Mechanical Fuel Pump Testing

E3_UK

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I've ordered a new pump, Pierburg was the only option I could find. To be honest I'm not 100% on this but if I fit the new pump and see good delivery before connecting to the carbs then at least I can rule the pump out. I've never had it run badly on the road, this is a fairly recent development, although wear in a component will tend to produce a slow deterioration, I can't say I've noticed it driving the car. Anyway, I'll report back once I've fitted and tested the new pump.
 

E3_UK

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Here's a video of mine. 1972 Bavaria 3.0, original pump.


It delivered about 2 ounces (60 ML) in a little less than 10 seconds.
Mine delivers less than that, thanks for doing this. I have stripped it and checked everything is ok and it does deliver a decent squirt when manually operated.
 

deQuincey

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may want to do a search here on the newer Pierburgs, reports are that some are junk


yes, those ones are not very good
you should look for the sealed type
BTW, we do not know which kind of pump @E3_UK has in his car, i would suggest some pictures
specs for fuel pumps in carbed cars state 0,21 to 0,25 Bar pressure
i have a manometer in line with the pump before front carb to check this easily, i would recomend it

note, my experience with these fuel pumps is that the small piece that transmits the movement between the pushing rod and the memebrane rod can be damaged due to wear, it is yellow metal,...just in case
 

E3_UK

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The current pump is also pierburg, i thought it might be the original but not sure now.
 

deQuincey

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some old information,...

 

deQuincey

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the repair and the case of the wear part,...

 

Stevehose

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The rebuild kit is 13311255184, not sure if it is available any more, save an eBay search. I rebuilt one a few years back, you need to make sure the diaphragm is tightened in place with the pump in the middle of it's stroke so it is not stretched one way or the other. Some other tips here:

 

E3_UK

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that is the veryvery early one
it s due time to change it, yes
have you checked the rod balancer like in my second thread fix
Yes, good idea. I'll keep the original pump and will overhaul it eventually.
 

Markos

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Well my car didn’t start today, so I’ll be doing the jar test tomorrow. The engine wanted to start with starter spray, so it is safe to assume that I have a fuel issue and not an ignition problem. My gas is two years old, my fuel filter only has about 10 miles through it. If the pump checks out, I’ll try new gas gravity fed to the carbs.
 

bluecoupe30!

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It should work fine
I agree. I have purchased many OEM parts for my E39Touring, that had the brand ground off. I suspect it said BMW, but was being sold under the actual manufacturer name. Regards the fuel pump. I went through this exercise a couple years ago. Read all that was out there. Believed there were some "copies" or substandard Pierburg units circulating. Was ready to move to some electric conversion. Then bought a new battery, replaced all rubber fuel line parts, installed check valve, put my "suspect" Pierburg back in place, and everything worked fine. In the past, my weaker battery could not summon enough fuel all the way to the carburettors, after a couple weeks of sitting, and the reduced power from extra long cranking on the battery, would lead me to think fuel pump was not working. I was wrong. Volts + new rubber hose + tight fittings + check valve = success. Hope you have same good fortune. Mike
 
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