6 cyl drivability problem. Help please! - Chevy Nova Forum
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Old 24th-October-2012, 10:42 AM   #1
Rotorbolt

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6 cyl drivability problem. Help please!

Hey guys, I've got a problem with my 64 nova. Its not running right at highway speeds. It loses power and stumbles when I get up 50 mph. Like its starving for fuel or somthing. It started this last week for very short periods a couple times and I assumed it was a dirty/ clogged up fuel filter. Which has happened before in the past. My tank has fine light rust particles in it and I keep the filter changed on a regular basis. I went ahead and put a new filter on because it was obvious the old one on it had fine rust particles clogging it up. On my first run with the new filter, it stumbles and acts like its not getting any fuel on the highway. Never dies though and I can't get it to go faster than 55-60 mph. If I pull the manual choke to the carbs closed all the way while running at speed, it does run better. But I can't get it moving any faster. Like somthing is dragging and holding it back. The engine runs great at idle and low speeds. I've even run the rpms up to 3000 running in park and held it there for several mins to see if it starts stumbling like it does when it actually is in gear and moving. Never once runs bad, stumbles or starves or dies from lack of fuel. The fuel pump is a new unit I put on it a year and half ago. seems to be working correctly and providing plenty of fuel for the dual 1bbl carbs on it. I've been driving the car for 3 years with no problems other than a couple clogged fuel filters. Its been running great untill yesterday. I haven't had a chance to check things out on it further because I've been tied up with work right now.
The engine is a 194 6 cyl thats rebuilt. .040 over, new rings, bearings, cam,lifters, rockers, timming gears, rebuilt head with hardened seats, rebuilt carbs, HEI with new cap/rotor, wires. Internal reg alternator conversion, Etc.. The TH350 transmission is used and I've always had to manually shift it because it upshifts too soon and doesn't downshift from 3rd to 2nd untill it comes to almost a complete stop. I did put a new modular on it to try and make it shift better, but no dice there. I have a suspicion that this is my problem. That the trans is going bad or about to cease working altoghether. I don't know anything much about them or how to diagnose them. I did run the car in 2nd up to 55- 60 mph and it didn't stumble or act up like it would in final drive. COULD THIS be the problem?? Any thoughts or suggestions on where to check or tests to perform first? Could somthing in the HEI distributor/ igniton system do this at highway speeds?. If the module was going bad, I would think it would run bad or not at all even at idle and running high rpm in park.. After thinking on this, I've concluded its either a fuel delivery problem, an ignition problem or a transmission problem. Opinions or suggestions are welcome. Thanks.
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Old 24th-October-2012, 10:48 AM   #2
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drop the gas tank once it's close to empty and buy a new gas tank. once they start to rust there's no fuel filter in the world that's going to stop the fine rust particles from screwing up/clogging up the system...

seeing the particles in your fuel filter is the indicator... save yourself future headaches and get a new tank. that bitchen looking carb set up doesn't need the trash floating through clogging things up.

and running multiple filters won't get you anywhere...

that's what i think the resolution is. stating you see the particles and that you keep the filter changed is the tell-tale clue... 86 that tank brutha
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Old 24th-October-2012, 10:49 AM   #3
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oh, and i think your engine & engine compartment looks bitchen... fantastic job.
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Old 24th-October-2012, 10:56 AM   #4
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X2 on the engine compartment really looks good. Heres a link for gas tanks. Also replace the sending unit while you're in there. RICK
http://www.ebay.com/sch/i.html?_trks...at=0&_from=R40
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Old 24th-October-2012, 11:01 AM   #5
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there are some lesser quality Chinese made gas tanks out there, that's the GOOD one that's made in Canada.

and yeah, i forgot to suggest a new sender with the new sock filter... thanks Rick w/ a K
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Old 24th-October-2012, 11:53 AM   #6
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X3 on the tank and yes your 194 and bay are amazing.
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Old 24th-October-2012, 12:15 PM   #7
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If everybody agrees that rust and debris is getting into the carbs and messing up the fuel delivery, why not clean up the carbs and put on a brand new filter and drive it. That to me would be a very small investment of time and money vs replacing a bunch of things and crossing your fingers that the problem then goes away. I'm not saying that your tank does not need to be replaced, you have rust getting into your filter so I too think you should replace it however it may not be your actual problem. My 6 had a flat fuel pump cam so the fuel pump stopped keeping up I thought maybe it was vapor lock as it was a hot day and my Nova suddenly died on the freeway and wouldn't restart until it cooled off. I replaced it with a generic electric pump and fixed that problem. But I also times where I did get vapor lock and also when I changed out my fuel line for my small block the original line had a couple areas it rubbed up against the floor and could have developed a pin hole similar to The broken straw in your cup you can't suck any fuel to The pump. Finally also the area that the sender connects to rubber line above the tank had a small crack in it and a small fuel leak. Any fittings too could cause an air leak. I'm just trying to give you places and things to check before you throw money at the problem. Checking these things out only cost time. Hope my experiences can help out.
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Old 24th-October-2012, 01:37 PM   #8
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Hey guys, I appreciate the quick responses to my problem. This is my daily driver and I can't have it down like this as it puts a cramp in my ability to retrive my kids from school and such when my wife is out working. I can't fit myself, my 10 month old daughter and my two sons in my truck cab. So I need to get cracking on fixing this thing without wasting time and money... Yeah, I need to replace the tank anyway. I was actually looking at them last week and telling my wife that I intend to replace it because I'm showing too much rust in the filter. I pulled it out last year and knocked a lot of rust dust out of it and even run my shop vac inside it to clean it out. It didn't look that bad when I took a peek inside. This was when I also replaced the fuel pump, filter and even put a new pickup sock filter on it. I'm wondering if that sock filter is plugged up now since I have replaced the inline filter next to my pump twice since. the tank probably has gotten worse inside. I plan on dropping it out. I just got to pump out half a tank of gas before doing so. But my thing is why does it stumble and lose power like its starving for fuel only when its moving? The only difference factor I can think of is because the engine is under load while moving at highway speeds and maybe is sucking fuel at a greater rate than it does while running in park..even at 3000 rpms for several minuites??? I thought about putting the rear up on stands and running the car in drive and see if it stumbles then. Reguardless, I need to replace the tank. I'm thinking and hoping that is the problem because it would be a lot less expensive than replacing the thransmission.. I also noticed yesterday when I disconnected the inlet line off the inline filter that very little gas was present when I tried to empty out the filter and check for rust debris. Unlike when I replaced it a few days ago, a whole bunch of fuel came pouring out of the filter and siphoning out of the tank line as well. Almost seemed like there was maybe a blockage in the line preventing the pump from pulling fuel through it. I don't have clear fuel lines next to my carbs anymore so I can't see how much fuel is getting to them, unlike last time I delt with this.. Also my filter is one of those metal case deals and I can't see whats going through at that point either. I've got one of those glass inline filters I can try on it to see whats maybe going on. I'm also wondering if the bowls in my carbs have rust sediment blocking the jets. But then wouldn't they run like crap even at idle or at higher rpms in park? I'm going to try and check it our some more later when I get the time. Keep the thoughts and sugestions comming please.

Last edited by Rotorbolt; 24th-October-2012 at 02:01 PM.
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Old 24th-October-2012, 01:50 PM   #9
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the gas tank can be swapped in less than an hour with simple hand tools... this is a very easy job. just make sure it's almost out of fuel...


the rust particles are very very fine. there is not a fuel filter made that will prevent the particles from entering your carbs. it will collect in the filter yes, but that's after it gets bombarded and clogged. particles are still entering the fuel system.

the sock will get clogged after a while when running. the suction starts to collect particles and it will impede the flow. after turning off the engine many may fall/float away from sock and now the engine starts/runs again but as the engine runs it will start to collect them again...

there is no cure for this other than to replace the tank or have it dipped and coated. dipping and coating was the old school way prior to the restoration suppliers coming out with reproduction tanks. the cost of dipping/coating was real close to what a new tank goes for these days so to dip/coat... it's going backwards. if you were cutting/modifying a tank then yes. it needs to be coated but in your case it'd be best to replace it and be finished with it...

my next door neighbor worked on an Ol'50 Merc that had the same issue. every week the guy would be back for my neighbor to swap filters etc. the guy just wouldn't spring for a new tank. labor costs, filter costs etc adds up. i think the guy could have bought TWO tanks for what he paid my neighbor to continually fix it for him...

swap the tank & sender assy and be done with it brutha... the job can be done so quickly. it's a weekend job, an Hour job...
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Old 24th-October-2012, 02:02 PM   #10
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the gas tank can be swapped in less than an hour with simple hand tools... this is a very easy job. just make sure it's almost out of fuel...


the rust particles are very very fine. there is not a fuel filter made that will prevent the particles from entering your carbs. it will collect in the filter yes, but that's after it gets bombarded and clogged. particles are still entering the fuel system.
Kind of like small granules of sugar going in the cylinders. Not good.
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Old 24th-October-2012, 02:14 PM   #11
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Whoooyaaa!! Right on Flyer. RICK
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Old 24th-October-2012, 02:43 PM   #12
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X2 on the engine compartment really looks good. Heres a link for gas tanks. Also replace the sending unit while you're in there. RICK
http://www.ebay.com/sch/i.html?_trks...at=0&_from=R40
Thanks for the link. Tanks aren't too expensive. interesting how they vary in price. It's definately a no brainer to get the "good" better made canadian one since its not that much higher in price. Although I'm slightly confused on the sending units. Theres 2 different ones. a 5/16th and 3/8ths in 0-30 ohms.. I've got 5/16th lines on it now..would uprading to 3/8th improve anything?
I'll put it another way. I may one day swap in a V8. I assume the 3/8th line size is for a V8 application.

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Old 24th-October-2012, 03:27 PM   #13
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I would install the 5/16 for now and later on when you do the engine swap then change to the 3/8 sender. The sending units aren't very expensive to replace at a later date. You might even be able to sell the 5/16 later when you do the engine swap. RICK
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Old 24th-October-2012, 07:55 PM   #14
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i agree on the fuel tank / line replace . but , i cant help but think it may be a timing issue as well . hook a timing light up and double check it is my 2 cents
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Old 24th-October-2012, 08:51 PM   #15
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Its been running great untill yesterday. I did run the car in 2nd up to 55- 60 mph and it didn't stumble or act up like it would in final drive. COULD THIS be the problem??
So, it runs great in 2nd, but not in 3rd? Tranny fluid is OK? I'm sure the fuel delivery is part of the problem, but when you said that you pulled the choke, and it ran better but no change in speed has me leaning toward something else. Your carbs could be just a little lean from the colder air, and the choke just helps a little.... This crap can drive ya nuts!

My vote is tranny!
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