Vapour Lock

[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.