Symptoms of vapor lock

[Michaelgt450]

I have a 73 Dodge Charger 400 big block I think is suffering from vapor lock it turns on fine when it's cold then when it's hot it has a hard time turning on also while I'm driving sometimes it all of a sudden loses power and then it gets power.. are these signs of vapor lock?
What I have is a 750 Edelbrock Carburetor with the Heat Insulator gasket

[Todd Wilson]

My experience living in Kansas with 100+ summer temps is vapor lock rarely occurs. Very rare.  I highly doubt its vapor lock in February.  Sounds like ignition timing and perhaps some carb adjustment!



Todd

[Gold Rush]

When I bought my second '74 SE Brougham and brought it home to Texas (it spent its entire prior life in Las Vegas) several years ago, I found the original owner had put an insulation cover over the steel gas line from pump to carburetor.  I imagine he had some Vapor Lock issues back then.

I know it gets HOT here but maybe not enough to boil the gas in the lines.  I have never experienced Vapor Lock on any vehicle.  I did see it once on a motorhome pulling a heavy trailer up a very steep hill.  The engine died right in the middle of a second steep grade.  No stutter or missing.  Just instant shutdown.

I suppose there are various levels and symptoms of Vapor Lock but before you chase that possibility, swapping out the coil might save you some time, energy, and money.  Slip a know good coil in and give it a try.  Might do the trick.

Good luck on that journey.  

[NHCharger]

How close is the fuel line to the exhaust manifold/exhaust? Try insulating the fuel line between the pump and carb.

[Gold Rush]

If original the line routes up behind the alternator bracket and over the engine front close to the distributor then along the passenger side valve cover next to the carb.  Shouldn't get anywhere close to manifold.

[Michaelgt450]

My experience living in Kansas with 100+ summer temps is vapor lock rarely occurs. Very rare.  I highly doubt its vapor lock in February.  Sounds like ignition timing and perhaps some carb adjustment!



Todd

I had my car Dyno Tuned the guy that tuned it put it at 36 total timing maybe I'll look at the carburetor adjustment or lower the timing

[Michaelgt450]

How close is the fuel line to the exhaust manifold/exhaust? Try insulating the fuel line between the pump and carb.

The fuel lines were close to the exhaust how is it supposed to be routed do you have any pictures... I'll try insulating the fuel line I'll put some heat shield on the rubber hose

[Michaelgt450]

If original the line routes up behind the alternator bracket and over the engine front close to the distributor then along the passenger side valve cover next to the carb.  Shouldn't get anywhere close to manifold.

Ohhh okay I'll try to Route it that way... I was working on the car today and I noticed one of the screws on my ignition control module was kind of loose I tightened it up where is the fuel filter supposed to be at on top of the intake manifold or by the fuel pump also is it supposed to be a hose or Steel hose for the fuel line

[Michaelgt450]

When I bought my second '74 SE Brougham and brought it home to Texas (it spent its entire prior life in Las Vegas) several years ago, I found the original owner had put an insulation cover over the steel gas line from pump to carburetor.  I imagine he had some Vapor Lock issues back then.

I know it gets HOT here but maybe not enough to boil the gas in the lines.  I have never experienced Vapor Lock on any vehicle.  I did see it once on a motorhome pulling a heavy trailer up a very steep hill.  The engine died right in the middle of a second steep grade.  No stutter or missing.  Just instant shutdown.

I suppose there are various levels and symptoms of Vapor Lock but before you chase that possibility, swapping out the coil might save you some time, energy, and money.  Slip a know good coil in and give it a try.  Might do the trick.

Good luck on that journey.  

I just ordered an Accel ignition coil cross my fingers hope it works

[b5blue]

Get a cheap laser pointed heat reading gun and start checking temps. 

[Gold Rush]

Ohhh okay I'll try to Route it that way... I was working on the car today and I noticed one of the screws on my ignition control module was kind of loose I tightened it up where is the fuel filter supposed to be at on top of the intake manifold or by the fuel pump also is it supposed to be a hose or Steel hose for the fuel line

The line from the pump to carburetor is one solid formed steel line.  Don't know if it's available new still or not.  If you can locate one then you'll see how the routing goes...  That being said, The filter has to go between the hard line from tank to the rubber line connecting to the pump input.

[Michaelgt450]

Ohhh okay I'll try to Route it that way... I was working on the car today and I noticed one of the screws on my ignition control module was kind of loose I tightened it up where is the fuel filter supposed to be at on top of the intake manifold or by the fuel pump also is it supposed to be a hose or Steel hose for the fuel line

The line from the pump to carburetor is one solid formed steel line.  Don't know if it's available new still or not.  If you can locate one then you'll see how the routing goes...  That being said, The filter has to go between the hard line from tank to the rubber line connecting to the pump input.

Is this it
https://www.ebay.com/itm/284264553771?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1uiRffOrjQDaUE9HIteKw8g9&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=284264553771&targetid=1599090335417&device=m&mktype=&googleloc=9031569&poi=&campaignid=15275224983&mkgroupid=131097072938&rlsatarget=pla-1599090335417&abcId=9300697&merchantid=131376395&gclid=CjwKCAiAyPyQBhB6EiwAFUuakk6yQlopzSIRCYTEGyTqgEruQT42aIQptiumDHKltNUBIWbiUt23BhoCw20QAvD_BwE

[JimShine]

I used to think I was getting it. I noticed it when the car got really hot, it would have moments where it would sputter during acceleration. It went away after I changed my entire fuel line and pickup. My car was a factory 2bbl setup and I tried to cheap out and use the factory line and pickup with a new 4bbl carb and intake. Going to the proper larger size solved that issue.

[Gold Rush]

Is this it
https://www.ebay.com/itm/284264553771?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1uiRffOrjQDaUE9HIteKw8g9&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=284264553771&targetid=1599090335417&device=m&mktype=&googleloc=9031569&poi=&campaignid=15275224983&mkgroupid=131097072938&rlsatarget=pla-1599090335417&abcId=9300697&merchantid=131376395&gclid=CjwKCAiAyPyQBhB6EiwAFUuakk6yQlopzSIRCYTEGyTqgEruQT42aIQptiumDHKltNUBIWbiUt23BhoCw20QAvD_BwE

That one is for a 318 engine.  You are on the right track but not quite there.  I looked around some and think this one is close.  Can't find one for a '74 but the '73 400 engine should be the same I think.  Here is the part #:  RPC7301OM-CPP

Look at a few others in the examples.  Once you do, scroll down to the Compatibility table. Make sure you find a 6.6l or 400 cid engine listed.

[Michaelgt450]

I used to think I was getting it. I noticed it when the car got really hot, it would have moments where it would sputter during acceleration. It went away after I changed my entire fuel line and pickup. My car was a factory 2bbl setup and I tried to cheap out and use the factory line and pickup with a new 4bbl carb and intake. Going to the proper larger size solved that issue.

This car used to be a 2 barrel carburetor also... I'm a try what you're doing do you have any part numbers or links to the fuel line and pick up??

[JimShine]

I bought my parts in person from vendors at Carlisle. You will just have to do some shopping online. You want the 3/8" diameter line and sending unit.

[Michaelgt450]

Is this it
https://www.ebay.com/itm/284264553771?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1uiRffOrjQDaUE9HIteKw8g9&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=284264553771&targetid=1599090335417&device=m&mktype=&googleloc=9031569&poi=&campaignid=15275224983&mkgroupid=131097072938&rlsatarget=pla-1599090335417&abcId=9300697&merchantid=131376395&gclid=CjwKCAiAyPyQBhB6EiwAFUuakk6yQlopzSIRCYTEGyTqgEruQT42aIQptiumDHKltNUBIWbiUt23BhoCw20QAvD_BwE

That one is for a 318 engine.  You are on the right track but not quite there.  I looked around some and think this one is close.  Can't find one for a '74 but the '73 400 engine should be the same I think.  Here is the part #:  RPC7301OM-CPP

Look at a few others in the examples.  Once you do, scroll down to the Compatibility table. Make sure you find a 6.6l or 400 cid engine listed.

Thank you I will look... will this one work https://www.ebay.com/itm/143868759695?hash=item217f3f0e8f:g:4q4AAOSw--hg3KYG

[Gold Rush]

I just don't know for sure.  I looked at photos I took several years ago when first bought my '74 SE  that does not look the same.  Have also looked at several vendors and '74 model year anything seems to be very rare.  I'd hate to tell you that line would work and then it NOT. 

I know you are running rubber hose now and that gets gas to the carb.  If miss and sputter continues just maybe the insulation will solve the issue.  Maybe someone has one and will offer it to you...

Good Luck...

[JimShine]

I changed the entire tank to pump fuel line to the larger size. Yours would be like this:

https://www.inlinetube.com/products/sdbf7302

[Gold Rush]

I think for the most part we have been discussing the line from the fuel pump up to the carburetor; not the one from the gas tank to the fuel pump.  I agree part of the equation should probably be replacing the original tank to pump line with the 3/8 inch steel line. As you know it's not easy but can be done.  I used the same new line as you did.

As I said earlier, the rubber fuel line hose will work and might benefit from adding insulation.  Ideally, the original steel line (and maybe insulated also) would be my choice. 

[Michaelgt450]

I think for the most part we have been discussing the line from the fuel pump up to the carburetor; not the one from the gas tank to the fuel pump.  I agree part of the equation should probably be replacing the original tank to pump line with the 3/8 inch steel line. As you know it's not easy but can be done.  I used the same new line as you did.

As I said earlier, the rubber fuel line hose will work and might benefit from adding insulation.  Ideally, the original steel line (and maybe insulated also) would be my choice.  

I will add installation to the rubber fuel line and add a new ignition coil hopefully this will work.. the only problem is that the new ignition coil comes tomorrow

[6pkrtse]

Try an insulated carb spacer. Phenolic or one of those laminated wood spacers. I had this problem on a car with the fuel bowling in the bowl which made it feel like vapor lock. The problem went away after I installed the spacer.

[b5blue]

I'm using a Jomar brand spacer. Nice product. 

[Michaelgt450]

Thank you all for your replies and suggestions I think I finally found the problem I think it was the ignition coil I put a new ignition coil and Bam no more hard starting when it's hot... I also relocated the ignition coil originally I had it on the intake manifold I put it back on the fender where it Factory came at and it's been running good ever since

[Todd Wilson]

Good to hear!


Todd