Volvo 850 wagon (nonturbo)

Fuel pump defective.

Here's a link to your one fuel pump that your Volvo uses,it's in the gas tank. Spectra Premium Fuel Pump D5031M Read Reviews on Spectra Premium D5031M Here's another link on replacing it Ray. Repair Guides Gasoline Fuel Injection Systems Fuel Pump AutoZone com

Check the air valve, clean the throttle body, adjust the TPS, possibly replace the fuel pressure regulator after a fuel pressure test. Check the MAF: with the engine off, unplug it. Now start the car. Does it run 'better'? If so, the MAF is defective. You can also try cleaning it with MAF cleaner as well. Check the fuel system radio suppression relay (this is located either on the left or right side of the engine bay) is operating - cracked solder joints will also cause this misbehavior. You can easily verify this by swapping it with the AC fan relay next to it, otherwise 20 dollars will net you a new one.

Sometimes problems with the main pump (under the driver seat) check valve will cause this. A failed pre-pump will cause misfiring when cornering, especially right turns. A failed check valve results in low fuel pressure.

Rarely, the ignition crank angle sensor (top of bellhousing, rear of engine) is getting weak or the insulation has failed around the sensor, or possibly the connector is dirty.

Given this condition, also check the grounds on the fuel rail and along the front fenders as well.

Check the fuel pump inertia switch or fuel cutoff switch.In case of rearend mishap this switch will cut the fuel off.It maybe faulty

pull off the fuse box cover under the hood. held down with 4 T25 screws. Replace the red relay.

check the crank position switch

Hey Jruthesq

The 850 is equipped with an Idle Air Control Valve (IACV) which supplies the engine with air when idleing (a necessity since the main throttle body valve is completely closed when no throttle is applied, thus the engine would lack air without the IACV when idleing). The IACV is suspended in a rubber mount on the front of the throttle body itself, and is easily removed and inspected/cleaned. If it's dead a good cleaning usually gets it going again. Also make sure that the air from the IACV is unhindered on its way from the IACV to the throttle body (it's actually common for the holes in the throttle body to be gunked up so bad by hardened carbon deposits that one sometimes needs a nail or even a drill to open it up again).

Just thought I'd mention this since you said that the gas needs to be feathered for the engine to start. When you press down on the gas the main valve in the throttle body opens up, closing the IACV and supplying the engine with enough air.

Oh and if your fuel pump relay is a green one marked 103 you should replace it with the new and improved red one. The relay is located under the fuse box cover under the hood. Remove the 4 torx srews holding the cover in place and you'll see the relays under there.

Good luck mate!

Hey Rob!
I can almost guarantee you that your problem is the infamous fuel pump relay. Open the hood and remove the fuse box cover (4 torx screws) to gain access to the relays. One of the relays is probably a green one marked 103. If so it needs to be replaced with a red, improved version. If it's not the relay the problem is probably the pump itself. Here's a link to some useful info on the relay and fuel pump: http://www.volvo-forums.com/index.php?showtopic=15505&st=80&p=80586&#entry80586

You should also check for spark when the problem is present. No spark could indicate faulty coil, camshaft position sensor or crankshaft position sensor. Checking a plug for spark is easy: Unscrew the plug and hold it to ground with a pair of insulated pliers or something similar while the problem is present. Have someone crank the engine while you look for spark. Should the engine start while lacking one plug it will sound horrible, but will not be harmed as long as you don't run it too long and don't rev it.

Good luck!

Hi!

You meant a 2.4 litre engine, right?

Check:
- Fault codes from the diagnostics system.
- Fuel pump relay, located under the fuse box cover under the hood. If it's a green one labeled 103 it might be the culprit and should be replaced with the new and improved red one.
- The fuel pump itself, measure voltage to the fuel pump and make sure it's getting sufficient power. Can you hear the pump working when turning on ignition?
- Fuel filter might be clogged up. Located under car, by the right rear wheel.
- Unaccounted air entering through vacuum hoses. Spray them with start gas while the engine is idleing, if engine revs up you've found a leak.
- Throttle body might be in need of cleaning, probably a good idea anyway as it usually gives the engine a tad better performance.
- Mass airflow sensor might need replacement or cleaning of connector.
- If idle is rough check idle control valve.
- Make sure all plugs are firing, engine might be missing one cylinder, causing it to vibrate depending on engine RPM.
- Check that coil is ok.

Your problem doesn't sound like a camshaft/crankshaft position sensor, but you never know. Have the codes read, that'll probably help alot!

Well, that should give you some idea as to where to start checking...
Good luck mate!

Common fault is the fuel relay.You can either replace relay 103 in the relay box, next to the fuse box, or repair it by replacing the two capacitors inside the relay housing.

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