Where is the check valve located on the pump on a 1994 12 valve? Is it on the return line between the injector pump and the motor? I bought one to put in. But eith neck injury I want to do as little looking as possible and just change it if I can. Truck is wonderful. It just needs a bunch of little things fixed. Which I can do.

 

There's a check valve inside the lift pump, but I don't believe there's any others.

 

If you mean the overflow valve, ir is at the front of the pump, next to the block. Stuff a rag between the block and the pump so that you do not lose the washer.

 

Yes I meant the overflow valve Smokee. Thank you for the quick and prompt reply. Since I have been laid up I have gotten to read up on this new truck and this is a great forum with lots of great people and great information. Hope I can help in the future. Tractor mechanic, ex school bus mechanic mechanic. Cummins are tough motors.

 

Oops wrong valve.

 

Good source for overflow valves, Marty 517 694 1522 Goodluck,, Rick

 

if you decide to run 370 or bigger injctors you can shim the over flow valve wth a small wahser which will increase fuel pressure and make the truck run better. A trick I learned from a pump guy.
DM01

 

How much turbo boost is to much?

Mine is about 40+ running empty and overdrive.

Can this cause blown headgaskets?

 

All you need is a 3/4'' or 19mm open end wrench, a rag to keep from losing the washers and 5 minutes to replace the OF valve. On some trucks the valve hits the manifold before it will come out, the solution is to grind or file a little bit off the manifold first as has been done in this diagram.

View from front, oil fill at lower left