Runs great except when it don't

[472viper]

64.5 coupe, generator car, 6cyl 170 automatic. Previous owner intalled manual choke. Has oem distributor, Petronix ignition and flame thrower coil.
Pull the choke all the way out, starts right up and runs great. Push choke half way in, let her warm up, all the way in and off we go. Little 6 cyl just runs great, smooth, no smoke, lousy acceleration but she really tries. Eng temp indicator usually reads about 1/4 up from cold. Everything is fine until I get in stop and go traffic. Sometimes, when setting at a stop light, while idling, the engine stumbles then quites. Starts right back up, some times needs alittle choke but always starts. Seems as if it happens when in alot of stop and go and the eng temp increases just slightly. Never gets to 1/2 between cold and hot, but if it goes past 1/4 is when idle problem occurs. Any ideas as to why ?

 

[2Blue2]

sounds like a fuel filter, then check your timing.

 

[472viper]

sounds like a fuel filter, then check your timing.

I will do both of those. I haven't had the car long and those are both things I should check anyway. Thanks.

 

[2Blue2]

maybe vapor lock?

 

[472viper]

maybe vapor lock?

I don't think so because it starts back up right away with no waiting.

 

[wicked93gs]

When I still have the 200ci in mine, the car started easier than most modern cars, ran beautifully, but would sometimes stall out as I put it in gear on a hot day...ended up being the carb that was in dire need of a rebuild and was dumping too much fuel in that situation.

 

[rise66]

Welcome to the club. More than likely you have vapor lock and or fuel boiling due to the fuel in todays market boils at a much lower point. My fuel line was so hot your could not even touch it for more than a second. Here's what I have found at this point and the thing I have done.
1. Rebuild the carburetor (helped lower the temp of the fuel line but did not totally fix the problem), Purchased the carb kit from Mikes carburetor. Watch his video's on line.
2. Check the radiator for proper operation. I found mine was circulating but had a lot of blocked tubes due to age. replace the radiator more consistent operating temperature.
3. I installed a phenolic riser insulator raising the carburetor 3/8 of an inch. They also come in 1/2 depending on your clearance. (purchased on Ebay)

All three of these really helped but still not a 100 % fix. So after searching all over the internet and speaking with life long Ford mechanics I ran across you tube videos on vapor lock. I found that in the 60's and the 70's that Ford, Dodge, Plymouth and other used a vapor separator in the fuel line just after the mechanical fuel pump. This returns the access fuel and vapor to the fuel tank allowing a Constance flow of fuel preventing over heating of the fuel. These cars came with a return line to the fuel tank from the factory. This is the same as today with fuel injection has return lines to the fuel tank. This all made since to me so I saw a video of a guy drilling a hole in the sending unit and JB welding it in (not sure I wanted to do that) fixed his problem 100%. So I went on the hunt and found the WIX 33041 vapor separator. I also found out the Ford used three different ones. They had .04, .06, and .08 orifices. The Wix 33041 has a .06 orifice in it and was used on 70 chevys. I also read about electric fuel pumps electric fans but this made the more since to me. I found on EBAY a fuel sending unit for 64 - 68 Mustangs with a 1/4 inch return line built in with a check ball only allowing fuel and vapor to return to the tank sold by MCM products. They also sell them on Summit racing but are twice the price. I also ordered 1/4 aluminum fuel line from Speedway racing parts and the filter from O'reilly auto parts.

Fuel sending unit 39.50
Vapor Separator 8.00
Fuel line 15.00
I will be installing this this coming Tuesday when my buddy's lift is free. I have 100% confidence this will be the cure!!
Will update soon!!

"

 

[472viper]

Welcome to the club. More than likely you have vapor lock and or fuel boiling due to the fuel in todays market boils at a much lower point. My fuel line was so hot your could not even touch it for more than a second. Here's what I have found at this point and the thing I have done.
1. Rebuild the carburetor (helped lower the temp of the fuel line but did not totally fix the problem), Purchased the carb kit from Mikes carburetor. Watch his video's on line.
2. Check the radiator for proper operation. I found mine was circulating but had a lot of blocked tubes due to age. replace the radiator more consistent operating temperature.
3. I installed a phenolic riser insulator raising the carburetor 3/8 of an inch. They also come in 1/2 depending on your clearance. (purchased on Ebay)

All three of these really helped but still not a 100 % fix. So after searching all over the internet and speaking with life long Ford mechanics I ran across you tube videos on vapor lock. I found that in the 60's and the 70's that Ford, Dodge, Plymouth and other used a vapor separator in the fuel line just after the mechanical fuel pump. This returns the access fuel and vapor to the fuel tank allowing a Constance flow of fuel preventing over heating of the fuel. These cars came with a return line to the fuel tank from the factory. This is the same as today with fuel injection has return lines to the fuel tank. This all made since to me so I saw a video of a guy drilling a hole in the sending unit and JB welding it in (not sure I wanted to do that) fixed his problem 100%. So I went on the hunt and found the WIX 33041 vapor separator. I also found out the Ford used three different ones. They had .04, .06, and .08 orifices. The Wix 33041 has a .06 orifice in it and was used on 70 chevys. I also read about electric fuel pumps electric fans but this made the more since to me. I found on EBAY a fuel sending unit for 64 - 68 Mustangs with a 1/4 inch return line built in with a check ball only allowing fuel and vapor to return to the tank sold by MCM products. They also sell them on Summit racing but are twice the price. I also ordered 1/4 aluminum fuel line from Speedway racing parts and the filter from O'reilly auto parts.

Fuel sending unit 39.50
Vapor Separator 8.00
Fuel line 15.00
I will be installing this this coming Tuesday when my buddy's lift is free. I have 100% confidence this will be the cure!!
Will update soon!!

"

VERY interesting, please post how it works for you. I am kind of suspecting bad fuel. The coupe had sat from November to 1st week in April. Tank was full when I left in November and I did use stabilizer but it acted up a bit on this tank of fuel. I am on a fresh tank of fuel now, and all seems fine but.....it has cooled off alot lately so I will have to wait for warmer weather to replicate conditions. I'll do some research on vapor separator but looks like you've done the heavy lifting.

 

[rise66]

I installed the Vapor Separator yesterday everything went well, really easy with the aluminum line bending it to match the fuel line. I drove the car reaching operating temperature and continued driving for another 30 minutes with no stalling at stops or sputtering. Turned car off and waited 20 minutes checking for restart problems and listening to the carburetor for fuel boiling. I did not hear any indication that it was, so let's try starting it, fired right up no problem. Next I drove about 30 minutes and stopped to refuel (no ethanol) loosened the gas cap and I could hear the release of pressure so that told me the Vapor separator was operating correctly. Filled the tank went inside to pay and returned. Turned the key and fired right up! So now I will continue driving and look forward to see what happens in 90 degree weather. I due believe I have found the cure!

For stabilizing your fuel go to VP Racing on line and they have one that can keep the fuel stable for up to 2 years.

 

[472viper]

Well mine is not bad fuel. Temps around here finally hit 80's last week. Went out on the hiway and run her up pretty good for about 15 minutes. Headed into town and first stop light she died. Oddly I don't have to wait any time at all before it restarts but it dies again soon as I put in drive. But, I agree with your diagnosis, vapor lock. I am going to try a simpler fix before I go the route of vapor separator. I am going to try using rubber fuel line and route away from engine block sooner. Also my oem fuel line has a real tight radius right out of the fuel pump. Rubber line will fix that. Also I recieved from Jeggs fuel line wrap that is reflective and should dissapate some heat. A phenolic riser would be easy also. I'll try those first.