First post here- awesome site!

Having issues with my 95 2500 Suburban with the 6.5TD. A week ago it died while driving down the road. After several attempts it would start but die again. Got it home. Pulled a code 35 but no other codes. Cleared that, but after dozens of attempts to start the vehicle the 3 1/2 year old batteries died. So I bought 2 new batteries. Vehicle still would not start. After all the internet/manual research, I decided to buy a PMD. It has not arrived yet. Yesterday, just for laughs, I tried to start it. It ran like a CHAMP! It used to stumble under hard acceleration but not now. With the vehicle now at least running, I decided to test the lift pump. Turn the valve on the water/fuel separator- engine dies. Can't feel or hear the lift pump run. Check voltage at lift pump- 13.5V. So, it seems the OPS is OK and the lift pump is shot. So I buy a new lift pump.

Installed it today. Guess what? NO NOISE, Can't FEEL it either!!! Censored Vehicle dies while sitting on an incline. Opened fuel filter- it is nearly empty.

No vacuum sound when tank cap removed.

What the heck? Is it the fuel pump relay in the fuse box under the hood?:help:

On your '95 its all behind that plastic cover on the driver's side firewall.

20a fuse on the far left side towards the quarter panel, and there's a 5 pin relay on the right hand side.

You said you got 13.5v at the supply pump and a new pump, and it never runs at all?
Do you have a good ground on the black wire to the pump?

I think alot of PMD's were purchased when it was fuel supply pressure to the IP causing the problems.

Half full of fuel at the filter? Sounds like you've got an air leak in the fuel system maybe?

Thanks for the posts. Yup, 1/4 full fuel filter. Here's a neat one- I can still move it up and down a steep driveway and drive to the gas station and back. And still, it won't pump fuel out of the air bleeder. ???????

I tested the old pump by direct wiring it to a 12V battery. The old pump WORKS!!!!!!!!!! Another 90 bucks wasted, or, if you are a glass half full type, I now have a spare.

I cannot uderstand why the pump isn't running when it has proper voltage. I am at a loss.

All the fuses are OK. Is there a way to test the relay??

The relay only works when the starter is engaged and the OPS takes over once its running. Back probe the lift pump power wires at the lift pump when it's running, on mine I could bleed it on starting key engaged and get it running. But it would lose prime once it was running, bad OPS. Replaced OPS and installed relay at the OPS to take the load off the OPS.