Unrepeatable Miracle ... again

Maintenance/Repairs
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21

Have you tried (carefully) giving the engine a shot of starting fluid? Follow the directions on the can, don’t just hose a ton of it into the throttle body. Keep your face away in case it backfires through the intake. If the problem is accumulated fuel, it may be that if you give it a shot of fluid that it will fire enough to clean out all the crap. You can also try holding your foot to the floor while cranking–this will cause the fuel injectors to be inoperative and put the system into “flood clear” mode. After doing this and cranking for about 10 seconds, then release the accelerator and see if it will start.

This is of course assuming you have spark.

22

thank you both mountain biker and oblivion. I would replace the plugs but I can’t seem to get the front 4 out. Not even the wire off the plug. Any tips? Or is that like asking how to worm a hook? The wires appear to be in excellent condition. The van ran fine until I parked it over 5 years ago. Oblivion, thank you for explaining the effect of flooring this vehicle. A lot more makes sense to me now because when it did start those two times I had had the pedal floored. … and I’ll try the starter fluid.

23

You absolutely cannot go by looks with plug wires. These are definitely old enough for the insulation to have broken down. And I’ll bet you’ll find corrosion when you look at the distributor parts as well. All of these parts should be replaced.

Getting the old plugs out…try soaking them overnight with a penetrating oil. Try twice. Know that if they should break coming out you can always remove the debris, clean out the cavity (the cylinder) of debris with a vacuum and “tech equipment nozzle”, and retap the threads. A broke plug won’t render the engine trash. It’ll just need to be cleaned up and retapped. Maybe, worst case, helicoiled.

By the way, you’ll be replacing the plug wires anyway. I’d cut 'em if I couldn’t get 'em off and use a deep socket instead of a spark plug socket (which won’t go on if the wire isn’t properly unclipped from the plug). Do them one by one, so you don’t accidently mess up the firing order…always a good practive when doing spark plug wires or vacuum lines.

24

Yeah! Success … sort of. I succeeded in pulling all of the plugs and replaced them with new Champions (the cheap ones). Not even touching the gas pedal, I just turned the key and the engine instantly started … just like the olden days.

I let it run without touching the pedal for about 7 or 8 minutes. The engine, although it was not “chugging”, was running rough at this low idle. At first the tailpipe was emitting white smoke (H2O), but after 2 or three minutes I started to see more and more black smoke indicating unburnt fuel.

So after those 7 or 8 minutes of low idling, I revved it up and was getting a lot of black (not blue) smoke, and then after a while the engine seemed like it was going to die, and only flooring it (as per what Oblivion said) seemed to limit the overly rich mixture, … and that was only temporary because after a little while the engine died anyway. The only way it would start again was with the pedal floored,
and it didn’t keep running, it died again. That’s where I stopped and where I am.

I’m not scared, … I’m frightened that I may be entering my 3rd round of “Unrepeatable Miracle”. I should mention at this point that before I stopped using the van 5 years ago, there was an intermittent problem where, while driving, the engine which was running fine, all of a sudden started running very poorly, and putting out lots of black smoke, and then, randomly, that would stop and it would run fine again. I had always suspected a bad O2 sensor, but I never got it fixed. That might be my problem now, … or maybe something else is wrong. I have great fear that just running the engine for a total of 10 minutes or so, with all that black smoke coming out, might have totally fouled up my new spark plugs. Thoughts ?

25

Well, your work was not wasted. It had diagnostic value. It’s clearly flooding. So you know you need to look at the injectors and the fuel pressure regulator next.

There’s an old “scientist joke”. It goes like this.
student: "professor, we’ve tried 1,000 different things and STILL no success. We’ve learned NOTHING!"
scientist: “yes, we have. We’ve learned 1,000 things that WON’T work!”

26

Thanks Same Mountainbike. The injectors are two throttle body injectors (tbi) that I just replaced with re-manufactured units. One can actually see the spray output, and I confirmed that both were emitting a pulsating conical spray. I didn’t replace or look at the fuel pressure regulator. On this TBI system the regulator consists of no more than a spring and a diaphragm. I suppose it is a suspect, but considering my past intermittent problem with the engine randomly running rich, I have a greater suspicion of the O2 sensor. Do you think my new spark plugs are all messed-up now ?

27

Succeeded in replacing all the spark plugs. G20 van started instantly without touching the gas pedal, but within a few minutes started to emit lots of black smoke. Before mothballing this vehicle it would seemingly randomly suddenly go from running fine to running very poorly and emitting lots of black smoke. … Never did get that fixed. I suspected the O2 sensor, but I guess it could also be the MAP sensor or the fuel meter (not exactly a fuel pressure regulator), or who knows what else. … Where to go from here ?

28

It’s easy enough to find out of the new spark plugs are carbon dusted now. I’m betting they are.

One question; do you think it’s possible that the carbon is coming from oil? If the engine sat for 5 years, it’s very possible that the rubber valve stem seals are totally shot. During the intake stroke, especially during deceleration (even just coming down from revving the engine), the cylinders’ vacuum spikes, and if those seals are shot the cylinders will draw in oil. Oil will also leak into the cylinders when the engine is off. There’s no real definitive test for bad valve guide seals that I know of, but they’re a very real possible source of soot…oil is, after all, another hydrocarbon.

29

I mentioned a year ago in the original "un-repeatable’ miracle thread, and then I think in this one as well, that I KNOW it’s got bad valve stem seals. After driving it, then letting it sit overnight, upon starting I’d get whafs of blue smoke. That would soon go away, and it would run fine. The smoke I am currently getting is coal black.

30

Update. I accessed the van’s self-diagnostics, and received a code which simply states the fuel mixture is too rich. I knew that already because of the black smoke, so that diagnostic code was not particularly useful, except that I did not get any other codes, which makes me think the problem is NOT the MAP sensor or the engine coolant sensor because if there is a problem with those units, there should be an associated code which is flashed.

I had always suspected that the O2 sensor might be going because before I moth-balled the vehicle, very occasionally the engine would start to emit black smoke and run terribly, and then that would stop and it would be OK again. So a few days ago I replaced the O2 sensor with a new Bosch unit. The engine started right up by turning the key and ran pretty well, only emitting white smoke (water vapor) because it was cold outside. I was hoping that as it warmed up the van would run great, but instead what happened was that the engine idle very gradually got slower and slower, and then it started emitting black smoke and the “check engine” light came on, and again the diagnostic was showing the same code as before … too rich. Now my brand new O2 sensor is fouled as well.

Next I visually inspected all the vacuum hoses that I could see well ( the 3 vacuum connections on the front of the TBI are very hard to see and access for they are right under the dash. I did find two hoses that were kind of cracked around the nipple, so I cut the bad part off and reattached. Then I pulled all my spark plugs AGAIN and cleaned them with carb cleaner and a toothbrush and a file and replaced them into the van. When I started up again, the engine seemed to run even better for yet a longer duration, but then again, gradually the idle got slower and slower, and then it started to smoke and the check engine light came on with the same code as before.

So now, my main suspect is the fuel pressure regulator diaphragm, which I didn’t even look at when I previously replaced the 2 tbi injectors. I took the regulator unit apart, but am not quite sure what to make of what I have found. There was some dried and hardened residual fuel residue which I cleaned out with carb cleaner. The rubber diaphragm itself seemed intact and certainly better than a picture I saw online where the rubber was stretched and sort of ballooned. However what I did find, was that the circular metal disc which sort of rocks back and forth in the diaphragm unit had uneven wear where that disc contacts the end of a metal tube for the purpose of blocking the fuel flow. So I am wondering if fuel may be slipping by when that should be completely shut, and perhaps that is causing the problem.

I’ve already dropped almost $300 on parts and fuel tank cleaning, and am not eager to spend yet $30 more on a regulator diaphragm which may or may not solve the “running too rich” problem. Any thoughts from anyone as to what I should do from here ? The behavior of the engine is very consistent. If it hasn’t been started for a day or so, the engine starts right up and seems to run quite nicely for a while, but then the idle speed gradually gets slower and slower, and then it starts to emit black smoke and the diagnostic emits the “running rich” code.
Thanks for any help you can give.