Power Loss

[darville]

I recently changed my fuel filter and had a tough time getting the engine to turn over. Once I finally did, I was able to drive it for a little bit before losing power and eventually having the engine shut off. Now the vehicle starts but after shooting out tons of white smoke I have loss full power. By reading some other threads it sounds like I may have air in the system. However, I thought it would work itself out by now. I have a 1991 Chevy Suburban with a 6.2L motor in it.
Any advice? I am new to diesels so I am not familiar with all of the terminology that is used so bear with me if I ask for clarification. Thanks.

[BrIONwoshMunky]

Did you reprime and bleed the air out of the new filter when you installed a new one? Or just try to start the truck immediately?

I was having trouble with smokey starts, then after replacing the glow plugs with Kennedy's quick-heats, it would start, then die about 5 seconds later, and then take FOREVER while cranking to get it to fire. Mine ended up being a combo of bad juju. I ended up replacing the lift pump AND the Oil Pressure Switch.

If I were again in the situation, first, I'd try and bleed the air out of the system, then I'd look for visible leaks, and finally, I'd try and verify if your fuel lift pump is working correctly.

With the truck off, I'd go to the fuel pump fuse on the passenger side firewall, remove the fuse, and put battery power from one of the junction block terminals to the holder. You should hear your fuel pump inside the drivers side frame rail start to pump.

If you hear it, your fuel lift pump (FLP) is CAPABLE of running, then I'd try to see if it's running when the truck is turning over during startup, and while it is running.

I'd remove the gas cap while testing this to lessen the chances of having vacuum in the tank starve your engine of fuel while you're troubleshooting.

Once the truck is started, I'd remove and replace the fuel pump fuse and see if you can hear it engaging and disengaging the lift pump as you do it. If you can't hear it, you may want to have someone remove and replace the fuse while you feel the lift pump with your hand. If the pump is working, you may have an air leak somewhere. If the pump is not working, and was working with the fuse trick, your Oil Pressure Switch (OPS) could be the culprit.

On my truck, my OPS is located very near the filter housing, on the driver's side of the engine valley near the firewall, almost a bit under it. To remove it you'll need a 1 1/16" VERY DEEPwell socket, or a specific Oil Pressure Switch socket. I got by with a 1 1/16" deep well impact socket. Once I had the air filter housing off the truck, and found the switch, it took all of 45 seconds to replace.

Once I found the correct metric wrenches, the lift pump was replaced in about 5 minutes as well. Of course, as I was doing it, fuel was peeing out of the line, so I got my butt in gear. $4/gal spilling onto the ground will get you MOVING. I didn't lose but MAYBE a cup of fuel.

The OPS AC-Delco Part number is: D1808A

The AC-Delco FLP Part number is: EP158



Most parts stores and dealers should be able to cross those numbers into something they have in stock.

Hopefully it's something easy like a blown fuel pump fuse. :D