Fuel line heat wrap addition - reduce vaporlocking

[BrandonMc]

Hi,

Update on something you may be interested to see. Because of Vaporlocking, I've been meaning to wrap the fuel line with hot-rodders fuel line heat wrap. It works kind-of like a chinese finger trap. Unfortunately, the old line needs to go, because the wrap will not fit over the nuts.

This will be nice to do at this time, as I currently have plenty of access after removing the radiator. The belts are all new, and the radiator has been professionally rodded and cleaned at the shop. This heat wrap is hopefully the solution to the dreaded vapor locking that has stranded me along the road and became an issue for the ole 454. This was suggested by someone else over the internet.

[BrandonMc]

After removing the wiring to the alternator, and a few hoses, I was able to bend the line down near the engine and fab a double flare on the 3/8" line with that kit. The other end came already prepared. Will report back on any improvements, although I would expect more cooling with the whole approach to the front end. Supposed to reflect 60% of heat from the line.   

[stanDman111]

got a part number & a supplier name  for the heat wrap?

[Froggy1936]

  If your original fuel lines run inside the frame rails move them to the outside ! Frank

[cook elandan]

Brandan, do you have a fuel pump in the tank also. This was added to help with vapor lock.  without the tank pump what i read stated that the vapor lock would happen somewhere between the tank and the mech. pump.  If you have the tank pump, then you are going in the right direction with insulation the fuel line to the carb and moving it away from any heat source.

[Warren]

Link to Thermo Tec products.   Click on products.  Have used their products for years on hot rods, etc.
Used their exhaust header wrap on the Onan genset in the Brave when we did a overhaul.  While it was out,
detailed in genset 'box' with two types of sound deadener,  and wrapped the exhaust pipe from the  genset down
to the muffler. 
Purchase from Summit Racing on line.   http://www.thermotec.com/

[Rickf1985]

Frank, That is the 1/2" fuel line coming in from the tank. Since it is 1/2" that tells me you have the in tank pump. Have you ever checked to make sure that pump is working and the regulator is getting the proper pressure up to the front pump? That will eliminate all of your vapor lock problems. If you have 1/2" fuel line from the tank and an inoperative pump you will almost never be able to draw fuel that distance with the mechanical pump. Also, have you changed the fuel filter along the passenger side frame rail roughly by the entry step?

[legomybago]

It's possible he doesn't have the in tank pump with the 1/2" line, our 1985 chassis rig has factory 1/2" fuel line with no factory in tank fuel pump. I think chevy added the 1/2" line with the return line system to help aid in vapor lock issues before they actually fixed the issue correctly by adding the electric pump set up.

The only way to fix vapor lock issues on your rig is to have an electric fuel pump. Todays fuel blends are prone to vapor lock issues.

[BrandonMc]

got a part number & a supplier name  for the heat wrap?

Hi, I purchased it on amazon, and it was made by heatshield products. I almost did a product shot. It's made of fiberglass and is similar to a spark plug hot-rodder heat shield.

In the first picture Is that a radiator hose laying against the fuel pump ? If so that is a definate no no N:(  and will cause vapor lock heating the fuel syestem in any way is bad   The veh was not designed that way some one has put the wrong hose on there !  If your original fuel lines run inside the frame rails move them to the outside ! Frank

I'll trace it down, thanks for the tip. It was like this when I purchased, so it hasn't yet been a consideration.

Have you ever checked to make sure that pump is working and the regulator is getting the proper pressure up to the front pump? That will eliminate all of your vapor lock problems. If you have 1/2" fuel line from the tank and an inoperative pump you will almost never be able to draw fuel that distance with the mechanical pump. Also, have you changed the fuel filter along the passenger side frame rail roughly by the entry step?

I have not yet checked the rear tank pump at all, however I have replaced the fuel pressure regulator that was leaking on the trip up to the engine. Hopefully my March trip won't see too hot of weather. I will make a note to do inspect the tank fuel pump at some point. Also yes, I did repair the in-line fuel filter and dry rotting fuel hose near the step, and totally rebuilt the carburetor and the small fuel filter there as well.


Thanks for the note about the in-tank pump, good to know its there.

Brandan, do you have a fuel pump in the tank also. This was added to help with vapor lock.  without the tank pump what i read stated that the vapor lock would happen somewhere between the tank and the mech. pump.  If you have the tank pump, then you are going in the right direction with insulation the fuel line to the carb and moving it away from any heat source.

I'll check this after a few more items up front. Thanks for the note, I have been putting it off for sure.                               

[Rickf1985]

It's possible he doesn't have the in tank pump with the 1/2" line, our 1985 chassis rig has factory 1/2" fuel line with no factory in tank fuel pump. I think chevy added the 1/2" line with the return line system to help aid in vapor lock issues before they actually fixed the issue correctly by adding the electric pump set up.

The only way to fix vapor lock issues on your rig is to have an electric fuel pump. Todays fuel blends are prone to vapor lock issues.

He has an 88, it should have electric pumps in the tanks.
If the relay is bad then it probably is not feeding either tank. And if you used the wrong spring from the regulator kit then it will not pass any gas under pressure because the tank pump only puts out around 15 lbs. pressure.

[BrandonMc]

If the relay is bad then it probably is not feeding either tank. And if you used the wrong spring from the regulator kit then it will not pass any gas under pressure because the tank pump only puts out around 15 lbs. pressure.

interesting... i remember using the most comparable spring to the older one. Maybe I still have the other ones on hand somewhere, will keep an eye on it.

[Rickf1985]

Are the pumps running? You should hear it run for 3-5 seconds when the key is turned on if you have the gas cap off and your ear to the hole and someone turns on the key. Or if you hold a broom handle against the tank and the other end in your ear. The odds are with two tanks if you have a good pump relay then at least one should work.

[BrandonMc]

a review of the aforementioned heat wrap for the forum... I believe at low speeds, it can help shield the heat away from the line. Ran hot at more than several lights on the way home, and it it didn't sputter. I was a little worried after driving all the way home.

Still vaporlocked going up the road at speed - at nearly the exact area/hill/incline that it has in the past while carrying much more weight this time. I had researched a little, and came to a post about vaporlocking bulletin cause and cure, so I can finally have the awesome responsibility to figure out the best way to siphon gas and get this tank dropped to replace the pump if its bad...

Or possibly test this relay first?

single 50gal tank

Are the pumps running? You should hear it run for 3-5 seconds when the key is turned on if you have the gas cap off and your ear to the hole and someone turns on the key. Or if you hold a broom handle against the tank and the other end in your ear. The odds are with two tanks if you have a good pump relay then at least one should work.

for some reason, I can never remember to get myself back under there when I have an extra set of hands. At this point though, it's all but certainly bad. Thanks for the tip, will report back.

[tmsnyder]

It's easy to check the in tank fuel pump, first listen for it or have someone with good ears listen for it when you turn the key on, before starting it. It's like a humming noise from the fuel tank area.


If your helper doesn't hear it, you may have a bad fuel pump relay.  There is a way to jumper the relay to turn on the pump, there are entire threads devoted to this, and that infamous relay so just search for it. Hopefully it's not this.



If you do hear it, at least you know the fuel pump relay is working.  The next step would be to check for pressure at the mechanical pump inlet to see if that electric lift pump is working.  That's a bit of a pain if the engine is covered up, wheels on, etc, so I just simply loosened the fitting at the fuel filter which is along the frame pretty much under the front passenger's seat.   You did change that fuel filter right?  My RV has an access hole covered by a cloth wrapped rectangle of plywood held on with 4 screws.  Just take out the screws and remove the cover and there is the filter.  Loosen the rear fitting and see if fuel starts to come squirting out, have a catch can ready.


If you do, then you know you have a working fuel pump!  If no squirt, then you need to figure out why, but at least then you would know why you are getting vapor lock.

[Rickf1985]

Another item is the fuel pressure regulator. Although they are famous for leaking, it is a regulator and they can fail open or closed. If it fails closed or mostly closed it will block the volume of fuel needed at wide open throttle. Most people do not realize just how much gas is being consumed at wide open throttle by a big block. At wide open throttle you can be sucking a gallon per minute or more. Take a gallon milk jug and fill it with water and start pouring it out and timing it, you will be amazed!