404 petrol pump debate

Edmund

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Fellow Frogger
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Jun 17, 2012
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Location
Johannesburg, South Africa
Hi fellas. I recently got myself a 404 Automatique and we had issues with the fuel pump, my mechanic then gave me his used one which was good for about a week or so. I'm in the process of replacing it but when my mechanic came over yesterday, he advised that I would have non-stop problems with petrol pumps because to his surprise, there's no oil between the petrol pump and the engine block where the pump attaches....the pin from the block that presses against the pump is nice and moist, so there is oil in the engine but he says there should be a little bit more oil coming out of the engine to surround the pump area so that the pump and its components are nicely lubricated otherwise the pump will have a shorter lifespan. He also mentioned that's another reason there's a gasket between the pump and the block, to prevent this oil from leaking. He warned that he needs to strip the block to investigate this issue before I waste money on a new pump that won't last long. Oil circulation seems to be fine though across the engine......when we first started the car, we did so with the tappet cover removed, oil reaches the tappet area like it should. What do you guys think? Do we have reason to strip the block or should I just fit a new petrol pump and hit the road? Thanx in advance
 
There's a little of oil action going on inside the bottom part of the fuel pump.
Usually if the fuel pump fails, the culprit would be the diaphragm.
Another thing is that there is a wire mesh sort filter in the fuel tank, over the years it gets clogged up, I have removed mine, replacing it with one of the newer after market fuel filter fitted just before the fuel pump.
 
That oil action you are referring to isn't present on mine and my mech says the diaphragm will be killed by this lack of lubrication. Should I be concerned? We did clean the fuel tank........where in the tank is the filter you are referring to? I'm only aware of the filter in front just before the carb and I fitted a new one.
 
First, get a metre of new 6mm fuel line, connect to the hard fuel line in the engine bay which leads back to the fuel tank, and blow back to make sure there is not a blockage in the line to the tank or within the gauze filter in the tank. If your satisfied all is clear, fit a NEW pump, (always suspect secondhand ones, unless you know it was good), then fit an inline fuel filter prior to the fuel pump.
I've never heard that sought of story ever (lack of oil to the pump components)?? The only thing that clags out over time is, as Peugeotnut said is the diaphram. You DO NOT want oil contaminating the diaphram. As long as the pin moves freely everything is good. Just make sure the hole in the block below where the pin protudes is not blocked. A tiny amount of oil comes through with the movement of the pin and drains back through that hole into the sump.
 
As mention by LO203404, the oil lube is minimal, mainly just to lube the pin that actuates fuel pump lever.

The best is removing the tank from the car to see the fuel filter. The wire mesh gauze filter is at the starting point of the fuel line inside the tank and is mounted to the bottom of the tank. You could see the filter by removing the fuel gauge sender unit.
Mine was so badly clogged and I did not want to cut the tank open. I used a 2mm diameter steel wire hard but flexible and push it through from the fuel line exit at the tank to punch through the rust and dirt at the filter.
I also use a long flat head screw driver to remove whatever was left of that mesh filter. The fuel gauge sender unit hole is large enough to do this.
 
Edmund.
My call on the lubrication of the pump push rod is that it would be "splash" fed from the camshaft, very little oil would be evident.
 
That oil action you are referring to isn't present on mine and my mech says the diaphragm will be killed by this lack of lubrication. Should I be concerned? We did clean the fuel tank........where in the tank is the filter you are referring to? I'm only aware of the filter in front just before the carb and I fitted a new one.
Hello Edmund, have a look at the fuel pump gaskets (1451.03) in the sent image. As you will see, there are 4 holes in the gasket, 2 are for the hold on bolts, 3rd hole at the top is for the pin, bottom 4th hole is for the oil drain hole back to the sump. Other than that, it is a solid gasket, no other holes for crud to find its way into the pump. The camshaft driven pin basically only tickles the actuating rod on the pump by a mm or 2. The diaphragm is made up of a number of 'sheets' of special material which will fail prematurely if contaminated. That's part of what that gasket is for, as well as a seal.
 

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Thanx everyone for your input. Lo203404, the gasket illustration that you sent has been very helpful, it pretty much settles the argument for me. I will go ahead and fit a new pump😀
 
From my decades of VW experience, the early (36bhp) 1200's had a really large fuel pump body cavity.

Its lube was via packing the bottom with grease before installation. It was mounted a fair distance from the "action" so splash was limited.

The later ones were smaller so less grease but they were mounted closer to the cam & crankshafts.
 
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