Two fuel pumps?

PDLarson · Post by **PDLarson** » 08 Sep 2014, 19:08

So I have a '99 V70XC with an occasional hard starting problem and I decided to replace the fuel pump. I know there are some who loosen the subframe and do it from underneath and others have cut a hole in the floor. Now I see there is a fuel pump and a fuel transfer pump! So when people cut a hole in the floor to get at their fuel pump, which one are they most commonly replacing?

As for my occasional hard starting problem, I can retry cranking until the battery is dead with no joy but if I turn the key to on for a few seconds I can usually hear the pump running. If I turn the key off for a few seconds, back to on until the pump stops, repeating until I'm tired of repeating or until the pump doesn't run when turned on, it will fire right up. I've already tried a check valve in the fuel line near the fuel filter, I think I replaced the fuel filter at that time as well. No leaks anywhere that I can see or smell under the car or under the hood. I'm comfortable spending the money on the pump. I'll be sick if I do all the work and that is not the problem but I've read similar problems cured by the fuel pump but there are two, which one!?

I also have codes related to evap leaks. Everyone says check the J hose but I can't find one on my XC. I've asked here where it is and everyone says somewhere else. I'd like to look for vacuum leaves related to evap system when I'm under there. Any suggestions where to look?

Thanks!!!

Post by **Ozark Lee** » 08 Sep 2014, 20:08

The pump that goes bad is the one on the right hand side. I'm not sure what the transfer pump is about, I think it may transfer fuel from one side of the tank to the other but I've never cut a hole in that side of the floorboard. If you hear the pump running though it is normally good. What does a fuel pressure gauge at the fuel rail tell you? Before I go to all of the effort of changing out the pump I would test the pressure at the rail.

The J hose / rollover valve assembly is hidden up above the tank at the back of the car. It is right next to the fuel filter and it is difficult to inspect it visually due to all of the other stuff around it.

...Lee

PDLarson · Post by **PDLarson** » 14 Jun 2018, 22:40

Intermittent hard starting was the fuel pump relay.

Post by **scot850** » 14 Jun 2018, 23:04

The "pump" on the LHS of the saddle tank is not a pump as such but more of a syphon. It uses returning fuel pressure to help push fuel from the LHS to the RHS where the pump is. It also has the level sensor for the LHS of the tank that the fuel system uses to average the remaining fuel in each side as there are level sensor in both 'pumps'.

The only real issue that can happen with time is the level sensor may go bad so you do not get a correct fuel level reading from the LHS. The 'ejector' as Volvo calls it is more expensive from Volvo than the actual pump. So unless you are pulling the whole rear suspension to drop the tank to replace the pump (I know you say the system is now ok) I would leave it well alone if the fuel gauge is giving a fairly accurate level reading.

Neil.