Why does Cutlass start up then die when I let off the gas?

[jamesejam]

I have a 1987 Cutlass Supreme with 57,000 miles on it. It rained the other day and I hadn't started the car in about a week. Today I went to move it for the street cleaners, and it would start up and run fine as long as I had my foot on the gas. As soon as I let off the gas, it dies. Any suggestions would be greatly appreciated...

 

[pontiacgp]

it could be...vacuum leak, weak fuel pump, partially plugged fuel filter, bad gas (the car, not you), carb adjustment/repairs required, distributor, cap, rotor and maybe wires...

 

[jamesejam]

Thanks for the help. After a while, the car started running on its own even though I didn't change anything. However, it runs badly. I'm pretty sure it's only running on a few cylinders, because the idle didn't change when I pulled a few random plug wires (only one removed at a time). I pulled 3 plug wires, and the idle only changed when I pulled one of them. However, I pulled one of the spark plugs that supposedly didn't fire, and it looked fine, and when I pulled that corresponding wire off the distributor, I got a decent shock, so it seems like it was getting spark. I'm thinking that maybe it's the coil on top of the distributor that went bad? Or could it be something else? The car had a tune up (plugs, wires, rotor, cap) only a few months ago but I didn't change the coil on top of the distributor.

 

[svltrack]

Spark testers are cheap & well worth it for this type of diag.

 

[pontiacgp]

start with the simple stuff first.....I'd go back over the tune up that was done and make sure all the plug wires are on correctly

 

[madmaxstyle]

Well said pontiac. Also I was thinking if it runs good warm and it ran good before. And you never messed with anything too bad. then ma by your choke could be acting up. Old quadrajets are good for that.
It sounds like it could be a vacuum leak too.....which would allow too much air for the idle circuit to run without adding extra fuel.(ie foot on the gas)
That would be the first thing I would check (because fixes are cheap and easy)

 

[treed_cutlass]

Another thing to check is the cleanliness of your carb's idle circuit. If the idle circuit plugs up, it won't idle well (of course), but put your foot on the gas and it supplies enough fuel to make up for it.

 

[pontiacgp]

and while your making sure the wires are on correctly make sure the wires are separated so you don't get cross fire induction through the wires...

 

[jae]

If you got a shock pulling the plug at the distributor, which you shouldn't do while running, that tells me the coil is firing. A not so better alternative is, naw never mind. I would take an DVOM and check the resistance on the wire(s). Too high and the plug is not going to fire, or if there's a break in the internal winding / strand the spark's going to stop or jump to ground. Even though it has low miles a wire swap may be in order.

You mentioned it was tuned a few months ago, how did it run then? Also, was the fuel filter changed? When was the last batch of fuel put in the tank?

With the rain, was the cap area wet? A quick check of the inside of the cap to see if it's wet in there may be in order, may have had condensation on the inside. If this is the case, the cap may have a crack in it. Take a look at the contacts on the outside, but more importantly the inside and the tip of the rotor, make sure they're clean.