Lean Fuel Codes, Need Some Help

What do you think could cause it? I was thinking perhaps too much amperage, but how? The pump went from 44 PSI to 9 PSI. If it was drawing too many amps, the fuse would blow and/or the electric pump motor most likely wouldn't work anymore. It's working, but barely. We changed the filter and blew the lines out thinking there was an obstruction, but no such luck. They were clean. The fuel regulator could be a culprit, but it's new and after a pump change, everything works, so that's not it, plus the Schrader valve is before it. Plus the sound of the pumps that have failed are totally different from what they were when they worked.

The only other thing I can think of is a high resistance short in the wiring or degraded wiring preventing the pump from getting the correct amount of amperage to operate. I was hoping the relay was the culprit of this theory, but I jumped the contacts removing that variable and the results were same. I'll load light the circuit to verify, but I doubt that's it. I should have intermittent problems opposed to the constant failure that car is in now and was before. We'll see I guess.

Sounds like something on the fluid suction side of things. Low operating voltage would cause low pressure, but not damage the pump. Blocked tank venting, sludge of some sort in the tank, detached tank baffle, etc. are just some things that come to mind doing long-range trouble-shooting. If the pump sound when running actually changes when it fails, it almost certainly indicates overheating from cavitating or running dry.

Good thoughts. I got a new Spectra to put install tuesday. I'll make a special point to make sure there's at least 10 gallons of fuel back in it. Can't really prime the pump before either like you do with oil pumps in engines.

On a side note, I'm flushing the heater core right now, a lot of dark fluid came out, hopefully that's a good fix for no heat!

Heater works now. That's some good news I guess.

If you had not taken notice, there is a harness connection in the left rear corner. Under the stoplight. You can use a 12 volt DC source to test the pump before tearing it out. Three wires, use black as ground, gray to +12. Purple is the fuel gauge, not used for this test

are you sure the sending unit is still good (connections, wiring) ?

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I've had the damn hose inside the tank burst, between the pump and the outlet. When you jump the connection at the back of the car, listen for the whirl of the pump. If it sounds like splashing, it's either a burst hose, or it popped off.
Still will need to drop the tank, but if its splashing at least it might be a simple hose issue.

That you mentioned SOME pressure, even nine pounds might indicate the pump is pressurizing, but with a hose split, not much is able to get out of the tank.

94Woody wrote:

I wouldn't waste my time or money on a tech 1 or any other scanner. Laptop, numerous free software titles and a cheap cable make much more sense. Plus they can do so much more than an overpriced scan tool.

I have laptop + free software, 2 brands of commercial software, an OTC 4000E and a Chinese Tech2. I've also used the Snap-On scan tool. The OTC was my favourite for the RMW until I got the Tech2. It has become my go-to diagnostic tool every time for any GM now. Waaaay ahead of the free software solution.

That said, a free software solution that can read the live data stream in real time is far better than a simple code reader.

Brandt51 wrote:

The fuel regulator could be a culprit, but it's new and after a pump change, everything works, so that's not it, plus the Schrader valve is before it.

The fact that the regulator is after the test port is irrelevant, it still limits the fuel pressure. It dumps excess fuel back into the tank via the return line. A fast check to see if the regulator is stuck open (perhaps from a bit of dirt or rust) is to plug off the return line and see if the pressure jumps. On cars with a rubber piece between the regulator and steel return line, a pair of vise-grips can be used to pinch it off. On cars with nylon return lines, you have to disconnect it and cap off the return at the regulator with a bit of rubber line, some hose clamps and a bolt that fits in the line.

I am another that once had the rubber line in the tank pop off after a pump change. Make sure the clamps are tight when assembling the pump to the sender. With the line completely off, I had no fuel pressure at all, but a leak or split hose could very well drop the pressure significantly.

Hmm, all good info. The new pumps were complete drop in Delphi assemblies that included the sender. Maybe they sat on the shelf too long in this hot as hell city and the hose split after getting fuel? Hmmm, I'll find that harness behind the tail light to test the power going in and then jump that for the test.

Very perplexing.

The harness is accessed from under the car. It is BELOW the tail light. The is no need to go BEHIND the tail light.

Ok, I checked power at the connector under the tail light. 12.5vdc, so that's way good. I was going to shoot for amps, but I didn't want to risk damaging my Fluke, it's only rated for 10 amps and the fuse is a 15 amper. Plus I'm not a fan of shooting amps, that can get you hurt fast if you mess up. I did plug in the original fuel pump that was in the car when I bought it, spins up great. I swapped out the fuel pump relay with the cracked case too.

I had a look at that first pump. It appears that where the supply hose connects to the top of the electric fuel pump has the leak. There's a rubber grommet looking seal where the electric motor mates to a plastic boss that the hose is connected to. That seal seemed smaller than it should be and consequently doesn't make a solid seal. So when the pump pressurizes the line, a lot of that pressure is squirting out. I'm guessing it shrunk over time.

That explains pump #1. Pump #2 and #3 are still mysteries. #2 is gone, but it sounded like it had a split hose or something similar when running. I should have #3's story soon after we swap it out with the new Spectra.

Once this fiasco is fixed, I need to get back to that fault code 44.

Thanks again with all the help!

I noticed that the typical hose that comes with most pumps, is a molded nonreinforced piece of worthless rubber. I buy a foot long piece of fuel compatible hose that has the visible threads running through it. And use metal screw driven clamps to secure both ends. No hose issues since I started doing that. I am running high volume, high pressure pumps for my TPI set up, usually 48 lbs at the Schrader valve to feed 460 up.

I will stress FUEL compatible hose. Otherwise, the stuff will essentially melt after a while. And you'll hear another splashing sound and be looking for your jack stands again. That's why years ago , when the tank was down, I put a transmission pan drain in it. I knew it would not be the last time it would have to drained. Murphy's law is that it will need to be dropped just after you fill it all the way up, and have 25 gallons in it.

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Think these O2 plug wires would cause my 44? FML. I'm glad I caught it. Tough spot to repair AND I'm still using a walker. Hahaha. But I'm still a man, so I'm going to fix it.

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It's all kind if messy from tired gaskets I guess. I changed the connector and all seems well. I'm pissed at my myself for not catching it when I looked the first time. But it's really hard for me to get on the ground right now. I was just swapping the sensor and even Ray Charles would have seen how bad it was. All four wires were exposed and touching each other, and not in the good way. I got to drive it to work tomorrow, so we'll see if this is the legit fix. I do NOTwant to crawl around on the ground again!

I also fixed two windows that didn't work with new rollers and put new speakers in the door. This car is becoming new again.

Ran better than ever this morning.

So, going on several days now and no issues....yet.

If your AIR pump and tubing is still in place and the pump still works, replace the check valves ASAP. They're dirt cheap and protect the AIR pump from failing. Although the piping is stainless and they can be very troublesome to loosen.

Brandt51 wrote:

All four wires were exposed and touching each other, and not in the good way.

lol. Congrats on fixing it. I chased a similar problem on my brother's caprice several years ago. There was a break somewhere in the O2 wiring. Had to run a new wire from the PCM to the O2.