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Time To Replace Fuel Pump?


fatphil

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Our 1969 1602 ran fine and started easily after an engine rebuild about 350 miles ago (for some reason, my mechanic did not replace the fuel pump).  Today, I started her up and she kept an idle for about 1/2 a minute then stalled.  I started again, same thing -- stalls after less than a minute.  It seems gas is not reaching the carb properly. 

 

I checked fuel filter and noticed it was empty (first time I saw it empty).  I always check the fuel filter since I notice some floating mass in it and I've cleaned it twice already since the rebuild.  I figured I eventually need to clean out my gas tank.

 

I then took off air filter pan and didn't see, nor smelled, any gas in the carb.  I pumped the gas linkeage and don't see gas squirting in the carb.  Carb remains empty of gas.  Jets are in open position.

 

Is my fuel pump dead?  I believe it's a mechanical fuel pump.  

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Sure sounds like a fuel pump.  You started the car and it idled while draining the carb bowl.  Now the carb is empty and it is getting no more fuel.  Pumping the linkage will only squirt gas if there's some in the carb.  Stock fuel pump would be mechanical, attached to cylinder head, near front of driver's side.  If it's an electric pump, it's possibly in the trunk, an aftermarket thing.  Of course, you have checked that there's fuel in the gas tank, right?

Good luck.

 

John

'74 2002

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Thanks for the responses. 

 

Yes, there is gas.  I actually filled her up Christmas Day.

 

Yes, I will be checking the simple things tomorrow.  But all the hoses in the engine bay were replaced during rebuild.

 

I don't recall placing anything heavy in the trunk recently.  Maybe some gifts to/from Christmas gathering.  But yes, I will pull out trunk cover tomorrow and check for smell or visible cracked tubes. 

 

If fuel pump is the ultimate culprit, I assume it's a simple unbolt and replace procedure right?  I assume gaskets should be replaced too.  Anything I should be careful of?

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Coupla more thoughts on your no-fuel-at-the-carb dilemma--if you have any of the old original cloth-covered fuel hose anywhere in your system, I'd replace that before replacing the fuel pump.  A mechanical pump doesn't suck worth a darn if there's a leak in the upstream (inlet side).  Those cloth covered hoses can crack and become porous and still look just fine on the outside because the cloth covering hides the problem.  And if you have a loose hose clamp somewhere...same thing.  I'd especially check the short length of hose under the trunk floor that connects the gas tank pickup and the translucent fuel line that runs to the firewall.  Betcha it's original...and cracked.

 

One more little wierdity..if you still have your original air cleaner, check the fuel pump top--on mine, the underside of the air cleaner can rubbed a hole in the fuel pump, creating an air leak so it wouldn't pump--until I dismantled the pump, soldered up the hole and then put a rubber buffer on the air cleaner to keep it from happening again.

 

mike

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So I checked the hoses for leaks -- nothing.  Checked for smell of gasoline in trunk -- nothing.  Checked pump itself for holes -- nothing. 

 

I decided to remove the fuel pump and unscrew the top -- I figured, if the pump was broken, there was nothing I could do make it worse. 

To my surprise, I found about 1/2 teaspoon of gunk (same floating gunk I find in my fuel filter) trapped on one side of the screen inside the fuel pump.  Cleaned that up immediately.  Checked the pumping action of the springs ... it was pumping gas.  Reassembled, reinstalled, and put a little gasoline in my carb.  Started the car and she started right up.  Fuel filter is now flowing with gas.  Engine idles properly.  Drove the car a few miles and she runs beautifully.

 

Not sure if I got lucky, or if it was a warning that I should uninstall, empty and clean up my gas tank sooner than I planned.  That's a bigger project. 

 

Thanks again to everyone for their input ....

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You must have one of the original style pumps that were used on all 1600s and the single barrel 2002s.  They can be dismantled to get to the filter screen--and can even be rebuilt with a new diaphragm.  You can't buy the rebuild kits from BMW any more, but they're the same as the one used on air cooled Beetles of approximately the same vintage.

 

That crud is gotta be coming from somewhere...I'd pull the fuel pickup/gas gauge sender unit and check the screen at the bottom; they've been known to fall off.  You might also want to consider running the gas tank 'till it's nearly empty, then removing it and cleaning it out.  Should be some archive threads on R&Ring gas tanks...and while it's out check the mounting lip for rust and repair as necessary.

 

I'd also pull the carb top off and check the float chamber for crud.  If your filter and pump were clogged, betcha there's crud in your carb...

 

cheers

mike 

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+on pulling the sender. Sounds like the screen may be blocked. Just pull it up SLOWLY to let it drain into the tank. If you've got crud in the lines, there's crud in the tank. I'd pull it out, rinse and drain. Or buy a case of filters. Ethanol turns into sludge, so if you store the car, find some additive. Or find Ethanol free gas.

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Pulled the sender this afternoon.  Opened it up (via a small screw holding the screen to the gizmo inside it) and found more crud -- although less than what I found in the fuel pump.  I could see crud at the bottom of the tank, however.  I'll wait til gas runs out and put gas tank restoration at the top of my looooong list to do.  Mama mia!!!  Happy New Year!!! 

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Pulled the sender this afternoon.  Opened it up (via a small screw holding the screen to the gizmo inside it) and found more crud -- although less than what I found in the fuel pump.  I could see crud at the bottom of the tank, however.  I'll wait til gas runs out and put gas tank restoration at the top of my looooong list to do.  Mama mia!!!  Happy New Year!!! 

Here's a link to dealing with the gas tank: http://www.bmw2002faq.com/topic/147085-gas-tank-refurbishing/

 

Regards, Maurice.

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