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  #31 (permalink)  
Old 12-29-2010, 07:43 PM
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I think a timing light should be a serious consideration soon.
You mentioned never checking the timing so far.
Timing should be checked as soon as you get rid of the bad fuel.

I had a 79 Chevy that someone had installed a bolt that was too long and the distributor could turn by hand after the bolt was tightened.

Backfiring at highway speeds sounds like it could be a timing issue if its not a fuel problem.

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  #32 (permalink)  
Old 12-29-2010, 09:35 PM
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Hey 123pugsy,

Quote:
Originally Posted by 123pugsy
I think a timing light should be a serious consideration soon.
You mentioned never checking the timing so far.
Timing should be checked as soon as you get rid of the bad fuel.

I had a 79 Chevy that someone had installed a bolt that was too long and the distributor could turn by hand after the bolt was tightened.

Backfiring at highway speeds sounds like it could be a timing issue if its not a fuel problem.
I do want to mention that there was absolutely no backfiring until we did the tune up. The truck ran absolutely flawlessly. It isn't just backfiring at highway speeds, but also when its reved high enough (can't remember the exact rpms but it was well above 2500). I feel it may also be worth mentioning that the truck also suffers from hesitation at times when accelerating, especially when reversing uphill, as in a drive way.

I am not ruling out timing as a possible issue (after all, when things break or go wrong with cars, it definitely seems to be a domino effect, at least for me). I have a feeling the backfiring can be attributed to an arcing wire (Im sure I know which one and will be replacing it asap), as well as incorrectly gapped spark plugs.

I am presently basing the above on the one damaged wire I've found, as well as what I've read URL=http://www.aa1car.com/library/vacleak.htm]here[/URL] (third bullet in the list, labeled "Hesitation or misfiring when accelerating".

Please do point out if I've misunderstood what I've seen or read.

Thanks for the tips!
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  #33 (permalink)  
Old 12-29-2010, 09:38 PM
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Timing does make sense, i dont know about on a small block but on my big block the distributor has to be loosened and turned to get to the distributor cap retaining hooks in the back. If this is the case then it could easily be off time if you didnt move it back where it was at. Try moving the distributor a little at a time back and forth and see if it helps it any.
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  #34 (permalink)  
Old 12-29-2010, 09:51 PM
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Quote:
Originally Posted by Torque454
Timing does make sense, i dont know about on a small block but on my big block the distributor has to be loosened and turned to get to the distributor cap retaining hooks in the back. If this is the case then it could easily be off time if you didnt move it back where it was at. Try moving the distributor a little at a time back and forth and see if it helps it any.
I am now going to demosntrate my ignorance with the next question: If the distributor was moved (it is held down by a bracket and a bolt, which were never touched during the tune up), wouldn't there be some signs of a problem throughout the rpms? Or only at wide open throttle?
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Old 12-29-2010, 09:55 PM
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Quote:
Originally Posted by lt1silverhawk
I am now going to demosntrate my ignorance with the next question: If the distributor was moved (it is held down by a bracket and a bolt, which were never touched during the tune up), wouldn't there be some signs of a problem throughout the rpms? Or only at wide open throttle?
Not necessarily. Unless it was way way off. It could be that the truck was needing a tune up so bad that it had to be advanced or retarded in order to run and then once it was tuned up, its timing needs changed and now its off.
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  #36 (permalink)  
Old 12-29-2010, 10:01 PM
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Quote:
Originally Posted by Torque454
Not necessarily. Unless it was way way off. It could be that the truck was needing a tune up so bad that it had to be advanced or retarded in order to run and then once it was tuned up, its timing needs changed and now its off.
This is actually something that has been concerning me as I continue researching the problems. I have a strong feeling things were messed with by the previous owner to perhaps mask some issues or problems. For one thing, it has no EGR. Now, the other issue is the funky choke setup as pointed out by Cyclopsblown and T-Bucket.
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  #37 (permalink)  
Old 12-30-2010, 06:16 AM
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Did you check to see if the choke is functioning.
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  #38 (permalink)  
Old 12-30-2010, 11:50 AM
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Quote:
Originally Posted by T-bucket23
Did you check to see if the choke is functioning.
Good morning Chet and Gang!



I did not test out the choke as suggested just yet.

However, I did start the truck this morning and made a video to see what happens.


In Case You Can't See the Video:

The truck doesn't start right away. I then "prime" it three times and then it starts up. From what I can tell, the choke engages immediately but the motor also begins to die down very quickly. All the high revs you hear are me working the pedal (one time as high as 3500 rpm). As also seen in the video, the fuel filter right before the carb is originally empty but fills up quickly and stays full for the duration of the run. In the second half, fuel can be seen shooting up out of the carb, near the accelerator linkage. I also noticed that there no backfires this time.



Right after the video, I swapped the two fuel filters in the back for two new ones. One of them had reddish gunk flow out, which you can see in the pictures below.




After swapping out the filters, I decided to check the gap on the spark plugs that came with the truck. The gaps are around 0.050", not the standard 0.045" or the CA-emissions 0.060"



Tests will continue throughout the day as time permits. Tank is low on gas so will need to pick some more up. I will try to re gap the spark plugs and do vacuum testing next.


As always, thanks for the help!
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  #39 (permalink)  
Old 12-30-2010, 12:36 PM
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Looks like the choke is opening fully right away. This is why you have to nurse it. It also sounds like you have a solid skip to me. I would double check the firing order and all plug gaps.
Pay close attention to #5 and 7 as they are real easy to mess up. They are right next to each other on the cap and the engine end.
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  #40 (permalink)  
Old 12-30-2010, 12:45 PM
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Quote:
Originally Posted by T-bucket23
Looks like the choke is opening fully right away. This is why you have to nurse it. It also sounds like you have a solid skip to me. I would double check the firing order and all plug gaps.
Pay close attention to #5 and 7 as they are real easy to mess up. They are right next to each other on the cap and the engine end.
Will check on that asap. I originally messed up #1 and 8. Took me a while...
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  #41 (permalink)  
Old 12-30-2010, 07:13 PM
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I didn't get to do much else today due to a whole of running around.

I did spray the carb with carb cleaner and finally opened up the carb's inlet to remove the filter but there wasn't one inside. There was a somewhat gunked-up spring inside that is in the picture below.



Shortly after this picture, the spring was lost in the depths of the engine bay and I realized I better wait until tomorrow before continuing anything.

After putting the inlet back on the carb, minus the spring, I primed the carb and fired it up. It start powerfully (at least when compared to recent starts) but died within 30 seconds.
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  #42 (permalink)  
Old 01-02-2011, 11:18 PM
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A very happy and blessed New Year to you guys!


So, I haven't been able to do much due to the weather and my being sick.


I did siphon out almost six gallons of contaminated gas yesterday but the tank still shows as 1/8 full.


I've been doing some thinking and have come up with some questions which I hope you guys can help me with. The questions are in regards to the video I posted earlier.

- Once the truck starts, the glass-cased fuel filter right before the carb always remains full. Near the second half of the video, fuel can be seen shooting out of the carb (a pump of some sort) near the throttle linkage every time the gas pedal was pressed. What would cause that?

- Could flooding be the reason behind the motor dying so quickly (and thus fuel shooting out of the carb)?

- Or perhaps the idle needs to be adjusted on the carb?


Aside from that, plans for tomorrow include pouring more fuel into the clean tank (its damn near empty), removing the glass-cased fuel filter right before the carb and running a hose to the carb, and starting her up. If time and weather permit (very unlikely), mess with the spark plugs and cables as well.
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Old 01-02-2011, 11:35 PM
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A stream of fuel shooting down the carb when the throttle moved is normal. That is called the accelerator pump and it provides temporary enrichment of the air/fuel mixture when you push the throttle when it would otherwise it would lean out for a moment. If the carb was flooding it would likely be smoking and have a strong smell of raw fuel.

Try this next time you have problems starting the truck. Hold the gas pedal to the floor. Do NOT pump it, just mash it to the floor and hold it while you crank the engine. If it starts, and slowly builds up speed while kind of chugging and clears up after a couple seconds (after which you can release the throttle) then flooding is evident. Holding the throttle wide open allows maximum air flow through the carb and helps clear up the excess fuel.
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  #44 (permalink)  
Old 01-03-2011, 01:29 PM
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Happy New Year Torque!

Quote:
Originally Posted by Torque454
A stream of fuel shooting down the carb when the throttle moved is normal. That is called the accelerator pump and it provides temporary enrichment of the air/fuel mixture when you push the throttle when it would otherwise it would lean out for a moment. If the carb was flooding it would likely be smoking and have a strong smell of raw fuel.
The stream of fuel I was referring to can be seen shooting up towards the windshield, rather than downward into the carburetor. But I do see the accelerator pump part and now know what its called . I have also seen the smoke coming out of the carb before as I noted in earlier posts, so now I know what it is a symptom of.




Quote:
Originally Posted by Torque454
Try this next time you have problems starting the truck. Hold the gas pedal to the floor. Do NOT pump it, just mash it to the floor and hold it while you crank the engine. If it starts, and slowly builds up speed while kind of chugging and clears up after a couple seconds (after which you can release the throttle) then flooding is evident. Holding the throttle wide open allows maximum air flow through the carb and helps clear up the excess fuel.
Got up this morning and waited for the rain to ease up so I could try what you suggested but the battery was dead. On the bright side, the rain will be over today rather than Wednesday so I'll be able to work on it some more soon.




Presently, I am researching the Rochester carbs and found what seems to be a handy article.




Thanks for the continued help guys!
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  #45 (permalink)  
Old 01-05-2011, 12:00 AM
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Finally got to work on the truck tonight.

Dropped in the battery after charging it all day. Found out the glass-cased fuel filter right before the carb was facing the wrong way so I switched it to the correct position. I also discovered that a vacuum hose from the carb was removed when previously working on the fuel hose so I put that back on.

Then, I followed Torque's tips below to start her up.

Quote:
Originally Posted by Torque454
Try this next time you have problems starting the truck. Hold the gas pedal to the floor. Do NOT pump it, just mash it to the floor and hold it while you crank the engine. If it starts, and slowly builds up speed while kind of chugging and clears up after a couple seconds (after which you can release the throttle) then flooding is evident. Holding the throttle wide open allows maximum air flow through the carb and helps clear up the excess fuel.
I made this video of the start up (its all sound since it was too dark for the camera).

In Case You Can't See The Video
At Torque's suggestion, I floored the gas pedal and had to crank the truck several times to get it started (it sounded like something blew off on the second cranking). After truck finally started, I feathered the throttle to keep it going. I eventually revved it mildly and kept revving it every few moments. After a couple of minutes, I revved it much higher and kept it there. Once I let go of the gas, the truck began idling normally. But after a couple of minutes, it died and smoke/steam came out of the carb. Going by what Torque stated, there is flooding.




I did some more research online and this article from Grounds Maintenance website (yes, its about gardening equipment but sounds relevant) suggests:
Quote:
"The single-most common cause is dirt in the fuel. Dirt usually gets into the fuel system via the fuel tank. If the area around the filler neck is left dirty, you can easily knock it in when you're refueling. Typically, the fuel filter traps the dirt. However, if the fuel line doesn't have a filter, or it fits improperly, the dirt settles to the bottom of the fuel bowl. As you use the equipment, the dirt bounces around until it is caught between the inlet valve and the seat. This will cause flooding because the valve won't seat to shut the fuel off."
As mentioned many posts ago, there was debris in the contaminated fuel tank and I wonder if that is the cause of the flooding. And if it is, would a rebuild be the solution?
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