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1986 Spider Veloce
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148 Posts
Discussion Starter #1
Hello,

I have what I think is a new sound coming from around my fuel pump. I just replaced the fuel filter and have spent some time under the car while running recently test/checking that and this sound was not there while I was doing that. It could have been before and I didn't notice.


I drove for a bit yesterday after noticing the sound and I think the sound came on and off, but it's hard to tell for sure while driving 40 mph with the top down :)

I'm planning on replacing the fuel line on either side of the fuel filter today with FI rated line. If the pump is bad I'm thinking I should just wait until I can get a new one and replace everything at the same time. On the other hand, if that sound could be the hose sucking air then putting the new hoses on could address the whole problem and save me $150.

Noticed the rubber caps are rubbed through too - not sure that could have an affect.

1641473


Thoughts? Should I do the hoses now or is this obviously a fuel pump ready to fail and just wait to do everything together?

Thanks!
 

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Premium Member
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If you put your fingers on the pump while it's making the noises, does it feel like it's coming from the pump? Generally my view is, the fuel pump should have a steady low volume hum, anything else is an unhappy pump. The only protection the pump has from junk and detierious from the fuel tank is the sock at the bottom of the in tank pump. The pumps in general are not foreign object friendly at all. The big filter there is after the pump and just protects all the stuff in the engine bay.
 

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But Mad North-Northwest
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First step is to make sure the in-tank pump is working. If that fails the main pump can get rather noisy.
 

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well it is not normal, obviously....
it is not the hoses sucking air (they'd leak fuel first) nor those rubber boots over the connectors.(though it would be wise to replace those so that water does not get in, you can get rubber boot kits for fuel pumps)

I think Tom's idea of checking the in-tank pump is best....
first test the in tank pump is working properly:
as your battery is in the trunk just jump the pump direct from the battery.. it should hum nicely, no odd noises.
use 12v + to pink/white wire (middle of those 3 connectors) and negative to black spade on side.
 

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Premium Member
1986 Spider Veloce
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148 Posts
Discussion Starter #5
well it is not normal, obviously....
I'm making headway! I knew it didn't sound like a good sound :) (and I didn't remember that sound when I was doing the fuel filter work.)

it is not the hoses sucking air (they'd leak fuel first) nor those rubber boots over the connectors.(though it would be wise to replace those so that water does not get in, you can get rubber boot kits for fuel pumps)
This is helpful - thank you!

If you put your fingers on the pump while it's making the noises, does it feel like it's coming from the pump? Generally my view is, the fuel pump should have a steady low volume hum, anything else is an unhappy pump.
I gotta say - I couldn't tell. I put my fingers on the pump and the sound didn't change and I didn't feel anything different then a steady vibration. Since the sound didn't change when I touched it I figured it wasn't it moving around that was making the sound, but that's about as much as I could determine.
I felt the hum of the pump and could feel the fuel move through the hoses - but nothing I did changed the sound.

First step is to make sure the in-tank pump is working. If that fails the main pump can get rather noisy.
I think Tom's idea of checking the in-tank pump is best....
first test the in tank pump is working properly:
I'm going to plan on doing this before changing out the fuel lines from the standard to FI - If I need to do that pump or the inline I'd prefer to do it all together then piecemeal replacements. That being said, I've been driving it and it's running ok so I'll plan to keep driving it while I'm working through this phase. (Not for long, but could be a week or so.)

as your battery is in the trunk just jump the pump direct from the battery.. it should hum nicely, no odd noises.
use 12v + to pink/white wire (middle of those 3 connectors) and negative to black spade on side.
Sorry for the novice questions here - but not entirely sure how to jump the pump direct from the battery. I'm going to take a first guess.
  1. Find some 12v wire.
  2. wrap positive to pink/white
  3. wrap negative to black spade (not sure what the black spade is, but I'm not looking at the car right now - hope it's self evident or in the mechanic's manual)
  4. Touch positive wire to red terminal on battery
  5. Touch negative wire to black terminal on the battery
  6. (Hopefully) Listen to the peaceful hum of the in-tank pump.
Anything I'm missing to ensure I don't do damage to my car or myself?

Thanks!

a.
 

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Sorry for the novice questions here - but not entirely sure how to jump the pump direct from the battery. I'm going to take a first guess.
  1. Find some 12v wire.
  2. wrap positive to pink/white
  3. wrap negative to black spade (not sure what the black spade is, but I'm not looking at the car right now - hope it's self evident or in the mechanic's manual)
  4. Touch positive wire to red terminal on battery
  5. Touch negative wire to black terminal on the battery
  6. (Hopefully) Listen to the peaceful hum of the in-tank pump.
Anything I'm missing to ensure I don't do damage to my car or myself?
yep that's all there is to it. By 'black spade' I meant the ground spade connector with black wire.
in tank pump wires.jpg
 

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Premium Member
86 Veloce
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1,162 Posts
I run a short length of hose off the tank sender so when you jump it you can see if it pumps fuel into a container. I'm not sure if listening for the running pump will tell you if it is pumping fuel or not, stepped hose may be compromised....
 

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Premium Member
1986 Spider Veloce
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148 Posts
Discussion Starter #8
All I have is some heavy duty speaker wire, which I think is much thicker the what is in the photo.
I know thinner is bad b/c it could overheat, but will using a thicker wire cause issues to test this?
 

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Premium Member
86 Veloce
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1,162 Posts
Not to worry, very small draw from the pump. Just about any wire will work for a short test, just never run the pump dry, the fuel is its lubricant.
 
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Premium Member
1986 Spider Veloce
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Discussion Starter #10
Thanks for the instructions Dom, and the clarifying on the wire, Brian.

First time a charm! (except for a little spark when touching positive to the battery.)

Note to those trying this for the first time - 1) touch negative to battery first, then positive to battery. Basically swap steps 4 & 5 above. 2) when you touch the positive to the battery - make it a good "touch" - if you just barely scrape it it sparks :)


Anyway - sounded to me like the motor hummed nicely. I did note that the motor sound "felt" like it came more from under the car then in the tank, but I'm going to base that on location of the motor and the cement floor.

Brian, I didn't have the time to remove the hose and put into another container this AM, but will do that when I have time next.

I did notice the hose coming out, that's held under that rubber block, looked a bit kinked to me, but I can't see another way around it unless I use @Mauricio101 special 90 hose. Are others folks the same as mine?

2020-08-02 10.26.52.jpg 2020-08-02 10.28.31.jpg
 

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78 Alfa Spider
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94 Posts
Hey Adam,

Try this.....

With the pump running, take note what it sounds like. Is it smooth, or does it sound like its girgling, or whining? Now, keep the pump running and remove the fuel filler cap. Does the sound change? If the pump WAS girgling but now sounds smooth, you have a vacuum issue. If it continues to whine loudly its probably time for a new pump. The pump should run smoothly with both the cap on and off.......at least this has been my experience.
 

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yes, I wouldn't be happy at all with that outlet hose on top of the in tank pump...it is kinked and might well be causing your main pump under the car to groan. It really hot temperatures it will kink even more as the rubber softens.
I'd change that.

It is difficult just to use a longer length and make a softer loop, because it all has to fit under that big rubber block protector thing and the trunk carpet....so maybe that multi formed hose would be a good call in this case ?.... in the right size (ID)

my S4 has a proper 90° preformed bend there
alfa s4 fuel pump in tank.jpg
 

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Premium Member
1986 Spider Veloce
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148 Posts
Discussion Starter #14
Morning! Thoughts and questions below - thank you!

In-tank Fuel Pump
Humms smooth when jumped (see video). No gurgling sound or issues. Still need to try Brian's suggestion of pumping into a jar or something to ensure it's not just running, but it's smoothly pushing fuel.
Will try removing the cap and see if that changes.

How long can I run the pump jumped to the battery w/o damaging it or putting too much fuel (or pressure) into the system?

Main (under car) fuel pump
The gurgling sound in the original video (Fuel pump - is new sound air entering, pump dying...) I believe is new. I was under the car to test/check replacing the fuel filter and the fuel line and I don't remember that sound at all. It is also sporadic - I didn't have it last time the car was running, but it wasn't a smooth hum like the in-tank one when I tested it jumped to the battery. It was a louder, but consistent hum.. with no gurgling sound.

The car was at 1/2 tank when I noticed it, but it stopped while it was at 1/2 too. I filled up the car and I still don't have the sound, but it did stop before I filled it.

Can I/Should I try jumping the main fuel pump to the battery to to see if it makes the same sound? If so, how can I do that and how long can I leave it running w/o damage?

Fuel Supply Hose off tank kinked.
This is another area where I’m curious what folks who have the original hose on their car have.
Does everyone have a 90 degree bend and I have an odd ball or was this the way it came from the factory?
I believe this is an original hose b/c it's the braided style.

All the images in the mechanic's manual basically show it going straight up and with none of the cover/carpet - so that's no help 😐

Due to a mis-purchase when fixing the fuel leak in Leaking fuel line on road trip - Help?!! I believe I have some F.I. rated 1/2 inch hose and it could be long enough to replace what's there.

Worthwhile thing to do? I don't think it'll solve the kinking issue unless I decide to drive the car w/o the rubber cover and trunk carpet in place.

New (and possibly helpful) info?
Not fully confirmed, but when driving back after replacing the leaking fuel link off the filter we had to drive with the top up b/c it had rained and the top was wet. I noticed that at the top of a hill, after pressing the accelerator to push to the top, if I took my foot off the accelerator (and maybe braked because there was a car slowing in front of me?) - I got a puff of gasoline smell. It quickly dissipated but I think I kinda reproduced it a few times on the drive. Not scientific or proven yet, but figured I'd add it in case that helped someone suggest a place to check or thing to try.

And..

Yes.....When working with fuel, always disconnect the battery first and don't reconnect until your finished. Just a reminder.
Yes - thank you! I don't do that everytime although I know I should.
My positive terminal is a bit of a trouble to get off and on - it's a bit chewed up - so I try to do it as little as possible. (That's another project to try and replace that). But I'll at least remove the negative and if I'm going to do do a project on the fuel related I'll take the time to remove it. (trying to not damage it more then it is)
 

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I always remove negative only anyway when disconnecting a battery

in this old IAP still they just show a length of hose too....and the shop manual doesn't show much better.
If it were mine, I'd want a bend in there so it sits nicely under that plastic cover, but it seems to be just like you have it:
gas hose trunk1.jpg

and another photo from BB: but yours is kinked compared to this:
fuel hose.JPG

EDIT: A quick fix would be to remove the hose and simply swop ends:)
so the end where the kink has formed on the pump is attached to the other hard line, which won't be kinked as it is a much straighter feed
as you can see here:
gas hose trunk.jpg
 

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Richard Jemison
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7,590 Posts
You might likely find that the short section of hose connecting the in tank pump to the output/fuel level mechanism is deteriorated allowing air to be sucked in when fuel is below 1/3 full. Common issue.
Change the intank fuel filter on the pump as well.
 

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78 Alfa Spider
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I got a puff of gasoline smell. It quickly dissipated but I think I kinda reproduced it a few times on the drive. Not scientific or proven yet, but figured I'd add it in case that helped someone suggest a place to check or thing to try.
This is characteristic of a vacuum issue. Did you try running the pump with the cap on and then taking the cap off? Did you notice a difference in the sound of the pump? Also, drive the car for a while, then pull over somewhere and open the fuel cap. Does it open cleanly, or do you hear/feel a rush of air/vacuum? Sounds like you're heading down a road that every Alfa owner has gone or will go. If you're having this problem let me know. It's a pretty easy fix once you know it.
 
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