1999 s70 b5254t stalling MVSOLVED Fuel pump relay

isaiah54 · Post by **isaiah54** » 06 Jun 2015, 11:26

set timing and cvvt, the engine will start and run anywhere from 5 to 10 seconds and dies. wait a few minutes and the same thing. sounds like it runs out of fuel, took fuel pressure test, key on, engine off, fuel pressure is 51 lbs, let it set for 20 minutes and pressure drops 5 to 8 lbs, when engine starts fuel pressure starts between 40 to 50 lbs and then drops to 15 to 20 lbs and engine dies.. talked to service dept. at dealership, he said this will happen if timing is really far off or it could be a bad fuel pump. this system has no fuel pressure regulator. anybody run into this before ?

Post by **Ozark Lee** » 06 Jun 2015, 18:25

Start by installing a jumper wire around the fuel pump relay and see if it will stay running. Stick the wire in the socket positions associated with pins 15 and 87 on the relay.

...Lee

Post by **misha** » 06 Jun 2015, 18:29

Do not exclude immobiliser problem.Could be immobiliser itself or a chipped key fault.

Post by **Ozark Lee** » 06 Jun 2015, 18:35

It could be the immobilizer but that typically causes the car to die within about 1 second of starting - it will also set a P code but not necessarily a CEL.

...Lee

isaiah54 · Post by **isaiah54** » 08 Jun 2015, 10:58

lee, their is no fuel pump relay, dealer also said that on this model that there is none . is it possible that the vvt control valve could cause this ? if not, do you have any other suggestions ? i dont think its in the timing like the dealer says that it could be . thanks for your input and help

Post by **Ozark Lee** » 08 Jun 2015, 14:39

isaiah54 wrote:lee, their is no fuel pump relay, dealer also said that on this model that there is none .

I beg to differ. The fuel pump relay is relay 103 and it is located under the fuse box cover. You need to remove the four T-25 Torx screws that secure the cover to get to it.

The CVVT valve won't cause the car not to run, it will only cause it to not run as well as normal if there is a problem with it or its timing adjustment. It will also trigger the Check Engine Light (CEL) when it detects a problem. When the ECU does detect a problem it disables the CVVT altogether and the car will run more or less normally with a little less pep and a little worse fuel economy.

...Lee

Post by **misha** » 08 Jun 2015, 15:08

"Stealership".....did they E V E R solved somebody's problem

Post by **renns** » 08 Jun 2015, 15:34

EDIT: Below are details related to my '98 V70. These numbers may not be applicable to '99 and newer due to the change to return-less fuel system.

The fuel rail pressure should be 3 bar (43.5 psi) above manifold pressure. With the engine off, after priming, pressure should show about 43.5 psi, as manifold pressure is equal to atmospheric pressure. After startup, the engine will idle creating a vacuum in the intake around 18-20 inches Hg, or 9-10 psi vacuum. Therefore when you measure fuel pressure at idle, it should be in the low-mid 30's psi (43 psi minus the vacuum value of 9-10 psi). Actual pressure will vary slightly depending on engine load (alternator, a/c), idle speed, engine condition, etc. If you punch the throttle from idle, you should see the fuel pressure spike back up to near 43psi momentary while accelerating the engine, and then drop back down to 30 or so as it decelerates back to idle.

As you see fuel pressure dropping far below that, to the 15-20 psi range, then you have a fuel delivery problem. Fuel pump relay, as already stated, fuel pump, or possibly a blockage either at the inlet to the pump, or in the fuel filter are typical causes. Follow Lee's advice, and start with the relay as it's an easy test and common failure item.

EDIT: Below is a picture of my fuel pressure gauge with engine at idle, a/c off.

Post by **abscate** » 09 Jun 2015, 05:11

Does the fuel pressure regulation in ME7 follow the atmospheric pressure? There is no FPR on the 1999 models of course. It does sound like a fuel pump relay or fuel pump.

Post by **renns** » 09 Jun 2015, 09:30

abscate wrote:Does the fuel pressure regulation in ME7 follow the atmospheric pressure? There is no FPR on the 1999 models of course. It does sound like a fuel pump relay or fuel pump.

Ah, the switch to return-less fuel systems came in '99. Sorry for mis-leading post. I've put an edit in my post, in case this data is not applicable to the newer cars.