Checking the OPS [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: Checking the OPS


Bass94
05-09-2005, 12:41 AM
I just wanted to know can you jump the terminals in the lift pump relay to bypass the OPS turning the pump on I cant hear my lift pump come on before I start the truck it seems to be pretty hard to start in my opinion it takes longer to start than other diesels ive been around once it starts it runs good you get a good steady supply of fuel out of the air bleeder on top of the filter once its running it could just be that the truck is starting to get old and loose compression but i would rather think its the lift pump or OPS ive already replaced the relay. If you can test it by jumping the relay what terminals do you jump?

knkreb
05-09-2005, 06:54 AM
Fuel coming out the bleeder while the engine is running indicates that your lift pump is working. OBD-I systems (pre-96) did not engage the lift pump during the wait to start period. Once your oil pressure is built up after cranking, you should hear the purring of the lift pump working.

If hard-starting is your problem, do you have white smoke on startup? You may have some glows gone to lunch.

Bass94
05-09-2005, 07:10 AM
No white smoke when it starts I get a black puff and then it goes away. I have found that if I tap the gas while its trying to start then it will start a little faster.