Any car guys that can help? – Why is my car vapor locking?

SharpByCoop said:
Start by isolating the problem. Fuel or ignition? You need to get to the point where it doesn't run. (Always the dilema. Failure on demand isn't always that easy.)

Find the air inlet or a spot where you can spray some starting fluid (ether) in there. Just a 2-3 second squirt. This stuff is very effective, but has a danger potential. Be careful.

Bottom line: Spray a few shots in the air ducts and then try to start it. If it fires for 1-2 seconds, then it is starving for fuel. No difference? Look at an overheated ignition component.

It may fire and still be electrical. The overheated electrical component may be the fuel pump. The plot thickens...

Coop
Click to expand...

Coop, I can get this to "fail on demand" without much problem. It is very consistent.

I implemented your suggestion. I tried multiple times with starting fluid and it still did not want to start at all. The starting fluid made no difference. After an hour of sitting, it started right up with no starting fluid.

To address a few other comments:

- I incorrectly mentioned a carburetor in my first post - it actually has throttle body fuel injection.

- My engine is very clean so I don't think I have a heat problem related to a dirty engine.

- I tried removing the gas cap when the problem was happening and that had no effect. Thanks for the suggestion though.

- This car has an in-tank fuel pump.

- I am not ignoring the gas draining suggestion - I am just saving until later since I have almost $50 of gas in the tank and no place to drain it.

- This thing does not have to get very hot - 10 minutes or less of driving will do it.

Thanks all. I will keep trying.

--SAK
 
this is a stretch-but i had a 4banger cavalier that would stall after 10 minutes or so-it was a bad temp sensor-caused the engine to flood when hot-

does it run gutless right before it stalls-
again run the diagnostic to check-
 
If the car is fuel injected, that's the problem. Sounds just like a fuel injection system malfunction......
 
Diagnostics, diagnostics, diagnostics.....

I'm less convinced it is fuel related now. But......

Now that you tested the ether and it made no difference (Ether is a substitute for fuel.) I would pull a plug wire (and spark plug) and attach it to a spark plug grounded on the engine somewhere. It will run on three and not hurt anything, although it wll make a racket. Try doing that while it IS running to verify you can see the spark. Then once it stalls, do it again.

No spark: Ignition failure. (Heat related. Coil is breaking down. Not unusual.)
Has spark: Still fuel related.

Could have too much fuel, such as an injector that did not seal and has been leaking pressurized fuel into the manifold, flooding the plugs. Also would explain why ether would not make a difference.

Double check your oil level. Any change? Smell like gas? Tha's a tipoff that the extra fuel from an injector leak has been gathering in the crankcase after slipping past the rings.

Diagnosises are always interesting.

Coop
 
rosconey2 said:
also do you know how to jump read the computer?
find the computer plug under the front of the dash,jump from 2 pin holes(use a paper clip) with key on (some its the outside 2 pins sometimes inside -either way you wont hurt anything) and watch the engine light-it will flash-flash's fast and slow-2 slow and 4 fast is a 24 code ect ect- if it has more than 2 codes one for its started one for its finished,deterime what codes it reads-it will help find the general area of the problem-you can get the codes online or at napa
Click to expand...

Thanks Rosconey2. I tried this. The only code I get is a code 12. From everything I can find online, a code 12 just indicates the diagnostic mode of the system is operating properly. In other words, a code 12 by itself means there is no problem.

--SAK
 
try again and give it more time-i think you should get 2 readings -the 12 is the first first but a second says its run the system-56 maybe?
cant hurt
 
SAK said:
Thanks Rosconey2. I tried this. The only code I get is a code 12. From everything I can find online, a code 12 just indicates the diagnostic mode of the system is operating properly. In other words, a code 12 by itself means there is no problem.

--SAK
Click to expand...

That is correct.
 
rosconey2 said:
try again and give it more time-i think you should get 2 readings -the 12 is the first first but a second says its run the system-56 maybe?
cant hurt
Click to expand...

In a GM that old, all he will get is a 12 if everything is ok.
 
rosconey2 said:
try again and give it more time-i think you should get 2 readings -the 12 is the first first but a second says its run the system-56 maybe?
cant hurt
Click to expand...
I tried it (code reading) multiple times. It continued to be 12 - over and over and over.


SharpByCoop said:
Progress report?
Click to expand...
Thanks for asking. My brother (who I haven't seen for a few years) is in town for a short stay and I haven't get much car work done.


CODE 3 said:
That is correct.
Click to expand...
Thanks for confirming Code 3.

--SAK
 
A friend of mine has a GMC van and hot starting was becoming unreliable. One day we were driving to his cottage, turned off the engine at Tim Hortons, got coffee and when we got back the van wouldn't start. It was a boiling hot day. We waited an hour and it still wouldn't start. It was towed to a garage and the mechanic said if the fuel pump is wearing out and the pressure in the fuel injection manifold drops below (from memory) 58 PSI, the van won't start. Again, IIRC it should be 72 PSI. After 3 hours the van started. when we got back, he took it to his own mechanic and changed the in-tank fuel pump. The van has been fine ever since.
 
Fwiw it is worth we changed in tank fuel pump on the Taurus mentioned earlier and haven't managed a repeat failure yet. Maybe we just haven't driven far enough from home.:confused:
cheers
 
Seems like the easy stuff has been discussed.

Good fresh fuel (cheapest fix).

Clean fuel filter (cheap fix).

Ignition, plugs and coil (not too expensive).

Fuel pump (expensive).

Catalytic converter (expensive).

Black Box (expensive).

Valves warping or not sealing (expensive).
 
I had a pick up that developed a crack in the manifold that allowed enough heat to rise above it to heat up the gas line going to the carb. Enough heat to vapor lock it after shutting the engine off and simply walking into a store. When I'd come back out the thing would not start but would be locked. I'd have to carry a bottle of water and soak a rag in it to physically use to cool down the gas line and then the truck would start right up. Once I eventually got around to repairing the manifold the problem went away though.

STR
 
PROGRESS!

SharpByCoop said:
Now that you tested the ether and it made no difference (Ether is a substitute for fuel.) I would pull a plug wire (and spark plug) and attach it to a spark plug grounded on the engine somewhere. It will run on three and not hurt anything, although it wll make a racket. Try doing that while it IS running to verify you can see the spark. Then once it stalls, do it again.

No spark: Ignition failure. (Heat related. Coil is breaking down. Not unusual.)
Click to expand...
Coop. YOU ARE A STUD!


Today I was finally able to follow up with the testing you suggested – Bingo!

  • Checking spark after car had been sitting for two weeks = Sparks and Starts.
  • Fire up car and drive for 7 minutes, then turn off and wait 2 minutes = No Spark, No Start.
  • Wait 30 more minutes = No Spark, No Start
  • Wait 30 more minutes (an hour total) = Sparks and Starts.
Two different tests now show the problem is electrical instead of fuel related.

The problem is very repeatable and it doesn’t take much heat to cause the problem. It only requires between 5 and 10 minutes of driving (and then turning off) to get this to occur. Today the outside temperature was only around 80F.

Now I just need to isolate the electrical problem. This car uses a system that GM refers to as "DIS" (Distributorless Ignition System). The system consists of a coil pack, ignition module, cranshaft sensor, interrrupter rings and the electronic control module. (Wow, they sure made it hard to reach the ignition/coil).

Thank you to ALL of you that have been responding!

I will keep trying.

--SAK
 
Earl,

Thanks for the ideas, but it looks like this is electrical. When it is cold there is spark and after it is driven for a while and then been shut off there is NO spark at all until after it has set for a while.

--SAK
 
You must log in or register to reply here.
Back
Top