loud vibration from fuel tank or fuel pump

[loosenut]

mechanic for 25 yrs
so my fuel pump went out on my 99 v70 xc. i cut the hole in the floor no problem.
replaced the pump. and a day or so later or as it turns out when the fuel level reached about 1/4 there was a very loud and bothersome in your ear vibrating noise that sounded like a very bad fuel pump. So i bought another fuel pump this one factory.
same thing..... same exact thing.
so i am guessing that it it vibrating all of the time and only gets very very very very loud at 1/4 tank
so i unscrewed the pump cap and was hoping the noise would go away as i loosened the cap. no deal.
so i thought if i took the cap off and rotated the pump it might stop, no deal again.
i lifted the pump out of the whole a bit and still vibration......
anyone see this before? im starting to think it is going to be a fuel line on top of the tank at this point.
any one?
ill post if i find it. two new fuel pumps same vibration, cannot be the pump.....or can it..

thanks for listening.

[98v70dad]

Did you leave a tool or a hose clamp or something on top of the tank maybe? I lost my wire nippers and couldn't find them for months and at my next oil change they were staring at me on top of the engine. They were apparently happy up there. I know a good mechanic (I'm not a good mechanic) never leaves his tools in the work area, but sometimes stuff happens when you're working on you own car.

Also, maybe a fuel line got pinched and its causing the pump to labor hard or its causing the fuel line to vibrate at the pinch.

[loosenut]

he, thanks for the reply although i did not have the tank out of the car, i cut a hole.
i did run across this though. and i am going to do a bit mor research on it
I do notice that when the cooling fan kicks on that the noise does change due to the electrical load....oh one more thing i did not mention is that in a self help post i read on cutting the access hole is to splice the fuel pump wires from the new one. I DID NOT DO THAT. i ran the wire through my access hole and to the pump....
so i read this this morning........
Technical Articles Search > 10061 Fuel Pump Whine - 1998-2000 V70XC Models
Fuel Pump Whine - 1998-2000 V70XC Models
Created on 2011-03-09 by IPD Staff

For some reason the 98-00 V70XC fuel pumps tend to whine in a very noticeable way.
To tell for sure if it is the fuel pump, start the vehicle and sit at idle with all the windows up in a quiet area. Lift up on all four window switches at the same time for 1 second then release.You will notice the pitch of the sound changes slightly due to the momentary increase in electrical load. The increase in load decreases the system voltage causing the pump to slow momentarily which changes the pitch of the pump. If you have run into this and you’ve been told ‘you’ll have to live with it’ you can have peace and quiet!

The pump noise seems to resonate from the U shaped tunnel under the (second row) rear seats.The way to eliminate or at least reduce the noise is to follow the bulletin that was circulated through the dealers around the time these cars were new.

Remove the bottom rear seat cushions and pull forward the carpet.Note the U shaped structure that supports the seat bottom cushions and located the holes throughout this channel.These holes must be filled with a foam rubber or similar material to help lessen the resonance through this area.Another step that can be taken is to apply Dynamat or similar material to the top and front of the seat support structure to reduce the amount of vibration that may contribute to the noise. Be sure to use a good amount of material to fill the cavity in the seat structure and then reassemble the seat cushions. Following this method, you should notice the noise is greatly reduced.

hope it helps someone as well as me...i will post results.....

[98v70dad]

he, thanks for the reply although i did not have the tank out of the car, i cut a hole.
i did run across this though. and i am going to do a bit mor research on it
I do notice that when the cooling fan kicks on that the noise does change due to the electrical load....oh one more thing i did not mention is that in a self help post i read on cutting the access hole is to splice the fuel pump wires from the new one. I DID NOT DO THAT. i ran the wire through my access hole and to the pump....
so i read this this morning........
Technical Articles Search > 10061 Fuel Pump Whine - 1998-2000 V70XC Models
Fuel Pump Whine - 1998-2000 V70XC Models
Created on 2011-03-09 by IPD Staff

For some reason the 98-00 V70XC fuel pumps tend to whine in a very noticeable way.
To tell for sure if it is the fuel pump, start the vehicle and sit at idle with all the windows up in a quiet area. Lift up on all four window switches at the same time for 1 second then release.You will notice the pitch of the sound changes slightly due to the momentary increase in electrical load. The increase in load decreases the system voltage causing the pump to slow momentarily which changes the pitch of the pump. If you have run into this and you’ve been told ‘you’ll have to live with it’ you can have peace and quiet!

The pump noise seems to resonate from the U shaped tunnel under the (second row) rear seats.The way to eliminate or at least reduce the noise is to follow the bulletin that was circulated through the dealers around the time these cars were new.

Remove the bottom rear seat cushions and pull forward the carpet.Note the U shaped structure that supports the seat bottom cushions and located the holes throughout this channel.These holes must be filled with a foam rubber or similar material to help lessen the resonance through this area.Another step that can be taken is to apply Dynamat or similar material to the top and front of the seat support structure to reduce the amount of vibration that may contribute to the noise. Be sure to use a good amount of material to fill the cavity in the seat structure and then reassemble the seat cushions. Following this method, you should notice the noise is greatly reduced.

hope it helps someone as well as me...i will post results.....

I did see that you cut a hole. My car has an access hole already there - its not that big. Its pretty easy to drop a socket or some similar small tool and have it roll away or be pushed away on top of the fuel tank. I actually did that and had to make a hook out of coat hanger wire to pull it back out. Theres not that much room in there on my car so its possible that something stuck between the tank nd the car might buzz. I really doubt that this is your problem but you asked for suggestions and nobody chimed it.

[shiloh51933]

mechanic for 25 yrs
so my fuel pump went out on my 99 V70 XC. i cut the hole in the floor no problem.
replaced the pump. and a day or so later or as it turns out when the fuel level reached about 1/4 there was a very loud and bothersome in your ear vibrating noise that sounded like a very bad fuel pump. So i bought another fuel pump this one factory.
same thing..... same exact thing.
so i am guessing that it it vibrating all of the time and only gets very very very very loud at 1/4 tank
so i unscrewed the pump cap and was hoping the noise would go away as i loosened the cap. no deal.
so i thought if i took the cap off and rotated the pump it might stop, no deal again.
i lifted the pump out of the whole a bit and still vibration......
anyone see this before? im starting to think it is going to be a fuel line on top of the tank at this point.
any one?
ill post if i find it. two new fuel pumps same vibration, cannot be the pump.....or can it..

thanks for listening.

The vibration noise gets louder because it has more space to echo throughout when at 1/4 full. It's possible during installation to have the FP aligned improperly causing the fuel pump itself rattling up against the tank. The FP(fuel pump) is a spring loaded assembly to help with the pick up being as close to bottom of tank as possible I believe. The suggestion mentioned about possibly dropping a tool or something on top of fuel tank would make sense, along with nearly empty tank causing vibration to echo louder.

[loosenut]

hello every one..
thanks for all that have taken the time thus far to read my post and reply.
just want to put this out there...I did not have the tank out of the car, the access hole that i cut is at almost straight up and down and only big enough to get the cap off and the pump out. you cannot drop or leave anything on top of the tank the way i did the work.
As far as misaligned..thanks although i physically had the pump "floating" in my hand away from the bottom of the tank and still was resonating...
I'm going to replace the new volvo pump with something else.

thanks again and i will keep you posted

[scot850]

I have never had a 'vibration' problem with the fuel pumps and definitely not the OE ones. The fact that you said you had the pump 'floating' would say to me the pump is not the issue. Assuming you did not have the issue prior to changing it out, the issue has been introduced by the process of repair either through the part or the work done. Did you replace the seal when you fitted the new pump? Volvo has a special tool set for fitting and aligning the pump as it needs to be orientated correctly to ensure it works correctly and empties the tank fully. Did you drop anything into the tank by chance then replacing the pump? The pipe that runs across between the 2 tank 'pumps' along the front upper edge of the tank is easily bent so that it can resonate on the bottom of the car. Try fitting some foam around the pipe to see if that is the issue. It will be difficult.

These pumps can get noisy when the tank gets down to 1/4 or so as has been mentioned above, but never heard of the 'vibration' issue.

Many of the aftermarket pumps are louder than the OE.

Good Luck.

Neil.

[wizechatmgr]

Happen to replace the fuel filter at the time you did the pump? Wondering if you're dealing with some back pressure that is unreasaonable.

[loosenut]

hey scott850 thanks for the post. did not know about a special tool for alignment. will look into it.
mostly thanks for giving me a few things to check.
also as i posted is the "tsb" thing when i pull up on all four window switches the noise does change.

at wizechatmgr, yes i did replace the filter.

thanks everyone. i will keep you posted,.

[loosenut]

Ok.
Problem solved.
What I forgot to do in the replacement process was what I would always do when unscrewing a fuel pump ring type of seal is MARK IT. I had thought I had gotten it tight well it eas tight enough to not set any evap codes yes. Although the last like 5th or 6th time that i had messed with it something just said to me......go back out there and tighten the hell out of it. So I did. Got a quarter turn out of it using a brake shoe adjuster tool and a good leverage spot.
So some advice to a diy er. Make a mark and count your turns to off. Im no rookie although i sure did make a rookie mistake.
Hope this helps someone.