This new girl has a problem!

[babydoll]

Hi everyone! My first post!
On hot days (above 93) my truck ('72 Cheyenne Super) runs really rough and if I don’t play with the gas and keep high rpm it dies and won’t start until it cools down a little and then only if I hold the gas to the floor as if it were flooded. There is no cooling problem as the temp stays around 195. My boyfriend thinks it’s vapor locking but is there another possible explanation?
Thanks!

[kingsolver72]

Welcome to the board..Its sounds like your boyfriend is correct. I had an old falcon with an electric fuel pump that would vapor lock on hot days.

[BMERDOC]

Welcome! If it has a filter in the engine compartment make sure its on the pressure side of the pump and not the suction side.

[PanelDeland]

You might also look at the way the fuel line is routed.If it runs near manifolds,or exhuast ,you may be able to reroute it to keep the fuel cooler in it.

[C20-67_N_MO]

Originally Posted by PanelDeland

You might also look at the way the fuel line is routed.If it runs near manifolds,or exhuast ,you may be able to reroute it to keep the fuel cooler in it.

Good advise.

Plus keep the fuel lines away from the raditor hoses if it all possible as well.

Good luck and welcome to the board!!

[Shyguy]

Good suggestions in previous posts. What engine and carb does your truck have?

Some carbs, especially Edelbocks, are affected by heat some and need a phenolic spacer between them and the intake to prevent float bowl boil problems.

[babydoll]

Thank you so much for the warm welcome and advice!!

I'm pretty sure the filter is on right since this only happens on hot days. Totally agree with checking the lines for heat sources. I have a spacer on the intake for the quadrajet carb, but perhaps need a thicker one? I’m also thinking of getting a 185 thermostat, which was the original anyway.

By the way, here's a picture of my baby!

[Double Stack]

Nice truck!

[C20-67_N_MO]

Wow!

Nice looking truck.

And it's kinda cool to see a bed that is painted white too.

[srvivor71]

Welcome from Upstate NY! Beautiful truck! I'm really glad you brought this up because my truck was running poorly during some very hot weather earlier this summer. I'll be looking at this over the weekend.

[babydoll]

Interesing you should say that about the bed. We're not crazy about it. Thinking about a wood bed, in which case the sides would be red, I assume. And the top of the cab needs to be white, of course.

[71meangreenc10]

Nice Truck.....


Smitty

[OhOneWS6]

You can try clipping wooden clothes pins to the fuel line. Put as many as you can fit. The wood will act as a heat sink. This is not a pretty fix but it may help you diagnose that it is in fact a vapor lock issue.

[Shyguy]

Originally Posted by babydoll

Thank you so much for the warm welcome and advice!!

I'm pretty sure the filter is on right since this only happens on hot days. Totally agree with checking the lines for heat sources. I have a spacer on the intake for the quadrajet carb, but perhaps need a thicker one? I’m also thinking of getting a 185 thermostat, which was the original anyway.

By the way, here's a picture of my baby!

Great looking truck.

Q-jet carbs are also bothered by heat. A metal spacer does little to help with that, it has to be phenolic. Also Q-jets have a problem with leaks in the bottom of the carb that can cause problems.

I usually run a 180 degree thermostat, but 185 should work also.

[sanford66]

I think you have my trucks twin! Nice truck and welcome from Kansas. Joseph

[71swb4x4]

If your timing is too far advanced it can do the same thing.

[Meatman]

Originally Posted by 71swb4x4

If your timing is too far advanced it can do the same thing.

Another good idea there. That usually makes it hard to start too.

[bigsnookmaster]

Welcome to the board from Florida! Nice truck! And nice to see another chick into these trucks! You are at the right place!!!

[70cst]

and from Ohio. That is one truck you have.

[MagmaJct]

Clothes pins on a fuel line? Was that optional equipment for trucks destined for hot climates? Come on, we have a female who likely doesn't want to be "taken for a ride". Show some professionalism. Now for my comment...

In addition to the vapor lock problems, check the fuel pressure, as vapor lock can be a sign of a failing fuel pump. In addition, the problem could be over heating, float level set to high. What engine and carb does the engine have?

[68shortstep]

No BS ---- that clothespin thing works. Ugly, but it works.

My first car was a '50 Chev 2 dr & it had three clothespins on the metal fuel line to that mighty inline 6.

I thought: "What's this cr*p?" & took them off. Wouldn't start at all when it was hot. Put them back on, & it'd go.

I went "high-tech" & wrapped the fuel line loosely with aluminum foil, & that worked too. Didn't look much better than the clothespins, but it worked.

[cdowns]

have you checked to see if you have the right gascap? if you take the gascap off and here a wooshing pressure/vacume sound you have a bad gascap causing fuel starvation

[special-K]

I always run 180 degree thermostats in these trucks.

[OhOneWS6]

Originally Posted by MagmaJct

Clothes pins on a fuel line? Was that optional equipment for trucks destined for hot climates? Come on, we have a female who likely doesn't want to be "taken for a ride". Show some professionalism. Now for my comment...

In addition to the vapor lock problems, check the fuel pressure, as vapor lock can be a sign of a failing fuel pump. In addition, the problem could be over heating, float level set to high. What engine and carb does the engine have?

You comment is insulting. I am not "Taking anyone for a ride". I have personally used this method to trouble shoot several times. Ask any mechanic from the age of carburetors and he will tell you it works. I not only gave you the tool, I provided an explanation as to why it works. The other theory is that is acts as an insulator and protects the line from the surrounding heat. Either way, it is an inexpensive easy tool to help in diagnostics. If it fixes the problem, you know you have a vapor lock issue and you can proceed to resolve it with a more permanent solution. IE check fuel pressure, re-route the fuel line etc... etc... etc...

Even though you were being a smart ass I will answer your ridiculous question about new trucks in hot climates, Obviously clothes pins on the fuel line was not an option. When these trucks were new off the line they did not have weak fuel pumps, re-routed fuel lines or any number of other changes that may cause a vapor lock issue. Seems to me you are the one who needs to "show some professionalism."

[1970 Bowtie]

68shortstep and OhOneWS6,I would agree with you both,the clothes pin trick does work for trouble shooting the problem.My father was a hot rodder back in the 50's when there was not a speed shop or auto parts store on every corner.You had to make do with whatever parts you could find or salvage to build your car.(Rat Rod) I think the problem is in todays world is if you dont read it in a book or plug a cpu in to tell you whats wrong must people think its BS.Babydoll,did not mean to hijack your thread with my rant. and to the board.