Main Pump Not Working 91 Volvo 240

iaguilera · Post by **iaguilera** » 19 Oct 2021, 16:29

Good day all, I am new here, my son really wanted a 91 Volvo 240, or just a 240 period, he found a 91, I have replaced both pumps and the pumps relay, the in tank pump was shot, the high pressure pump is not humming, it only does if I connect a ground to 86/2 pin on the relay, then I hear the main pump running, any ideas how to go about fixing this?

Post by **volvolugnut** » 19 Oct 2021, 17:01

The main pump may not make enough noise to hear it. I believe the pump will only run when the starter is engaged OR the engine is running.
Does the fuel pump produce pressure to the engine fuel rail? You can loosen the fuel connection carefully at the fuel rail after trying to start the car to see if fuel is present. Use a rag to catch leaked fuel. If fuel is present then check for proper fuel pressure with a fuel pressure gauge.

It may be that there is another reason if the car is not starting.

volvolugnut

iaguilera · Post by **iaguilera** » 19 Oct 2021, 17:09

car starts fine, but it almost seems like it wants to shut off, giving it a bump on the accelerator, it evens out and runs fine, but as mentioned, if I connect ground to 86/2 on the relay I can hear the pump working, but I should check to see if it is humming while running.

Post by **volvolugnut** » 19 Oct 2021, 18:24

Touching the pump might be an easier test of pump running. Compare the pump feel with and without engine running. If you have a rough idle, you may have a vacuum leak somewhere. A vacuum leak would not be surprising at this age. Use a spray bottle to direct water at the hoses. If idle smooths out, you may have found the leak.
volvolugnut

iaguilera · Post by **iaguilera** » 20 Oct 2021, 11:34

pump is running, checked it this a.m. with a mechanics stethoscope, as far as leaks, i had checked with a smoke leak detector, absolutely no leaks.