Fuel pump repair kit

[Knightowl61]

Have you tried a different pump, such as an electric one just to see if it's any different?

I've tried 2 different pumps with 2 different new kits.
IDEA -to keep original looking could I put an electric pump near the spare tire and leave everything else the same?
If not I should be able to pop out the check valves and pull out the lever assembly.

 

[Knightowl61]

One other test, plumb gauge to end of fuel pipe at rear of vehicle which goes to fuel pump inlet, run engine. Should reach 18 plus inches (takes longer to pull vacuum on long line) and it should hold that. My thinking is a leak in that line would produce your symptoms. Cold it may suck fuel and a little atmospheric air; hot the fuel vaporizes instead of being drawn. Or, a combination of restriction and leak back there. One last thought, since you worked on the rear fuel system, there is a chance the problem originated with that work.

Sorry, I don't understand your post. "plumb gauge" (vacuum gauge?), "to end of fuel pipe at rear of vehicle which goes to fuel pump inlet" {disconnect fuel line at the gas tanks?), "run engine" {how if the fuel line is plugged?).
The engine gets hot which gets the fuel pump hot, the gas tanks and fuel line to the pump remain at near air temperature.
I will check the lines to the tanks and try an electric pump .

The ol gray matter..it aint what it used to be.....aint what it used to be......aint what it used to be...

 

[sunalp]

I've tried 2 different pumps with 2 different new kits.
IDEA -to keep original looking could I put an electric pump near the spare tire and leave everything else the same?
If not I should be able to pop out the check valves and pull out the lever assembly.

That's what I'd try just to see if that solves the problem, even if it's temporarily. I get the originality aspect, but reliability is important too. I've mounted electric pumps where you suggest and it works out fine.

 

[Shannon Boal]

Sorry, I don't understand your post. "plumb gauge" (vacuum gauge?), "to end of fuel pipe at rear of vehicle which goes to fuel pump inlet" {disconnect fuel line at the gas tanks?), "run engine" {how if the fuel line is plugged?).
The engine gets hot which gets the fuel pump hot, the gas tanks and fuel line to the pump remain at near air temperature.
I will check the lines to the tanks and try an electric pump .

The ol gray matter..it aint what it used to be.....aint what it used to be......aint what it used to be...

OK, sounds good. I think you will like the electric pump mounted near the tank. Hope to hear how you mount, wire and plumb it. If it is also good at preventing vapor lock, I may go that way myself!.....
(re misunderstanding: connect vacuum gauge to line at tank allows you to see if pumps sucks and holds vacuum, reveals any vacuum leak between pump inlet and tank outlet. Engine will run if gas is in carburator.) Now if fuel line were to be plugged a teed in vacuum gauge would measure a restriction.....it should be less that 2" during a twenty minute road test.) This is a fuel tank, a fuel line to the pump, and a fuel line to the carburator. You have substituted a fuel pump or two. The line to the tank may leak vacuum or be kinked. There is not much left, you are CLOSE to fixing this!

 

[Knightowl61]

I installed a 2.5-4 psi electric pump near the gas tank outlet and tested with the mechanical pump in the engine and got a good flow going thru the pump to the disconnected line at the carb. Also the manual pump works (cold). After the engine was hot, the mechanical pump was warm but I could keep my hand on it without discomfort. Again disconnecting the line at the carb, the mechanical manual pumping (abiut 15 times) resulted in no gas and was getting bubbled in the glass bowl. Turned on the electric pump and gas flowed after about 15-20 seconds.
Apparently the gas is siphoning back to the tank. I put a check valve near the carb and after running the engine hot and stopping, the gas remains high with no bubbles in the glass bowl. IT WORKS - I"M DONE.

 

[sunalp]

That's great news! Check your gas tank filler cap as it is supposed to be vented to prevent the
siphoning back to the tank. The tanks can build pressure which can result in what you've experienced.

 

[Knightowl61]

That's great news! Check your gas tank filler cap as it is supposed to be vented to prevent the
siphoning back to the tank. The tanks can build pressure which can result in what you've experienced.

Good point, I double checked and couldn't hear any air pressure when opening the cap. The cap is new and I can easily blow or suck thru the vent holes.
Thanks all for your support.

 

[Barry]

A word to the wise from the school of hard knocks. A looong time ago, a friend installed an electric fuel pump in a "pass through the mechanical pump" setup. When the diaphragm in the mechanical pump ruptured, he quickly had an oil pan full of gasoline and every bearing in the engine was destroyed.

If I were doing a "pass through the mechanical pump" setup, I would remove the actuating lever (aka, the mechanical pump rocker arm) and replace the "rubber" diaphragm with something more substantial.

 

[Alpine 1789]

FWIW, I have long planned on installing an electric pump on my SV, but liked the idea of keeping the original pump on to have a ready back-up. My thought was to fill the pump with a really light oil, something like 3-in-1, and then loop the inlet and outlet to just have it circulate the oil to keep the diaphragm from drying out. If it did fail, it would only dump a cup or so of light oil into the sump, which shouldn't be an issue.

This is something I intended to share with the forum when I finally got around to putting the electric pump in, but now seems like as good a time as any. Good idea or yet another stupid one?

 

[Tim R]

Everything you are describing suggests fuel vaporisation to me. Remember modern fuel vaporises at a much lower temperature than the 1960s stuff did. Do your fuel lines run as standard or have you routed them round the back of the engine bay to cool the fuel? Also do you have a one-way fuel valve between pump and carb?
Tim R

 

[Knightowl61]

I'm thinking that if the check valves in the pump are working (missing or leaking) rout the gas lines to the pump like normal. Pull the cam lever out of the pump and put in a thick blocking plate that would resemble the insulation spacer. Remount the fuel pump and it would look like the original pump.
Per Tim R - Also have a one-way fuel valve between pump and carb.