6.2 fuel starvation?

[Ham]

I have a problem with my 1985 suburban. It starts fine, but when I put the engine under load it's not getting fuel(water in fuel light comes on). It will go out when not under load after a minute or so. I changed the fuel filter, also the lift pump and lift pump rod. I also bled the filter, the fuel doesn't appear to have water in it. This engine has 145,000 or 245,000 miles and the injection pump looks to be original or on there for a long time. Could it be the fuel tank pre-filter or blockage, or air leak? I'd appreciate any sound advice.

[john8662]

The WIF light coming on under a load isn't a good sign, this can mean two things, plugged filter/restriction or water in the fuel. If you suspect water in the fuel, get a glass jar or something to catch some fuel with. Then locate the drain hose on the bottom of the fuel filter housing, most have this hose that will end just near the bottom side of the frame. Anyways, there is a water drain valve thats on the right hand bottom side of the fuel filter housing. You'll want to get your jar ready to catch the fuel, then crank up the engine and let it idle. Either already have the valve open or have a helper open the valve while you hold the glass container. Then take a sample of the fuel. I'd get a pretty good sample that you can let sit for about a day, if you have water then it will settle and you'll be able to see.

Other things that could affect the running are a plugged fuel system. Check under the vehicle for any crimped lines or pinched rubber fuel lines this would also cause what you're seeing.

Finally some other things to consider, the fuel filler cap could be bad. Before you start the rig, open the fuel filler cap, and leave it loose. Go for a drive, same problem? Another thing it could be is a plugged fuel pickup sock in the fuel tank. All of the symptoms can be tested by connecting a fuel pressure gauge (0-15 psi) on the connection at the fuel filter housing on the line that goes to the injection pump (1/4" line). You should see about 8psi fuel pressure at idle.

[Ham]

It turned out to be a sludged up tank and pick up sock. The pick up sock was impregnated with sludge. I'm replacing my sock and tank because the tank is rusted as well. I appreciate the advice. Thanks, Ham.