around the issue again...I sure am off the rails asking you for the same evidence you require (and ignore) from me.
A cursory Google search turns up many articles stating that vapor lock is less likely thanks to fuel injection...but none which call it impossible, or even suggest that it could never happen, especially in regards to the low pressure, check-valve-free Crossfire system.
A cursory Google search turns up many articles stating that vapor lock is less likely thanks to fuel injection...but none which call it impossible, or even suggest that it could never happen, especially in regards to the low pressure, check-valve-free Crossfire system.
You DO have a point about considering the purpose of the valve, and I can't deny that the name of it could certainly suggest the function you're convinced it has. While the diagram as it exists shows otherwise--fuel MUST pass the diaphragm before it can reach the valve--the FSM has been wrong before. If it does as you say, it should be drawn as a passage from the injector reservoir to the return line, which bypasses the regulator diaphragm. Instead, it's drawn as a passage sequentially following the diaphragm, and inaccessible by any other means. I suppose between poorly drawn diagram, and useless valve, I'll bet on the former.
I'm probably opening a can of worms here, but let's assume the diagram is in fact wrong, and there is a "constant bleed" irrespective of regulator diaphragm position. Going back to another point you declined to respond to, what about the accumulator, which has no bleeder valve? Can you explain why boiling fuel could not possibly evaporate and remain in the line between the fuel at the top of the pump, and the closed diaphragm in the accumulator?
Racer
Joined: May 2015
Posts: 265
Likes: 21
From: Grand Rapids MI
Meaning there is no check valve to prevent drain-back through the supply line, as there is with TPI and later systems.
I don't agree the diagram is wrong. I think the passage is drawn properly. The regulator diaphragm does not obstruct the flow of fuel to the constant bleed valve. The regulator diaphragm is connected to the valve that opens and closes. Lets call this the pintle. I agree that the illustration looks weird because it would seem the constant bleed orifice is separated from the injector reservoir, by (for lack of a better name) ill call it the pintle shaft, but in the three dimensional world the fuel passes around the pintle shaft, some exhausts through the constant bleed valve, and once the proper pressure is achieved, the diaphragm will flex allowing the pintle to open and pressure will be regulated. Regardless of all that it sounds like your willing to accept the constant bleed valve does what its name implies. I just want to be certain its for the right reason and not because of a crappy diagram.
I believe you have expanded my understanding of what's going on internally within the regulator body, so thank you. THIS is the kind of information that should populate these threads...rather than nit-pick at details in my argument that are ultimately trivial, I much prefer to see someone explain why they're right, so I can understand why I'm not.
We'll have to agree to disagree about the diagram being poorly drawn. I think the fault lies in the illustrator attempting to show too much visual detail, on a diagram that should be limited to clear, sequential function, and explicitly defined avenues of flow. I think I could now draw a better one, referring to your explanation.
You might have opened a can of worms here. There wouldn't be a bleeder in the throttle body with the accumulator. There is no valve to obstruct the free flow of fuel to the other throttle body. There is no pintle, no seat no anything. Just a passage to the other throttle body. The accumulator diaphragm doesn't close anything. If it did then it would be a regulator. The purpose of the accumulator is to accumulate fuel pressure against a spring. Hence the name. Its does this to ensure fuel pressure wont pulse with the opening and closing of the injectors. The spring absorbs this.
I was hung up on the bit labeled "Diaphragm and Plate Assembly." I see the one at the regulator is labeled "Diaphragm and Self Aligning Valve Assembly," so perhaps the difference between them is the most important distinction I missed, and what convinced me that there was an area in the line where vapor could isolate and expand.
I retract my theory--thank you for taking the time to 'SPLAIN & show me why I should reconsider!
Last edited by 84Z51J; Apr 12, 2016 at 05:51 PM.
Melting Slicks
Joined: Feb 2004
Posts: 2,244
Likes: 122
From: st paul minnesota
FWIW my '84 experienced the same hot start issues as the OP while on the caravan with the Corvette Museum group for GM's 100th anniversary. In my case it was a new fuel filter that solved the problem-one of the caravan members suggested that as a fix and it worked. Mine had the original filter that was some 20 years old with 21,000 miles on the odo. There could be other contributing factors, I'm sure, but in my case there was instant improvement.
