71 big block ignition problem?
Thread Starter
5th Gear
Joined: Aug 2011
Posts: 5
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71 big block ignition problem?
hello this is my first post here. about 3 months ago i bought a 71.it was a ls5 454 but now has a gm 454HO crate motor in it that the prev. owner installed. it also has a hei distributer.i have put about 3 or 400 miles on the car so far without a single issue.last week when driving on the highway at about 65 or 70 mph the car started to run bad. now i am not a machanic by any means but it seemed like maybe a cyl wasnt firing. i could smell some gas and it ran bad but i made it home ok,abt 3 miles. nowi can start the car fine when cold and idles ok. when i start to drive the car it seems to run poor again. after about a 1/4 mile the think will hardly run at all and wont idle. i have looked over the plug wires and stuff and dont see anything lose or burnt in half. could this maybe be a coil problem? where should i start? thanks a bunch guys any help would be great dustin
Thread Starter
5th Gear
Joined: Aug 2011
Posts: 5
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ok well i took the coil and cap off and looked them over. seemed ok so i put back on car at started it. ran good in garage so i took it up the street. ran good abt 3 miles, got on inerstate and and was still going good crusing abt 65. i ran it up to about 85 and backed off and then i noticed that i was having the problem again. idle was ok but over like 1500 rpms it was braking up really bad on the way back to house.this info help any?
Thread Starter
5th Gear
Joined: Aug 2011
Posts: 5
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i know the carb is a holley the guy told me it was a street avenger? could this be right? i can see that the tank is newer and so are the fuel lines up under the hood i will take a look at the filter thanks. i was reading on here abt some guys having a problem with the module that goes with the distributor? sounded like some similar problems
thanks
thanks
Thread Starter
5th Gear
Joined: Aug 2011
Posts: 5
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ok had autozone test the module. said it was fine. got a new coil while i was there and installed. car ran great in garage so i went up the street. 300ft and it shut off and would not restart. sat for 20 min and still no start. i pulled a plug and had wife try to start and it had spark. so i put a little gas in the carb and the thing fired right up.ran it 20 seconds and shut it off and it would not restart again. so i put more gas in carb and drove it back to house where i let it idle for about 15 min without a problem. so what do u think? would my car have a fuel pump in the tank? or up near engine? maybe a clogged filter?
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
Ls5 should have an electric pump. Disconnect fuel line at carb, stick rubber gas hose on line into a bucket and see how much it pumps. Check electrical connections, filters or pump itself.
If the pump has no sump, you may have to keep a minimum level in the tank.
If the pump has no sump, you may have to keep a minimum level in the tank.
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Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
I'm not familiar with the 454HO, I don't even know if it has a provision for a mechanical fuel pump, but here is a link to a picture of one, let us know if your car has one or not.
http://cgi.ebay.com/ebaymotors/Big-B...-/190442852489
It's the little doo-hickey sticking of the side/front of the engine in the pic, with the black fuel line coming up out of it. If your engine has a plate bolted to the block instead of this pump, you must have an electric fuel pump.
Scott
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
A 1971 LS5 should have an electric pump? I think you may have gotten something mixed up here. The car may very well have an electric fuel pump, but it sure didn't come that way. Nothing personal, noonie.
I'm not familiar with the 454HO, I don't even know if it has a provision for a mechanical fuel pump, but here is a link to a picture of one, let us know if your car has one or not.
http://cgi.ebay.com/ebaymotors/Big-B...-/190442852489
It's the little doo-hickey sticking of the side/front of the engine in the pic, with the black fuel line coming up out of it. If your engine has a plate bolted to the block instead of this pump, you must have an electric fuel pump.
Scott
I'm not familiar with the 454HO, I don't even know if it has a provision for a mechanical fuel pump, but here is a link to a picture of one, let us know if your car has one or not.
http://cgi.ebay.com/ebaymotors/Big-B...-/190442852489
It's the little doo-hickey sticking of the side/front of the engine in the pic, with the black fuel line coming up out of it. If your engine has a plate bolted to the block instead of this pump, you must have an electric fuel pump.
Scott
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
An easy thing to do would be to remove one of the bottom two bolts holding the front fuel bowl on, and let the gas drain out into a container of some sort. If a buncha crud comes out with the gas, that could be the problem. Then remove the float bowl and visually inspect it. You will probably need to dis-connect the fuel line to do this, so you might as well do it while you are performing the pump test that noonie was talking about. Pull all the spark plugs, and with the fuel line in a bucket or something, crank the engine over with the key. Either way, electric or mechanical pump, fuel should flow. Let us know how it works out,
Scott
Scott
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Problem sounds more like the ignition module...an intermittant problem due to heating of the module. If so, that's why the module checked OK at the parts store--it was cold. For the money, I would replace that module. Hold onto the other one as a spare...just in case the problem is still there.