Starting Problems

[TANGO7]

Hi All,

Before I go searching for "dud earths"  I wonder if anyone can suggest a possible cause of the following in relation to my HPC (Vauxhall on carbs)?

I am having problems starting (especially from cold), the engine turns over fine but takes 4/5 extended cranks before it fires, and generally fires as I "back off" the ignition key. On switching on the ignition the petrol pump makes a loud clicking noise (of frequency about 3 clicks a second) and the fuel gauge rapidly fluctuates between 1/4 full to full (tank is about 3/4 full). Leaving on the ignition but not trying to start the car after about 20 secs. the frequency of the fuel guage fluctuation slows down and the range of fluctuation also reduces slightly.also the clicking from the pump slows slightly. When running and as the revs increase the fluctuation of the gauge steadies around the 3/4 mark. When running this is generally OK but I get an occasional misfire.

Thanks

[Jonathan Kay]

Changed anything recently?

What's the battery voltage:

1. At rest, everything off
2. Minimum during cranking
3. At 3,000 rpm?

Then I'd disconnect, inspect and clean all the starter connections, including the earths.

Jonathan

[Paul Deslandes]

The fuel gauge fluctuation sounds very odd unless the fuel is sloshing around in the tank, which it obviously isn't.

The Facet pumps usually make a loud 'clacking' noise when priming itself and the carbs and then keep 'clicking' but a bit more muffled once system is primed.

I'm wondering whether the pump and fuel sender are somehow interacting due to a dodgy earth, which they might share as the pump is mounted to the rear bulkhead and may be earthed to the same point as the tank.  The pump earth should be a strap across one of its rubber cotton reel mounts.  Check the earth from the sender body on top of the tank to the chassis by temporarily adding a piece of wire to known good earth point.  You could also pull the fuel pump fuse and see if the gauge fluctuation stops.

I suspect the gauge/pump issue is unrelated to the poor starting. 

• What year is the car? 
• Does it have the original ignition coil and contact breakerless distributor arrangement?
• Does it restart normally after warming up and running for a while or are multiple attempts needed every time?
• Could the problem be related to time-of-the-year damp issues?

Vx HPC engine ignition problems are usually the standard HT leads, dizzy cap, plugs issues plus crank sensor although as yours eventually starts I doubt it's the sensor.

Sorry the above is a bit rambling.  1995 Vx build manual with wiring diagrams available here.

Paul

[BlackSeven]

I think the clue here could be "...and generally fires as I "back of" the ignition key."

Sounds like a classic symptom of a fault in the igntion switch i.e. there is no voltage to the ignition feed during cranking. Could also be a ballast issue if fitted.

Put a multimeter on the ignition system feed during cranking. If its zero but jumps to 12v when the key is released back to the "ign" position - its dirty or burnt contact in the ignition switch. Have seen exactly these symptoms before and was able to dismantle and clean the ingition swich contacts which sorted it.

If however you have voltage during cranking, then start checking earths as has already been suggested.

Rob 

 

[revilla]

Could also indicate voltage dropping too low whilst powering the starter to run the ignition; as you back off the ignition key the voltage rises and the engine is still turning so fires.

[Paul Deslandes]

As standard these carb Vx engines have an MBE 900 series ignition unit without any form of load sensing, e.g. TPS, so it might well be affected by low voltage whilst cranking from either cause suggested.  As well as checking the switch it might be worth pulling the ignition LT and crank sensor connections and squirting some contact cleaner and 'working' the connectors a bit.

Paul
 

[TANGO7]

Hi All,

Thankyou for all your suggestions - I will work through them. 

Regards,

Ian