wont stay running at idle

[1985crownvicltd85]

2 barrel 302 crown vic wont idle for more than 30 seconds, it will start running rough and then shuts off, if I hold the gas it will stay running. Fuel filter, plugs, wires, cap and rotor have been changed two months ago, prior to these events occuring, any help would be appreciated, thanks.

[Kodachrome Wolf]

When you’re holding down the gas, does it run smooth or does it seem broken up?

[1985crownvicltd85]

when im holding the gas it does feel rough

[Kodachrome Wolf]

What ignition system are you using with carburetor setup? Are you using the original TFI system, a Duraspark system, or something completely different?

[1985crownvicltd85]

original setup

[Kodachrome Wolf]

I might consider the pickup in the distributor to be getting flaky or the TFI module itself is shot. Some part stores will test the TFI. It may take a few tests to determine if it’s shot. I had similar symptoms when mine went out. Car ran, then ran crappy and wouldn’t go unless floored, and it ran poorly while doing so. If it cooled off some, it would crank up, but eventually failed to where it wouldn’t restart.

I might check there first considering you’ve already done most of the other ignition stuff.

[1985crownvicltd85]

I might consider buying a new distributor aswell, not really sure which one to get on rockauto, there are 5 different options and they say incorrect part# will cause damage. I also looked at my distributor and i dont see the mounted module, i only see the vacuum advance, i do however have the fender mounted module. I dont understand why the distributor is different.

[Kodachrome Wolf]

So is your distributor:

No.1


No.2


Considering your '85 has been carbureted, I would figure a lot of the electronics that drove the CFI system are missing.

Since you mentioned you have a fender mounted module, I would be led to believe it looks like this?


That's a Duraspark module. It also can fail out on you and cause running trouble.

[DerekTheGreat]

You sure that's a carburetor and not CFI? With the air cleaner in place the two systems look very similar. I had an '85 LTD CV, was CFI....

[Kodachrome Wolf]

You sure that's a carburetor and not CFI? With the air cleaner in place the two systems look very similar. I had an '85 LTD CV, was CFI....

I though he said it was carb swapped in his other thread, but I may have misread that.

[1985crownvicltd85]

i have the no1 distributor with the fender mounted module, im positive the carb has been swapped before, because im pretty sure its supposed to have the variable venturi

[Kodachrome Wolf]

i have the no1 distributor with the fender mounted module, im positive the carb has been swapped before, because im pretty sure its supposed to have the variable venturi

Is your car a US or Canadian market car? Canadian cars kept the carburetor until SEFI was introduced. US market cars use CFI, which look like a carb but have two fuel injectors mounted inside.

Got any pictures?

[gadget73]

Does it smoke black or grey when it starts to do this? Thats a sign of over-fueling. Could be stuck choke, improperly adjusted fuel mix, leaky needle seat, float level set wrong, or too much fuel pump pressure that is forcing the seat open.

[1985crownvicltd85]

the car is a canadian vehicle and it does have white/ grey smoke only when cold. once weather is warm I have no issues.

[Tiggie]

If it’s a cold issue only, verify the choke cap is getting 12v with the engine running. Verify the choke moves freely and can close and open.
With the engine cold and off, press the accelerator once and slowly release. Verify the choke is closed. Also it should catch a high idle step down below the choke. In theory the car should start. In reality, I usually have to give it a bit of gas pedal while cranking. Watch the choke, it should slowly open once the car starts. If it opens too fast, it’s adjustable on the choke cap by turning it. Can’t remember which way but they are usually marked.