Help with run/start. Ignition? Fuel?

[1971RR]

I'm on my phone so I'll try and keep this short. 70 model 383. New Mallory Unilite 4757701, coil, wires, ballast and power filter (goes between distributor and coil/ballast/ground connector). Distributor red wire to ballast left terminal (facing the engine) with single wire. Green, negative coil. Brown, ground to intake. New Edlebrock 1406. New fuel pump. On cold start, electric choke goes into high idle. Car runs rough. Backfire in exhaust, very rough idle. Blip the throttle plug of high idle, car settles down, idles great. Drives great initially. Once warmed up, it lays down after about 4000 rpm. Let off throttle and get back into it, sometimes it continues pulling, others, it will fall flat again. Get into second gear and it may pull smoothly, or it may pull, stumble, pull, stumble. The only piece I have not replaced is the ignition module on the firewall. I actually unplugge while the car was running and, it made no difference. I thought it could not run without this module? It is an older two prong module. I'm not saying that is my problem, but that is the ONLY part of the ignition and fuel system I have not replaced. Ideas?

 

[1971RR]

Bueller? Bueller? Anyway, on my way out the door this morning I had to retrieve my keys from the RR. Just for grins, I reached down and squirted the carb a couple times (hood was still up) and then reached in and bumped the starter. Started immediately and went right in to a smooth high idle. So, I have a problem I believe that had to do with heat. I do seem to build alot of pressure in the fuel line and tank after driving for a couple minutes. I don't think the gas cap I got for the car is vented. Can this cause hard starting and poor running once it gets hot?

 

[bigmanjbmopar]

Do you have a fuel gauge in line? If not get one. May have a pump issue or clogged line or filter

 

[1971RR]

I put a new fuel pump on yesterday. I hope any blockages were left on the garage floor when all the gas drained outta the fuel lines. I have a clear filter and it looks fine. My issues seem to occure when the car gets warmed up. I am speculating I may have a gas cap issue, hopefully. I did get a second on that from another member so I'm crossing my fingers.

 

[5.7 hemi]

I dont see how the gas cap could affect this.

 

[1971RR]

I dont see how the gas cap could affect this.

I dont either to be honest. But when I took the the top of the carb off to check for any debris I got ALOT of pressure release from the carb. Then when I removed the fuel line from the carb, mind you the fuel filter looked empty (its clear), gas and air shot from the line for about 5 minutes. Even when I thought it was finished I could hear a slight hiss coming from the line while putting the carb back together. I went and opened the gas cap and even had a pressure release from there too. After the car has been run for a bit the fuel filter starts emptying out with. You can see the fuel just kinda spurting into the filter. This is only when it is hot. Cold? The thing fires right up with barely squeak coming from the starter.

 

[Azure]

Is the gas tank vent blocked?
Also, Edelbrock carbs in my experience seem to be prone to heat transfer from the intake causing problems. You can try any number of non-metalic spacers or thick gaskets for this.

 

[1971RR]

Is the gas tank vent blocked?
Also, Edelbrock carbs in my experience seem to be prone to heat transfer from the intake causing problems. You can try any number of non-metalic spacers or thick gaskets for this.

If I knew where it was I would check. I did put a new tank on it last year. I routed the four lines out to same locations of the four lines on car.

 

[67 coronet]

1)a unilite is not used with a factory ign module at all.remove it.
2)what coil are you running?some dont like the signal from a unilite.
3)gas tank vent should be around the filler hose,look around with a flashlight and you sould find a smaller line near the fill tube or attached to it.you shouldnt have presure back there.may cause a flooding problem when car gets hot.

 

[1971RR]

1)a unilite is not used with a factory ign module at all.remove it.
2)what coil are you running?some dont like the signal from a unilite.
3)gas tank vent should be around the filler hose,look around with a flashlight and you sould find a smaller line near the fill tube or attached to it.you shouldnt have presure back there.may cause a flooding problem when car gets hot.

1. Ok. Good to know. I didnt see anywhere in the Mallory instructions to remove this, but like stated in my original post, didnt seem to alter the performance of the car when I unplugged it. Out it goes!

2. Mallory Chrome Electronic Ignition Coil 29216. Their recommendation.

3. I replaced the tank awhile back. The only lines/hoses I recall all came out of the driver side of the tank. I'll look around and see if I didnt kink something. You are thr 3rd person stating that this could cause flooding/stalling when the engine is hot. I hope y'all are on to something.

 

[Sonny Black]

I am very interested in this thread.......
I had simular "symptoms"....
I am at a loss for a solution/s.

 

[1971RR]

Anyone know where I might could locate a schematic of the fuel tank and fuel system setup for this year model b-body?

 

[67 coronet]

how many total lines do you have going to your tank,and where do they go?remember to look by the fill hose as well.the vent could come out of the top of the filler tube,near the cap,hidden by the body.

 

[1971RR]

how many total lines do you have going to your tank,and where do they go?remember to look by the fill hose as well.the vent could come out of the top of the filler tube,near the cap,hidden by the body.

I have 4 lines coming out of the driver side of the tank. I don't recall any additional hoses by the filler neck when I put the new tank in. I have a similar threads in the engine and transmission section. that thread also zerod in on the tank vent and emissions system. you guys are genius. I hope. ;)

 

[1971RR]

Since I didnt know if I was suffering electrical or fuel related issues, I posted the question in the Engine/Trans/Driveline section and have gotten some interesting responses. Anyone interested in this should checkout that thread. "Wrong gas cap causing start/run issues?" They have posted lots of schematics too. They also seemed to have zeroed in on the evaporative emissions system as maybe being the culprit.

 

[1971RR]

For those interested, Called Mallory today. Tech immediately zeroed in on the coil being bad. Lets hope he is correct. Gotta send the old one in and they will send a new one back.

 

[67 coronet]

For those interested, Called Mallory today. Tech immediately zeroed in on the coil being bad. Lets hope he is correct. Gotta send the old one in and they will send a new one back.

hope it solves your problem.good luck.

 

[hendo0601]

That does make sense that it runs like crap after it gets hot...the oil inside the coil is getting too hot and the coil will start to malfunction. Good info!

 

[1971RR]

Here's another curve ball. Went to start it this morning to tinker with another coil I have. Barely turned over. Turns out my alternator died and killed my new battery. Been running on battery power for the past couple weeks! Parts store actually had one in stock. The car appears to be much happier now. Not perfect but better. Still a bear to start when hot. I'm going fan shroud hunting to try and solve that issue. BTW, the other coil I had laying around has a 1.4ohm resistance. Mallory says no ballast is necessary with 1.4 or greater. I have a 30 amp fuseable link where the ballast was. I'm still sending in the other coil just to see what happens. It's a .7ohm coil. It needs the ballast.