Dalannex

The owner of the company I work at has a VERY nice 84' that he drives very little because he says it vapor locks once it gets warmed up then won't start. He says the local Chevy dealer doesn't know what to do about it. They told him all cross fires do that and to live with it. :bs Somebody please explain to me in detail what this vapor locking is, where it happens, why it happens, what to do to fix it. I'm tired of the people I work with calling it a piece of cr#p when it's really a VERY nice car. 30k on the odometer, and it looks like it has closer to 30 on it than 30,000. I would like to be able to help him out with this vapor locking thing if I could. I think the car should be driven more than once a year. If I can't help him fix it he's probably going to get rid of it.

lbell101

I'm probably going to show my ignorance here but...
I only encountered vapor lock with one car and it was fifties vintage.
As I understand it, the phenomina is mostly associated with cars that have fuel pumps by the engine. Apparently the pressure within the line become low due to the sucking of the pump. Add some heat to the mix and the gasoline turns to vapor. Then the fuel pump can't handle it.
(OK guys - corect me if I'm wrong).

I never had a problem like that with my '84. Mine just wouldn't start due to electical problems not vapor lock. Is he sure it's vapor lock? I'd suspect it's something else. I'd go to a different Chevy dealer (that knos what they are doing) and get it fixed.

Desertdawg

You also need to add plenty of heat to get it to vapor lock...

I would almost guess that he has old gas? weak fuel pump? dirty injectors? or even an electrical prob. with the ignition???

Just guessing...Even broken clocks are right twice a day :jester

Dalannex

I considered the above suggestions. Is there anything in the ignition that would cause it to start everytime, the first time, when it's cold, but if he shuts it off after running it and getting it warmed up it won't start until it cools down again????? I can't think of anything that would cause these symptoms, but I don't know much about cross fire injection either.

Desertdawg

Sounds like you need to do some investigating.
After it gets warmed up, shut it down, if it won't start back up remove the aircleaners to see if its pumping fuel while you crank it( real easy to tell). no fuel pumping, that will tell you if you need to check the fuel system(pump,filter,computer???),pumping fuel, check the ignition system (coil, distributer, computer????) ...

I wouldn't start blaming the injection system right away, mine has worked flawlessly since I bought it, and others I have talked to say the same thing.

SCALF

Are you saying it won't turn over or won't start?
If it turns over but won't start I would check the oil pressure switch adjacent to the distributor first. If it is bad it will not send an oil pressure signal to the ECM. You will get no fuel and no spark. Also, check coolant temp switch

Crossfires are bad for fuel puddling in the manifold, but never heard of one vapor locking...


[Modified by SCALF, 10:07 AM 11/19/2001]

Dalannex

I'm gonna see if he'll let me look into this a little. Will a faulty coolant temp or oil pressure switch set off a code in the computer. I am going to check them anyway, but if you guys know it will save me digging out the books.

RedHot

I’ve heard them referred to as Cease Fire before. :rolleyes:

Twin_Turbo

The fuel pressure on a CFI should be around 10-13psi, too high for vapor lock. However, if the fuel pump is worn you probably could get poor performance and vapor lock.

Check the fuel pressure, also check coolant temp sender (will set no code, a quick test is when car won't start, disconenct CTS and push a 640Ohm resistor in the connector, that'll trick the ECM into open loop, if car starts now it's probably a lack of fuel -> pressure related)

Also check the oil pressure sender like SCALF said. Another suspect is the ignition module (heat soak)

Check on http://www.crossfire.webhop.net for more info.

Marck

Dalannex

This is great! I was just looking for a little assistance and now I want to tear into a cross fire. :D You guys are making me want to buy one of these, so that I can get into it myself. I guess the car I'm looking for assistance on now is for sale, but $9500. :eek: I think that's a little steep for an 84', even though it is REAL nice. He'll probably have it for awhile at that price.