not get 12VDC to coil of lift pump relay, pins 85 86

[Drago]

I'm not getting my 12 volts to the coil of the lift pump relay, I jumpered 30 87 and the pump started, truck started.

Where does the coil voltage come from? Does the pump run continously or just come on long enough to get fuel up to the rest of the system priming it? I saw a dicussion on it but cant seem to locate it



1995 GMC 1500 NatAspirated 140k

 

[Drago]

I found this, what is an "OPS" ? http://www.thetruckstop.us/forum/attachment.php?attachmentid=24364&d=1296942405

 

[Drago]

oil pressure switch, about where is it? :???:

 

[ak diesel driver]

underneath the intake at the rear of the engine or on the rear behind pass side head

 

[DieselCash]

See if this helps!

http://www.thetruckstop.us/forum/showthread.php?30240-Oil-Pressure-Sender

:thumbsup:

 

[ak diesel driver]

edit should have been drivers side

 

[Turbine Doc]

More here from the technical reference library http://www.thetruckstop.us/forum/sh...t-Pumps-amp-OPS-operation-and-troubleshooting

 

[Drago]

I picked off 12 from one of the fuses just so I could get to the parts store, will replace the OPS as soon as it cools off, thanks for all the info, I'll keep you guys posted

 

[Drago]

I replaced the OPS but I didn't hear the lift pump "pump" it started right up. Does the pump run continously or does it wait for a pressure drop?

 

[ak diesel driver]

It will dead head .

 

[3500GMC]

If you don't have a socket, this is a good one to get. Lisle #13250

Orielly auto has 'em and the Borg Warner switch (USA) as well.

 

[Drago]

what is "dead head"?

it starts up and runs continuously now so I guess I got it. Thanks guys

 

[ak diesel driver]

what is "dead head"?

it starts up and runs continuously now so I guess I got it. Thanks guys

when the engines not running the pump should pump up to max pressure and stop, dead heading