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2000 Chevy Prizm Fuel Delivery Problem

Exactly one year ago (10/31/2013), my car would not start. I went through the normal diagnostics (checked fuses, fired the car up with ether in the manifold, etc.) and arrived at the fuel pump as the likely issue. I replaced it with one from Autozone and it did not fix the problem. At that point, I towed it to the local shop to have them diagnose it. They diagnosed it as a Fuel Pump and tested both the OEM and the Autozone ones and said they were bad. They replaced it with a third which they thought fixed the problem, but did not start the car after it sat for a night. Finally, a fouth pump was installed and it worked OK for the better part of a year. I say OK because the car never started on the first try. I always had to crank it once, then wait for the pump to prime and click off then crank a second time. Until this week, when it wouldn’t start at all. Two towing bills and two more fuel pumps and a fuel pressure regulator later, it still won’t start, and the shop is out of ideas. The car only has 90k miles on it and is in otherwise great shape. I was planning on passing it on to my kids for their car to learn to drive on, but at this point it is worthless. I’m open to trying just about anything at this point.

I see no mention of whether the fuel filter was changed or if the fuel line was checked for a clog.

I’m curious how they tested it. If it was through the vehicle wiring, that may be the issue.

Answers: The fuel filter has not been changed nor the fuel line checked for a clog. An OEM filter is on order along with an OEM fuel pump. The original fuel pumps that tested as bad were bench tested after removal.

Fuel pressure is easy enough to test with the pump in the car. Replacing the filter after measuring pressure along with the pump would have killed 2 birds with one stone. 2 many failed pumps for me to believe they know what they’re doing. I doubt they tested the pump for volage and ground. These guys sound like bozos.

What really needs to be done here is to put a pressure gauge on the fuel rail, then turn the key to the on (not start position). The fuel pump should kick on for a second or two - the pressure should come up to the specified pressure and hold there. If it drops back immediately it’s usually caused by a bad check valve in the fuel pump (which in this can’t be after 6 fuel pumps) or a forward leak in the pressure regulator, but they have already replaced that.

Can you hear the fuel pump kick on when you turn the key?

I’m wondering, as a long, shot if there might be a fuel line leaking inside the fuel tank allowing the pressure to bleed down immediately after the two second pressurization.

Fuel pump does not run until the starter cranks. I can then hear it run for a couple seconds and click off. Nothing happens when I turn the key to ACC. To my knowledge they have not measured fuel pressure.

Fuel pump shouldn’t run in the ACC position. You don’t hear it run in the on position? (not the start position).

Get a new mechanic.

@T-Ram‌

“To my knowledge they have not measured fuel pressure.”

If that is the case, these guys are complete morons

If somebody replaces expensive parts, without doing diagnosis, they shouldn’t expect a proper repair

They pretty much deserve to lose customers

I wonder how many more fuel pumps they would install before it would occur to them that, gee maybe it isn’t that.

As @My 2 Cents mentioned. You should hear the pump run when you turn the key to On/Run position.
Answer that question and we can go from there.

yosemite

FP doesn’t run until I crank the engine

They may not be the best trouble shooters but beyond the initial FP replacement cost I haven’t paid a dime. Once I go to a new mechanic I lose that warranty situation, butting may be time to go that route. I was here looking for suggestions I could make to them before giving up on them and moving on.

If they are not checking fp and just replacing pumps, they are not fixing the problem. They are wasting your time.

If I was the shop here how I would do it.

Check for fuel pressure at the fuel rail. If the fuel pressure is OK check to see if it is holding pressure. If the pressure is low install the gauge with a “T” before the fuel filter, if pressure increases you either have a plugged fuel filter or a restriction in the line. If the pressure is the same your problem is most likely the pump or something in the tank preventing it from supplying correct pressures.

If the pressure was OK but did not hold install a fuel pressure gauge in place of the fuel filter, turn the key on and watch the pressure if it comes up and drops the check valve in the pump is bad. If the pressure holds your problem is most likely a leaky injector. I believe your car uses a return-less fuel system. If the fuel system uses a return line the regulator is also a possibility.

Steve

When the ignition is turned to run the position, the computer runs the fuel pump for a second or two to prime the fuel system and then shuts the fuel pump off.

When the ignition is turned to the start position, the computer checks for engine rotation via the crankshaft position sensor. If the computer see’s engine rotation it runs the fuel pump.

If the computer doesn’t detect engine rotation it’ll run the fuel pump for second or two and then shut the fuel pump off.

If you don’t hear the fuel pump run for a second or two when the ignition is turned to the run position, I’d say there’s something wrong with the computer.

Tester

Thanks for all of the feedback and advice. Currently trying to locate a used ECM (new one worth more than half the car’s retail value). Also gave the shop the direction to check the pressure throughout the line prior to replacing the fuel pump / filter that is currently on order. I’ll let you know the ultimate resolution.

@T-Ram‌

No offense, but I’d spend a little more time diagnosing it, before I condemn the module

The module is usually only replaced as an absolute last resort, after all testing has been performed, and everything else has been ruled out

In my experience, on various vehicles, the module has very rarely actually been the problem

None taken. I’m without a vehicle, and I’m dealing with a shop that is trying hard and standing behind their work, but may not have the right level of diagnostic competance to fix this problem on their own, and I’d really like to get it fixed ASAP. They are doing the pressure checks recommended here. But the fact remains that with a new fuel pump and new fuel pressure regulator, the pump still does not engage when it is supposed to (when key turned to “on” vs. post crank) I used to work for an ECM manufacturer. I know it is a frequently over-diagnosed solution to problems, and it is one of the most expensive parts to replace (in my case, >$500). I found one at a salvage yard for $50. To me it was worth it to buy it and bring it to the shop to install and either rule it out or determine that it is indeed the problem. If it is not the problem, then the only thing left is a clogged line or the fuel filter, or the sensors that feed inputs into the ECM. What am I missing?

It’s a bit unclear to me how you’re reading the pump operation. As Tester stated, the pump only runs for a second or so when the key is first turned then it shuts off unless the starter motor is cranking the engine.

I’m a bit suspect of a shop that replaces the same part countless times and if they’re bench testing pumps while dry that might not work so well either. Those pumps are high winding and will burn up or drag very quickly with no fuel going through them.

A brief look at a schematic shows a main relay which is triggered by the ECM. Power goes from that to the fuel injectors and the fuel pump relay so the power source for the pump goes through 2 relays actually.
The white/blue lead out of the main relay should have power with the key on.
The fuel pump lead from the pump relay is pink and should be powered up with the engine cranking.

Testing all of this is a bit deeper than that but I’m trying to avoid overload… :slight_smile: