Beating Back Vapor Lock
We spent 2 years restoring a 1968 Toyota Land Cruiser. We rebuilt the original 3.9 liter inline 6, all 135 HP worth. With a 3 on the tree, it is very very nostalgic to cruise through town and the local back roads. During the restoration we added a auxiliary fuel tank and Vintage Air Conditioning. With the auxiliary tank, we added a 3 way valve that allows switching between the the original tank and auxiliary tank. Fuel is supplied to a Rochester B series single barrel carburetor through a Facet electric (solid state) fuel pump. So between the AC, and local summer temperatures that run in the 90 to 100 degree range, I had a terrible time with vapor lock. The issue was further exacerbated buy running on pump gas at up to 15% ethanol.
I blame myself for some of the problem, I installed the fuel pump, the 3 way valve and the fuel filter in the engine compartment. Actually built a sweet little mountain plate just aft of the battery support bracket. With all of the fuel delivery components inboard to protect from water spray and on a hot day, the 200 plus degree air from the radiator and AC condenser would heat the fuel delivery components until you could hear the fuel pump rattle (a true death rattle) as the fuel flashed to vapor and the pump lost suction.
Now, most of you will say, just move the fuel pump, valve and filter to under the vehicle and closer to the fuel tank(s) and problem solved. That wouldn’t have been an easy task since I ran all of the fuel lines inside of the frame rails....out of sight....protected...impossible to get to. I saved that for a last resort. Or maybe find non-ethanol gas...in the area we live in, 300,000 residents, there are only 3 stations that carry it...and they are way way out of the way.
My first attempt at curing my design oversight was using DEI aluminized silicon sleeving over the fuel lines from the 3 way valve all the way to the carburetor. This partially corrected the problem. However, in town, idling for any length of time, engine compartment temperatures still caused the fuel to flash at fuel pump, starving the carburetor.
As a final solution, I ended up building an insulated heat shield out of thin gage aluminum and lining it with Noico sticky back sound and heat insulation. I also ran the AC drain hose to the base of the fuel pump. There were several iterations of this shield. It worked better each time, but didn’t quite cure the issue. The final iteration, completely covering the pump, valve and filter has, ‘dare I say’, cured my vapor lock issue.
The other item that seemed to help ‘heat soak’ at the carburetor and hard starting after sort engine shutdowns, was insulation the exhaust pipe using Heat Shield Products 1/4 inch ceramic and aluminum blanket material. The original cast iron exhaust manifold was ceramic coated during the restoration, mostly for aesthetics, but I think between that and the exhaust pipe insulation, they keep that side of the engine compartment at a more reasonable temperature. I’m still playing with the pipe insulation but it all helps.
Back to the fuel system.....after a good longe drive on a 90 degree day, at engine coolant temperatures upwards of 212 to 215, the fuel pump area was at ambient....sill at 90 degrees.
We run a Dakota Digital, and I set the engine temperature warning feature at 210. Anything over 210 degrees flashes the temperature in the odometer window. As all of you know, with a 12 psi cap, 50/50 antifreeze, and a 180 degree thermostat, anything under 220 at speeds in excess of 60 on a 100 degree day are pretty darn good for these old rigs, especially with the AC at full blast. Around town, I never see the rig over 190 or so. Of course...that’s putt putting around at 35 and 40.
So between modern insulation material and the AC drain hose blowing just a tiny bit of cool air across the fuel delivery components, I can burn modern fuels without having to pull over with the hood up, waiting for the engine to cool.....and I can keep my sweet mounting bracket that looks cool but caused all of the problems to begin with.
Original Install (Nice and Neat but ‘Oh’ the Heat!)
Heat Shield with Noico Insulation (under the truck looking forward)
DEI Fuel Line Insulation
Heat Shield Products Exhaust Pipe Insulation
We spent 2 years restoring a 1968 Toyota Land Cruiser. We rebuilt the original 3.9 liter inline 6, all 135 HP worth. With a 3 on the tree, it is very very nostalgic to cruise through town and the local back roads. During the restoration we added a auxiliary fuel tank and Vintage Air Conditioning. With the auxiliary tank, we added a 3 way valve that allows switching between the the original tank and auxiliary tank. Fuel is supplied to a Rochester B series single barrel carburetor through a Facet electric (solid state) fuel pump. So between the AC, and local summer temperatures that run in the 90 to 100 degree range, I had a terrible time with vapor lock. The issue was further exacerbated buy running on pump gas at up to 15% ethanol.
I blame myself for some of the problem, I installed the fuel pump, the 3 way valve and the fuel filter in the engine compartment. Actually built a sweet little mountain plate just aft of the battery support bracket. With all of the fuel delivery components inboard to protect from water spray and on a hot day, the 200 plus degree air from the radiator and AC condenser would heat the fuel delivery components until you could hear the fuel pump rattle (a true death rattle) as the fuel flashed to vapor and the pump lost suction.
Now, most of you will say, just move the fuel pump, valve and filter to under the vehicle and closer to the fuel tank(s) and problem solved. That wouldn’t have been an easy task since I ran all of the fuel lines inside of the frame rails....out of sight....protected...impossible to get to. I saved that for a last resort. Or maybe find non-ethanol gas...in the area we live in, 300,000 residents, there are only 3 stations that carry it...and they are way way out of the way.
My first attempt at curing my design oversight was using DEI aluminized silicon sleeving over the fuel lines from the 3 way valve all the way to the carburetor. This partially corrected the problem. However, in town, idling for any length of time, engine compartment temperatures still caused the fuel to flash at fuel pump, starving the carburetor.
As a final solution, I ended up building an insulated heat shield out of thin gage aluminum and lining it with Noico sticky back sound and heat insulation. I also ran the AC drain hose to the base of the fuel pump. There were several iterations of this shield. It worked better each time, but didn’t quite cure the issue. The final iteration, completely covering the pump, valve and filter has, ‘dare I say’, cured my vapor lock issue.
The other item that seemed to help ‘heat soak’ at the carburetor and hard starting after sort engine shutdowns, was insulation the exhaust pipe using Heat Shield Products 1/4 inch ceramic and aluminum blanket material. The original cast iron exhaust manifold was ceramic coated during the restoration, mostly for aesthetics, but I think between that and the exhaust pipe insulation, they keep that side of the engine compartment at a more reasonable temperature. I’m still playing with the pipe insulation but it all helps.
Back to the fuel system.....after a good longe drive on a 90 degree day, at engine coolant temperatures upwards of 212 to 215, the fuel pump area was at ambient....sill at 90 degrees.
We run a Dakota Digital, and I set the engine temperature warning feature at 210. Anything over 210 degrees flashes the temperature in the odometer window. As all of you know, with a 12 psi cap, 50/50 antifreeze, and a 180 degree thermostat, anything under 220 at speeds in excess of 60 on a 100 degree day are pretty darn good for these old rigs, especially with the AC at full blast. Around town, I never see the rig over 190 or so. Of course...that’s putt putting around at 35 and 40.
So between modern insulation material and the AC drain hose blowing just a tiny bit of cool air across the fuel delivery components, I can burn modern fuels without having to pull over with the hood up, waiting for the engine to cool.....and I can keep my sweet mounting bracket that looks cool but caused all of the problems to begin with.
Original Install (Nice and Neat but ‘Oh’ the Heat!)
Heat Shield with Noico Insulation (under the truck looking forward)
DEI Fuel Line Insulation
Heat Shield Products Exhaust Pipe Insulation
