Problem replacing 96 Tahoe fuel pump.

Hi all,

I've been lurking on this forum for a long time and gathering much useful advice from searching others threads to find out how to fix my problems.

Well I'm in the middle of fixing a fuel pressure bleed down problem on my 96 Tahoe 5.7l 4x4. I've used MT-2500's detailed diagnosis info from several other threads to isolate the problem to the in-tank fuel pump.

So I started on the job today, but only got part way before running into this problem. I can't get the nut off the stud on the front tank strap. The whole stud and nut are just spinning in the farm rail. The whole area under there is pretty rusted up. In fact the fuel tank skid plate that supposed to protect the poly tank has been coming off in chunks for over a year.

Anyway I got the flange bolt that holds the rear tank strap out fine with a bit penetrating oil and some grunt. But now I'm stuck with the front strap not coming off. I'd appreciate any advice from someone who has done this before, especially anyone having the same problem. My belief is that there is a captive stud in the frame rail that the nut hold up the front tanks strap to. If this isn't true is there anyway to get to the top of the stud/bolt in the frame rail to get this sucker out.

it is what's sometimes caled a j-nut. might be other names for it. is a thin peice of metal holding the stud in place, and prolly due to the afformentioned rust issues, has broken free. had one do that when the nut was halfway down the stud. i got lucky there as i was able to use a grinder to cut it off. in this case, you may be able to do same, but will need new stud, j-nut holder, and nut. other option is to cut strap without cutting tank and replace that as well as the other hardware mentioned. i hope someone else has a better idea that will be easier for you. best of luck.

it is what's sometimes caled a j-nut. might be other names for it. is a thin peice of metal holding the stud in place, and prolly due to the afformentioned rust issues, has broken free. had one do that when the nut was halfway down the stud. i got lucky there as i was able to use a grinder to cut it off. in this case, you may be able to do same, but will need new stud, j-nut holder, and nut. other option is to cut strap without cutting tank and replace that as well as the other hardware mentioned. i hope someone else has a better idea that will be easier for you. best of luck.

i'll just add that in the GM manual it states that whenever the tank is removed to replace this mounting/strap hardware. this appears to be planned and i bet they charge lot for it......

it is what's sometimes caled a j-nut. might be other names for it. is a thin peice of metal holding the stud in place, and prolly due to the afformentioned rust issues, has broken free. had one do that when the nut was halfway down the stud. i got lucky there as i was able to use a grinder to cut it off. in this case, you may be able to do same, but will need new stud, j-nut holder, and nut. other option is to cut strap without cutting tank and replace that as well as the other hardware mentioned. i hope someone else has a better idea that will be easier for you. best of luck.

Thanks 16th hippy! I got the front strap off yesterday, but I took more than an hour to cut the nut with an air hammer. I'm going to replace it with the same OEM bolt and body nut as on the back strap.

i'll just add that in the GM manual it states that whenever the tank is removed to replace this mounting/strap hardware. this appears to be planned and i bet they charge lot for it......

j cAT don't you think this is really a ploy to go buy high priced parts unnecessarily. Seems that way to me. Either that or something bad happened "once upon a time in a place far far away" and now the GM lawyers are making them say that to avoid any possible litigation. Anyway the straps are fine, but I do have to replace the front strap bold and body nut (see earlier posts).

Also as it is 4WD the tank had a big old skid plate under it. That skid plate was absolutely toast. It's been rusting out and falling off in little pieces for over a year and for most part the rest crumbled as I was taking it out. In fact a couple months back it developed this awful grinding noise and I thought I had a huge problem until I looked under to find a piece of it falling off and rubbing on the drive shaft. Only took one kick to knock the piece free.

Anway that crumbling skid plate sure made a pleasant time dropping the tank while having all sorts of rusted chunks rain down on my for over an hour. Anyway, I don't think I'm going to replace the skid plate as I never off road the truck and just use the 4WD on winter roads and slick boat ramps. I will put some rubber strips between the metal straps and the tank though.

no rubber needed on straps. if you live in "salty" areas, then i would suggest replacing the studs and j-nuts when doing pump, if for nothin else than ease of removal for next time the tank has to come off. only had this problem once in all the pumps i did. glad you got it taken care of though.

A question please!

I had an awful time trying to get those little quick connnect fittings off the fuel pump barbs while dropping the tank. The little disconnect tools, and I tried 3 different ones, both plastic rings and metal plier like things, just wouldn't go into in and release the spring tabs. After about an hour of fiddling with it and jerking it around throught the rear wheel well I kinked and cracked one of the short nylon lines. In the end I just wound up cutting the nylon line on both of them close to the tank end fittings. After I got the tank down and out from under the truck I found the culprit to be the tank end fitting all plugged with sand and other gunk. A little cleaner and tooth brush followed by some compressed air cleaned them out enough to get the disconnect tool in and get them off.

However, now I need to repair the nylon lines that I cut to get the disconnect fittings back on. So, my question is what's the proper way to do this? Can I use some high pressure fuel hose and regular hose clamps, do I need to replace the nylon line with the same material, or do I need to get some special preformed lines from a GM parts dealer?

Thanks for any help!

no rubber needed on straps. if you live in "salty" areas, then i would suggest replacing the studs and j-nuts when doing pump, if for nothin else than ease of removal for next time the tank has to come off. only had this problem once in all the pumps i did. glad you got it taken care of though.

Got it! That sounds like a good plan. Thanks!

BTW, I forgot to mention in my prior post that the real problem was, at least partly, the check valve on the supply line side on the pump assy between the actual pump and the barb fitting outside the tank. Just 20 or so lbs. of backward air pressure on the supply side barb made obvious bubbles in the internal line going to the pump. So clearly the check valve was leaking back to the tank badly and allowing the fuel pressure in the line and the injector body to bleed down over a short time, only 3 hrs to bleed down from 60 to 20 lbs. and to 0 lbs overnight. I hope just the new Delco pump assy fixes it.

on hardware that i know i will be servicing in the future I will wire brush and spray a cold galvanizing paint on to the stud/nut area. also when ever i remove rusted hardware i spray rusted area with a mixture of dish soap and water then remove with wire brush the rust. then after it dries i spray a penetrating oil and allow it time to work in......this way as you remove the nut the rust will not be present on thread to lock up threads on nut. anti sieze and thread sealants require special consideration as to if this is correct application for use. having a gas tank shield made of stainless steel would have been the proper metal . and tank straps with a heavy galvanized plate would be proper. GM does not want you to keep running this vehicle more than 7years and 100,000mi. you are screwing GM. how are those nice car sales persons going to feed thier families. don't you feel the their pain.....

GM does not want you to keep running this vehicle more than 7years and 100,000mi. you are screwing GM. how are those nice car sales persons going to feed thier families. don't you feel the their pain.....

NO i don't. i have had my '98 S-10 for 6 yrs and almost 1 month. bought it used when it was 4yrs old and had 73K miles on it. now has 135K, and still running strong aside from the fact that the exhaust leak totally melted/disintegrated the upper control arm bushings on driver side, has the other typical chevy front end problems, and the typical exhaust problems that caused the other front end problem i mentioned. a few other SMALL problems, but think she will last past 200K, and i LOVE not having a truck payment.....but i LOVE the way the new silverados look.

P.S. sorry, got off on a rant there.....i would personally reccomend replacing the lines with the right ones(no patch jobs). you may be able to find them at a parts store, or goto http://www.gmpartsdirect.com and you may be able to find them alot cheaper than dealer. since you live in a rust prone area, last thing you want is to have to do all this again next winter cause one of those clamps came apart from rusting. but if you really plan to give it a try just to get you going, make sure it can handle all the pressure.

[quote=16th hippy]NO i don't. i have had my '98 S-10 for 6 yrs and almost 1 month. bought it used when it was 4yrs old and had 73K miles on it. now has 135K, and still running strong aside from the fact that the exhaust leak totally melted/disintegrated the upper control arm bushings on driver side, has the other typical chevy front end problems, and the typical exhaust problems that caused the other front end problem i mentioned. a few other

question 16th hippy. how is it that you could operate your vehicle with that exhaust leak so large it damaged the control arm bushings. didn't you injest the co into the cab ? that is a dangerous place to have a leak for any period of time.

question 16th hippy. how is it that you could operate your vehicle with that exhaust leak so large it damaged the control arm bushings. didn't you injest the co into the cab ? that is a dangerous place to have a leak for any period of time.

stupidity, and even more for letting it go that long. for some reason the 2.2's exhaust manifold likes to crack close to the flange. this along with fact that the flex coupling likes to come apart internally. maybe explains why i am comfortably numb and happy when driving my turd bucket s-10...lol