Repititious vapor lock stalling problem - Toyota Nation Forum : Toyota Car and Truck Forums

Puddle Jumper · 07-25-2005, 05:09 PM

Hello everyone out there, this problem with vaporlocking is driving me bats!

I get spark and have decent compression, but the fuel just doesn't wanna come out when the underhood temp gets hot.

At first the old fuel pump went out, and I replaced it. Then came summer temperatures...and with it my vapor locking problem.

I haven't owned this car for a year yet, and this is my first summer with PJ...so I don't know if this was a concern with the previous owner.

I leave PJ's hood open whenever I park it so that the fuel doesn't vaporize, however it happens sometimes.

It makes me a little angery knowing that all the other parts are in decent condition, but I need some ideas here: in about a month I need PJ road ready so I can go to a meet in Vacaville (DodgeTalk.com)...that's about 120miles from where I live ONE WAY!!!!!

Has there been any recalls? Check my sig for PJ's info.

Thanks in advance!!!

matrix37495 · 07-25-2005, 05:56 PM

I dont have very much (if any) experience with carbs so this is only a suggestion....
have you tried insulating the fuel lines? I've seen this tubing type stuff that yo can put over fuel lines to help reduce vapor lock. Try a local parts store or summitracing.com maybe even jegs.com . They all might have this stuff, im not really sure what its name is. I hope this helps a little.....

matrix37495 · 07-25-2005, 06:29 PM

I found this,you might want to take a look at it: http://www.jcwhitney.com/autoparts/P...010263/c-10101

$13.99 plus $7 shipping
Should get it in7-10 days

ToyotaTechGeek · 07-26-2005, 06:31 AM

you theorhetically could also try an ice can to help with the vapor lock

Puddle Jumper · 07-26-2005, 12:56 PM

Thanks matrix37495 for the information and the link, however I'd like to try and find the cause to my problem rather than put a band-aid on it (I just might have to anyway).

ToyotaTechGeek, time to get technical!

I've cooked up a miniture list of things to check, although I'm pretty sure they all may not really be the problem:

Engine running excessively lean,

Heat riser stuck partially closed,

Cheap fuel pump design,

Excessive spark timing,

OR

Thermostat stuck partially closed.

Now for the thermostat idea: I don't really think the thermostat is bad because my engine runs within operation temperature.

However since the fuel pump sits right next to and above from the exhaust manifold I think that a lean running engine coupled with too much timing advance could cause that excessive heat-causing-vapor-lock.

Funny though: wherever I go I have to pop open the hood whenever I park just to ensure no vapor lock will occour.

Thanks guys.

Donald · 07-26-2005, 05:38 PM

Why do you think that it is a vopor lock ?

What are the symptoms that you are experiencing ?

Have you tried pulling the fuel tank cap off to see if you are having a vacuum problem caused by a plugged fuel cap vent ?

Check your fuel filter too.

Puddle Jumper · 07-27-2005, 01:30 PM

The little 3A-C dies only when it has heat soaked for awhile (that's why I leave my hood open), and if it doesn't heat soak...it doesn't stall out.

When it does stall out I am getting spark, and the engine fires up but dies immediatly afterward.

Kinda sounds like this: Vwaaaoooommm*dies*. I have fuel to the filter and to the pump, and the pump has been replaced.

Donald · 07-27-2005, 06:53 PM

Forgive the seemingly obvious questions but.
Do you pump the gas pedal when you are starting ?
Do you have fuel coming from outlet of the pump when it won't start ?
If you do I'd look into having the carb cleand and the float level checked.

If you have a float level too high, what can happen is that with a very high underhood tempreature you get fuel boil-over (liquid expansion due to heat) from the float bowl. This fuel goes into the intake and floods out the engine. Too much fuel will not burn.

Try leaving your hood down, then just before you start, pull your air cleaner off, open the throttle valve (piston in your case I think) and look down into the bottom of the intake and see if it is wet in there. That would be a sure sign of fuel boil-over.

If it is wet, try starting with the gas pedal held to the floor. DO NOT PUMP IT, just hold it down until it starts. If that works, it is time to have your float level checked.

If none of that works, you might have to get an in-line electric pump installed.

Donald.

Puddle Jumper · 07-27-2005, 09:34 PM

Thanks Donald, I'll "haveta" go and check that!

Puddle Jumper · 08-01-2005, 03:59 PM

Still couldn't find the problem, so I dropped the Puddle Jumper off a Penners Auto Repair here in Orland California.

We'll see what little monster was plaguing it later.

Puddle Jumper · 10-17-2005, 07:46 PM

Hey hey hey everyone, I'm back and sorry for the huge pause between posts.

I had taken the little PJ to Penners and told them to be nice and harsh against it just to make it die...however it didn't die for them (go figure).

After that event the Tercel didn't die more than two more times before the weather started cooling off for autum.

Then came an even more serious problem that is still going on right now: the car will not stay running without me keeping my foot into the accelerator pedal and once warmed up can sometimes stay running (only in park or neutral) by itself.

At first there was a considerable amount of blue smoke when it would struggle to run while cold...and so I thought that it was a big valve oil seal problem (it does have the problem at start up and help contribute to the problem).

However I noticed that the exhaust stays very much clear when PJ is warm and goes through its dieing stages: so I began to check EGR and ignition timing...until I found what I think is the problem.

Donald guessed right folks: now it doesn't need to be that warm underhood to get the carb hot enough to boil the fuel and kill the engine. When the engine dies or is shut off you can hear a boiling sound and see the fuel vapors comming out of the little carb.

In fact, if you look inside you can see fuel boiling at the bottom of the intake manifold.

And since this comes to be my problem: what could cause this to happen other than high coolant temps (the coolant gage reads normal and cooling fan cycyles just like it should).

Is the idle circuit leaning out the engine causing it to run poorly during idle (and cause it to get pretty hot, fast) while soon boiling the fuel which then riches out the little 3A-C?

Thanks for your input.

Donald · 10-17-2005, 08:44 PM

Check your float level.
When I used the term boil over I didn't mean boil literally, but heat expansion. Gasoline change volume very rapidly with tempreature variations. I learnt very quickly not to fill the gas tank of my motorcycle just before parking it because the heat rising from the engine causes the full tank to overflow.
You seem to be having overflow from the float bowl, which will vaporise in the hot manifold.
The posibilities are, your float is leaking (I am not sure if it is a solid or hollow float) the float valve and seat are worn or there is gum deposit building up in the float chamber.
Any which way, the carb should be disassembled, cleaned and adjusted.

If you find that you need any parts for it let me know. I still have the carb off my old 3E engine. I haven't looked inside it so I don't know what condition the internals are in, but I figured that someone might probably need something off it so I haven't thrown it away.

Good luck. Holler if you need anything, I'll be glad to help.

Puddle Jumper · 10-18-2005, 10:59 AM

Thanks Donald.I'd accept that used carburetor of yours but because I haveta keep PJ smog legal: I'll need a little 3A-C Carb Rebuild Kit.Anybody out there know how to get one?Thanks once again for your help Donald!

Donald · 10-18-2005, 06:54 PM

Oops! I forgot what year your car is.