Starting woes

[deedohaw]

So... we finally got son Michael's '78 Cordoba plated and insured. It started up every day just fine... but for it's first proper drive today it started up ok but only ran for about 1 minute then died. It started up again and ran for 30 seconds and died. Ether got it to fire for 2 seconds. When it sits for a few minutes with ignition off it will then run for a 1/2 minute or so. Swapped the ballast resistor... same thing.
What do you think? Fuel pump? Ignition?
It is a totally stock 360 lean burn.
Thanks, David

 

[1toolguy]

Thsi first thing I would suggest is dump the lean burn and convert to a standard style ignition. The lean burns are almost impossible to troubleshoot unless you have a known good one.

 

[Sweet5ltr]

So... we finally got son Michael's '78 Cordoba plated and insured. It started up every day just fine... but for it's first proper drive today it started up ok but only ran for about 1 minute then died. It started up again and ran for 30 seconds and died. Ether got it to fire for 2 seconds. When it sits for a few minutes with ignition off it will then run for a 1/2 minute or so. Swapped the ballast resistor... same thing.
What do you think? Fuel pump? Ignition?
It is a totally stock 360 lean burn.
Thanks, David

We have had this problem on newer model GMs, and the fuel pump has almost always been the culprit (if it is electric). The truck(s) would shut off while driving, and you could start them ten or fifteen minutes later, and drive for a few miles and would shut off again; repeating the process. I would check the fuel pressure prior to cranking the engine and when the engine is running. Does the fuel pump prime like normal? But initially, I would check the fuel filter and go from their on down the line. I am not too fimiliar with the 'lean burn' system, so this could be an issue that they have and I am not aware of. Others will surely and hopefully chime in.

 

[deedohaw]

Great suggestions... thanks Sweet5ltr. As soon as we get chance we'll check the fuel filter (very quick and easy) and then try a simple check of the fuel pump (no meter is available to us for checking pressure but we can see if it squirts).

1toolguy... Michael wants to convert from lean burn and is saving his pennies. If these simple fuel ideas don't work... I guess he'll be converting sooner than later.

Regards, David

 

[Sweet5ltr]

No problem, I hope you get everything worked out; let us know what the problem was once you solve it!

 

[deedohaw]

Will do.
David

 

[deedohaw]

Well... a) checked fuel filter... clear and clean
b) fuel pump... pumping
Next chance we get... we'll check for spark immediately after it dies again.
It is certainly looking like an ignition/leanburn problem as so many have predicted.
David

 

[silvercloud]

If you have access to an autowreckers with older Chrysler stuff and aren't adverse to using used parts, the conversion can be done relatively cheaply. Need a distributor, control box and wiring plug. Somewhere I have a link to an article that details doing the conversion-I can find it and pass it on if you're interested.

HTH
Jason

 

[deedohaw]

If you have access to an autowreckers with older Chrysler stuff and aren't adverse to using used parts, the conversion can be done relatively cheaply. Need a distributor, control box and wiring plug. Somewhere I have a link to an article that details doing the conversion-I can find it and pass it on if you're interested.

HTH
Jason

Sounds well worth considering Jason. Thanks.
There is a wrecker who specializes in older Chryco about an hour North of us.
David

 

[67 coronet]

it is very common for the lean burn computer to fail as it heats up.like you said check for spark right after it fails.best way is with a timing light if you have one.also you can heat up the computer with a good hair dryer and see if you get same result.

 

[silvercloud]

Here's a link to a Moparts tech article describing the wiring etc. : http://www.moparts.org/Tech/Archive/elec/3.html

Mopar Action had/has a really good article on doing this conversion-however, I can't find it online. I can try to scan and email to you if you want, or copy and fax, or copy and mail?

I can get you a measurement/picture of where the control box mounted from the factory if you need-I have a '76 'Doba that was a donor for my '74 Charger project. It was a big block so the harnesses wouldn't interchange unfortunately.

HTH
Jason

 

[67 B-body]

Get the ECU from your local autoparts, stop by the junk yard and snatch a electronic dist, cut the harness plug off of the junk yard ECU and take it home with the Dist. Get yourself a role of wire and follow that diagram at the top of the link Silvercloud provided. I made ALL of my electronic dist conversions myself! I even went as far as using my current points dist and buying the tune up kit that Wells offers and placing it all in the points dist. It came with the pickup coil and reluctor. This was all that was needed to convert the points to electronic and I didn't have to hunt down an entire dist.

 

[deedohaw]

I am gathering that the Mopar ignition replacement kit does not work all that well with the 2bbl carb that comes on a Leanburn motor. He would likely be better off in the long run with an aftermarket manifold and 4 bbl... opinions?
David

 

[1toolguy]

It is a performace oriented set up but it should work just fine on even a stock motor.

 

[deedohaw]

Well, Michael finally had enough free time (he has been "on call" the last few weeks) to come over to mess around with the car.

It started eventually (lots of pedal pumping) but stalled after about one to two minutes of smooth running. It then fired somewhat a few times but wouldn't actually run. With "quick start" (ether) it fired right away and I could only keep it running with quick bursts of the ether. Since it runs on ether it must be firing... so I can't see that it is a sparking problem.

This is starting to seem more like a fuel delivery problem. Michael thinks the computer possibly controls the vacuum which affects fuel delivery (?).

When he pumped the gas pedal... I could not see or feel fuel squirting.

Before, when we removed the fuel filter and cranked the car... gas spurted out.

David - still kinda stumped

 

[john.thompson068]

Okay, so when it quits running, pull the coil wire and carefully hold it near something metal. Then turn the motor over and look for a rather robust spark. If you have spark, proper timing, and gasoline it should run. I just went through this same type of situation not once but twice since last summer. First it was the ECU. Then the pick up coil went bad. My car has electronic ignition though. It took me a long time to figure out what was happening.

 

[egrand1508]

I've got a 77 Cordoba with the Lean Burn that I tried to make work and have the service manuals for, so I'm familiar with it. The only thing the computer controls is the ignition timing at the distributor. It recieves inputs from several things, including manifold vacuum. That is why there is a hose going to it, but it doesn't control vacuum. Also, if the computer fails it has a limp mode that should let the engine start and run. When it works, Lean Burn is fine. My problem was that nobody has parts anymore and when it is in limp mode the engine pings terribly at speed.

It sounds to me too like you have a fuel problem. You said you have a 360 2bbl, so I'm guessing it is a Holly carb. They have the nitrophyl floats, same as the Thermoquads, and they are notorious for absorbing gas over the years and sinking, making the bowl to overfill.

If you want to go the cheapest route first, I would say trace back all the wires and vacuum hoses and make sure there aren't shorts or leaks. Then I would rebuild the carb. For about 40 bucks you can probably get a rebuild kit, float, and can of solvent. Then I would look at replacing the lean burn. You can buy conversion kits for about $160.00 on ebay.

I would bet that rebuilding the carb will do you a lot of good anyway, even if it isn't what is causing your current problem.

 

[306Doba]

Fuel filter might be clogged. only thing I can think of that hasn't been mentioned.. Same thing happened to me last year after dumping a can of seafoam in a half tank of gas. I think a new filter was around 4 bucks so I ended up buying a few just incase there was more crap floating around in the tank.

 

[deedohaw]

Fuel filter might be clogged. only thing I can think of that hasn't been mentioned..

Thanks 306Doba... but fuel filter is clean and flowing like new.
David

 

[deedohaw]

I've got a 77 Cordoba with the Lean Burn that I tried to make work and have the service manuals for, so I'm familiar with it. The only thing the computer controls is the ignition timing at the distributor. It recieves inputs from several things, including manifold vacuum. That is why there is a hose going to it, but it doesn't control vacuum. Also, if the computer fails it has a limp mode that should let the engine start and run. When it works, Lean Burn is fine. My problem was that nobody has parts anymore and when it is in limp mode the engine pings terribly at speed.

It sounds to me too like you have a fuel problem. You said you have a 360 2bbl, so I'm guessing it is a Holly carb. They have the nitrophyl floats, same as the Thermoquads, and they are notorious for absorbing gas over the years and sinking, making the bowl to overfill.

If you want to go the cheapest route first, I would say trace back all the wires and vacuum hoses and make sure there aren't shorts or leaks. Then I would rebuild the carb. For about 40 bucks you can probably get a rebuild kit, float, and can of solvent. Then I would look at replacing the lean burn. You can buy conversion kits for about $160.00 on ebay.

I would bet that rebuilding the carb will do you a lot of good anyway, even if it isn't what is causing your current problem.

I wasn't aware of that "limp mode" egrand. Everything you are saying makes sense and we should try your suggestions and some of the other ones from other people that we have not had chance to try. Michael is away in Ottawa working this weekend. He should be making enough money these days to do anything that is necessary :eusa_angel: