Volvo 850 random stalling and hard to start. Testing Fuel Pump and Fuel Pump Relay – Volvo Forums…

22 Jan 2015 | Author: | Comments Off on Volvo 850 random stalling and hard to start. Testing Fuel Pump and Fuel Pump Relay – Volvo Forums…

Volvo 850

random stalling and hard to start. Testing Fuel Pump and Fuel Pump Relay

Hello all,

I notice that here in the Volvo 850 section of these forums a decent percentage of the number of threads being posted involve someone trying to diagnose and fix a Volvo that either turns over but doesn’t start and run or has a start-sputter-die situation due to fuel starvation. Among many possibilities, one likely cause of these problems is the fuel pump relay. Many people seem to want to know how to test if their fuel pump is running, and if it is not, how to test if the relay is working correctly, so I have put together this write up/How-to for the steps of how to test your fuel pump and fuel pump relay.

Perform the tests listed below WHILE your car is acting up. Many of these issues are intermittent, so it doesn’t really help to do the test when the car is wanting to start!

Steps for listening for fuel pump :

1. Walk over to your gas filler on the right side/rear of car.

2. Lie down near this section of the car.

3. With the car parked in a quiet area, have another person turn the key in the ignition to the ON position but do NOT start the car.

4. Once the key is in the ON position, you should be able to hear a humming that runs for a few seconds and stops.

If you don’t hear anything, your fuel pump is not running. From there, diagnose whether its the pump or the relay (or possibly both) that are bad. NOTE: Even if you hear the pump run initially but when you try to start the car it sputters and dies, you still need to check your fuel pump relay.

Steps to test if the fuel pump relay is bad :

1. Open hood and remove four screws holding down the cover over the fuse box that is located in the top right of the engine bay.

2. Remove the red relay labeled 103 (see picture attached below).

3. Bend a paper clip or wire to connect between ports 15 and 87 in the fuse box where the relay previously was.

4. Either try to start the car OR do the steps above for listening for the fuel pump, then start car once you have determined that the fuel pump is running. NOTE: if you do decide to listen to the pump before you start the car, it may run continuously rather than shut off after a few seconds.

If your fuel pump runs and your car starts and stays running while the paper clip/wire is connected in the relay socket, your relay is bad. This is the part you need:

If this test does not run your fuel pump and your car does not start, you either have a bad pump, a wiring issue, or some other problem that needs to be looked into.

This test is not recommended to be a permanent fix, but rather just as a test for the fuel pump relay.

Hope this helps all of you having starting issues involving fuel starvation!

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