Ok guys I'm new to this forum. I've owned numerous Fords and have always been an observer but I've got a problem that I need help fixing!

I just replaced the carb on my 75 F250 (with a 79 300 I6) with a reman Carter YFA from Advanced Auto. The reason I did this is because the other day after I filled up the truck wouldn't start and gas was pouring from parts of the old carb which I knew would need replaced soon. The previous owner had installed a very simple manual choke 1 barrel that only had a gas line coming in and the line from the distributor.

I have capped off all of the lines coming out of the YFA (maybe my problem???) for now until I can figure out where they all go except for the fuel line and distributor, which I think I have in the right slot. If I give the truck gas, when I start the engine it will fire up so long as I keep the key in the start position (very briefly of course) but the instant I let off and it falls back to the run position the engine immediately cuts off.

Any ideas fellas? I have lost 2 days this week waiting on the new carb and then screwing with it to no avail. The weather is finally nice and I need to be making money painting...not sitting at home like I did all winter!

The fuel pump is working....I've got 6 volts to the coil in the run position. I don't know if maybe that is my problem? I never checked before because quite frankly I never needed to know.

Thanks for the help.

 

I think 6 volts at the coil + seems a little low, try running a jumper wire from battery POSITIVE to the coil + for a short test to see if it stays running.

 

It seems buying a carb isn't plug and play, may need to adjust the idle fuel/air mixture, the idle speed screw, or perhaps the float level.

 

I forget what the voltage drop should be from the ballast resistor (if so equipped), but what it sounds like is that there is a wiring problem somewhere. I believe one of the power leads to the ignition module is hot when the key is in run, the other when the key is in start, IIRC. Might have a bad module or bad connection somewhere.

 

The DS2 ignition module has 2 power wires, the red one is input power with the key in start and run positions. the white wire has power in the start key position.
Both wires are in the 2 wire connector on the module.

 

This is all 100% correct.

Did you have this no-start problem before you swapped carburetors? If not, it doesn't make sense to chase the ignition system.

 

Does it die as SOON as you let off the key? Or will it run if you keep the gas down? If it just won't idle, you may not have your idle speed set.

 

Well guys I got it working. I cant say what the root cause of the problem is but as a fix for now I ran a fused wire into the cab with a switch going to the coil. Now I flip the switch and turn the key to the start position. The truck fires right up and idles perfectly. At this point I can take the key out of the ignition and to turn the truck off I flip the newly installed switch. Any ideas what the underlying problem is? I don't feel like totally tearing the electrical system apart to find the problem as long as this method doesn't do any damage. Thanks for the help!

 

Cool, anti-theft device.

 

if you have a round coil you will need to add a balast resistor to lower the coil voltage in the "run mode" to around 8-9 volts.

napa will see you a 1.3 ohm for a few $$... it alot cheaper then burning up a DS2 ignition module.

search any 70's dodge to get a part number for the ballast resistor if the parts guy cant help with the P/N.

PS... leave the key in the RUN position when driving... might need it to keep other things ON and working.

 

" it alot cheaper then burning up a DS2 ignition module."

or burning up your coil... something will get hot.. too hot!

 

Could be a problem with the ignition switch itself not getting the right connection to the ignition module. I agree, you want the ballast resistor - although, it's kind of interesting that MSD sells aftermarket parts that can be connected 'in line' and pretty much void the voltage drop provided by the resistor - although, it's recommended to use one of their coils with the add-on multi-spark ignition box. If you've disconnected the wire coming from your DSII module for your 'repair', then the module shouldn't burn up. The coil is oil-filled, might take the 'abuse' of your 'repair' for a while, but when it goes, better hope you have a fire extinguisher onboard.

You'll need to trace out your wiring and find where the problem is, could be a connection problem somewhere or the battery isn't putting out enough voltage - possibly (a) dead or dying cell(s).

 

Well guys thanks for you help! All is well. Everything is fixed. Had an interesting problem that you should read about in the new thread I'm writing!