LQ4-E39

iTrader: (3)

2002 Silverado RCSB with a 4.8. I've done a bunch of work to the truck - built my own turbo kit, 4L80E swap, 8.8 rear, etc. Ran fine the last few weeks while tuning my VE tables in prep for the turbo. It's running a new Walbro 450 that was installed last year - the truck ran great with the new pump for a couple thousand miles.

I drove it around today for a good 15 minutes playing with VE, shut it off and went to start it an hour later. Cranks all day long but won't start. With the key turned to ON, I hear the pump priming. Can also trigger the pump to run continuously using HPTuner VCM Scanner, so I don't think it can be the pump. 3/4 tank of 93 in it. With a fuel pressure gauge hooked up I get ZERO pressure at the rail with the key on. Ignition key is fussy and seems to be sloppy as I can remove the key when it's in the ON position. Could this be my problem?

1FastBrick

iTrader: (17)

Just because you hear it doesn't mean it priming. If the mechanical gauge is good and you physical have no PSI Then something is wrong.

Maybe the blade came off the shaft?

Maybe there is an internal leak?

Or possibly a restriction?

trxmxzx

iTrader: (7)

Or even the hose came off in between pump and housing... burst line-

LQ4-E39

iTrader: (3)

Good point. It's unlikely but possible...just weird because it drove fine for so long. You'd figure if all of a sudden there was a pressure loss it would have happened ages ago. I will be pulling the fuel feed line off the intake manifold today and seeing if I get flow when priming.

Possible...I am really not looking forward to pulling the bed off again

MikeGyver

iTrader: (5)

If you used any kind of rubber hose to connect the pump to the hat, even Gates submersible, it's very possible that the hose split.

LQ4-E39

iTrader: (3)

If I recall correctly I used whatever hose they included with the Walbro 450. I don't recall what kind.

My plan tonight is to work my way backwards from the fuel rail, first unhooking the feed line and seeing if I get any flow whatsoever there. Then I'll check the filter, and finally I'll have to go to the pump. Considering cutting a hole in the bed rather than lifting it again

I suppose it wouldn't be a bad idea to start it on starting fluid to rule out a spark issue too

LQ4-E39

iTrader: (3)

Got a couple buddies to help push the truck inside the garage last night. With the feed line pulled off the rail, I'm getting a semi weak stream of gas out the line. Same story when I removed the filter, it wasn't clogged and had a weak stream. But at least the pump is still running which rules out any major electrical problem like a relay or fuse. I'm going to chop a hole in the bed tonight and pull the pump to see if my suspicion of a split fuel hose inside the tank is correect.

MikeGyver

iTrader: (5)

You won't be the first one to have an access hole in your bed. Mine is about a foot square, I made sure it was big enough to work through. Don't be lazy like me and just lay the rubber mat back down over the open hole. Someday I need to weld tabs on the piece that I cut out and lay it back in there.

LQ4-E39

iTrader: (3)

I was thinking a nice big piece of plywood cut to fit the entire bed

Nah I'll probably make a patch piece and sheet metal screw it in place

LQ4-E39

iTrader: (3)

Turns out the hose they ship with that 450 is junk, it's fuel injection hose but NOT rated for submersible.

Step 1: cut shitty hole in shitty truck


Step 2: remove fuel pump you installed 6 months ago


Step 3: admire failure of incorrectly spec'd hose




Step 4: ride newly acquired road bike to store for new fuel filter, clamps, hose, etc




She runs again!