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

SAK said:
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
Click to expand...
NO spark....is your coil pack one piece or is there one for each spark plug?
If you have multi coil packs it would be the crank sensor...single coil pack with multiple wires coming out ...crank sensor....check the connection that is sending the + voltage to the coil and ground,could be loose under heated engine it would loose contact
And old shade tree trick ...touch the coil after your engine has heated up and see if it is excessively hot....do this with the engine off ....don't ask why.
 
Evil Eye Earl said:
NO spark....is your coil pack one piece or is there one for each spark plug?
If you have multi coil packs it would be the crank sensor...single coil pack with multiple wires coming out ...crank sensor....check the connection that is sending the + voltage to the coil and ground,could be loose under heated engine it would loose contact
And old shade tree trick ...touch the coil after your engine has heated up and see if it is excessively hot....do this with the engine off ....don't ask why.
Click to expand...

Hi Earl,
My coil packs are one pack for 2 spark plugs (thus I have 2 coils packs total for the 4 cylinders). Based on having 2 spark plugs per coil, are you thinking it is the crank sensor?

I was guessing it was not a coil problem because if just one coil pack failed then I would think it would still try and run on 2 cylinders.
Unfortunately, this still leaves many other parts to check:
  • Crank sensor,
  • Ignition module,
  • ECM (electronic control module)
  • and possibly other sensors that feed the ECM.
The crank sensor, ignition module and coil packs are all on one assembly and they are buried down low on the engine between the engine and the firewall. (You would think that having a big ol' car like this with a little 4-banger in it, that there would be room to access all the parts - BUT NOOOO.) I can't figure any way to get in there to measure the voltage though I will be able to snake my arm far enough to feel the coils for heat.

Thanks,

--SAK
 
Yep possible that the crank sensor is bad or the mounting bracket is bent or loose.The coils will not get fire unless the crank sensor trigger is working.
 
Finally! SOLVED!

Attempting to hook a meter anywhere near the ignition was impossible – no space and no open access points. Trying to trace wires was about impossible since they all go into black plastic flex tubes and meet up with others. Once they are in the tubes you can never tell where they end up.

Anyway, after looking around trying to puzzle this out for the 1000th time I found, or rather felt, something I had not noticed before. Coming out of the bottom of the flex tube, quite a distance from the ignition unit, were 2 wires with lugs on the ends. They did not connect to anything. Because these were down low and on the bottom side they were not visible. Since they were black I figured they had to be ground wires. I figured lack of ground would correspond rather nicely to lack of spark so I found a nearby stud on the engine block and connected them to that.

Voila!
Been driving it for a week with nary a problem. Before this, the problem happened on EVERY drive.

It is amazing to think that without these ground wires it would start and run just fine (until heating up).

WOOT!

THANKS EVERYONE!

--SAK
 
sounds like everyone is going in the correct direction. the only thing is if you get vapor lock it really acts up when its hot outside. I had a volvo at one time that could not go 5 miles if it was over 90 degrees outside. also a lot of times before it conks out with vapor lock you can sort of feel it in the gas pedal. change fuel filter,if you can get one of those cheap see thru plastic ones and put it where you can see it (near the carb) and start it up more oftencause the gas is not good after sitting for a while-antique car guys have this problem all the time the gas can actyally break down and coat everything inside the fuel system with a varnish like coating and then you have to clean out the whole system. also put a can of gum out in the gas tank and take it for a 30 mile ride on the highway is your carb good?? thant could be a prob also. when you start it up when its cold make sure the little butterfly flap on top of the carb is almost closed but not completely. then when car gets warm is should open up to straight up write back anthony
 
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