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Discussion Starter · #1 ·
I've got a good idea what needs to be done but some of you know alot more. All the smog stuff was removed and dual exhaust with no cats or 02 sensors was added by the previous owner. In his infinite wisdom he left intact the electronic Quadra jet and distributor. The ECM is now confused. (Limp mode I suspect) For the past year I've been able to start it if it didn't sit for long. After a week or so it would take a few pumps of the pedal and then start. At this point it sat for a little too long and will not start. I'm thinking the carb is no longer willing to cooperate and it's time to replace it as well as the distributor. Or could it simply be the fuel pump? All input is welcome but please no lectures my wife has already taken care of that. Thanks in advance.
 

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Fnlowrider, the fact that your engine fires, runs, and dies when fuel is added via the carb means you have a fuel problem. The fact that the motor fires says your ignition side is operating, however, inefficiently that may be. Since you let the car sit, more than likely, fuel evaporated or evaporates from the carb which requires replacement; fuel can also disappear between the carb to the fuel tank depending on how long the car sits. These carbs are old and the gaskets are probably not sealing. If there is fuel in the carb bowls and accelerator pump well, pumping the gas pedal becomes necessary. This action also says a carb rebuild is needed. But you need to decide what you want to do. You have two routes: just get the old gal running in the short term or complete the removal of the ECM + wiring, replace the carb and distributor, and rewire the ignition to function without the computer control setup.

For the short term, to get your EC running again, you need to use the process of elimination to identify the point of where your fuel delivery is being blocked.

1. Look down into the carb and move the throttle as if pressing on the gas pedal. If you see fuel being injected/squirted into the front two barrels, then fuel is being delivered to the carb. If you do not see fuel, then back up to the fuel line at the carb.
2. Disconnect the fuel line at the front of the carb and place a catch container in front of the line, as you (or a helper) turns the key to crank the motor. If fuel shoots out of the fuel line, the blockage is in the carb. If no fuel appears at the end of the fuel line, then back up to the fuel pump.
3. But, before tending to the fuel pump, go back to your gas cap and open it. Listen carefully if you hear any hiss or sounds like that of releasing a vacuum. Sometimes, a bad gas cap especially in hot climates prevents/makes it hard for the fuel pump to suck fuel forward. If you hear a sucking sound, then a vented gas cap is hindering fuel delivery.
4. The likelihood of your fuel line between the pump and carb being clogged is slim but is an easy item to check. Disconnect the fuel line at the pump and carb and blow air into either end. If no blockage exists, then move onto the pump.
5. If further cranking the motor shows no fuel exiting the fuel pump, a fuel pump replacement is likely warranted. Hopefully, this is were your issue lies because the last two: fuel line--between the pump and fuel pick-up and fuel pick up itself--which resides inside the gas tank are a big pain in the butt.

As an aside, the fact the the previous owner did not do a complete removal of the computer-controlled system is troubling because that begs the question of "what else didn't the do?"

Good luck!
 

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Discussion Starter · #8 ·
Fnlowrider, the fact that your engine fires, runs, and dies when fuel is added via the carb means you have a fuel problem. The fact that the motor fires says your ignition side is operating, however, inefficiently that may be. Since you let the car sit, more than likely, fuel evaporated or evaporates from the carb which requires replacement; fuel can also disappear between the carb to the fuel tank depending on how long the car sits. These carbs are old and the gaskets are probably not sealing. If there is fuel in the carb bowls and accelerator pump well, pumping the gas pedal becomes necessary. This action also says a carb rebuild is needed. But you need to decide what you want to do. You have two routes: just get the old gal running in the short term or complete the removal of the ECM + wiring, replace the carb and distributor, and rewire the ignition to function without the computer control setup.

For the short term, to get your EC running again, you need to use the process of elimination to identify the point of where your fuel delivery is being blocked.

1. Look down into the carb and move the throttle as if pressing on the gas pedal. If you see fuel being injected/squirted into the front two barrels, then fuel is being delivered to the carb. If you do not see fuel, then back up to the fuel line at the carb.
2. Disconnect the fuel line at the front of the carb and place a catch container in front of the line, as you (or a helper) turns the key to crank the motor. If fuel shoots out of the fuel line, the blockage is in the carb. If no fuel appears at the end of the fuel line, then back up to the fuel pump.
3. But, before tending to the fuel pump, go back to your gas cap and open it. Listen carefully if you hear any hiss or sounds like that of releasing a vacuum. Sometimes, a bad gas cap especially in hot climates prevents/makes it hard for the fuel pump to suck fuel forward. If you hear a sucking sound, then a vented gas cap is hindering fuel delivery.
4. The likelihood of your fuel line between the pump and carb being clogged is slim but is an easy item to check. Disconnect the fuel line at the pump and carb and blow air into either end. If no blockage exists, then move onto the pump.
5. If further cranking the motor shows no fuel exiting the fuel pump, a fuel pump replacement is likely warranted. Hopefully, this is were your issue lies because the last two: fuel line--between the pump and fuel pick-up and fuel pick up itself--which resides inside the gas tank are a big pain in the butt.

As an aside, the fact the the previous owner did not do a complete removal of the computer-controlled system is troubling because that begs the question of "what else didn't the do?"

Good luck!
Good stuff Thanks. I'm on it. Update to follow.
 

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I've got a good idea what needs to be done but some of you know alot more. All the smog stuff was removed and dual exhaust with no cats or 02 sensors was added by the previous owner. In his infinite wisdom he left intact the electronic Quadra jet and distributor. The ECM is now confused. (Limp mode I suspect) For the past year I've been able to start it if it didn't sit for long. After a week or so it would take a few pumps of the pedal and then start. At this point it sat for a little too long and will not start. I'm thinking the carb is no longer willing to cooperate and it's time to replace it as well as the distributor. Or could it simply be the fuel pump? All input is welcome but please no lectures my wife has already taken care of that. Thanks in advance.
My ElCo did EXACTLY the same thing when I got it. I could dump a bit of gas down the carb and all was good for the day. If it sat overnight looooooooong cranking and pedal pumping would finally start it. The carb would leak down and be empty overnight. After a little research, I decided I didn't want to play with a computer controlled carb. Decided if I'm gonna have a computer might as well upgrade to an LS!

You might have multiple problems though and 57's suggestions are right on!

Good luck!!

Joe
 

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This generation of Qjets also had a problem with leaking plugs at the bottom of the bowl. A car sitting overnight would allow all of the fuel to leak out of the bowl. To start, you would have to crank long enough for the fuel pump to replace the lost fuel.

It could also be an issue with the removed smog stuff. If they just plugged the line that went o the charcoal cannister, then you do not have a vent on the tank, and it can pull a vacuum and prevent fuel from flowing to the carb. I think this was addressed above.
Without the O2 sensor, you no longer have any control form the ECM. If you added an O2 sensor, had the carb rebuilt, then you would be back on track. Otherwise, you will need a new carb and a new distributor.

The good news is that it will run much better once fixed, and your mileage should improve dramatically.
 

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O² sensor is only applicable after the car is running for a while and the exhaust reaches the temp range to activate the ecm according to the O² sensor in closed loop. Otherwise it should start and run initially according to carb settings, the ccc bypassed initially.

305 5th gen used 2 line fuel for carbs, with a mechanical pump on passenger side. 1 line was to carb, other line from cannister. The carb line is low pressure, 6lbs on average, coupled with a weak pump, generally supplies only what's needed by the motor. TBI uses 2 lines, one to the pump and a return for unused fuel.

What I'd think is the pump is shot. It has seals internally to hold the fuel volume, preventing fuel from draining back to the tank. If the seals go, the pump can lose its prime and take forever to get it back, hampered sometimes by a vacuum condition in the tank, as described in earlier posts.

If you plug the cannister line going back to the tank, jury rig a tire valve into a old gas cap and add some small amount of pressure (5-10lbs) to the gas tank that way, it should help force the fuel back up the line into the pump.

Assuming that there's actually enough gas in the tank to begin with to get picked up.
 

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Discussion Starter · #13 ·
O² sensor is only applicable after the car is running for a while and the exhaust reaches the temp range to activate the ecm according to the O² sensor in closed loop. Otherwise it should start and run initially according to carb settings, the ccc bypassed initially.

305 5th gen used 2 line fuel for carbs, with a mechanical pump on passenger side. 1 line was to carb, other line from cannister. The carb line is low pressure, 6lbs on average, coupled with a weak pump, generally supplies only what's needed by the motor. TBI uses 2 lines, one to the pump and a return for unused fuel.

What I'd think is the pump is shot. It has seals internally to hold the fuel volume, preventing fuel from draining back to the tank. If the seals go, the pump can lose its prime and take forever to get it back, hampered sometimes by a vacuum condition in the tank, as described in earlier posts.

If you plug the cannister line going back to the tank, jury rig a tire valve into a old gas cap and add some small amount of pressure (5-10lbs) to the gas tank that way, it should help force the fuel back up the line into the pump.

Assuming that there's actually enough gas in the tank to begin with to get picked up.
Great stuff, You've added some boxes to be checked for my list. From one Mc Guiver (Google the name) to another, Thanks.
 

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Sure, no worries, and I'm plenty old enough to have watched many episodes of MacGyver 🤣.
Back then, the majority of engine related stuff ran on 3 things. Mechanical, vacuum or thermal or any combination of such. Very little actual electrical. Unlike modern vehicles where tracking down canbus issues between multiple body control modules is a nightmare.

So the mechanical pump up front creates a vacuum in the line, pulling fuel up, then shoves it up the pipe to the carb. If there's a break in the line anywhere, and that includes bad seals in the pump, once the motor is off, air will leak back in and allow the fuel to return to the tank.

Loss of prime, leaking seals makes for a really weak pump, and results in no-start without cranking forever. It's possible to jump-start the priming if you dump some gas in the carb and keep it running by doing that, a motor running has far higher rpm than a starter can produce, and with a mechanical pump tied directly to the rpm of the motor, that helps. Just close the choke and pour very slowly. Don't touch the gas pedal, especially don't floor it as thats designed to clear a flooding, which is the opposite of what you need.
 

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Good information for me also I removed all electronics and changed out the carb to a nonelectronic style. Hard start after sitting for more than one day but a 350 in going in at this time. I will T/S later with everyone's help on a new thread if I need more help. I like the fuel pressuring idea, I have seen a mechanic put his lips on the fuel neck on a Fiat blow in and it started. I wish I had that picture.
Joe
 

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Another item to consider is that if you're still using the Quadrajet, they have a filter at the fuel inlet that tends to plug up quite often. Removal of the Vapor canister and plugging the line could create a vacuum in the fuel tank like handyman 57 and darbysan said, since 5th gens. didn't use a vented fuel cap. Your fuel tank needs to be able to breathe to work properly. The vapor canister has no effect on performance, its main purpose is for when the engine is not running, so unless it's being removed for looks, there is no reason to remove it.
 

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Discussion Starter · #17 ·
Well I got to the bottom of my problem today. I'm not going to say I feel stupid because this is the way things go with old cars. What I found was there is a red wire going to the relay under the hood with an inline fuse. I was able to look at the fuse without pulling it and it was not burned out, however I pulled the fuse anyway and upon doing that I saw that the terminal inside the insulated connection was melted which was not visible from the outside. So I cut out the fuse connections and installed two female terminal ends, connected a new fuse and lo and behold I turn the key and fuel dumped out of the fuel line which I had disconnected at the carburetor. I knew then that I was all set. I connected the fuel line back to the carburetor and the car fired right up. just goes to show you you need to look deep and check all the dumb stuff first. Thanks for all your input guys.
 

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I’m curious why it has an electric pump, not mechanical…
Patrick
I don't have a technical answer for you all I can say is it must be a transitionary year because it appears that is what it came with
see post #1 above

"All the smog stuff was removed and dual exhaust with no cats or 02 sensors was added by the previous owner. "

I bet he did a few other things too...
 
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