Hi Guys,

Took my car out today and it drove nice except I noticed a buzzing/humming sound. It is in the boot and below the battery. Bad fuel pump or fuel filter? Car has 32K miles so probably not fuel pump right? Plugged fuel filter? I have the past service records and will check to see if the fuel filter has been replaced. Any ideas? Maybe its not a thing but I never really noticed the buzzing before. Thanks.

Checked records and the fuel filter was replaced at 28K miles. 10 years ago... Can a filter go bad from age/sitting?

 

At 10 years I would replace it. Any old gas left in the system tarnish lines and breakdown filter element restricting flow. Not to mention be plugged with rust from tank

 

The buzzing is the pump trying too hard to pull fuel through the sock filter inside the surge tank under the battery. I suggest you do the following:
Empty boot as fuel will spill! Disconnect the battery Unbolt and remove the covers under it to reveal the surge tank. Disconnect the fuel feed pipe from the tank and block it off; having first checked that there is really good gravity feed (someone recently on here had a fuel problem because this feed was blocked). Then get under the car below the surge tank and you will find a rubber bung in the floor that gives access to the surge tank drain hole. Undo the drain plug and drain the surge tank.

Then undo the locking ring in the surge tank and pull out the tube that feeds to the pump. You will see the filter over the end of it. Clean out the surge tank which may be full of crud, renew the filter, and reassemble with a new locking ring. If the pump still buzzes loudly after this, the pump is also going home.

Greg

 

I will do a search but anywhere online that you can recommend where to find the surge tank filter and the locking ring?


What can I use to clean out the surge tank? Do I have to remove the surge tank or use something to flush it out through the bottom drain hole? Thanks.


The fuel filter was replaced 4K miles ago but the car sat and only 4K miles have been put on it in 10-12 years. I did use a few bottles of Redline SI-1 fuel cleaner this past fall and maybe it loosened up some stuff in the tank.


Thanks for your help. Except for this and the window lift relay, the car has run fantastic.

 

Read this in Kirby's book. What do you think of this procedure to drain the surge/sump tank?


John Goodman owns a 1989 XJR-S 6.0 litre: "I have just cleaned out my sump tank, no signs of a filter!" Who knows, maybe Jaguar decided it was more trouble than it was worth.
Goodman also came up with a neat procedure for emptying the sump so you can work on it. "What I did was to clamp the fuel hose from the tank to the sump with some vice grips, start and run the engine till it stalls which soon empties the sump." Since the sump is vented, the pump can draw out of the sump without drawing a vacuum. The pump draws the fuel out of the sump and returns it to the tank; it would empty the tank by itself if you can run the pump without starting the engine.

 

Any of the specialist jaguar suppliers will have them. The parts are not at all expensive. Once the pipe is out of the tank it is easy to look inside and see if it is full of crud. If it is, it is reasonably easy to unbolt it and take it out to clean it; Might as well change the filter again to be sure.

Here is the parts diagram and numbers. Glad the car is good otherwise!
Fuel Sump Tank - Parts For XJS from (V)139052 to (V)179736 | Jaguar Classic Parts UK

Greg

 

Looks like I will need to order a fuel filter EAC3112(OEM), sealing ring ARA1502J and the sump tank filter CBC5649... Hopefully I did not forget anything. Thanks Greg...

 

I ordered the parts and will make checking the sump tank filter part of my maintenance routine. Thanks...

 

i'm going through the same procedure myself. my pump buzzes like a beehive if i drive more than 30-45 minutes.

ordered the sock filter from ebay.
ordered the gasket/sealing ring from motorcarsltd (assuming this is a reputable and timely group)

questions:
does the sump tank have to come out? or can the rinse out be done in situ?

what might be the best solvent to use to clean the sump tank? i saw someone on the forum used seafoam. any reason to or not to use seafoam?

 

You may be able to flush it out through the drain hole, or vac it out, or a combo of the two. The bits in there will be insoluble grit etc etc. Get a brush in there though the filter hole and work it about and then try to vac or flush it flush it out with white spirit or paraffin. Unbolting the sump tank is not too bad if you really have to. The thing is to get it really clean!

greg

 

My parts will be here on Wednesday from Terry's Jag. I removed the spare tire, carpet, etc today and noticed that the bracket/screws holding the fuel filter were very loose. I wonder if that caused the humming sound. It did sound like it was coming from behind the tire. I am still going to replace the fuel filter and drain out the sump when the parts show up. Very tempted to turn it over and see if it still hums or not. I would almost bet, that was causing the sound I was hearing...


I was also surprised on all the sharp bends in the rubber fuel lines in the trunk area. The way Jag fed the lines, I would think it would somewhat restrict the flow of fuel through those lines. Oh well.


I may just flush out the tank with fresh gas.. Thanks guys.

 

The fuel filter brackets are like that, rather rubbishy. Tighten them up and wrap the filter cannister in a bit of foam if it worries you. Believe me that is nothing to do with your buzz (and I'll take the bet)! very sensible of you to nevertheless do the thing properly.

Sharp bends are Ok because the OEM hoses are made that shape. The trouble only comes when people take a straight hose and try to bend it to fit, thereby kinking the flow.

Greg

 

If I pinch off the main rubber fuel line going to the surge tank, I can then open the bottom surge tank drain, right? Thanks.

 

Received the parts today and will attempt the filter replacements tomorrow.


I just have to decide which hose to remove or pinch off, to stop the flow of fuel to the surge tank. I will then open the bottom drain to remove fuel in the surge tank. I hate the idea of removing a fuel line and letting fuel spill all over. Possibly finding a rubber fuel hose to pinch off may work better? I'll have to figure which one leads to the top of the surge tank.

 

Got it done and the pump and filter are much quieter...


Pretty sure it was the fuel filter that was making the humming sound. Flushed out the sump tank and it looked really clean/new inside. The original sump tank filter was still in good shape and was not dirty. I'm thinking that the fuel filter, even with low miles, just needed to be replaced because of age. Thanks for your help Greg...

 

Just a quick question since we are in the trunk. On the XJS, are the four open one inch holes under the spare tire and battery for ventilation or should they be plugged?

Answer: 1. Left open 2. Plugged

 

I have an all original low mileage 90 XJS and it has the plugs installed(2).