Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
These are bottom referencing modular fuel pump assemblies. You have 3 springs pushing the pumps bucket to seat on the bottom while sitting on rubber feet, so there is going to be a strategy for the install.
While the dealer uses a spanner socket the fits the retaining ring, you don't have this tool, unless you befriend a tech with a coupler of beers and have him/her come over to your garage to put the ring in place. (As long as this is a factory setup)
Make sure the tanks seat is clean. Clean the pumps sealing area, install the o-ring, lubricate with some trans gel or vaseline. A little goes a long way. Get a helper. Locate the pumps ring so it will index into the tank. (Yes, it have a long tab on on side on the pump and the locking ring as well) Place in proper location, push down on pump assembly with helper. You position the ring in place, while pushing down on it, take a long blunt punch and tap on this ring and move from tab to tab in order to rotate the ring to seal.
I admit, it gets easier after you do 20 or so of these installs, but once you think it's holding, use a mirror-on-a-stick and focus a flashlight, then do a good visual inspection of every spot the ring locks into.
Older pumps are top referencing, lovingly called "Pump-on-a-stick". Yes, they had a lock ring too, but they did not fit back during the install. Next "2nd GEN" is your pump, with 3 long springs on metal tubes that disappear into a plastic bucket. These fight you when putting the lock ring on, plus, they now have 3 plastic tubes on top to get in your way. (Fuel pressure, Return, Vapor)
Now come the "3rd GEN" of fuel pumps. They have a 3 wire sensor that plugs into the pump to measure inches of H2O for EVAP operation to sense leaks. This only adds to the mess of parts on top that get in your way during install.
This changed the fuel sender from 0-90 ohms, now 40-250 ohms for better info to the PCM to perform EVAP test when fuel is between 80 full and 10% empty. Otherwise, this test aborts.
"4th GEN" pumps include a high pressure bleed, that is used in the bottom of the plastic bucket. It attaches to a brass venturi to draw fuel into the bucket which covers the pump, cools it and provides more fuel when low or turning to keep from add air to the fuel. This results in a misfire which is also a no no.
This is the best information I can give you as these are harder to install. Double check your ring to make sure it is fully seated, as the fuel cap can release pressure, but OBDII, increased the pressure from 1 PSI to 2 PSI for tank pressure release to the atmosphere which is a no no.
This is why gas cans sold a home improvement stores have double in price and the can's cap, looks like it need 3 hands to operate. As the people at CARB (California Air Research Board) does not want hydrocarbons to run free as they cause low atmosphere smog.
A lot of guys at shops across this nation, pull the bed off, then replace the pump. I am sure you did not want to hear that, but it's true. It gives them great room to pre-clean and replace the pump assembly and lock it in. Also, inspect your vehicle sides connector. Look for burn't, brown, twisted or dis-colored terminals. If so, Change the connector as this will result in a voltage drop and low fuel pressure.
Just give it the "Yankee" try and a re-due is required. Just don't bend anything metal or break anything plastic. Yep, you'll want that dealer spanner socket, singed out at the "Tool" room.
Also, Friendly reminder, as already asked, when start you thread, Please give us the year, make, model & engine so we have something to go on...all GMT400's are not the same!
ASE Master Tech since 1978 / Retired
Still waiting for "This" answer!!!What vehicle, year, engine, etc?