Vapour Lock

[willincalgary]

Last summer when I was doodling around the US (cambrianadventures.blogspot.ca (http://Cambrianadventures.blogspot.ca)) I had some issues with vapour lock, particularly when temperatures got into the hundreds. I installed an electric fuel pump closer to my fuel tank selector valve and bypassed the mechanical fuel pump at the block. This mostly alleviated my problem of vapour lock but now I had to listen to the whine of a cheapo electric fuel pump when I drive around town.
Most of the time my truck does not have any issues with vapour lock as I live in relatively northern climes and the temperature is rarely hot enough. What I want to do is run the mechanical fuel pump again and have the electric plumbed in with a switch to activate it in case issues arise. Does anybody see any issue with running the electric fuel pump through the mechanical one, or vice versa? My ony concern is the mechanical fuel pump will now be constantly pressurized when the electric fuel pump is active. Thoughts?

[albersj51]

Make sure the mechanical pump is in good shape. If the diaphragm is bad, I am told you could push fuel into the engine and dilute your oil. Someone will correct me if I'm wrong. You could try a carter 4070 vane pump, which is quieter than the cheap Napa pulse pumps.

[mearstrae]

I use the Carter pump and hardly notice any noise. These pumps work best when closest to the tank, as they are pusher pumps. If you have a good elec. pump you hardly need a mech. one (although I've seen them being run in tandem). This would eliminate any problems with the diaphram failure on the mech. pump, and causing gas to get into your engine and kill the bearings or worse.

'95 R.R.C. Lwb
'76 Series III Hybrid 109
'70 Rover 3500S

[bugeye88]

I use a Facet solid state pump just after the mechanical one. I use it to fill float the float bowl after sitting for a time, to reduce the cranking needed to do this. Also good for hot days and vapor lock situations. On/off switch inside the cabin so usually I only use it for brief periods of time. No problem for the mechanical to push through this pump. It's a nice back up for the mechanical one also.

Rob

[SafeAirOne]

There are no problems running an appropriate fuel boost pump ahead of the mechanical pump--2.6l 109s have done this since the dawn of time.

[jeff kropp]

This is sort of off the mark, but in summer I carry a mister bottle of water. When hot weather VL prevents starting, I spray from fuel pump to the carb, wait 5 min., and start. Someday will try electric pump.

[SafeAirOne]

I wonder if you'd get the same result without the spraying; Just open the hood?

[crankin]

I will back up that running both is not a problem. But like others have said, if the diaphragm is old in the mechanical pump you could push fuel into your oil...which could be bad.

I also run the carter and do not notice it running around town.

[jeff kropp]

Spraying hastens the recovery process compared with just opening hood. All depends on how hot the day is.

[SafeAirOne]

Spraying hastens the recovery process compared with just opening hood. All depends on how hot the day is.

Why not just pour water on it like lotsa folks do?

[ArlowCT]

I would disconnect the fuel line at the carb and turn the motor over until fuel came out the line. By placing the line in a catch can you can just dump the fuel back in the tank. Used this method to get back up and running in a min or so a whole bunch if times!

My dad blew some fuses one time with the bucket of water trick, so be careful with that one!

[SafeAirOne]

My dad blew some fuses one time with the bucket of water trick, so be careful with that one!

I imagine you want to keep it away from the stuff that can crack when shock-cooled too.

[JimCT]

LR's have spent much of their life in hot hot climates. I think what you are seeing as vapor lock is worn fuel pumps, not just the internals but the arm that rides on the cam. I think they only need an electric pump if there is something else amiss.




I imagine you want to keep it away from the stuff that can crack when shock-cooled too.

[ArlowCT]

Our fuels today are much different then they were back when these trucks were made. They are specially formulated to be used in sealed/pressurized systems and our rovers do not have that. The suction placed on the fuel line causes the fuel to turn to vapor at a lower temp helping raise the occurrence of vapor lock. Google vapor lock, Rovers are not the only old vehicle having this problem and the most common fix is removing the mechanical fuel pump and replacing with a electric.

[SafeAirOne]

Our fuels today are much different then they were back when these trucks were made.

They're getting worse too--The Supreme Court just refused to hear an appeal from automotive organizations who were trying to prevent the EPA from forcing 15% ethanol onto the market (http://www.dailytech.com/Supreme+Court+Kills+E15+Protest+Greenlights+Lower+ MPG+Destroyed+Engines/article31829.htm).

Stand by for even MORE vapor lock, diminished fuel economy and engine destruction than the current E10 (10% ethanol) gasoline is causing.

[Boston]

Amazed that I seem to be hearing about VL more frequently this year than ever before.
Weird.

[bugeye88]

As for the ethanol in fuel; remember always use a ethanol neutralizing fuel additive and a lead substitute when filling up. Ethanol has MANY negative effects on our Landy's.
Cheers,
Rob

[printjunky]

Another option. I use this in my old boat motor ('77) and should probably remember to use it more in the Rover ('73).

http://pure-gas.org/

[Opabob]

Reviving this thread. I was hoping someone could advise me on a couple of questions related to running an electric fuel pump. 1) it sounds like this Carter pump might be a good choice: Carter P60504 Electric Fuel Pump -- any thoughts pro or con? 2) I don't think anyone has mentioned installing an inertia cutoff switch. Is that just an obvious thing I should do? or would it just go off all the time because I have old springs and my truck rides like a coal cart? Any recommendations on which switch I should consider? Thanks for any thoughts on this!

[bugeye88]

A couple of things to consider when installing an electric fuel pump. First it should operate at low pressure 1 1/2 to 3 PSI I believe. The Carter or any other good pump will do. I would mount it after the mechanical pump with a filter between the electric pump and the carb. I have a switch under the dash that I can turn on or off when I want. Usually I'll switch it on on initial start up to fill the float bowel for a quick start up, then switch it off for running. When it's hot I'll leave it on to prevent any vapor lock condition. As far as an inertia switch, it's probably overkill in my opinion with the above operation followed.
Cheers,
Rob
68 series 2a "Bugeye"

[mearstrae]

Here's another way of installing the Carter fuel pump. Mount the pump as close to the fuel tank as possible (these are "pusher" pumps and work best at the back) and install a large fuel filter between the tank and the pump. On my Series I also covered the pump and filter with a stainless steel box to protect them off-road. At the front: remove the mechanical pump and fabricate a block-off plate (why have two pumps?), also add a fuel pressure regulator (I think my last install used an Edelbrock regulator). This will get the fuel line away from the engine somewhat and help prevent vapor-lock. I also add a cut-off switch on the dash between the (fused) ignition feed wire and the pump, instead of an inertia switch (these are only 6# pressure not 40#). Some folks add a return line near the regulator, this really isn't needed as Carter pumps have an internal return if they are pumping too much fuel.

'95 R.R.C. Lwb
'76 Series III Hybrid 109
'70 Rover 3500S

[siiirhd88]

I've had inertia switches trip from water pressure in a car wash, so I don't think one would function well on a bumpy Series. Holley, Carter and others make a low oil pressure cutoff switch, that shuts off power to the electric fuel pump at 7 or so psig oil pressure. They hava a bypass on engine cranking so that the pump operates before building up oil pressure, and you would need to add all the right T fittings.

Bob

[bugeye88]

The thing to remember if you are installing any electric pump as a "pusher" is to remove and block off the mechanical pump as described by mearstrae. The reason is if the diaphragm fails on the mechanical pump the electric will pump fuel into the crankcase.... Not Good! That's why in my case, where I'm using an electric on a part time basis, I mounted it after the mechanical as a "Puller" pump.
Cheers
Rob

[Opabob]

Thanks for the advice. It is good to get some opinions on this. My main problem is hard/no start with hot engine probably caused by vapor lock probably down around the pump. I also should have mentioned the previous owner installed a Weber carburetor.

[bugeye88]

I also run a Weber 34 ICT carb. I have found it to be an excellent set up. I've run Rochester's, which were a good carb also, but find the Weber has better milage and good running throughout the power band. As for the Vapor lock (if that's the real problem) the electric pump, wherever its placed, should cure that. The Weber is prone to clogging at the jet in the bottom of the float bowel, so use a good filter between the pump and the carb. Best of Luck on the fix.
Cheers
Rob

[siiirhd88]

A filter with a return line just before the carb helped on my 109. I had no problems while moving, but stopped in traffic or post engine shutoff I found the fuel boiling in the line underhood and in the carb bowl. The return on the filter allows a vent path back to the tank instead of the fuel in the carb and lines pushing into the intake manifold. It also helps by allowing a constant cooling flow thru the fuel line at slow speeds. I don't remember the part number, but I use a filter for a Chrysler product.

You would need to add a return line and fitting to the tank, if not already there.

Bob

[tmckeon88]

I had a similar problem of no restarting a hot engine in the summer, and I drilled a couple of holes through the inner surface of the gas filler cap- not entirely through, just through the inner lining, to allow air into the gas tank to replace the pumped fuel. Alternatively, if it vapor-locks you can try just loosening and re-tightening the gas cap. Never had a problem with it since. You might experiment with the gas cap trick before committing to having an aftermarket fuel pump installed.

Tom

[Opabob]

Thought I would update with a status. I tried all of the things suggested without results. So I went ahead and installed the electric fuel pump, adding in an aux fuse panel, dash switch and relay. So far no vapor luck; but it is not summer yet :) Also, the truck is running much better, so I am suspecting the mechanical pump was probably struggling. I did not want to replace the mechanical pump not knowing if it was the problem, but in retrospect, I suppose I could have got a fuel pressure gauge and checked it. Thanks to all for your suggestions.