1999 V70XC 9434225 Strange buzzing noise on start ..solved with new fuel pump relay Topic is solved

Post by **loosenut** » 28 Dec 2017, 07:13

good morning volvo people. i had started to hear a strange buzzing noise from under my dash of my 99 v70xc awd turbo.
it is very cold here in virginia although i am not confirming that it is a cold issue..
it sounds like a very loud relay and for a short time..coming from the drivers side up near the dash speaker..heard it a few times..

so my whip (lol thats the sound it makes when the turbo spools so at the shop we call it the whip) any way...im having starting issues right now in fact it wouldnt run this morning so i had to drive my other v70xc awd turbo (it doesnt have the tune so it sounds normal SAD) lol Ant way so thing is that when i hear this buzzing sound it will start..when i dont hear the buzzing noise it wont start...
the area of the noise could possible be the relay box wight next to the windshield...out side in the engine bay....

have a relay and will try it tonight and keep posting untill i figure this out. hope this helps someone.

Loosenutbehindethewheel.....

Post by **loosenut** » 29 Dec 2017, 05:09

ok, went out early this morning, heard the fuel pump come on the car started and died in 3 seconds. didn't hear the buzzing noise. tried it again there it was a buzzing noise coming from the upper area on the drivers side like where the speaker is.

so i switched out the fuel pump relay and there you go...the relay was buzzing so loud that it sounded like it was coming from inside the car due to the location of the relay..car starts right up haven't heard the buzzing again

hope this helps someone

Post by **wizechatmgr** » 29 Dec 2017, 22:12

Good catch. =)

Post by **abscate** » 30 Dec 2017, 06:35

Outstanding, volvo team. Green check box and part number added for search

Post by **sleddriver** » 04 Jan 2018, 14:30

OP: You just helped me verify what's going on with a recent cold-start sled issue. Same thing happened: Buzzzzing dash, no start, batt. light on, just crank & crank. Then it'll light off. I've read there's an electrolytic cap inside the FP relay. These eventually dry out, stop acting like a capacitor and cause havoc. I'm going to pull mine, test the cap's ESR and look for a substitute in my electronic parts bin.

Thanks for your post!

Post by **sleddriver** » 07 Jan 2018, 13:51

sleddriver wrote: ↑04 Jan 2018, 14:30 OP: You just helped me verify what's going on with a recent cold-start sled issue. Same thing happened: Buzzzzing dash, no start, batt. light on, just crank & crank. Then it'll light off. I've read there's an electrolytic cap inside the FP relay. These eventually dry out, stop acting like a capacitor and cause havoc. I'm going to pull mine, test the cap's ESR and look for a substitute in my electronic parts bin.

Thanks for your post!

Update:
Built a male-to-male wire jumper. Sled fired right up from dead 30°F cold. Replaced both 20yr old electrolytics in the FP relay, stuck it in the freezer for 10min., then tried it in the car. Fired right up! The tall silver cap had an ESR of 68 Ohms!! It was clearly Toes Up.

I've added the jumper to the car's tool kit.

Post by **abscate** » 08 Jan 2018, 01:34

What was the ESR on the replacement stuff?

1999 was the beginning of capacitor plague if I remember right, so a bit too early to make the OEM supply chain

Post by **sleddriver** » 09 Jan 2018, 13:49

abscate wrote: ↑08 Jan 2018, 01:34 What was the ESR on the replacement stuff?

For a high quality Panasonic low ESR cap, about half an Ohm.