Tired and hot

[1hot57]

Just bought a 1995 Chevy C3500 6.5 Turbo to pull my horse trailer, yesterday it was hot so i turned the air on while driving down I 65 So. The air was cold for about 20 minutes then i noticed that the air was not coming out the vents as at first. I tryed all settings and nothing seams to work. another thing is that after about 20 or so startes the engine will starte then in 3 to 5 seconds it will die, to restart I have to go into the fuse box and remove the lift pump relay and jumper the two diagonal terminals so i can hear the lift pump running and it startes right up, for another 20 or so startes. HELP

 

[Brooklyn Tow]

Sounds like the relay or the connection.....I also have a problem with the A/C relay Connector....That terminal seems to be a little skechy, the relay is good but sometimes looses the contact.

I've heard of people taking that relay/fuse center apart just for that issue...."Wear and Tear?"

 

[buddy]

Well, youve answered your own question on the starting. You lift pump isnt working. And if you read the sticky on LP operation, posts specific to OBD1 then you can find your answer. You can tell if the LP is actually working when running if there is pressure out the drain. You need to become very familiar with the LP AND how it gets power.

It could be that your OPS is not working so while driving the IP is sucking fuel from tank and when you shut down there is no prime. The relay only powers it during cranking, and there is a fuse that is between the ignition and relay, in my 94 its called CRK, but in 95 its probably something else. You can tell if the OPS is at least passing voltage by checking on the OBD1 port, pin G or F, one or the other should have 12V on it while the truck is running.

 

[1hot57]

Ok since I am new on this web, dont quite know all the ins and outs. I have replaced the relay and PCM is a remote thats about all I know about this truck. I have only had it for a month. Can you tell me were the OP switch is, as I understand there are 2 a upper and lower???? Thanks So Much George

 

[ak diesel driver]

Just 1 OPS at the back of the engine behind the intake manifold in the valley

 

[ak diesel driver]

the intake is a 2 piece and referred to as an upper and lower

 

[1hot57]

Sounds like the relay or the connection.....I also have a problem with the A/C relay Connector....That terminal seems to be a little skechy, the relay is good but sometimes looses the contact.

I've heard of people taking that relay/fuse center apart just for that issue...."Wear and Tear?"

I think you misunderstood my question. Everything still works but the air is not coming out the vents, like some flap is closing inside the heater box.

 

[buddy]

The PCM doesnt act as the remote for your LP, that is in OBDII trucks, and yours is OBD1. Only thing that triggers OBD1 LP is IGN in the start/crank position via the LP relay and oil pressure over 6psi via the OPS. The voltage inputs (OPS and relay) are in parallel, so failure of one doesnt cause the other to fail.

You can test your relay function with the truck off by putting the truck in gear and then turning the key to start/crank. It wont crank but it should run the lift pump. That is only good for the 95 year, not 94 and earlier.

 

[Brooklyn Tow]

I think you misunderstood my question. Everything still works but the air is not coming out the vents, like some flap is closing inside the heater box.

another thing is that after about 20 or so startes the engine will starte then in 3 to 5 seconds it will die, to restart I have to go into the fuse box and remove the lift pump relay and jumper the two diagonal terminals so i can hear the lift pump running and it startes right up, for another 20 or so startes.

I was reffering to the LP relay......Just used my "A/C relay problem" as an example.