Loud fuel pump

[wmnewlife]

My friend has a 1974 coupe with downdraft webers and he tells me that the fuel pump noise is loud and distracting. He thinks it's in the tank. Isn't the stock pump sufficient and would the problem go away if he had that reinstalled?

 

[MMercury]

My friend has a 1974 coupe with downdraft webers and he tells me that the fuel pump noise is loud and distracting. He thinks it's in the tank. Isn't the stock pump sufficient and would the problem go away if he had that reinstalled?

Coupes with carburettors were typically equipped with mechanical fuel pumps bolted to the cylinder head. You seem to be describing an aftermarket electric fuel pump installed somewhere in the rear of the vehicle. This could be in the gas tank as found in some later model fuel injected vehicles. The pump could also be mounted in the trunk near the tank or even under the vehicle similar to where electric pumps were originally mounted on fuel injected E9s.

Abating the noise you describe can be accomplished in many ways. First might be to replace the pump with a quieter version of the same. A noisy pump may be a pump that is straining and portending failure. Other obvious means of noise abatement include placement of the pump further away from the occupants, employing strategically placed sound deadening material/s and isolating the pump from the car's body to avoid resonation.

Without knowing pump type and location, acoustics advice is unfocused. If it is tank mounted, it can be removed, repaired and/or replaced. An eternally mounted electric pump can be remounted so that it is less likely to resonate through the car. Original fuel injected pumps, which is probably not the type installed, were held to the body using rubber mounts. (See below)

Far less effective ways of dealing with problem include earplugs and heavy metal music.:roll:



hth

 

[61porsche]

The issue to me seems to be what type pump besides isolation. BMW uses a roller type pump which tends to be a little more expensive. The usual substitution is a pulse type pump which is noisier as it's magnetic. That action is inherently noisier. Cost difference is say $40 vs. $100, or even higher.

One more thing to note: carbs take much less pressure so do your best to select the right pump at the right pressure. Otherwise, the installtion requires a pressure reducing valve which has a cost; not to metion another component. I tend to try to keep it simple, but on a German car that wasn't the mindset.

For instance, day before yesterday, I changed my wife's battery in her BMW.( Hey- we should lobby for multiple car parts discounts from Heritage) Not even the manual said where it was...... in the trunk, behind three panels, below two panels, secured by a hold down that also held the battery horizontally and vertically. To get the clamps off, it darn near required a post puller. If the battery didn't have handles, it wasn't coming out. Oh well, just another day in the life. All's well now and the coupe is still snug in the garage.

Buy the other pump. it's quiter. Isolate it as our good esteemed colleage MM suggests.Zepplin would be my personal choice though and appropriate for my year coupe. But, I could get into Ozzy for a tune or two.

 

[rsporsche]

The issue to me seems to be what type pump besides isolation. BMW uses a roller type pump which tends to be a little more expensive. The usual substitution is a pulse type pump which is noisier as it's magnetic. That action is inherently noisier. Cost difference is say $40 vs. $100, or even higher.

One more thing to note: carbs take much less pressure so do your best to select the right pump at the right pressure. Otherwise, the installtion requires a pressure reducing valve which has a cost; not to metion another component. I tend to try to keep it simple, but on a German car that wasn't the mindset.

For instance, day before yesterday, I changed my wife's battery in her BMW.( Hey- we should lobby for multiple car parts discounts from Heritage) Not even the manual said where it was...... in the trunk, behind three panels, below two panels, secured by a hold down that also held the battery horizontally and vertically. To get the clamps off, it darn near required a post puller. If the battery didn't have handles, it wasn't coming out. Oh well, just another day in the life. All's well now and the coupe is still snug in the garage.

Buy the other pump. it's quiter. Isolate it as our good esteemed colleage MM suggests.Zepplin would be my personal choice though and appropriate for my year coupe. But, I could get into Ozzy for a tune or two.

my neighbor has an e46 328i wagon - and her battery went dead. i went looking everywhere for the battery. too well hidden to be taken stuff apart on a neighbor's car. then i heard from another bmw friend that you have to reset a computer when you change the battery. talk about NOT keeping it simple.

 

[Stevehose]

I also read if you don't do it right you can blow up the whole computer system.

my neighbor has an e46 328i wagon - and her battery went dead. i went looking everywhere for the battery. too well hidden to be taken stuff apart on a neighbor's car. then i heard from another bmw friend that you have to reset a computer when you change the battery. talk about NOT keeping it simple.

 

[rsporsche]

i am so glad that i told her that i couldn't help her. last thing i wanted to have to get thru was paying to help somebody.

 

[61porsche]

Well, nothing blew up.... yet.

Yep, the positive cable has a 20 ga pair of wires INTEGRATED into the post. No cutting the cable, putting on a generic clamp from the ol Pep boys.

The computer has a reserve for say 5 minutes.. then starts screaming. It's a little too late then when the battery is in the bilge and the clamps are glued on by corrosion from a 6 months expired battery. ( Hey, I finally got my money's worth!) Man, I had to chisle that crap off, and the bottom half of the post was plastic. I mean, what's up with that?

Got it put it back together, and fired it up. Just have to reset the clock. But daylight savings time is this weekend! So I have a day.

But the wife's not evil eyeing up the coupe for the grocery store. She grew up on a standard shift.:shock: There are female race drivers ya know.
maybe I should.. new RS's and a set of Perrili's would be the bargain.


All's well that end's well.

Now on to the hunt for that cable end before I get accused of substandard workmanship...on her car no less....I can just hear it now... all those parts you order.... to be continued.

And I'm free.. if that don't beat all.

 

[Mike Goble]

My friend has a 1974 coupe with downdraft webers and he tells me that the fuel pump noise is loud and distracting. He thinks it's in the tank. Isn't the stock pump sufficient and would the problem go away if he had that reinstalled?

I used the stock VDO-BMW electric in-tank pump from a 633CSI to provide fuel to my Webers and it does a great job with very little noise. No pressure regulator, no problems.

 

[aalto]

I ended up using an (early) e30 low pressure pre-pump assembly for my Webers. It had a "bayonet" style top that screwed directly into the existing tank. Extremely quiet and stock looking. Works well but doesn't go quite deep enough to get that last bit of gas out of the tank and the gas gauge doesn't read corrently either.

Question for Mike: I actually got a 633csi pre-pump assembly to try out (heard it was deeper) however it doesn't have the bayonet mounting but rather a whole series of screws seem to be required. How did you end up securing/sealing it to to the top of the existing e9 gas-tank?

 

[Stefan]

The original csi pump plays at high level,
as well as the air intake...

 

[Mike Goble]

I ended up using an (early) e30 low pressure pre-pump assembly for my Webers. It had a "bayonet" style top that screwed directly into the existing tank. Extremely quiet and stock looking. Works well but doesn't go quite deep enough to get that last bit of gas out of the tank and the gas gauge doesn't read corrently either.

Question for Mike: I actually got a 633csi pre-pump assembly to try out (heard it was deeper) however it doesn't have the bayonet mounting but rather a whole series of screws seem to be required. How did you end up securing/sealing it to to the top of the existing e9 gas-tank?

I used six short sheet metal screws and the stock gasket that comes with the pump. Mine is in a Bavaria and goes all the way to the bottom, but I'm not sure about the depth of an E9 tank.