Just found that the hole on top/front of tank where the check valve is supposed seems to be filled with rtv or something and is leaking gas. (I couldn't get a real good look) There's a hard line that's been left open close to it. I think it leads to the EGR valve but I'm not sure.

Symptoms:
Feels like not getting enough fuel. Runs fine just off idle but runs rough at idle and bogs out when WOT. Haven't checked fuel pressure yet.

PO said fuel pump was replaced.

Just wondering if the missing check valve would compound any other fuel problems. Would missing check valve depressurize tank and cause probs?

 

General consensus is no that front check valve does not cause drive ability issues but will throw an evap code. On a large percentage of fuel pump changes that valve get's broken. It's not connected to the egr but the charcoal cannister. There is one in line on the back of your tank also. The connection on the front is a small length of fuel line to the open hard line you speak of. They can both be plugged to stop the gas leak and evap code.
You need to check your fuel pressure. Must be key on engine off and hold above 55 for ten minutes.

 

sounds like fuel pump. water in the tank? if fuel can get out, water can get in...

 

Checked fuel pressure. Holds at 60 for about then starts to drop. Drops to 50 in about 10 minutes

 

50 psi would lead me to believe check valve in pump but it could also be fpr under plenum. Pay attention to how this isolates the problem with vice grips.

 

Thanks for the link to the video! This helped a lot! Hopefully, I'll get to working on it this weekend. I'm hoping it's under the plenum. I really hate to have to drop the tank!

I talked to the mechanic I got the truck from and he said the fuel pump was new and just wired incorrectly. When they got it, it wasn't running. feul pump was wired wrong. It was purchased for the engine but needed a SCFI config instead of the CPI.
Also didn't have an intake tube or air filter/housing. I installed an aftermarket short ram and installed an IAT (which was missing) to correct a surging idle.

Exhaust system had to be redone as well. PO hacked the stock exhaust and clamped and welded (poorly) a dual exhaust system so it's probably missing an O2 sensor somewhere. I had the muffler shop redo the exhaust y pipe to a single flowmaster 50. I think there's a sensor that's supposed to be between the cat (which is no longer there) and the muffler?

Idk if this thing is worth it but I'm at the "i gotta get this thing solved" phase. You know what I mean? I've got $900 into it so far which is still not bad, right?? lol

 

Well i peeked into the plenum and there wereo visible leaks. Had a mechanic friend take a look at it. Scan codes pointed to IAT sensor and EGR valve. Wires going into IAT were switched giving a false reading. He switched the wires on IAT and cleared the codes.

One of my spark plug writes had insulation burnt off. Electrical tape fixed that until i could change the wires.

That alone, seemed to clear up most of the driveability issuesfor a couple days. Today it started idling bad again but still driveable and now noticing hard brake pedal and stalling occasionally when braking. I was told that's that's the EGR valve getting stuck open.

Hopefully get to taking it off and cleaning it up this weekend.

This project is turning into more than i want to take on but, as always, is a great learning experience.

 

Stalling can always be egr, but hard braking + stalling sounds like vacum leak.