When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Has anyone replaced fuel pumps on a 2007 DB9 coupe? I've had a bit of a rough idle and intermittent fail to start with a message on the DIM to "Check Fuel System." When I look at the fuel pressure with my Foxwell the pressure is good at 50 PSI on bank 2 and holds pressure after key-off. Bank 1 however is only around 40PSI and the pressure drops to zero within a few seconds after key off. I'm 99% certain the pressure regulator or check valve on the bank 1 pump is at fault.
It does appear there is an access panel under the Linn amplifier. The 2007 has a different arrangement where the amplifier is under the parcel shelf rather than mounted low on the trunk front wall like I've seen in some of the Aston1936 videos. After removing the box that holds the tire inflator and first aid kit, there's a round panel under the amplifier where I assume allows you to reach the tank lid. It will be pretty tight and I'll probably have to work blind, but we'll see how it goes.. I'll probably replace both pumps, but as I understand it the left pump feeds bank 1 (right side of the engine) correct?
@embdenb Yeah, I was hoping it would be possible to go down that path. For the DB9 the whole pump is sold as a complete unit including the pump, check valve, and pressure regulator. The closest thing I could find for pumps was a Jaguar XK8 which has a nearly identical system. Here's a thread about it, but it doesn't sound like they were able to find a suitable replacement.
The part number seems to be 107775 2696 V4. At least that's what's printed on the regulator.
As for getting into the tank, I've started the process. It almost looks like one would be able to get to the access hole by removing the parcel shelf, but the interior of the coupe is just so small.
Interior trim and storage box removed.
Linn amplifier with fuel tank access panel underneath.
Linn amplifier removed.
Last edited by GT3 Chuck; Jul 24, 2023 at 01:24 PM.
Got the cover plate off. I was worried the tank was going to be much lower that it is, but the access hole is right at the top. It's nice of them to print the part number of the tank on the cover. Time to order parts...
And it's done. As it turns out the early Aston fuel pumps are unobtanium right now. I tried to order from the usual places and they're backordered at the factory with no ETA. Luckily, the pump module is very similar to the 2003-2006 Jaguar XK8/XKR. I ordered the XK8 pump since all I really needed was the pressure relief valve and the DB9 and XK8 have that in common. It's just a shame you can't buy just that piece. The module arrived a couple days ago so I removed the module, swapped over the valve and hoses, and got it installed again.
Overall it went a bit quicker than I thought it would. There *might* have been a bit more room to work if I'd gone in from the interior, but I really didn't feel like taking the whole rear of the cabin apart. I can definitely see why the service manual says to remove the tank from the car do service the pumps. The time and risk of damaging the interior parts on the pre 2006.5 cars probably isn't worth it if you have a shop capable of splitting the car. Even on the later years it's a pain to go in through the trunk. Every edge in the tank is razor sharp so expect to get cut up a bit in the process.
I took the car out after it was back together to re-learn the misfire corrections. It only took three runs from 70 down for the indicator to switch to learned on my foxwell. When I got back home after the re-learn I can definitely tell a huge difference in the idle. It hasn't run this smooth in a while so I call this one a win.
I took a few pics as I went. I'll upload them hopefully later today in case they're useful to anyone.
Can anyone post a pic of the fuel pump. Just wondering if it’s kinda the same concept as my bmw’s. I was actually able to upgrade my 5 series with a walbro unit for less than $100. But Bmw use a high pressure low pressure fuel
system.
Sorry for taking so long to upload these. Life got busy over the weekend.
So the XK8 pump assembly isn't exactly identical to the early DB9 pump. The cannister and pressure regulator are the same. Obviously the hoses are different, but were easy to swap over and secure with new oetiker clamps. I didn't use the fuel pump from the XK8 as it was significantly smaller. It's held in to the top plate with an adapter bushing. The top plate looks identical so not sure the reason for it being yellow. The extra nipple on the XK8 pump is blocked off in the casting so being a different color definitely makes sense. To use it would require drilling it out from the nipple side to open it up. This feeds the left side jet pump intended to keep the right side pump module full of fuel during cornering.
The pump installed in the DB9 module is VDO and has the numbers 121 and C17614G. I hope this all helps someone with a similar issue to me in the future.
Left fuel pump before removal
Left DB9 fuel pump (left) and the XK8 pump (right)
Verified the two pumps have the same pressure relief valve (107775)
Swapping the hoses to transplant the new valve to the old pump
Aren't the fuel pressure regulators on the fuel rail on the engine? If one side is correct pressure that should signify that the pressure to the engine is good. The regulators are Ford parts, cheap and easy to change.
No. The fuel system is return-less. Fuel pressure is regulated by the fuel pump drivers and measured with a sensor on the fuel rail. The "pressure regulator" on the pump is a safety device to vent over-pressure fuel back into the tank. In my case, the valve was stuck open and the system sometimes could not maintain pressure between the system priming at key-on and pushing the start button. The idle fuel pressure was also only 80% or so of the other rail due to the same. Both are now resolved after replacing the pressure relief valve.
Aren't the fuel pressure regulators on the fuel rail on the engine? If one side is correct pressure that should signify that the pressure to the engine is good. The regulators are Ford parts, cheap and easy to change.
Primarily due to emissions, vehicles no longer use fuel pressure regulators. Instead, a "returnless" fuel pump is used. Using sensors and pulse width modulation, the pump only supplies the necessary amount of fuel to the injectors based on the needs of the engine.
No problem! I think if I ever had to do the right side pump I might just use the 2008+ Aston pump and try to adapt it over like I did for the Jag pump. The important bits are the mounting on the bottom of the swirl pot, the bypass pressure, the pump flow rate, and the connector to the fuel filter. The bypass pressure and the pump flow rate should be the same since 07 and 08 have the same ignition and fuel system. At the minimum the tube going to the fuel pump might need to be swapped. If the mounting is different then the guts of the pump would just swap over to the old swirl pot. It would be a surprise for the next person to work on it for sure. Probably good to leave a friendly note under the access panel just in case. Especially if that next guy is me.
Thanks for the work above. It allowed me to fix my check valves. I did get put astray by not having enough gas in the tank when trying to start it. I finally pulled a pump to see why it wasn't working well. Turns out the inlet for the pump container is a small hole in the bottom. If the fuel level is low (EG, 5 gallons) it takes a while for the fuel to enter the pump assembly. And when you are priming the entire system after removing pumps it takes a bit of gas to fill the system. So - be patience is a virtue....
new hoses attached, new single ear clamps. bottom of fuel pump assembly - small square hole is the fuel inlet.
Glad this helped someone! The pump body should fill pretty quickly through that hole. A portion of the fuel is diverted to a venturi jet in the bottom, seen inside the square hole. Another hose feeds a venturi pump that dumps fuel into the top of the opposite side pump. The setup allows both pumps to be full of fuel at all times even with a low fuel level and during hard cornering. The lines going to the engine are another story. I had a similar long time to purge the main fuel lines and the first start was a little rough for the first few seconds.
