It’s awesome don’t know why I didn’t get one sooner

 

Pulled Fueltank in order to replace a pump with a broken return line,

On that subject would a broken return line nipple and a broken vapor return hose (the hose on the front end of the tank, looking for a P/N for that fitting thats on the tank itself) result in rough running?

 

Only if flow is restricted, or if airflow into the tank is restricted. Both will have opposite effects on the engine, resulting in rough running.

Blocked return = rich, blocked vent = lean.

 

Will definitely throw your check engine light on...

 

I had none oddly enough, granted it only ran for about 30 seconds with this issue and moved a grand total of my driveway before moving back up, i ask because it nearly died moving up the moderate slope when i tried to give it some throttle. It has all new injection and ignition components, it idles at about 1000 from cold (around 60F) assuming my tach is correct. Im replacing the pump and trying the fix from this thread - https://blazerforum.com/forum/2nd-ge...s-fixed-63397/ to fix the vent valve break.

 

The return was wide open, the nipple on the pump was straight up broken off. Im not sure how the fuel return system works on these or if it requires active pressure on the return or if it has any at all.

 

Fuel is pumped by the fuel pump to a regulator. Whatever isn't needed by the injectors goes back to the tank via the return line. The regulator should maintain specified pressure regardless of what the engine is using, or requiring.

On newer vehicles, there is no return. The computer pulse-width modulates the fuel pump based on fuel requirements of the engine. No regulator, and no filter on the frame rail these days. On GM trucks '07 and up, they use a fuel pump module, mounted conveniently above the spare tire where all the road salt, snow, and rain water can attack it. WHEN it fails, you buy a new one, install it, and your vehicle won't start. It needs to be programmed to function. Nice racket GM has created for themselves ... but I digress!

Keep the older ones running - you'll have much less headaches!

Anyway, a leak that large on a 2nd gen should be throwing a large, or gross leak code. If it's not, your monitors haven't run because either the battery was disconnected, or, a code was recently reset. Also if the drive cycle parameters aren't met, it won't run either. EVAP will only run when the tank is between 1/4 - 3/4 full. If your state doesn't do inspections, I wouldn't worry about it ... but I'd try and repair that busted nipple, and get a hose on there with a lawn mower fuel filter on the end, and placed somewhere up high in the engine compartment where water can't get in, but air can.

And yes, there will be slight pressure on the return, although not anywhere near what the supply is (55-60 PSI). IF the nipple is busted off on the pump or sender itself, you're going to have to replace that whole thing unless you can epoxy that nipple back on. Every time you fill up, you'll have a huge fuel leak on your hands.

 

My truck has cali emissions (despite being sold in ohio first and then florida where its at now, odd) so its vent hose runs back to what some sort of filter box under the drivers side rear bumper end cap. I'm going to follow that thread i linked earlier to be absolutely sure it doesnt break off any time soon. The monitors probably have not run yet since its only had power for the 30 or so seconds of total idle time across three runs and about 20 ft of total movement forward and back. The nipple is straight broken off the pump and i've already got it in the plans to replace it, Thanks for the details.

 

That black box your talking about, is a carbon canister. I dont think it has to do anything to do with cali tho.

I live in canada, I've seen that on every blazer ive come across...

 

i assumed it was part of it since it doesnt seem like its standard.