72 Squareback running poorly (stumbling/death)

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I have a 72 Square with the fuel injection still in place. It doesn't run (well). From dead cold, it will run about 5-10 minutes then start stumbling and it will eventually die. After this death, the car will not start again without stumbling and dying until it has sat at least overnight.

The car also surges at idle or a constant throttle position.

I have replaced the fuel filter (several times) and all fuel hoses at the front of the car. I took out the fuel tank and shook/beat out miscellaneous crud. I ran fuel injector cleaner through the engine. I've checked both temp sensors (they were good) and the trigger contacts (also good). Spark plugs spark and there is no sludge in the air cleaner. I am completely out of ideas--can anyone point me in the right direction?

Part of my confusion stems from the history behind the car. A summary:
Purchased in Jackson, MS in July 2004
Driven 300 miles to New Orleans on day of purchase
sat for about a month or so due to title snafu
wouldn't start b/c of disconnected wire on fuel pump relay (an oops from pulling the fuse box)
shipped to arizona in november
died one night on my way home--thought it was out of gas (no gauge or odometer--since remedied) walked to gas station, got gas, car ran
wouldn't start one day changed fuel filter, ran fine
started pulling the stumbling routine described above, checks above done, no dice

I am seriously at the push over cliff/shoot with 12 gauge stage right now (after the better part of 3 days work). Any help would be greatly appreciated.

[Russ Wolfe]

You say you got crud out of the tank. Sounds like your gas tank vent line that goes to the fill neck might be bad. There is a fliter screen in the bottom of the tank that gets plugged if water gets in the tank.
Check your fuel pressure. it should be 28-32 psi.
The idle speed warm should be about 950 rpm. Cold, it should be a little higher, maybe 1100.
_________________
Society is like stew. If you don't keep it stirred up, you end up with a lot of scum on the top!--Edward Abbey

Gary: OK. Ima poop.

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Is the vent line the approx. 1 inch hose coming out the side of the tank and paralleling the fuel filler? I'll give that a check. Can this really cause this big of a problem? It almost seems too simple.
I don't have that filter screen in the tank, though--Is that bad?
I don't have a gauge to check the fuel pressure, but I'll give the idle speed a look.

[Russ Wolfe]

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I started the car up last night and pulled off the smaller hose on the driver's side (the one that goes to the charcoal canister. There was no change in the running habits with this hose diconnected and the hood only on the safety latch. I'll try that bigger hose too, but for that I need to get the screwdrivers and such back to the car. They seem to connect to each other though (the big and little hoses). I can't figure out where the other end of the big one goes, though.

I came up with a theory last night. After thinking about the history for a while, it seems to me like it runs for a little bit every time I change the fuel filter. Since it ran back in Louisiana and Mississippi, I tried to think of everything that changed since then. Then, it hit me--there's ethanol in the Arizona gas. I think that the alcohol in the gas is causing the tank to shed rust. I checked down below, and, now that I have a clear fuel filter, I notice that there is an accumulation of fine red powder in the filter. There seems to be quite a lot of this in the filter. I think my next move is to get the tank derusted or replaced and change the filter again.

Could a clogged fuel filter cause this problem that I'm having? Does the ethanol thing sound plausible? And how exactly can I cobble together one of these pressure gauges--just a hose and a guage? Thanks for your help.

[squarebackinaustin]

I think you're on to something with the rust. No filter screen in the gas tank probably adds to the problem, too.

Checking the fuel pressure (at idle and while driving, especially when it's acting up) will tell you a lot. Buy a fuel pressure guage (make sure it goes up to at least 30 psi)--some of the auto parts store clerks are going to think you're crazy because the psi on most newer cars is much much lower. Anyhow, I "modified" my guage and you can do the same. Just buy some fuel hoses (I bought about 8 feet worth) and cut one so it's about a foot long (this will be for measuring fuel pressure while the car's at a standstill) and then cut another so it's long enough to run from the fuel pressure guage connection in the engine all the way to the front seat of you car (this oneis so you read the pressure while driving; it's easier, of course, if there's someone reading it for you while you drive). Make sure that you clamp the hoses down tight to the guage and to the guage connection in the engine.

This whole thing should run between $15-30, depending on what you area part stores charge. The guy at my parts store felt so bad for me, he gave me 8 feet of hose for free (but the guage was overpriced, so it balanced out).

There should be detailed instructions on how to measure fuel pressure in any of the manuals. If you don't have one, just ask, or browse through the threads to find out.

So, if the fuel pressure changes when the problem kicks in, you have a culprit somewhere in the fuel system. Remember, it should be steady throughout (28-32psi). You can adjust the pressure if it's too high or low by adjusting the pressure regulator. But first see if there are fluctuations in the pressure.

Keep us posted. And best of luck.

[Russ Wolfe]

I hate to tell your parts man this, but modern cars with FI are a lot higher than ours.
One Ford is 66 psi.
Most Chrysler products are 58 psi.
Earlier Chryslers were 49 psi.
Jeeps are 49 psi.
Saturn = 57 psi
Mercedes = 59 psi
Nothing we make is under 40 psi, and that is the very early Dodge trucks.
The company I work for makes the fuel pressure regulators. They are fixed pressure regulators. Not adjustable after they leave us.
_________________
Society is like stew. If you don't keep it stirred up, you end up with a lot of scum on the top!--Edward Abbey

Gary: OK. Ima poop.

[squarebackinaustin]

I've heard worse from some of the auto parts people. One guy had no clue what a fuel pressure guage was--he kept handing me air pressure guages and insisting they were the same. Some are very knowlegable. Others though...well...it was like me when I was 18 and didn't know squat about automobiles (technically speaking, I only know a tad bit more than squat now).

Years ago, a friend of mine was told that her carburator was not functioning properly. Later, when she was telling us about her car problems, she said, "I think I need a new burator." What's a burator? we asked. "You know," she said. "The burator...the car's burator."

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I drained the tank again today so that I could take it in to the radiator shop. I was having trouble with the siphon, so after I got most of the gas out of the car, I went underneath to disconnect a hose and drain the rest like that (used the small gas can). Only a trickle came out of the return and supply holes in the tank. After that, I pulled out the tank and poured about 1-2 gallons out of the filler neck into my gas bucket.

After thinking about this for a while, I remebered that someone had said on another thread that the well inside the tank has a slit for gas to get in and out. Looked inside the tank--no sign of a slit. Should this slit be obvious looking in the sender hole? I had some noon sun, so I got a good look at the inside of the well, and I didn't see anything that resembled a slit. I think this might be my problem--gas starvation.

Pondering that thought, I remembered that when I let it idle for a while and looked at the fuel filter, it seemed like every couple of seconds, the fuel pump would suck some air bubbles out of the tank. The fuel filter is also only about half full of gas when the engine is running. I think that this backs up the missing slit hypothesis.

Since it's after 1pm on a saturday, the entire phoenix metro area has shut down, so everthing is on hold until monday. Any comment on this latest theory of non-working? I have a source for a new tank for $60. It would cost almost this much to dip and coat the old one, so I think I'll be making a purchase on monday. I believe I'll buy some new gas too, because the dregs of the tank tunred the gas in the bucket a disturbing brownish-gray when I poured them out. I hope this works. I'm also going to pick up some timing and fuel pressure equipment. I just found out that you have to check the timing if you pull the distributor (and the trigger contacts were clean).

edit-I sucked about 3.5-4 gallons out of the tank, so plenty of gas was in there.

[squarebackinaustin]

I'm not sure about the "slit"--that is, I just don't know. Hopefully someone else does.

If the gas is coming out that dirty, it's probably a good idea that you get the new tank, especiaally at $60.

The timing tool can be made--Muir's book has a description (it's just a wire with a clamp/connector on one end and on the other a light bulb screwed into the light "socket" (not sure what the thing that the bulbs screw into is called)--the light bulb should be 12V or 6V, depending on your generator.

I found an accessory light with wire/clamp that people will use to light up their license plates. It's $4, and the bulb is 12V, and while the light is blue, it does the trick.

[Russ Wolfe]

Yes, that slit can be a problem. I have 2 tanks laying behind the shop that were that rusty, and would fuel starve after driving a while.
The well is there to prevent starvation when cornering with the tank below about 1/4 full. I think TomNotch had a picture of his when he made his conversion.
$60 would be cheap for a new tank. Be sure it is for fuel injection.
Once you get all the crud out of the system, ethynol should be no problem. It took about 3 fuel filters to get mine cleaned up after sitting for 15 years. It was parked because of broken vent hose.
I made a new one out of 1/2" copper street El, and some 5/8" plastic hose from the hardware store.
_________________
Society is like stew. If you don't keep it stirred up, you end up with a lot of scum on the top!--Edward Abbey

Gary: OK. Ima poop.

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It runs. I put in the new fuel tank (it looks a little different when the slit isn't full of goo) and the car ran like a champ. It turned out to be a used tank, but I only paid $50, so I'm thinking it was a good purchase--especially since it fixed the problem. No crud accumulation in the fuel filter yet (since monday), so I think this tank's pretty solid. It even came with a free fuel gauge sender, which is good because my old one is missing the nut/clip/whatever that hold the cylinder on the float assembly making the thing separate and jam the float. Two birds with one stone.

Yesterday, I pulled apart the spare speedo to see if I could get a working odometer for the car. Squeezed the die cast gear and peened the shaft--I now know how far I go. Had to epoxy the nedle back together, though (it was already cracked. Also epoxied the metal center thing back onto the plastic number plate. You have to remove to disassemble the speedo, but it's fused to the plastic--who designed this thing?

Just got done making some clips to bolt the gas tank to the car out of some 1/8th inch steel plate. It's probably overkill, but it's what was laying around. You see, when I changed the tank, I noticed that the old one was not secured to the vehicle. Not good. local shop donated some bolts and I made these clips, so it's now good and secure.

Thanks for all the ideas. Kind of glad it wasn't the fi. Kind of glad that I and now the proud owner of a cylinder head temp sensor removal tool (13mm socket with flats ground on). On to the brakes, I guess.

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So much for that thought. It died again today on the freeway, but this time it went without sputtering--just stopped running. It will crank, but it won't catch and sputter like before, it will just crank. Hazard flasher relay almost caught on fire (lovely smell). Fuel pump was wet with fuel by the hoses too, but the hoses were all tight. Maybe the pump ate itself. Who knows. Got it towed to pep boys, but I don't really expect results, and I'm about to give up on it. Thanks for all the help anyway.

[Tram]

[Bugman_Jeff]