How many fuel pumps in a ...

[Terry Donlin]

'91 Suburban diesel that started life with a 6.2 C engine? I'm not getting fuel from my mechanical pump after presurizing from the fuel tank to the firewall filter (fuel came out of the bleed port). Is there an electric pump to feed the mechanical pump? I'm removing the recently installed mechanical pump to make sure the rod is installed completely. I may just pick up a new mechanical pump.
Thanks!

[arveetek]

In the old body style Suburban, there should be just one mechanical pump. GM never installed both a mechanical and an electric pump. There will always be just one or the other, unless a PO installed a secondary pump.

Casey

[Terry Donlin]

Thanks Casey,

So the fuel is gravity fed to the mechanical pump then? And even though the lines enter through the top of the tank the actual pickup is in the bottom of the tank so that once its primed gravity takes over. Correct?

Terry

[Peter J. Bierman]

Not realy, the lift pump is able to aply sucktion on the fuel line. So it sucks fuel from the tank and push it up through the filter to the injectionpump. Inside the injectionpump is a vanepump to pressurize the pump housing.
The function off the liftpump is to overcome the resistance from the filter and to supply fuel to the vanepump.

Peter