engine and drivetrain 1972 Bmw 2002 - Fuel Pump Question

[Billsmith]

My car has two fuel pumps.  A manual fuel pump is located over the cylinder head and a separate electronic pump is located near the firewall.  The manual pump has a leaking gasket.  Gas is leaking onto the engine and there is a strong odor of gas.  The electronic pump is routed through the manual fuel pump.  Apparently this is as the car was originally manufactured.  I ordered a new OEM manual fuel pump and it is not the same size or shape as the old manual pump.  Is there any harm in bypassing the manual fuel pump and operating the car on a single electronic fuel pump.  I need help.

[esty]

there is a block off plate and gasket available for the mechanical pump...take it off, block the hole and run your electric pump directly to a filter then carb

 

 

here's a lead

 

https://www.google.com/search?q=site%3Abmw2002faq.com+fuel+pump+block+off+plate&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

[williamggruff]

I've seen this on several cars.  It's doesn't seem like a stock setup, as it makes very little sense.  One of the pumps is redundant.

 

First step is to determine whether the electric fuel pump is actually working.  This can be done by disconnecting the hose feeding the manual fuel pump, and seeing whether and how much fuel is being delivered by the electric pump by capturing it in a container.  If it isn't pumping, or it's pumping inadequately, you could either replace the electric pump, or replace/repair the manual pump.

 

It's possible the manual pump has been deactivated.  There's a push rod in the head that uses a lobe on the cam to activate the manual pump.  If that push rod is removed, the manual pump is just there for looks.  You can either remove the manual pump, or remove the valve cover to verify the existence of the manual pump push rod.

 

Personally, I hate electro gizmos, and would rather rely on a mechanical pump, as it doesn't introduce an electric droning noise to the car.  And manual pumps last a LONG time.  That said, you may have some challenges sourcing the correct pump.  If you haven't already done so, you could contact BluntTech.com to learn about manual pump options.

Edited January 31, 2014 by williamggruff

[Hans]

I switched to electric because my mechanical pump seemed to take a long time to prime the carbs. No problems so far. Used a regulator. In your case, as suggested confirm it works.

[Mike Self]

Coupla points or so:

1.  an electric/electronic fuel pump is designed to push, not pull, while a mechanical pump is designed to pull, not push.  Thus the electric pump should be mounted near the gas tank, while the mechanical pump is (obviously) near the engine.  So it sounds like your electric pump--if mounted on the firewall--is way out of place.  

 

2.  All carbureted 2002s came with a mechanical fuel pump, so a PO added your electric one, and apparently in the wrong place.

 

3.  If you're getting gas into your oil from the mechanical pump, then the pump's diaphragm is leaking and therefore shot.  Remove immediately so you're not diluting your oil with gasoline.  Gas is a poor lubricant and you'll eventually ruin your engine.  

 

4.  If your mechanical pump is the kind where upper and lower halves are held together with five or six small screws, you can buy a rebuild  kit from a place that specializes in aircooled VW parts.  Beetles used essentially the same pump, and the innards interchange. If your pump has upper and lower sections crimped together, you need to buy a new pump.

 

If it were my car, I'd either rebuild the existing pump (if rebuildable, see above) or buy a new mechanical pump, and lose the electric one. It's not mounted correctly anyway.  As was pointed out, mechanical pumps last a looooong time and are pretty troublefree.

 

cheers

mike