I've been having problems with my car, a '97 2.2L Cavalier, lately. I'll be driving down the road and lose power and coast to a stop. If I give it gas, it slows it down even faster. After stopping, it will idle, but if I give it gas it dies. So, I wait a couple minutes, and restart it and it runs fine. For another 2 miles, and it does it again. I know my fuel pump is going in the toilet from the intermittent humming, but from my experience with fuel pumps (which isn't much,) they either work, or they don't. I've read on other posts about MAP sensor problems, and it seems that this could possibly be a MAP problem. I'd like to think this is an easy fix. Any advice on the issue would be greatly appreciated!

Throwing any codes?

I suspect the fuel pump... as that's exactly what my 98, and my 2000 Z24's both did when they died.

No codes, that's why I'm more inclined to say it's the fuel pump rather than the MAP. Thanks for your time!

I would get a pressure test done on the pump, Then u know 100% get it replaced.

Good Luck.

Interesting, so no fuel pressure isn't an unheard-of thing on a J body.

Our '03 has no pressure at all at the fuel rail (nothing at all squirts from the test valve), and we can't hear the pump priming. Sounds from the handful of posts I've read that the pump may well be dead (though this car has only 61k miles). Short of going directly out to buy a pump, I'm *assuming* there's an easy way to hook jumper leads directly to the pump (haven't gotten under the car yet) to make sure it really is dead, but is there a typical electrical failure to look for, such as a fuel pump relay, as on other fuel-injected stuff?

Autozone.com lists a replacement fuel pump for this vehicle at over $240!! Is that at all typical? I checked Napa and their site says $270ish for a Napa pump or $419 for a Bosch. My "expensive" pump for my Ford was $55!

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Fuel pump on ebay for around 25 bucks. The Grey wire is the positive, check and see if it's getting 12 volts.




Your car may do 13 sec @ 103 mph, but my car does 146db @ 35 hz.

Michael West wrote:
Autozone.com lists a replacement fuel pump for this vehicle at over $240!! Is that at all typical? I checked Napa and their site says $270ish for a Napa pump or $419 for a Bosch. My "expensive" pump for my Ford was $55!

yes, because when you buy a pump from any automotive retailer, you'll get the whole sending unit assembly.



JBO Stickers! Get yours today!

Lanman31337 - Cavfire wrote:Fuel pump on ebay for around 25 bucks. The Grey wire is the positive, check and see if it's getting 12 volts.

I definitely found something that's getting momentary 12V when the key is turned to On (7-prong plug; top on the 3-prong side to 3rd down on the 4-prong side), so I'm assuming for now that's the power. I'll check the wire colors and see if that jives with your advice. Presumably black is ground? (I normally live in the world of mechanical fuel pumps ....)


The guy at our local Carquest said he might be able to help with cheaper options, so that'd probably beat having to wait several days. Got to get the thing out, first ....


Which brings me to the fact that at least on this '03 model the fuel tank is blocked from coming out by a huge exhaust shield that appears to be riveted to the floorpan. I'm hoping I'm seeing it wrong and they're actually little Allen screws, but it looks like I'll have to drill them out and find a way to reattach the shield later ....

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Edit to the above: Found someone on a site called Topix.com saying you don't actually have to remove the heat shield. Going to go fiddle with that some more. Hopefully he's right ....

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Nope, don't need to mess with the shield. There's 2 straps, just unbolt the one end and lower it with a jack.




Your car may do 13 sec @ 103 mph, but my car does 146db @ 35 hz.

Couldn't get it out that way. Drilled out the rivets and the tank fell on my head! At least it was out.


Here's the weird part. With the pump assembly on the bench, I poked at the connections with the VOM in continuity mode. Put it directly across the pump, beep. Put it across all combinations of the four pins on top, no beep. Unplugged the harness from the pump to the top, beep. Plugged that back in, beep. Plugged the whole thing back into the car, now it's squirting fuel onto the driveway when I hit the key. Weird! So either I'm a worse troubleshooter than even I thought, or else there's a gremlin in the little connector in the top shell thing?

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Well, I talked to the counter guy at Carquest, and he said to talk to the service guy, and the service guy said he'd go ahead and replace it because once it starts acting flaky it'll happen again, even if it tests good. Mentioned that he seems to get a new technical bulletin nearly every month about what to do about GM fuel pumps. Interesting.

So tomorrow I'll pick me up a new fuel pump assembly and toss it in.

Thanks for hopping in and helping out a stranger! Good to know a Ford guy can pop in at a different board and get helpful input.

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Oooo-kay. So the new pump assembly is in, everything's back together, and I'm getting no pumping. At least, the pump assembly (including wiring) checks out continuity-wise, the momentary 12V at the bulkhead connector checks out, and I'm getting no pressure at the fuel rail after repeated key cycles.

Is there usually some sort of preliminary priming procedure?

I've been checking it with the car on the ground and the tank half full.

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Used jumper wires to pressurize the pump, definitely heard it running and got fuel squirting from the test port, but the engine only ran until it'd used up the fuel in the system. Seems the pump still isn't actually running under normal conditions. Tried scanning codes and got two instances of P0440 and one of I think P0453. Cleared those and haven't gotten anything since.

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Silly thought, but your oil pressure sensor.




Your car may do 13 sec @ 103 mph, but my car does 146db @ 35 hz.

Always possible. A coworker of my wife's was just over, and his thought is that something's got to be triggering some sort of electrical failsafe. Does the oil pressure sensor itself tend to go bad somehow? I'm not used to those being connected to computer systems, only to the old-school "replace engine" light.

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Found my wiring diagram and poked at the relay connections on the underhood fuse panel. Everything checks out when tested individually: 12V ignition-on, 12V from the computer, ground, and continuity to the bulkhead plug. Relay tests okay. Ground from bulkhead connector tests okay, and I know from last night that the pump runs when applying 12V directly to the plug (though I'll test that again to be sure).

However, when I insert the relay with everything powered up correctly, it doesn't click, and when I plug in the pump and try jumping 12V directly to the proper plug on the fuse panel, nothing happens.

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Oook-kay! Slight progress! I seem to have narrowed it down to one thing that's acting weird.

The PCM doesn't seem to like being connected to the relay!

I hooked up jumper leads to the relay and connected my voltmeter across it. As before, with the relay disconnected, when I turn the key the signal from the PCM goes to 12V and stays there. When I turn the key with the relay connected, the signal direct from the PCM definitely goes to 12V and then drops to zero. Leaving the key on and disconnecting the relay, it goes back to 12. Reconnect the relay, it goes back to zero.

Does this seem to point to a faulty PCM?

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Oh yes, forgot to mention, code DTC P0452 "Fuel Tank Pressure Sensor Circuit Low Voltage" is back. Two instances so far. No idea whether that could be related.

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Well, this is highly embarrassing. On a whim, I tried the relay again, and the stupid thing is acting 100% normal now. No codes, no check-engine light, no nothing. Primes the fuel pump correctly, runs and drives correctly. The only thing I can think I might have done was left the battery disconnected for a while.

Does this mean I managed to solve the problem? Since I don't know much about modern fuel-injected systems, I'm more than a little suspicious that a problem that just goes away is liable to come back!

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

(Reggae Beat) ....I dont really care what people say, I dont really watch what dem was doo, All I really need is damsel in my bed to run that RELAAAYYYY

lol

Everyone I talked to over the weekend said that leaving the battery unplugged for a couple of hours effectively "reset the computer", thereby making it happy so it would work again. (I'd thought 30 seconds would "reset" it, but maybe that was for clearing EEC-IV trouble codes.) Sounds kind of crazy to me, but then, I wasn't on the committee that designed the thing!

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Sounds to me like you connected and dis-connected the relay enough times that you probably cleaned the connectors and it started working again. I'd get a new one they cost like 17 bucks.
The oil pressure switch circuit is a backup circuit if the PCM fails to power the fuel pump. If the pump dont start under normal conditions after cranking long enough to produce about 7psi the circuit will close and power the fuel pump circuit. So if it takes longer than normal to start but runs fine thats what is happening.

Get a new what? A relay? That seems odd .... if anything, I'd think it would be more productive to get new connectors, as they're a little loose. I'm sure they're not hard to replace ... possibly if I yank the fuse panel and beg the local parts stores to see if they have that sort of thing available.


.... so the story of this "oil pressure switch" is simply that it triggers a fuel cutoff somethingorother in the PCM's programming? Seems to me like a good way to make an otherwise good vehicle wildly unreliable ....


So if I'm understanding correctly, your concept is that there may be a possibility that an electrical contact issue at the relay that happens exactly once would cause the computer to refuse to run the fuel pump normally until I unplug it for a half-hour to an hour to "reset" it? In which case, the whole thing WOULD really be caused entirely by a problem at the relay, even though the symptom was the computer being stupid and not sending it the necessary signal based on a deliberately-programmed safeguard routine to keep idiots from ruining their engines?


I guess it's a change from the old-school "replace engine light" that came on when oil pressure was worrisomely low or coolant temperature was alarmingly high.



Sooo ...... if there's any truth to all this, and you surely know more about GM injection systems than I do, it sounds like the most obvious thing to do is to try to fix the loose relay terminals in the fuse box, and either scrub the relays' prongs thoroughly with sandpaper or buy new relays "just because"?



Just one thing .... right now, the only code stored in the computer (at least, that I've been able to read with the Actron scanner I rented from VatoZone, when it feels like communicating successfully with the vehicle) is a P0446, which is yet another emissions code. (It'd been showing me P0440 and P0442 prior to the last computer reset.) If the computer's doing its safeguard thingy, wouldn't it set a special error code to report on the situation (why not, if it has at least three codes just for emissions garbage?), so that someone can easily identify what's going on? Not doing so would seem to pretty much defeat the purpose of the OBD system .....

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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)

Wayell, this is interesting. I noticed today that there was no seal/gasket/grommet on the plug going from the pump harness to the bulkhead connector. That can't be doing anything any favors, and could help explain why it's been tending to go flaky when it's raining. I spent some time today tweaking the affected terminals with a pick and poking some sandpaper in there. I ordered a new seal from the Chevy dealer and will make sure to add some dielectric grease when I put that on.


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2003 Cavalier, base with auto/tilt/CD/AC (wife's) -- 2012 Mazda5 Touring with audio package (mine)