1993 GMC 6.2L: Ran fine, now won't start

[TonyS.]

1993 GMC 6.2L here guys. Truck has been running fine but now she just turns but won't start/run. I checked glow plugs by pulling each and with connector on tips red hot so gp's are all good. Batteries are good and I even jumped from my brother's truck. She turns fast but no start. Last thing I checked is bleed valve on top of fuel filter. There is NO fuel coming out. :eek: I did not run the truck empty so only thing I can think is lift pump is bad (replaced 2 years ago with new, not refurb) or getting air in system somehow. Should I check lift pump output line? Is it possible there's an air lock somewhere between the filter and IP and cracking an injector at the cylinder might bleed any air?

[TonyS.]

OK, pulled the fuel hose at the square filter above the engine and no fuel coming out. Looks like fuel pump is shot. Taking off input hose to pump first to ensure getting fuel to pump.

[TonyS.]

Yep, getting fuel from the tank but cranking engine still nothing from output side of pump going to filter. New pump $30. Wish me luck.

[TonyS.]

Nothin's ever easy. Apparently either myself or my brother stripped the nut on the metal fuel line at the pump so I had to cut the line. I got the new pump but they didn't have 3/8" fuel hose so will have to get some tomorrow. I'm thinking of replacing the whole metal line from the pump to the filter with rubber fuel hose. We shall see tomorrow.

[DmaxMaverick]

The OEM steel line is best, for many reasons. Unless you have another reason for replacing it, I suggest repairing the pump end. Later models, including the Duramax, use rubber fuel hose in some locations, and they can be problematic. Rubber hose should only be used as a vibration barrier or flexible joint, or as absolutely necessary. Used to be, 20 or so years ago, there was a repair fitting available for the pump outlet. It was a compression fitting that slipped onto the old line, with the flare and nut at the other end. It was about $5 then, so probably more now, if still available. I've used them, and I've also repaired the lines by flaring and using a coupler.

A good set of tubing wrenches goes a long way to prevent fitting damage. If necessary, you can modify a box end wrench (not perfect, but better than open end). Once you resort to pliers or vice grips, it's too late.

[TonyS.]

Thanks Dmax. I hear ya on the metal lines but I got a deal on Gates Barricade 3/8" injection hose so I'm using that.

I'm ready to throw a damn electric pump on there and call it a day but since I already have the pump.... Weird thing and I don't know if it's supposed to be like this but the cam/shaft that resides in the hole on the engine where the lift pump goes seems to not be lobed and it's parallel to the lever on the pump. Running my finger on it it just feels like a rod, even cranked the engine to see if it would turn but it still feels the same, like there's no lobe. I put the pump in and an inline filter (diesel rated) on the intake side of the pump. It was a major PITA getting the pump in and lined up to get the bolts in. So cranked the engine about 10 times waiting about 2mins between cranks and no fuel coming out the output side of the pump. :( So either the pump is bad or something's not right with the cam that powers it....?

[TonyS.]

Took off the new lift pump. I stuck my finger into the hole on the engine and now I can move the rod around with my finger. I don't think that supposed to happen, right? :o:confused: Looks like I broke whatever the heck that is...the cam? If this is true I guess it's time to get an e-pump. Any recommendations on an epump for this 93 6.2? Thanks.