88 2.8L, 5 spd, 260,000 mi (all original, by the way) just had a new fuel pump installed. i've noticed a couple of things: 1. with my tank about 1/4 full, the fuel pump squeels when i brake hard. this also happens on a hard left turn. a full tank of gas cures these noises. i'm guessing that the fuel pump is located at the rear left side of the gas tank. could the installer have screwed up the mounting? exactly how is it mounted? could it be a faulty fuel pump? i'm thinking i'm going to take it back tomorrow and see if they can fix this. i don't know what type of argument i should expect from them, but i'm worried that it might go out on me again. 2. after new fuel pump was installed i also noticed a lot of thumping when i go over bumps. it's feels like the gas tank is bouncing or perhaps the tailpipes/muffler is bouncing. i know that they had to remove these to replace the pump. any thoughts or comments?

THERE IS NOTHING WRONG WITH THE PUMP!!!!! My 85 Camaro did/does that whenever I'm low on Gas. I find it to be a warning system that one needs to get gas soon. Also, the gas gauge in our cars is not the most reliable so that whining noise actually helps determine how much gas we have

For the rattles, I would check the exhaust pipe to gas tank clearance. Chances ar you exhaust is hitting the Chassis somewhere (probably I-pipe around the wheelwell)

MD, is that the original pump or a new one? Artie, welcome to the board, do you know the brand of the pump? I've had my original GM one, that died, I put a BorgWarner in, that died, and I'm on my 3rd (free replacement because of warranty) BorgWarner pump, neither of them squeals.

Definately don't let the tank get that low... when the tank gets low, the fuel pump can run dry, and that's how fuel pumps commonly "burn out". Also, when the tank is dry, the pump just hangs in mid-air, and can get hot. When there's fuel in the tank, it helps cool the pump (pump gets submerged in gas), which helps the pump last longer.

There's only one way to put the pump in. From the top of the tank, there's a circular plate... pull the plate out, and the fuel pump bracket and fuel gauge float is there. The fuel pump goes in the bracket, the fuel pump outlet gets connected to the tank outlet pipe, a water strainer gets clipped to the bottom of the pump, and the electrical connections are made. You can't really install the pump backwards or sideways or etc. In fact, replacing the pump itself takes 15 minutes! The work is in removing everything to get the gas tank down.

As for bumps, check the fuel tank mounting straps to see if they're loose. There should be "anti-squeak" strips between the fuel tank moutning strap and the fuel tank; these look like beef jerky (seriously)! Like a tar paper, but thicker. If they're missing, the mounting straps don't fit tight against the tank. The tank is heavy and awkwardly shaped, so when the car is parked, the tank could "look like" it's tight against the straps. But you hit a bump, and the tank can move up. The bolts for the straps are above the rear axle, and (If I Recall Correctly) use a 13mm socket.

The thumping could be the I-pipe is not hooked back to the exhaust bracket, or one of the muffler clamps hooked to the brackets holding them up are not tigthened down all the wayGood point. I forgot about the "jerky" But I thought you needed that too to prevent chaffing from the straps on the tank.

Best way to figure this out is to find a test track, take mechanic for ride and duplicate the problems/noise over same road spot.

Both the pumps in my 85 did it -- the original and the replacement.

i talked to the shop this morning. they said they noticed the thumping when they test drove it (wonder why they didn't do anything...). i'm taking it down there tomorrow, with a printout of all your replies. thanks!

as far as the fuel pump, he says he's never heard of a problem like that. we'll see what they can do. it sounds like you guys are saying the squeeling is not a problem, right?

i don't know what brand it is. it has been replaced before at around 200,000 mi.

unfortunately, i filled up last night so i don't think they will be able to hear the squeeling. by the way, filled up meant 9 gallons. roughly 7 gallons still left if i'm not mistaken.

Well now I may have to change my opinion. My 85 did it when I was definitely low on Gas (1/4 tank). It would do it on left turns and hard stops. However, if it went ignored the car would run out soon after. So they may have screwed something up. Mine never really squealed.. more like a "whine".

Joe, yep, it prevents scratches, too. But if it's missing, the straps won't hold the tank securely. After I backed into someone, one of the anti-squeak papers was almost falling out of the side! (Damn parking lot attendant- "You need to back up sir, you can't go in this way." So I backed up- and hit the car behind me. 4 other cars followed me in. ) I started getting the thumping noise in my car, until I loosened the one strap, put the anti-squeak paper back in line with the strap, and tightened the strap bolt again.

MD, that's weird...my pumps never made any noise like that.. even my original one. 'Fact, on the original pump, I thought it was fun to drive on fumes, and have the car cut out when I went around corners. 'Course, then I had to replace the pump, and never did that again.

Artie, ask the shop if they replaced the pulsator. The pulsator is a piece of plastic that goes between the fuel pump outlet and the tank tube. It's job is simply to "quiet the fuel pump". Problem is, it uses o-rings to make a seal to the pump and tank tube. Over time, these o-rings break down from age and can leak, and you lose fuel pressure. I didn't know this when I did my first pump, and I wonder if it's why my second pump died. I reused my original pulsator.

Two options are available... one, buy a new pulsator for $40. Two, the one I chose, eliminate the pulsator completely. Use a short piece of high-pressure hose and two hose clamps. A 4 inch piece of hose came with my pump, I used it. I bought a pack of four "fuel injection clamps".. twice as expensive as regular hose clamps, but they looked like stainless steel, and had a 360 degree seal. I tightened those suckers up hard (but not too hard so as to crack the plastic pump outlet), and put the pump in. I haven't heard any excessive noise, so I don't see what purpose the pulsator even has. Maybe there's excessive noise on a v8 car? Maybe people were just a little too noise-sensitive and complained to GM about a little whirring noise? It was probably the same people that complained about excessive pedal pressure on 4 wheel disk 82-88 f-bodies. GM figured a performance driver, buying a car with 4 wheel discs, would want the most pedal response from their braking systems- apparently people complained, because GM released a TSB saying that you could put a disk/drum master cylinder (smaller bore = easier to push) on a disk/disk car if the customer complained. And after '88, GM used the disk/drum master cylinder for both brake systems!

I would definately question that squealing. Maybe the mech didn't hook up a vent hose or something. HEY: Ask on the Tech board about this... make the title "new fuel pump squeals" or something. We use the exact same pump setup (in tank, same hanger, same size) as the v8's, except v8 pumps have a higher flow rate for a larger engine. Then you can find out if anyone else's pump squeals, and how they fixed it. For what it's worth, when both my pumps died, one died silently, with a faint, sick-sounding hum. The second pump sounded like there was an angry bees nest inside the tank! It was LOUD!

latest update:

i took the car back in on friday.

they disassembled and reassembled and found that the fuel pump still makes noise. he also mentioned that there were some metal flakes in the tank.

there are going to replace the fuel pump and get the tank/mufflers put on correctly. i should have the car back tomorrow (tuesday).

i'll let you guys know what happens.

Good going for revisiting the mechanics.
Hope it works out well.

260,000 miles ...... I must say Chevrolet does stand by there saying " Like a rock "

just picked up the car. looks like there's still something wrong.

here's how it went.

when i picked up the car, the tank was nearly empty (about 3 gallons or so left). i drove it around for a bit, maybe 8 miles, and everything was fine. no more fuel pump noises or the thumping sound. running great!

i then filled the tank up with the 91 octane, which i usually use. no sooner than 1/4 mile later, the car started to cut out. at an idle, the rpms would fluctuate from 500 to 1200, every second or so. sometimes this would stall the car. the engine light also came on, although i don't think it's going to tell me anything. there's also a heavy smell of gas.

i haven't contacted the shop yet...

i can only think that they installed it incorrectly. again, the car worked fine before except for the noises.

any ideas?

Retrieve the code from the engine light. At 260K miles things tend to go bad one after another. There is a good possibility that something else is causing the condition.

what gets me is that everything was fine until i added gas. is there anything here i should explore?

Could be a number of things when we're talking about that many miles. By pulling the codes it will get you in the right direction.

Artie, glad to hear they didn't put up a fight when they replaced the pump again... ever find out where the metal in the tank came from? I wonder if before you added gas, the pump was "starving" for fuel... then you added gas, the pump is flowing the fuel like it's supposed to- and your ignition system is too weak to fire the full-pressure "shot" of fuel.

Happened to me on the first pump I replaced... changed the pump, tried to start the car, didn't run. My stomach sank. I checked fuel pressure.. it was fine! Found out a couple hours later, by pulling a spark plug and finding out the center was blown apart and MISSING, that my timing was extremely overadvanced. Apparently the car could run okay on a dying fuel pump, but at the correct pressure & flow, the fuel was putting out my spark.

Just a guess. Try pulling out some spark plugs to see how they look... if they're wet, they're not firing.

DAMMIT, would someone take this bag of candy corn away from me?!? If I keep this up, my car is gonna scrape the ground...

Of course, my theory says nothing about the obvious, the service engine soon light. Somehow I missed that bit. Like MD said, do that first!!

i'll check the codes somehow. i don't have my book with me, nor do i remeber which pins to short out, so it might take a couple hours.

and correct me if i'm wrong, but i always thought that the code will give you some type of faulty sensor probem (maf, oxygen sensor,...). i just can't believe that it's a coincidence that one of these should go out and be the cause of my problems (although i'm hoping it is!)

thanks, and i'll let you know what code gets put out.

It's in the thirdgen.org tech section, in the FAQ, I think in the FAQ's "Miscellaneous" section... but the pins are in the uppermost row (ignore the bottom row completely). It's the two on the right, in the top row. And remember not to crank/start the engine after putting the jumper in, just turn the key to "on", not crank, because you can blow your computer.

ok, got my book.

it's setting code 45. oxygen sensor , rich exhaust.

i haven't got the chance to check the plugs yet.

as far as the metal shavings, they didn't know where those came from...

latest update:

i was able to drive my car to the shop, about 7 miles away. on the city streets, stop and go, it was pretty rough. i had to keep the rpms up so that it wouldn't die out. there was also a VERY strong smell of gas. on the highway, i kept it at 3000 rpm and the car was running fine. i'm guessing that if one of the plugs were broken, it wouldn't run smooth throughout the rpm range. it also seems like the timing is fine if it runs well throughout the range. right?

i don't know what the shop is going to do. he said he would check it out. he mentioned that it might be the pressure regulater or some of the hoses. those all looked fine to me. we'll see what he comes up with.

should i ask them to put another fuel pump in? should i go out and buy a quality fuel pump somewhere? if so, where? the dealer?

maybe they put the wrong type in? too much flow or something. i should also mention that the fuel pump does not seem have any problems itself. i hear the constant hum. it sounds very good to me.

looks like i opened up a can of worms!

Ive never heard my pump squeel when the gas gets low. I run it down into the read zone all the time. course I never put in more than 10 bucks so I only get 130-150 miles which comes way too fast.

I know what they did.
When checking pressure at the Schrader valve on the engine, they disturbed a vacuum hose.
Does it idle or ya gotta rev it to stay alive?
I'll bet they knocked off/loosened that hose at back of engine by distributor driver side.

The code 45 says you're running rich. That would explain the rough running and smell of gas. I would have that O2 sensor changed and replace the plugs as they are probably pretty fouled up by now. The sensor costs around 20 bucks.

Also have them do an injector balance test. It could be the new pump is flowing more fuel and the injectors are old and worn out (or clogged).

Keep in mind that this whole thing is a fuel system. Any system is going to perform as well as the weakest part.

I have had the pump make noise only once. I had completely forgot to get gas that morning. I started hearing the noise when I hit the brakes or made a turn. I could not figure it out for the life of me. About 2 1/2 minutes down the road the car started to die and I relized I forgot to get fuel. The car died and I was able to roll right up to the fuel pump.~~Next story, this past Sunday I had just filled up the tank and I had started out to leave and I noticed the car spuddering. I let off the gas and the car died. Well, I looked over everything and find out that the fuel pump was not coming on. Anyway, after about 20 or so minutes I tried starting it again and the pump came on. It was very hard trying to drive it to church that morning, but somehow I got there. It is running fine for right now but either this weekend or next I am going to my buddies shop and putting the car on the lift. We were going to put the new springs in anyway so while we are under there I am going to replace the pump so it doesnt die out on me oagain.

~Josh~

generally speaking, i need to rev it at idle for it to stay alive. sometimes when i release the pedel, it will continue to idle smoothly, let's say around 2000 rpm, for about 5 seconds before it wants to die again.

i checked those hoses myself and didn't see anything wrong. i'll get them to inspect those as well.

Get some one to help ya with this.
Find some old heater core hose.
Long.
Have someone idle the car, put hose by the distributor area, driver side, by tranny housing.
Other end to ear.
You MAY hear the wosh of the air.
That's where it is disturbed, I think.
It's 1/2" hose, short, very fragile as it's aged.
Your answer describes that problem hose off/loose.
More loose or barely hanging on, due to engine vacuum at high RPM's

and the mystery continues...

this morning, i went to the shop where i had parked the car last night. we started it up, and it ran fine! we let it idle for about 15 minutes or so and there was no problem. i then drove it around for another 10 minutes and still no problem. keep in mind that up until i parked it last night the car running running pretty poopy, except at the high rpms.

here's what i'm thinking happened. after driving the car there last night, i had put about 30 miles on the full tank of gas. taking into account that it was running rich, i probably used about 1.5 to 2 gallons of gas. is it possible that these couple gallons were drowning the fuel pump or something? shoot, i have not idea what's going on.

i'm going to ask the mechanic to fill it up again and see what happens.

going crazy over here!

PERHAPS something is in the gas tank & is floating to cause the problem.

just got off the phone with the mechanic. after he filled the tank again (2 gallons or so), he noticed the same problems i was experiencing yesterday.

he checked the canister purge and noticed that it had some fuel in it. he cleaned it out and it ran fine.

make sense to anyone?

just picked the car up. it still has a problem, but not as bad. fuel smell is pretty strong.

Maybe the canister purge is bad and full of fuel again. I would hit the junkyard for one of those. While your at it check the condition of all of the vacuum lines going to and from and around it. If they leave a thick black residue on your hands, its time for new lines.

Glad to hear the mechanic actually witnessed the problem! Other than that, I have nothing really useful to say... can a canister purge valve break, and get stuck open?

the first 10 minutes of driving today were rough. after that, the car ran fine.

Okay, I might have some more ideas off the top of my head. One more test -- Fill the tank up with the engine fully warmed up and see if the sputtering returns.

The fact that it does it for the first 10 minutes of driving gives me these ideas

1. possible bad EGR valve (clogged)
2. Possible bad cold start injector
3. Possible bad coolant temp sensor
4. Moisture in the distributor cap (cracked)

Have any of these things been changed recently?

I've recently changed the distributor cap and rotor (about 1 month ago) along with the plugs and wires.

I'm going check all of these on the weekend and see how they look.

Checking the EGR is going to require removing it and cleaning the crud underneath it. Just an FYI

ongoing saga...

ok, so it seems like the car runs good (for the most part). the only problem is the smell of fuel after fill-up and especially on a hard brake. this lasts for about the first couple gallons and then goes away. is it possible that the gasket to the gas tank access cover is not completely sealed? there was a small leak from one of the gas lines near the tank. there were 4 lines. my book says they are:

1. Fuel feed line
2. Fuel return line
3. Fuel vapor line
4. another line with a backup pressure relief valve attached (i think that's what is was). this is the one that was leaking a bit. i tightned it up, but the smell still remains. i tried to get a new valve, but they don't carry them at regular auto part stores. i'll have to go to the dealer for one of these.

i also checked the plugs, timing, egr, pcv, cap, and rotor. they were all good.

Interesting problem......

Have you checked to see if the fuel system is holding rest pressure after you shut it off?

Are you having any hard starting/long crank problems?

A few things you can do:

-Pull the vacuum line off of the fuel pressure regulator and look/ smell for the presence of fuel.

-Pull the vacuum line off the purge solenoid....the one going from the solenoid to the engine. Plug that line and see if the problem still occurs.

the fuel i smell is from the rear of the car. it's not overfilled either.

i don't smell anything in the engine compartment. i've attached the diagram my book shows regarding the fuel system. i'm trying to get item 10, REMOTE PRESSURE / VACUUM RELIEF VALVE. this is attached to the hose that was leaking a little bit.

As to the gas smell, how's the seal on the gas cap?

gas cap seems fine. again, the smell doesn't come from the cap area. of course, i can smell a bit from there, but most of it comes from the wheel-well area.

i'll try changing the cap anyways. it's only a couple bucks...

i just filled up the car. it's leaking gas pretty bad. i'm guessing this is from the over-flow tube / remote pressure-vacuume relief valve. does this act as some sort of overflow?

Do you know where it's leaking from? Some guys have bent their filler neck while dropping the tank. I wonder if the shop bent the filler neck for clearance, and wound up ripping a weld open. The vent is really just a vent, I suppose if you filled the tank up to the very top, that gas would leak out of it- it looks like a very basic vent. Or, I wonder if they sliced a hose, like the fuel return hose or, more expensive, the fuel feed hose. Have you asked the shop again?

it's leaking from just inside the driver side, rear wheel, right where the four fuel lines drop down and then up. this is also where the relief valve is.

you make a good point about the neck. sound logical that when i fill it up it starts to leak. otherwise, if it were the relief valve, wouldn't that constantly leak?

i just talked to the shop and told them about your suggestiong that it could be the neck. he's more than willing to take another look at it. so i'll be heading back there shortly. i think i'll probably siphon some gas out to be sure i don't blow up on the way there.

thanks! i'll keep you all posted.

the mechanic says that it was leaking from the o-ring gasket at the top of the tank. i believe this is the access point for the fuel pump.

he also mentioed that i should not top off the tank on fill up. i question this, though, because i've been doing it for 260,0000 miles and have never had a problem. he said something about fuel getting into the evaporation hose...any thoughts on this?

well, got the car back today. it runs fine so far. i'm going to top off the tank tonight (when i'm closer to home) and see what happens.

also got a bolt in my tire! when it rains, it pours!

At least that's a straightforward fix

Good luck
ATLEAST YOU DIDN'T DO LABOR!!
Imagine if you goofed up!
Did the tire blow at 80 MPH?
You're doing ok!

looks like everything is ok now.

thanks for all your help!