Choke power problem...

[lapoltba]

I got the Motorcraft carb from Gronk installed yesterday and i'm happy to say she fired right up with no issues!  It even sounds healtier too. 

My problem is that the choke is not disengaging even after fully warming up.  I checked the voltage at the choke connector and got only a couple volts when running.  I traced the wire back to the relay on the passenger side fender and the plug looks corroded and terrible.... I'm assuming the relay is probably bad and/or the plug is fouled up.  Does anyone have a method for checking the wiring to make sure I have proper continuity after I check the relay?

[BenM]

That relay isn't the feed -- that switches power for the under-carb heater.

Power for the choke goes from a fusible link on at the distribution point on the solenoid to a flat plug, the whole choke-oil-heater wiring is a sub-harness that plugs it there. That harness runs to the three pin oil switch, which powers the choke and the relay. A separate wire in the harness powers the heater through that relay. The other side of the relay grounds through a switch in the intake manifold.

Check the power at the oil switch, it may be bad.

Be careful, the power there is unswitched, it's only the oil pressure that turns the choke and heater on. That's so they don't operate and run down your battery if you leave the ignition on, they draw a lot of current. It also prevents cold drivability issues if you are listening to the radio, have a hard time starting the car, or stall out.

[lapoltba]

Interesting, I'll have to look at the wiring diagram a bit closer.  The wire for my choke is blue with a white stripe and I could swear I traced it back to that relay.  I may have lost it somewhere in the wiring loom though.  I would bet my oil pressure sender is bad though.  Is this the one on the back of the engine near the oil pressure sender?


*EDIT*
I know where it is now.   It's the one covered in oil from when I tried to drive it the other day....    Didn't think to check to see if that was where the oil was coming from.  I just assumed it was the fuel pump leaking.  I'll grab a new switch and see if that fixes the problem.

[BenM]

Often when they go bad they leak oil. Sometimes dramatically. It falls right on the exhaust pipe and you smoke out everyone behind you.

[masternull]

i think i have the same issue also after doing Gronk's carb conversion.

the engine will idle high (~1000rpm) for a long time even after it is nice and warmed up, like 20 minutes... then it will eventually drop down to nnormal idle (600rpm)....

when i start the car up later in day it will not have this issue, only after sitting overnight.

does this sound like an electric choke issue?

[BenM]

That seems to be the pattern I'd see with a non-functioning electric choke. Check the voltage.

[lapoltba]

I'm not really sure.  I know for a fact my choke wasn't getting power and was never disengaging.  I just ordered the pressure switch and pressure sending unit (for a gauge) from RockAuto.  I think it cost me $18 and over half of that was priority mail shipping.  Advanceauto wanted $9 + $6 shipping for just the pressure switch.

I would pull your air cleaner off and start the engine from cold and watch the choke plate.   It should open up after the engine warms up.  If they don't seem to be moving tap the throttle to see if it's stuck on the cam.  You can also check for voltage at the choke terminal while the engine is running.  No voltage = choke will not open.

[carnuck]

No choke open = severely low fuel economy too!

[vangremlin]

I had pulled my stock oil sending unit (for the idiot light) out when I installed a mechanical gauge to check the accuracy of the gauge in the floor console.  After that I was having the problems with the high idle for extended periods, and dieseling when I shut the car off.  Then BenM set me straight on what the problem was.  I ended up running a separate wire to the choke before I knew that the problem was associated with pulling the oil sending unit.