Thread: 86 RRC Overfueling

G`day Rick ,

is the themp switch the coolant temp sensor ?

If so when it`s rich check that the black/slate wire that goes to it from pin 13 ECU is making earth . The ECU switches the earth . The sensor can be in spec but the wires etc still are needed or the ECU wants to run as if cold .

If you have specs for the CTS i guess you`ll have for the TPS ( throttle potentiometer ) as well check it also when rich .

You could also check the vaccum pipe that runs to the fuel pressure reg for any signs of fuel again when rich .

If it runs full throttle when rich it can`t be an intake restriction eg pipe squash/distort etc

It`s not unknown for dry joints to appear in the ECU but normal is to miss and splutter etc

Peter

So if pin 13 is earthed, it will run rich? Am i reading it right?

Yes, coolant temp sensor.

I have a spare temp sensor and 2 x spare ECU's i can try as well.

No i don't have and specs for other sensors/switches, searched the temp sensor specs from this site

86 model,

have you checked the flapper is moving freely on the MAF?

May have had a win, after a very uneconomical 50km drive home. Started to play up not 2km from work.

Swapped ECU...same. Disconnected cold start injecter (plug and hose)...same. Checked flapper moving free, checked fuel pressure (34psi). Checked TPS, was 0.0v idle 4.0v full. Adjusted to .4v idle 4.4v full. Still same.

There were 2 x temp sensors on the LH front (top) of manifold. Pulled plug on rearmost one, cleaned and refitted.........started and runs purfect

Will take it for a decent run in the morning, fingers crossed it will be all good.

G`day , no it has to have earth at pin 13 ecu to run right or not run rich .

The thing you`ve unplugged and cleaned is the connection for CTS so that would make sense .

The other`s for the cold start , thermotime switch .

So you finally found the Real Temp switch, not the the Thermotime switch which only controls the cold start injector .Good for you ! When you checked the fuel pressure , what were the readings at idle , cruize and WOT ?

Only checked fuel pressure at standstill looking for excessive pressure, so don't have readings for the other.

After a week and 500km running sweet, the overfueling problem returned .

Checking the temp sensor this time returned very inconsistant readings. At water temp at around 60c, 2.5 Kohm, sometimes a reading of 400 ohms at 80ish deg then jumps to 1.2 kohm. I had a spare (s/hand) sensor but it was very much the same.

Wanting to test that this was the problem, i found an old vacume solenoid off the Sierra that had a resistance of 90 ohms. With this plugged in the Rangie started and ran sweet.

Now, i suspect this may cause a cold start / running issue till it warms up, but will this cause and damage if ran like this for a few days till i get a new sensor?