mechanical fuel pump issue and question

J

JIMC

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Aurora, Colorado, USA
My 72 Euro with dual Webers has a mechanical fuel pump.Since it is parked nose up on a hilly driveway it has always taken some cranking to get it started.Now even with a new clear plastic fuel filter I don't see any fuel coming in from the tank (3/4 full).

I have put gas in a bowl after the filter and it will run until the bowl is empty.
I have sucked on the hose from the tank and gotten a mouthful.

1.The pump is original, can they lose suction with age, all the connections have been redone with new hose and clamps except for the original fabric hose that goes down to the hard line.

2.Will an electric fuel pump solve this, I can get power to it but need to know a source for the pump and also a mounting location.

Any help on this puzzle would be appreciated.
Jim C
 
It's weird, but you don't always see fuel flowing in the clear filter-but it's there. You can test the pump by removing the outlet hose and cranking it into a bucket or hooking it up to a gauge. If fuel is evaporating from the bowls over time either type pump will have to work to refill them before running.
 
Nose up means the float is not in the best of positions. Since you know it runs when you pour errr... dribble in gas, try this: if your carbs have the vent pour a bit of gas in there as it's a straight shot to the float which can hang up closed or open especially if it rubs the side of the bowl. Not very much lateral to swing. And if the gasket is wrong and it can be then the odds are it's going to hang up. If you know how- rap the side of the carb with a screwdriver handle. You might just get lucky. ( Not too hard.)

Hard cranking.. dial up your choke another 1/4". It shouldn't be that hard to start. It also means you could be a bit lean and need to open the idle mixture/ speed screws a bit or barely crank down ( close the butterflies) a bit or all three.

Better to run a bit rich than lean has been my motto.

Throw that plastic filter away! Seriously, it's a fire hazard and a huge restriction. Go buy a big honking metal one. The last you'll ever buy.

As Chris says, cloth hose... bada. Porsche says change evey year! All I know is that I can confirm if there's a small leak you'll never find it. That means suction too. But go through and tighten everything, clean the screen in the fuel sender/ tank. Then check the output. If you can find a small scale guage the pressure is 2.8. ( Think pool filter) Things get funky at 2.5. Yes they sometimes die a slow death. If your's original- you and all the previous owners got your money's worth. Shop around and you can get a deal. Buy two is my suggestion since last year they were $200. Now maybe $40-60.

Best of luck.
 
I don't think your problem is with the fuel pump on startup. I have dual Webers with an electric pump in my Bavaria. If I have the electric pump turned off the engine will start and run about 1/8 mile on the fuel that is in the carburetor bowls.
 
mechanical fuel pump issues and question

I did go and replace the fabric hose going down to the hard line and the fabric hose in the trunk and now all is running fine.

Failed Colorado emissions twice for too rich, correct setting to pass was 1 3/4 turns out on both Webers where it ran and sounded crappy, I'm at about 2 1/4 turns out now and it runs and sounds great.Can't wait for Colorado to dump the inspections so I don't have to deal with some 18 year old trying to slam the hood!
 
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