Fuel line decision and follow problem/question

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andrew
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Fuel line decision and follow problem/question

Post by andrew » Fri Dec 24, 2004 9:06 pm

A few weeks ago I posed a question about fuel lines, questioning whether others had any problems with the original yellow hoses and degradation – I’d heard from some credible vendors that the hoses degrade due to modern additives in gasoline. Given the relatively low miles I put on the car (approximately 500-1000/year), and other considerations (including originality and my willingness to replace them again if necessary) I decided to go with the yellow hoses over other options.

I called around and eventually ended up purchasing hoses from GT Car Parts, at a price much better than others’ (though still astronomical!). On their advice, as well as Partsource, I bought 8mm yellow hoses to replace both lines coming from the fuel bar (1 going from the hard line on the firewall to the rear of the bar; one going from the fuel filter above the left front wheel in the engine compartment to the fuel bar). GT Car Parts and Partsource both said that although all other yellow fuel hoses on the car were 10mm, these were 8mm, in order to increase pressure to the fuel bar that feeds the carbs. I hadn’t removed the leaking hose prior to ordering, so went with what I was told and ordered 8mm hose. After removing the old hoses, I measured them only to find that they were actually 10mm, which becomes relevant if you read on...

At any rate, I replaced both hoses today, only to find that the engine now barely starts/runs. I can only start the engine with almost full choke, and it runs extremely roughly. It seems completely out of tune. Revving the engine also does not help and it dies without either a lot of accelerator or full choke.

At first I assumed it was starved for fuel, and that I’d made some dumb mistake installing the new lines. I removed both lines and determined that they were both completely clear. Next, I attached a hose to the firewall hard line, and turned on the autoflux (electrical fuel pump at the rear of the car): very strong flow from the hard line (and through the yellow hose when it was attached as well). Then, I started the car with the front yellow hose unattached from the fuel bar: again, strong flow, this time rhythmically from the mechanical pump. Finally, I confirmed from both ends of the fuel bar that the flow was indeed going all of the way through the bar. So, I seem to have determined that it was not a fuel line problem.

Next, I figured I had loosened something when I had un/attached the firewall line, so I checked everything in the vicinity. I checked the coil wire, the distributor, the accelerator linkage, etc. Nothing was loose, and it appears nearly impossible to have dislodged anything anyway.

So, my question is: is it possible that changing from 10mm to 8mm hoses in these 2 places would make the car completely out of tune? There appears to be ample fuel, and it would seem that the 8mm hoses would provide more fuel pressure, not less. It also appears that there is plenty of fuel getting to the fuel bar, and thus to the carbs. If there’s sufficient fuel getting to the carbs, the mixture should be unaffected (because I didn’t change the mixture at all). The only other thing that I knowingly changed was to tighten one manifold connection that I noticed was loose, though this certainly wouldn’t account for the change.

Help! Any ideas? Can anyone think of anything else or explain my barely idling car that ran perfectly last week (though it did leak fuel, which it now does not!).

Thanks in advance for any suggestions.
'64 330 America s/n 5109

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330GT
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Post by 330GT » Sat Dec 25, 2004 12:58 am

A couple of things come to mind.

First, maybe you got some crud in the fuel log during the fuel hose changes. There are screens where the fuel log attaches to each carb. Check to make sure that they aren't clogged.

Second, did you drain the tank and only put a gallon or so back in? If so, you might have a cracked pickup tube inside the tank. This happened to both Tom Yang and me. The symptom is the car will start and run at an idle but won't rev up as the pump(s) are mainly pulling air instead of gas. The easiest way to check this is to fill the tank about 1/3 full. That will completely cover the pickup tube. If the car runs OK then, it's time to put a new brass tube in.

BTW, the 10 mm lines are from the tank to the mechanical pump. They're not pressurized so they need to be larger. The lines from the mechanical pump to the front filter/pressure regulator to the fuel log and from the electric pump to the log are 8 mm.
Regards, Kerry
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Stephanm
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Post by Stephanm » Sat Dec 25, 2004 2:45 pm

The 8mm or 10mm size is very difficult to measure because as you may have noticed, the SALVA fitting is tapered. I have never seen 10 mm at the fuel rail and suspect that you measured the SALVA fitting near the hexagon. THe fittings are measured at the bore of the fitting.

It sounds to me like crud in the small screens just upstream of the float chambers, so much stuff could have loosened upon removing the lod fittings. As noble as the cause may be, sometimes changine a fuel filted can lead to the same sort of disasters.
Very wise of you to check all the ignition stuff near the elect. pump feed line, very easy to accidentaly disconnect something there. I would in fact double check that area and remove the heat shields to feel for heat and whether it is a cyl. 1-6, of 7-12

Good luck, these are the most frusterating problems.

andrew
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Post by andrew » Sun Dec 26, 2004 1:22 pm

Thanks for the suggestions. Based on your ideas, I disassembled the fuel log/rail and even the top of the carbs to check for any blockage. Everything is perfectly clear and the flow of gas is strong to the carbs. On a sidenote that might be of interest to someone, my fuel rail has a small branch at the rear, with a pinhole-sized opening, that seems to reconnect to the hard line at the firewall through a small-diameter rubber hose (I'm assuming this is to relieve excess pressure or to vent the system?). At any rate, others' fuel logs/rails don't seem to have this, and it's pictured without the offshoot in the parts book -- just thought someone might like to know, in case theirs is also atypical.

Also, the tank has been about 1/3 to 1/2 full through all of this, and does not idle well under any circumstances at the moment (indeed, not since the fuel line change, but fine before), so the fuel pickup tube doesn't seem to be the problem.

So, I don't think it's a fuel problem...

Any other ideas, as I move on to other potential causes? I'll keep the interested parties posted as I resolve this, in the hope that someone else can learn from my experiences. Thanks again, folks.
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Post by 330GT » Mon Dec 27, 2004 1:01 am

The small connection from the fuel log at the rear is a return line to the tank. It keeps fuel flowing through the log even in an idle situation, thus helping to prevent vapor lock. I presume that the diameter is chosen to allow only a small flow while keeping enough pressure in the log to keep the carbs fed even under full load.
Regards, Kerry
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SLM
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Post by SLM » Mon Dec 27, 2004 12:02 pm

If they are still in one piece I would put the old hoses back on and see what happens.
Steve
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Jimmyr
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Post by Jimmyr » Tue Dec 28, 2004 9:29 pm

When you had the carb tops off did you check to see if the float jet was clear? It can easilly be checked by looking, first to see if the needle drops when the float is down, second blow through the inlet and see if air excapes from the needle. It sounds like as you have been told, there may be some crud lodged in possibly just one carb. This is all it takes to make the engine perform as you described. Clean all of them if you are checking, and clean all of the bottoms of the float bowls while you are in there. This is something that should be done often, even if the engine is running smooth. Jim Riff

andrew
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Post by andrew » Mon Jan 03, 2005 2:53 am

The jet appeared to be clear, and dropped fine, and I did take the opportunity to clean the float bowls when I had the carbs apart. I didn't blow through the inlet, but since I'm running out of ideas, I'll do so when I have some time to disassemble it all again -- I want to replace one of the screens anyway.
'64 330 America s/n 5109

Jimmyr
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Post by Jimmyr » Mon Jan 03, 2005 12:14 pm

Andrew, when you have the tops off take a can of Gumout spray choke cleaner and using the long spray tube squirt it into the various jets and see if the spray exits into the throats. I take the idle screws out and sruirt the cleaner into the hole and watch to see if there is flow into the throat. This is very important especially into the emultion tubes on the top, and the jet at the bottom of the float bowls.

andrew
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Post by andrew » Sun Feb 27, 2005 1:20 pm

Finally, 2 months later, I had the time to get back to the car (as anyone with 2 kids under 2 years of age knows, the formula is about one month per kid!).

At any rate, Jimmyr was exactly right (thanks!) -- although I had made sure the carb needle was dropping as it is supposed to, I didn't actually blow through it to guarantee that it was completely clear. After removing everything again and blowing through the inlet, it was obvious that one carb was completely blocked and another was partially blocked. My car was probably running fine on 4 cylinders as a result, weakly on another 4, and not at all on the final 4. The time also gave me the opportunity to find all of the fuel line gaskets and a missing carb stud to the air filter assembly and replace those since I was in there (it was remarkably difficult to find either fiber or copper washers of the right size -- anyone else noticed that hardware stores don't actually sell hardware anymore?).

After buttoning everything up, the car fired up on the first try and runs perfectly. A long wonderful ride, far, far away from my toddler and baby, was my reward.
'64 330 America s/n 5109

Jimmyr
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Post by Jimmyr » Fri Mar 04, 2005 12:46 am

Andrew, GT Parts in Phoenix carries the copper fuel line washers. I only use the copper, as the fiber ones may compress or shrink due to the evil stuff in our modern gas. The copper is stable with all that they can stick in this gas.
Glad you found the float problem, another result of this junk gas. Always use Loctite on the air cleaner studs into the carb tops, but never on the nuts; these are the nylok types. Never use any washers, locks or flat under the air cleaner hold down nuts as they can easilly flip into the carbs, note that the factory has never used any type of washers above the carb tops! Jim Riff

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