I work with a guy who has an 86 SE Duke 5 speed... he is having a problem with apparent vapor lock. The fuel lines get so hot the fuel is boiling and causing the engine to die. He has detached the fuel filter, trying to avoid burning his hands, and the fuel pumped out will boil in an open container. :WTF:

Anyone else experienced anything like this? I have absolutely no clue what could happen to a 10 PSI fuel system could do to cause this.

Ive never heard of vapor lock in a fuel injected engine. Common with carbed cars because of their low fuel pressure, usually around 6 pnds. You could always split a piece of hose and put it over the line if he thinks it is. The hose will insulate it from hot parts.

Is the converter bright red too?

Are you saying that the fuel is that hot at the filter? Is the filter in it's stock location?

Fuel line problem with stock routing? Maybe but Not likely.
Exhaust leak or missing heat shield? Very likely.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

[This message has been edited by theogre (edited 06-16-2011).]

I will take a look at it tomorrow... When he was telling me about it I was just kinda looking at him like WTF are you talking about... the car is kinda rough.

what are the symptoms exactly?

my 88gt, has a holley 4 barrel on it. i noticed that the hotter the engine gets the more likely it is to slowly idle out and die. could this be possible vapor lock?

my car used to vapor lock all the time. Was due to a head gasket that was almost blown. Enginge would get extremely hot and cause the engine to starve and die. You could open the shraider valve on the fuel lines and releave the air in the system... the car would start for a min but would die shortly after... Its not a commen thing on a fiero to vapor lock... your enginge is getting tooooo hot find the soure of that and you will be winning.

quote Originally posted by etofun: what are the symptoms exactly? my 88gt, has a holley 4 barrel on it. i noticed that the hotter the engine gets the more likely it is to slowly idle out and die. could this be possible vapor lock?

I found in my V8 Fiero that the problem was fuel boiling out of the fuel bowls in the carb. Put a wood/ fiber spacer under the base and problem solved. Theyre at speed shops if not auto parts store, less thean $10. 1/2" fixed mine. Only happened on surface streets, highway flowed enough air to keep it cool enough.

quote Originally posted by rogergarrison: I found in my V8 Fiero that the problem was fuel boiling out of the fuel bowls in the carb. Put a wood/ fiber spacer under the base and problem solved. Theyre at speed shops if not auto parts store, less thean $10. 1/2" fixed mine. Only happened on surface streets, highway flowed enough air to keep it cool enough.

sounds exactly like mine. is this spacer just a heat sheild or a gasket?

I had a problem with what I thought was vapor lock. The car only died while idling at redlights on hot days. I figured the missing cat heat shield was creating too much heat in the engine compartment.

While not at all trying to fix that problem, I came across a gas tank and sending unit in a salvage yard (mine had tons of rust and the baffles were cracked and broken). Swapping out the fuel pump actually fixed the problem.

Side note: later I replaced the cat which fixed the starter overheating problem. Then finally I replaced the starter that was damaged by the missing cat heat shield. Now if the fierostore could hurry up with that battery support I could fix that too!

It's somewhere between hard and impossible to vapor lock a properly operating stock Fiero fuel system with it's bypass fuel regulator. Fuel is always being pumped through the supply and return lines.

Vapor lock occurs when the gasoline vaporizes in the fuel lines. Since any gasoline that does vaporize in the lines will be pumped back into the fuel tank as soon as the key is turned on, pretty much ANY problems with vapor lock would indicate an improperly working system.

Low fuel pump pressure, that results in no flow of fuel in the return line is the most common cause of vapor lock in a Fiero.

Yes, You cannot get "Vapor Lock" in TBI setup. Ever in any kind of even remotely to normal operating. tbi units can take allot of abuse. tbi units don't need insulation etc.

Plus Boiling point is Higher with pressure...

System is build that way.... Is one of reasons why TBI has a fuel return line.

1. Replace Fuel Filter.
2. check fuel pressure. need an adapter, see my cave, tbi adapter in 4cyl engine section.
2a. read service manual. Driveablility problems, Chart A-5 A-6 and A-7... tells you how to test tbi fuel pressure. Download http://www.fieronews.net/fusion/downloads.php
3. Check Heat Shields missing etc.
4. Check all vacuum lines for cracks, leaking, etc.

few reason why tbi units will act like vapor lock.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)