volvo fuel pump setup

[Andrew McKenzie]

At 07:21 PM 20/10/98 -0500, you wrote:
>
>Volvo discovered in 1976 that their cars were suffering from vapor-lock
>and failed main pressure pumps under certain conditions, including low
>fuel levels in the tank.
>
>They were using a single pump, mounted under the back seat, and lower than
>the bottom of the fuel tank, and they were relying on gravity to get the
>fuel to the pump.  The pump was cooled by fuel flow through the system,
>which was K-jetronic and kept the fuel pressure at a constant 65 PSI.
>The return line dumped right back into the tank, no coolers.
>
>Their solution for 1977 and onward was to put a second fuel pump in the
>tank, which delivered fuel at about 4 PSI to the main fuel pump under the
>seat.  It worked flawlessly.
>
>The only downside is having two pumps to maintain, and that when the
>in-tank pump stops working an owner can go through two or three main
>pumps before they figure out what the problem is, since the main pump
>has to work harder when it's alone.
>
>The volvo 240 (their only car between 1975 and 1982 i believe) used a
>cross-flow head during and after 1976, but surely vapor lock problems
>were more common on the earlier engines with the exhaust manifolds
>under the intakes.
>
>Hope this helps someone,
>-Jake
>
Hi Jake,
        Holden Commodores (equiv. to Vauxhall Cavalier) used a two pump
setup in 1988 with there North-South Version of the Buick 3800 V6. One pump
was a low pressure (about 5psi) pump mounted in tank, while the high
pressure pump was mounted on the subframe. These cars were able to operate
from -20DegreesC to over 40degreesC without fuel problems. A recent 1994
service bulletin, from GM Holden, states that the low pressure pump is no
longer needed. Shortly after this bulletin, consumers were complaining that
the high pressure pumps would only last about a year without the low
pressure pump installed. Most persons wanting to have a reliable car have
spent the AUS$76(trade) to have a new low pressure pump fitted. I think a
low pressure pump is still a necessity in any car that is driven regularly.
And yes, I learnt to drive in a '78 Volvo 244DL.
Just my 0.02 cents worth. Hope it helps someone. Cheers.
__________________________________________________________________________
Andrew McKenzie <andmaca at tig.com.au>
Sydney, Australia
1970 Chevrolet Impala Super Sedan 350cid LT1 42,000 Miles
1981 Rover 3500 V8 S Series 1 Update 5 Speed Hybrid 266,000 KM 
Platinum with Nutmeg Interior VIN:RRKWV7AA146311	ENGINE NO:N832.153P
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