Hi Jim,

I'm not sure what Art meant there either. I don't recall ever getting that Key On buzz with a '78 245 (several years) or a '83 turbo wagon (also several years). My first relay "buzz" was on the '80gle V8, where I used the stock K-jet relay and an LH pump. And that was a surprise — it just started doing it one day. I replaced the relay, thinking it was going bad or something.

In the LH2.4 that "prime cycle" was built into the ECU for some "unknown" reason. I say unknown because I don't know what it's for. That function is never mentioned in any Volvo documentation, and diagnostically all it tells you is that the pump will run [if the ECU grounds the relay coil in a non-standard way that doesn't need ignition pulses].

I wouldn't blame your "5 to 8 seconds of cranking" on the missing "prime". That '83 turbo wagon was one of the fastest starting cars I ever had, even in the dead of winter after setting outside overnight. And none of it's 2 or 3 relays ever did the prime thing. I'd be more suspicious of the Accumulator. They generally keep some good backup pressure.

I think Art has said that a good system will have full pressure up in something like one or two pump revolutions. And that's how the good ones always seemed to me.

--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.