Mule Skinner

After starting cold engine with the grids cycling I noticed the fuel pressure guage would drop about 4 lbs when the grids are on and when they cycle off the pressure comes up that 4 lbs. Is this normal?
Thanks for any info.

Commatoze

The grids pull a total of 190 amps. It's very possible that the voltage drop during the cycle causes the LP to slow temporarily thus lowering the pressure.

Mule Skinner

I assumed that it might be an electrical draw, the pressure is still above 11 lbs at idle w/ grids on so I guess no need to worry.

Commatoze

I think you're OK. My 02 still idles at about 12 lbs with the OEM pump.

Tazman

Mule,

Sounds about right compared to my 98.5

On top of the electrical draw, the ECM/goveror tries to maintain a set RPM. This means a call for fuel to compensate for the alternator load.

More fuel = more flow demand from an already challenged LP = less pressure

Stack the 2 together........

jm2cw

Tazman

Rechecked this morning,

Not a 4 psi drop. More like 1.5 to 2.

Mike D

Mine does the same thing.

Geico266

Mine drops also, then when its done cycling it goes back to 14-15PSI.

I've also noticed a pressure drop when the fuel is really cold (-5F ). Then when you fill up its right back up to 15PSI.

Tom

Mule Skinner,

My fuel pressure also drops somewhat on cold mornings, when the grid cycles on and off. Mine seems to stops when I reach about 15 MPH

Tom

Fueling around

PCM cuts grid heater function at 15 mph road speed.

Geico266

Ya know that may explain something that happened to me. I was driving along (cold temps, -10F) and I noticed the grid heater seem to be stuck on. The voltage gauge was way over. I restarted it while I was moving, it cycled and was fine. Can these relays stick? Should I replace it?