I changed the fuel filter an in the process most of the fuel tank was drained. I just drove to the gas station and the car was running perfect.
I filled up started the car with no problems.
I went to exit the station and the car stumbled and died. I managed to get it home after about 20 minutes (which is a litteral mile away) and I needed to restart the car over a dozen times.

I am pretty sure I stirred up a lot of crap at the bottom of the tank and that is why my car started running so poorly.

My question is what do I do now? Do I just need to let the crap settle? Replace the new fuel filter with another one? Drain the tank (which right now is completely full)?

 

Did you get an engine light?
Check your fuel pressure.
I don't think you picked up much, the filter would have caught it. Also that would be a lot to clog the filter.
I would start looking at something like the fuel pump.

 

At one point the SES light was on but it turned off.
If its running the same now as it was last night I will not be able to get a fuel pressure reading because the engine just stumbles and dies.

Could be the pump. I just find it ironic that it was working perfect one minute then 20 seconds after I fill up the tank it barely runs at all.

 

The fuel pump inlet has a sock on it that is like a pre-filter. I have heard of stories where the sock gets clogged with debris and prevents fuel flow.

If this is the case, the only real fix is to replace the sock. I wouldn't just remove the sock and run the pump without it.

Any chance you got the fuel filter on backwards?

 

I got a pm suggesting that i blow compressed air through the fuel line to clear out plugging up the sock and to replace the fuel filter again.

I didn't put the filter on backwards. I triple checked.

 

You should be able to get a fuel pressure reading with the engine off, key on. Listen to make sure the pump primes at startup. Make sure it sounds okay.

Also, I've heard about the pump accidentally sucking up the filter sock in the tank. Could also cause your problem. But I'd definitely set my sights at a fuel pump, or something else in the tank being wrong.

 

I can't recall how the sock is attched to the fuel pump inlet, but use caution if you're going to blow compressed air through the fuel line. You don't want to blow the sock off the line or otherwise expose the fuel pump to "unfiltered" fuel.

 

I have a mechanical fuel pump system, but get the same problem. I have some debris in the tank that cloggs the darn filter sock on the fuel pickup. Usually only happens if I run that tank down past half. I blow compressed air gently down the line at about 20-30psi through a very tiny nozzel from right before my engine mounted fuel pump. Instant success every time. Just take the gas cap off, and send some air down, and listen for bubbling.

I need to drop the tank to fix this problem the right day, but I'm not liking the idea of that process very much at the time, so a shot of compressed air works for me.

 

I used to just blow the sock off if there was no in-tank electric pump, and install a filter (like a GF-61 or GF-61P depending on the fuel line line diameter) before the pump intake.

 

Ok, so I blew out the fuel line and let the dust settle before I tried to restart the car. The car will start but immediately stalls out.
I don't have a pressure gauge to measure the fuel pressure.
I took off the air cleaner and tried to start the car to confirm fuel is being injected. There is fuel and a fair amount of it. It almost looks stream like though and doesn't seem like its turning into vapor but wants to create a pool of gas instead.

Also the fuel pump sounds like it is priming just fine.

 

I don't think you have a fuel related problem.

Stick a scan tool on the car and find out what the SES fault was.

 

I got two codes from the ECM: 33 & 44

Looks like 33 is a MAP error. This could be because when I was working on the car I accidentally pulled the vacuum hose out of the MAP sensor and ran the car before I realized it. I had fixed this well before this problem happened.

The other problem looks to be that the O2 sensor is seeing a lean exhaust.

Update: I cleared the codes and restarted the engine. No codes are being thrown now. I found that I can keep the engine running by continually bliping the throttle from 0 to 10%. As soon as I leave the throttle at 0% for more than a half second, it dies.

 

Do the TBI setups have an idle air control valve?

 

Yes, I believe they do. I see where you are going with this and I should have been more clear. Even if I leave it at 10% throttle it dies. Any more than about 20% and it dies immediately.

I managed to control the throttle manually on the engine so I could see that the injectors do appear to be working well. Not sure if that is a suitable substitute to an actual fuel pressure test though.

 

Well I have banged on the EGR a little to make sure it was not stuck. I have plugged the brake booster hose to make sure it was not a major vac leak. I have now emptied all but 2 gallons of fuel and put in 2 gallons of fuel that I know to be good and still nothing.

The only thing different to tell is that now when the fuel pump primes it sounds like bubbles are being blown into the fuel tank. I think it may be coming from the return line because there is a delay from when the pump start until I hear the sound.

Is there a way to engage the fuel pump by jumping pins on the DLC?

My car is too low to get my jack underneath without driving on top of something first. The car will not run long or well enough to drive up on anything.

I probably need to test the fuel pressure and engine vacuum but I don't have a device to do either at the moment. The parts stores don't rent them and my neighbors doen't have one. I may need to break down and buy one.

 

Sounds like you might have gotten more water than gas in your tank when you stopped for gas. Try a can or two of dry gas .

 

Q1: After the engine starts and dies, does it start right back up and die again?

Q2: If the engine does not want to start, see of it will start by holding the throttle wide open.

I'm wondering if it the engine is flooding.....

 

You can prime the pump by jumping two wires on the fuel pump relay. My relay was on the firewall around a couple others (one being my electric fan...1991 Z28). I forget exactly which two wires....you can also prime the pump by putting 12v to the red wire on the fuel pump relay. I have mine hooked up to a switch for easy carb work, fuel pressure adjustment etc.

HTH

 

The car will start right back up every time. It just will not stay running or idle in any way. The only way it will run in some manner is to continuously vary the throttle while in park. Heavy throttle will immediately kill it.


CamarosRUS, thanks for the info. I have no idea if it is the gas or not but if I can empty it and fill it with gas that I know is good at least I can take that off the table as a possible problem.

 

Take out your IAC and clean it. Also check your TPS. I don't know how much power or resistance it is supposed to have. If you don't have a book you can at least see if the resistance makes a smooth transition from idle to wot.
This is not the best way to check fuel pressure, but you can take the line off the filter and turn your key to run. If it shoot's out, you at least have some pressure. If it kinda runs out, you probably don't have enough pressure.

 

Well I know I have some pressure. I disconnected the fuel line in the engine bay where it changes from the metal to the rubber line. I used the fuel priming to start the siphon in which I got most of the fuel out.

 

my car was doing that, cept it was because i only had 6 psi of fuel pressure due to a hole in the rubber line(and the resulting failed pump) replacing the pulsator on the sending unit. haven't finished putting it back together yet though, so i guess technically it could still be something else

 

Update:

Finally got back to it. I completely drained the tank and even put another new fuel filter on just in case. I put in 5 gallons of fuel in and let it set for a day just to make sure anything that would have got stirred up settled.
Well it didn't help what so ever. So the problem is not the fuel. The fuel pump is working well it seems, though I have not measured it.

I was sure it was fuel relatedsince it happened suddenly 10 seconds after I fueled up but I can't imagine what else I could do short of pulling the tank.

 

Have you actually put a gauge on it anywhere and actually measured your fuel pressure?

 

I don't get it. I dropped my 180,000 mile tank to do a fuel pump and there was absolutely no dirt or other crap sitting in the bottom of the tank that could possibly get stirred up to cause problems.

 

Well I finally got around to measuring the fuel pressure and it was about 3.5-4 PSI. I also got some starter fluid and it started and ran with that though it was a bit rough.

Brand new fuel filter... therefore fuel pump?

 

Might be the pump. Should have 10-14 psi w/ a stock pump.

It could also be the fuel pressure regulator. If it's not seating properly or the diaphragm is leaking the system won't come up to pressure. I suggest getting a replacement diaphragm or even a complete throttle body rebuild kit ($30) to see if that's the problem before dropping the tank & replacing the pump.

Another thought ... are you sure you're checking the fuel pressure on the pressure side and not the return? 3-4 psi might be reasonable for the return side, but I've never actually checked it.

 

Well I got the pressure by disconnecting the fuel line in the engine bay and attaching the gauge directly to the supply line. That probably is not per the book but its all I can manage at the time.

 

Both the supply & return lines are in the engine bay. The line that attaches to the driver side of the TBI is the pressure side. In my car, it's the upper line that runs from the frame over to the engine - but, I don't know if that's true for everyone. I verified mine by disconnecting one line to see which line the fuel was coming from the tank.

 

Yeah I know which one it is. I have been messing with them for the past few weeks now.

The 3.5-4psi was coming from the supply line. If I had the return line disconnected it would have been coming out of the rubber hose and I would have got no pressure from the line I had the gauge connected to.... and a big mess.

 

Take the return line apart and plug the side coming from the throttle body with your thumb over a catch container. Have someone turn the ignition on or jump the fuel pump relay while monitoring the fuel pressure. If you can get a reading more in the 10-14 psi range, the culprit is likely the regulator. If not, it's likely the pump.

 

Not to bring the thread up from the dead but I thought I would share the diagnosis. I went ahead and changed out the fuel pump. The fuel pump was fine but it doesn't matter because the work is pretty much the same. The little piece of rubber fuel line that connects the fuel pump to the sending unit had started to rot and crack. One of the cracks had made it all the way through and hence reduced the fuel pressure down to 4psi in the main line.