Thread: Fuel Pump & Coil

Hi all,

Well managed to get all the bits on in between rain showers, still stutters and not holding an idle. Will have a big investigate tomorrow, methinks it is the fuel temperature sender, which is quite loose or a bad earth in that part of the loom. On another subject, what model is the AFM in this car (94 series 1 1/2 3.9 V8).

Cheers in advance


Greg

Looks like it is my AFM - had it running beautiful and then wiggle the loom.... turned to ****e again.... have a second hand one winging my way down to me tomorrow morning.... will report back asap.

Cheers


Greg

Think there are few post about fixing this, give a slight (very slight) twist to the pins on the connector to make a better connection. Haven't had it myself but remember reading about it and this cost a big $0 dollars

pm sent

How did you go with the AFM? I have a similar problem and I am hoping to get a few tips!
Thanks

Hey guys,

A final update. I have done the following in the last few days:

Replaced in this order:

Ignition module with a BIM024
Rotor
Dizzy Cap
Leads
Coil

Got the car running this way, but was no better and in-fact still had a miss and would not start from hot still, very fuelly and rich. Checked the water temp, and it was showing under half on the gauge, but 95 degrees on a separate probe. Hmmm, me thinks the ecu is getting a hot reading from the two temp sensors and is dumping fuel in to cool the engine down, along with knock coming from the engine, low compression readings and really wet plugs.... seems like it was dumping fuel to cool the engine, but it was also scrubbing the cylinder walls of oil and thus lowering the compression, and the hydraulic lifters were not getting enough pressure either.

Notice that the viscous fan is wobbly on its shaft.... decide to replace the radiator and viscous with a 5 core radiator and twin thermatics from an EA Falcon.

The result of which is, starts hot and cold, no problems. Over fueling issue is no longer an issue. We checked the temp with a probe again, 92 degrees with the thermatics off, turn them on, back down to 84 degrees and running beautiful again.

Moral of story, don't trust your temp gauge, check with a separate probe and confirm the readings. These two innocent little temperature senders can make a huge difference to the running, starting and fuel consumption of the beasty.

Will keep you informed if and when the next problem ensues.....

Cheers all

Greg

Got the car running this way, but was no better and in-fact still had a miss and would not start from hot still, very fuelly and rich. Checked the water temp, and it was showing under half on the gauge, but 95 degrees on a separate probe. Hmmm, me thinks the ecu is getting a hot reading from the two temp sensors and is dumping fuel in to cool the engine down,

Only it doesn't do that.
The ECU only richens when the ECU temp sensor shows a cold reading, ie high resistance. This has nothing to do with the temp gauge which has a separate sensor with one wire.
The ECU temp sensor is on top of the manifold near no 2 injector and has 2 wires. It sounds to me like this has/had a poor connection which has now rectified, maybe by your jiggling. So revisit this and make sure it shows 300ohms when the engine is warm and that the connections are clean and tight.
Regards Philip A

To supplement PhilipA’s advice the coolant temp sensor enriches the mix when engine is cold (it does not dump fuel in when hot to cool engine down). The fuel temp sensor (located on fuel rail behind coolant temp sensors) enriches the mix to compensate for lower fuel density as fuel gets hotter/closer to boiling sitting in the very hot fuel rail. These resistive type sensor types seem to fail first intermittently when hot then finally fail open circuit. The ECU detects this open circuit and substitutes a relatively cool 36 degrees C as the default temperature. Sensor test values are approximately 300 - 400 ohms at 80 degrees C and 2400 – 2600 ohms at 20 degrees C.

Fuel temperature sensors are not known to fail and if they do, only result in hot starting difficulty. However the engine coolant sensor is prone to failure and shows far more severe symptoms of hard cold starting (too lean) and too rich when warmed up.

Sensors that have plugs disconnected or have failed open circuit (and therefore are in default mode of 36 degrees C) will not cause engine to not start or run as badly as you have experienced. You may therefore have a more severe intermittent type coolant sensor fault which is currently in hiding ready to return one day to drive you mad.