I recently replaced my fuel pump on my 96 s10 blazer 4dr. when putting pump back into tank, my friend and I had a heck of a time pushing the pump flush to put the retaining ring on. he's a big guy, and he literally had to put his entire weight on it to get it low enough so that I could slip the ring on. Not only did it worry me that we might break one of the nipples or connections, but it just didn't seem like it should be that difficult to put back in.

Well, about a week after replacing pump, I finally filled my tank to full. Right before the pump automatically shut off (from the tank being full), I noticed a considerable amount of fuel "flowing" from under my vehicle. It stopped flowing after a second or two after the pump shut off.

After making it back home, I did a little research and have concluded that the "O" ring must have been knocked off during the installation. We are planning on dropping the tank again tomorrow and were hoping that someone could tell us a better way to put the pump securely back into the tank. Hopefully a way that will prevent us from discovering again later that we need to drop the tank and try again!!

Thanks in advance for your insight!!

 

you have to make sure the pump is dead center in the hole when pushing it down and it should just drop in. if you have to force it in its not aligned. it takes some time and f'en around with to get it right. i know cuz i just did mine in the fall. also put some silicone lube around the o ring to help aid installation.

 

When you get it out drop it into the hole without the oring and make sure it will seat with less gap than the o-ring. There is a separate assy listed for 2 dr and 4 dr. I suspect tank depth may be different.
If you kept the old assy, compare them. The pump itself is the same, so if the old assy is usable you can swap parts.
BTW, folks always keep old parts a little while ESPECIALLY when they are assemblies.
Or plug wires caps, rotors plugs if reason to replace was routine tune-up.

Like War said, silicon lube the ring but the ring he's talking about is more a space filler do-nut type for plastic tanks.
Your O Ring really looks like a big O-Ring, that is a whole different story

 

Well, here's the update...
I went to the grocery store to pick up some lunch, and picked up some petroleum jelly (read somewhere that it works well for this purpose) while I was there. After applying a liberal amount all around the O-ring, the fuel pump just slipped right in. My buddy wasn't available, so I was a little concerned that I would not be able to get it down myself, but to my amazement the petroleum jelly made all the difference in the world. Not only was I able to do it by myself, but it was extremely easy. Thank you for your help, and thank god for Vaseline!

 

Good for you, BUT...Vaseline will be okay on fuel and oil exposed o-rings> DO NOT use it on just about anything else rubber-like.
Assume you know vaseline and condoms dont mix, right?

Silicone grease/ lube is great for just about anything flexible and can also be used as heat sink grease. It has a much higher temp flow range and wont wash away as fast as vaseline. And doesnt degrade rubber. You ought to see faucet and toilet orings after regular grease vs silicone. Makes the case 100%

It aint like it's expensive or hard to find. Get it at Lowes or HD plumbing dept, as Gunk brand plumber's silicone grease. it's a small container but a little goes a long way. No reason to slather it on.
I bought some at ACE.. DONT! There's is sticky and messy as hell to use.

 

So, I can use silicone grease/ lube on condoms? J/K, anyways re-update:

I put the tank all back together, and went to the gas station to fill it up, 14 gallons! 15 gallons! 16 gallons! 17 gallons? Just as before, it filled up more than the 16 gallon tank and then fuel pouring from under Blazer. I went underneath (spare tire still off so I can see easier) to have a look. Well, the "pouring" of fuel had stopped already, but it was definitely soaked all around the fuel pump. Did the O-ring really fall off as I was putting it on? Wow, this ring is really causing a headache... Now I have a full tank, and have to do some serious driving before I will be able to drop the tank a 4th time and have a look! YAY, the joys of DIY repairs...

 

just wondering are you sure you the rubber hose for the fill neck isnt ripped or loose and leaking? just a thought.

 

I checked it when I had the tank off, seemed to be okay. I will go ahead and replace both of them when I take the tank off next time, just to be sure. Thanks for your response.

 

I think at this point you might want to go to Petty's first idea. There's a chance you got the wrong part. This job is getting out of control. Maybe take that assembly to a parts store and ask them to pull the absolute correct part and compare. If its wrong you can sell it here or on E-Bay. Good Luck.

 

i dunno about you but if i pay for a part and the part guy gives me the wrong one weather i used it, or opened it or what ever im taking it back and getting the right one at the parts store exspense. i dont like being ripped off.


now back to the point:
i think you may have a faulty/wrong fuel pump like spitty said which is giving you the problems. where did you buy the pump and what brand is it? is your truck a 4dr or 2dr the pumps are different as pettyfog said, the 4dr tank is bigger than the 2dr and require different pumps.

P.S. what is the condition of the tank around where the fuel pump is mounting? take someone with you when you go to fuel it and have them pump gas while you look under the truck to see where its coming from might not be the pump at all.