Diagnosing Vapor Lock??

Mr Comet

Well-known member
Here is why I think my problem could be vapor lock. Car idles fine in garage. Fuel pressure gauge reads 6. I can drive around subdivision no stall outs maybe around 20mph. Take it out on highway get going about 45-50mph and about a mile the engine stalls out. within 5-10 minutes of stalling the car will start up however within driving a minute or so the stall repeats. I get out quickly and read the fuel pressure gauge and one time it read between 1 and 2 and until time flatline 0.


Setup is the old mech. mount on engine fuel pump.
Inline fuel filter from Oreilly.
3/4" alum spacer with line from PVC valve
1/2" plastic spacer
1100 autolite carb just remaned by a carburetor vendor


I am open to any ideas out there.


Thanks in advance
 
Depending on the location of the fuel filter (prior to of after the pump - which would determine the filter's impact of pressure reading), you might just start by changing the fuel filter. It is common for small filters to suck up debris and become clogged. This creates a situation which sounds very similar to the one you are describing.
 
yep, cheapest/easiest all ways 1st. (filter)

Thanks 4 putting in your location, Sagie river, bay, Huron - has plenty moisture/humidity.
Can be good for the VL development.

inch'n a 1/4 is pretty thick below carb, but...alu - increase vl, plastic - decrease vl.

When it happens (as it is the venturi & v.l. = 'frez') put your hand in there to see if it's cold.
To me that would be a great diagnosis (but not certain if not cold). Just a good indicator
if it was cold...
 
Soldmy66 & Chad. The filter is brand new. It is located between the pump and the carb. Since Aluminum is not a friend I will swap that out.
 
Sounds like maybe debri in the tank plugging the filter sock on the fuel sender pickup.
 
Econoline wouldn't that effect all types of fuel useage? Everything was working fine I just had a carter RBS carb which was too rich and fowling out plugs so I swapped out this Autolite 1100. I have never been able to take the car out for a drive with this rebuilt carb.
 
Mr Comet":jmygj8yz said:
Econoline wouldn't that effect all types of fuel useage? Everything was working fine I just had a carter RBS carb which was too rich and fowling out plugs so I swapped out this Autolite 1100. I have never been able to take the car out for a drive with this rebuilt carb.

I didn't see that part (i.e., everything was fine until the new carb) in this thread - so maybe my well-intended suggestion may not be accurate.
 
I see. If the tank gets near empty or if it's got a drain plug, it wouldn't hurt to check anyway at some point.

Did you ever try another coil?
 
The mechanical fuel pump might be part of your problem. When the engine gets hot so does the fuel pump.
If you have a Carter fuel pump that is your problem.
The plastic fuel filter will not absorb the heat like a metal filter.
Install an electric pump & delete the mechanical pump.
It worked for me.
 
Thanks Bill, by the gas tank? Do you have one you recommend? I do not know how old the fuel sending unit is and I have had the car for 14 and a half years. I am sure it has seen better days also. What do you think?
 
I'm running a Holley red pump with the pressure spring shimmed.
But there are better pumps out there. Check with Summit.
 
wsa111 was correct and the electric pump solved the stall issue. Thanks Bill. The only issue which remains is the idle speed. As I drive around town the idle can vary between 550 and 1200 rpms. I am doubting it is a vacuum issue. The throttle arm appears to not completely close the flap or flange, butterfly you get the idea. So I have installed a spring to completely close the throttle. On my autolite 1100 carb there is a small spring between the choke spring housing and the venteri housing. what is the purpose of that spring? Whats good to use to make sure all the parts are moving freely as possible on the carb? Thanks in advance.
 
"...Whats good to use to make sure all the parts are moving freely as possible on the carb? "
like the rest start @ begining: rug on gas peddle, rods or cable free travel, pay spec attent. to all that lill linkage @ the side of the carb (choke "finger or steps", idle cam), underside of A/C housing (holds air filter) is rubbin another guys on a current thread...

Do U have SCV/LOM system? or is a post '68 system on there...
:idea:
 
& me...backing up a step or 2.
If U have a SCV on ur carb U need the LOM (pre '68) diz. THAT could B ur problem.

Let's follow this line of thought further.
Did U get/read 'the Handbook' ?
/OR/
read above tech archive?
"All Se"t on this LOM/SCV system in terms of understanding?

It may B the same thing again - a Q worded w/the diagnosis imbedded in the Q.
We need the problem statement (details, what is: seen, heard, smelled, felt, & yes in some cases tasted).
Then the wise guys (used affectionately) here can go to town.
/OR/
May B not....?
 
plez read that recommended above for fuller (my last name, Charles Fuller III, LICSW) understanding.
Doesn't take long. I had to just to know what Qs to ask, how to ask them...I still gota long way ta go on automotive theory/understanding esp ele ina car - I'm fair on charging system, not all the ignit system tho). U don't need 2B. Just the LOM/SCV system.
 
Chad I do not own what you call the handbook. If anyone other than Chad wishes to help me I would greatly appreciate it very much. Has something changed in this Forum? I used to ask questions and get answers from people like bubba 22349, Rbohm, frankenstang, Ludwig, Stu from witchata and WSA111. Other too I can't recall all the names. If there are new rules to be in this forum please let me know where these rules are.
 
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