Too Much Fuel? Part 2

[DC_]

Ok gang i'm happy to say that all the problems with the dizzy seem to be cured as we found that the springs and bob weights had been loose.

So then the ALT, cleaned up all the wires on the solenoid and then got my 14 volts to the battery.

So..........................now i have taken the rangie for a test drive. It runs great when it's cold, but then when it's heated up, it cuts out.

Soon as you slow down to deal with a junction it cuts out.

Then after turning it several times it kicks in and revs up to around 2500rpm. Then after a few seconds (5 or so) it settles then cuts out again.

Any thoughts?

I unplugged the engine coolant sensor and it got me back home with it off, but then as i was slowing again for junctions, it continued to cut out.

Help needed again

DC

[DC_]

Also found this on another site, do you think this could also be a factor as i did get a backfire when it was running on LPG, then after this my cutting out problems started really.................

......................................At the left hand of the engine there's a little, "stupid" tube that makes the entire engine run badly if it breaks (marked with an arrow in the picture).

Some days ago, my RR 3.9 Fi '90 with LPG made a "gunfire" from the engine. I discovered that this little tube was cracked and, instead from it, the engine was taking "free air" making this effect. Also the rpm of engine was irregular, both at minimum and over 2000 rpm.

Repairing: I cut out a little piece (1/2 inch) that was broken and I refix it. Now, the engine runs perfectly.

[Hybrid_From_Hell]

Ok gang i'm happy to say that all the problems with the dizzy seem to be cured as we found that the springs and bob weights had been loose.

So then the ALT, cleaned up all the wires on the solenoid and then got my 14 volts to the battery.

So..........................now i have taken the rangie for a test drive. It runs great when it's cold, but then when it's heated up, it cuts out.

Soon as you slow down to deal with a junction it cuts out.

Then after turning it several times it kicks in and revs up to around 2500rpm. Then after a few seconds (5 or so) it settles then cuts out again.

Any thoughts?

I unplugged the engine coolant sensor and it got me back home with it off, but then as i was slowing again for junctions, it continued to cut out.

Help needed again

DC

It would be good to narrow problem down to either fuel or ignition.

The High Pressure pumps can be odd when they are on their way out, best is to see if the fuelk pressure is OK both without engine running (cold) running (cold) and then Hot but still runniung then again hot and manually opening the ADFM Flap to see the pressure.

Basically an easy way is to shove a pressure gauge into the 9th injector (plenum top one) and read, drive and read etc

This may show up an error, if not then I would consider AFM, Ignition Amp, Coil itself, Fuel Filter blockage for starters, swap with known good units, also see the diagnostic manual I have posted now in the tech forum for flapper system

Nige

[geoffbeaumont]

No ninth injector on hotwire, Nige...

[DC_]

Idles great on petrol and also idles great on LPG until it warms up, then it starts to chug and struggle.

[Hybrid_From_Hell]

DOH

For some reason I had it in me mind this was a flapper system

Ooops.

The manual for Hotwire is also in the tech archive. You do have a benifit in the hotwire system allows the AFM to have the plug disconnected

This will then make max fuel and max air, but is a quick way to see if being connected / disconnected has any effect......

Fuel pressure is a tad more awkward to get to check as no 9th injector , but all comments re tests above still apply

Lastly have just thought (as did one on a RR this weekend that had similar issues) check the TPS via multimeter for smoothness as throttle is depressed and settings value

Lastly get it running perfectly ON FUEL ONLY, then and only then worry about LPG, trying to do both will just add confusion

Nige

[FridgeFreezer]

Try swapping the ignition amp, they often fail in a heat-related fashion. If it's the type that sits under the coil you can replace it with a GM one for about £25 'cos new ones are £eeek

[DC_]

Ignition amp..........................ok back to basics, Thats the amp on the side of my dizzy is it not? Black box with plug attatched?

Hybrid thanks for the info but slightly too advanced for me. AFM air flow meter was unplugged when running and the engine cut out, so i take it that's ok.

Coil= i have one ready to go on so will do that at weekend.

Ignition amp = will look into it.

Any thought on the engine coolant sensor??

Stepper motor??

[FridgeFreezer]

Some amps are on the side of the dizzy, some are under the coil. All suffer from heat-related faults (IE fail when warmed up).

Coolant sensor if it fails will usually fail either reading dead cold or really hot, so you'll either be massively rich when warm or massively lean when cold.

Stepper motor controls the idle speed, if that's not the problem then don't worry as they're £££. Apparently there is a universal one in the US that fits in its place and costs a lot less.

[DC_]

My amp is on the dizzy.I will look to see how much they are.

Sensor = When on petrol it looks likely that it is running rich by the carbon deposit on the spark plugs.

If this sensor is failing would this be a likely symptom?

[FridgeFreezer]

You can measure it yourself to see if it looks right:

2 Celcius = 4000 ohm

74 Celcius = 362 ohm

94 Celcius = 212 ohm

The full range is in this text file, ignore the extra columns.

[DC_]

Ok, just need to figure out how to measure it now with my multimeter LOL

DC

[FridgeFreezer]

Measure on the ohms (or K ohms) scale, the sensor has two contacts and your meter has two leads, polarity isn't important.

[DC_]

ok, will have a look at my meter and see if it's on it.

Cheers

[jwriyadh]

You appear to have two problems, one with idle speed and one with mixture when engine is hot.

The coolant sensor can be replaced with a 180-200 ohm resistor when the engine is warm. Disconnect the coolant sensor, start engine, the disconnection makes the ECU think the engine is very cold, warm up the engine. Now insert 180-200 ohm resistor into coolant sensor socket. If engine runs OK then sensor or wiring is probably faulty. You can check wiring by switching off the engine, removing the ECU plug and checking resistance across pins 7 and 25 (blue/red, red/black). Get those pin positions from hotwire fault procedures mentioned above. Substitute the sensor with a new one.

To set the base idle speed you need to warm up the engine, remove the air hose from the stepper motor, block both openings now revealed, find the air bypass adjusting screw from hotwire fault procedures above and set the idle speed to 525 rpm. If the idle speed will not adjust properly you need to check the throttle assembly is adjusted correctly or you may have an air leak. Once the base idle is set to 525 rpm reliably then replace the stepper motor pipe. When started the engine should fast idle and then settle down to about 730-800 rpm.

That should keep you busy for while,

jw

[DC_]

quote from Hybrid "manually opening the ADFM Flap to see the pressure."

Sorry ADFM flap, i don't know what this is.or what i'd be looking for to measure the pressure.

"check the TPS via multimeter for smoothness as throttle is depressed and settings value"

Throttle Position Sensor?? CHecking it via multimeter...............can you talk me through it.

Sorry again.

[DC_]

Hi jwriyadh

Idle speed is ok as far as i know, it's only when it's started that it runs fast then settles down to around the 800rpm in around 3-5 seconds.

Idles great until it heats up then the problem starts. Heating up usually takes around the ten minute mark then it starts to cough.

resistor?? i've still to fully figure out how to check the ohms on anything. Is this a part or somthing i should already have?

Again sorry, i really am learning from the start.

DC

[Bowie69]

quote from Hybrid "manually opening the ADFM Flap to see the pressure."

Sorry ADFM flap, i don't know what this is.or what i'd be looking for to measure the pressure.

"check the TPS via multimeter for smoothness as throttle is depressed and settings value"

Throttle Position Sensor?? CHecking it via multimeter...............can you talk me through it.

Sorry again.

All tests like this are well detailed in the Haynes, which I have heard, is a lift from the actual workshop manual, I ran through everything over the weekend, except the fuel pressure... took me about an hour.

[FridgeFreezer]

ADFM = a typo for AFM = Air Flow Meter

TPS = Throttle position sensor, the little black lump with three wires (red, yellow, green) on the side of the plenum. Green is GND, yellow should be +5v and the red wire should have 0.283 volts (I think) on it at idle/closed throttle and rise smoothly as you open the throttle. Any jumps or drops mean it's knackered.

A resistor is a basic electronic component that (you may be surprised to hear) has a resistance to the flow of electricity. The coolant sensor varies it's resistance with temperature, which the ECU measures. Replacing the sensor with a fixed resistor means you are fooling the ECU into thinking your engine is up to temperature.

JW is not quite right, if you stick a resistor in place of the coolant sensor and the engine runs fine, then the wiring isn't faulty but the sensor probably is. If you want to be really sexercisey, splash out on a 5Kohm variable resistor which will let you dial in a range of temperature values. It may cost a whole pound, compared to 1p for a normal resistor. Hell, I'll post you one FOC if you like.

[DC_]

Awwwww ma heed!!!

Right i'm off for a beer and to watch Doc Martin.

All this learning in one night

Cheers gang, i'll be at the bar all night with all the help you lot are giving me, Really do appreciate it.

DC

[Rustyrangie]

Hi jwriyadh

Idle speed is ok as far as i know, it's only when it's started that it runs fast then settles down to around the 800rpm in around 3-5 seconds.

Idles great until it heats up then the problem starts. Heating up usually takes around the ten minute mark then it starts to cough.

resistor?? i've still to fully figure out how to check the ohms on anything. Is this a part or somthing i should already have?

Again sorry, i really am learning from the start.

DC

Don't apologise for not knowing something. better that than being all macho and pretending you do and getting it wrong.

I used to have to write "idiot guides" on technical systems for non-technical people so they didn't hurt themselves or the systems, so I can understand where you're coming from.

Ohms is the unit of electrical resistance. On your multimeter it may be the Omega symbol, a bit like an upside down U. or simply "R", Switch your meter to this and touch the leads together, it should read 0 (zero) or thereabouts. With the leads not touching it should read full scale or maximum.

A resistor is a device which has resistance.

If you're not familiar with the term it might help to think of a resistor as being like an electrical "water tap". With the tap almost shut off, little water flows = high resistance, With the tap fully open, lots of water flows = low resistance.

the coolant sensor resistance varies according to temperature as previously mentioned.

The TPS (throttle position sensor) resistance varies according to the position of the centre shaft, which is attached to the throttle itself.

It's acts just like the volume control knob on an old radio or telly.

All the various sensors in the efi system are very basically resistors which vary according to an external situation. (Temperature, airflow, throttle position, engine revs, road speed etc. etc.)

Each one thus provides a voltage at it's connection within the ECU which the ECU uses to determine the correct amount of fuel to squirt into the manifold.

The ECU is basically a clever box with a lot of inputs from the various sensors dotted around the engine etc. Using voltages caused by all these it does its little "sums" and then tells the injectors to open. The sum works out how long the injectors should be open to allow the correct amount of fuel out for the conditions existing at that specific moment in time.

Hope this doesn't look too patronising, if it does I apologise.

Good luck,

Bob

[geoffbeaumont]

quote from Hybrid "manually opening the ADFM Flap to see the pressure."

Sorry ADFM flap, i don't know what this is.or what i'd be looking for to measure the pressure.

You don't have one - you have a 'hotwire' (Lucas 14CUX) system, not a 'flapper' (Lucas 14CU) one. There are numerous differences between them, but one of the key ones, and the one from which they take their common names, is the way the Air Flow Meters (AFM) work. In the earlier flapper system, air flowing through the meter moved a metal flap, operating a potentiometer. In the later hotwire system (yours), the air flows over a heated wire, cooling it and altering its resistance.

As before with the ninth injector (which only the flapper system has, to aid cold starting), Nige just forgot which system you had.

[DC_]

Thanks guys for the input, i just feel like i'm bugging and not understanding some of the time.

Idiots guide sounds great rustyrangie lol

Would work for me.

Right so.................i need to test the ohms for the coolant sensor and the TPS?

I have taken the TPS off whilst the car was running as it didn't change anything, mind you, i think it was still relativly cold.

[Hybrid_From_Hell]

Hiya,

Sorry mate didn't explain v well, am up to me neck with work at the m and did a fast type hping it would help

Ok have a few mins :

It doesn't help when my little brain gets the system you have wrong, you have the later Hotwire type (vs the Flapper type)

the amps are known for playing up, these are the little black box with a plug going into the top which sits on the outside of the dizzy, the reason they go wrong is they get hot being where they are then cold water / air etc lands on it, net result they can play up.

Worth changing, often tho they just stop the engine completely and then allow restarts when cooled down, but easy the change - remove plug from top, I think 2 screws to body of dizzy and off it pops, can be done with dizzy in place (although your learnt this bit !!) make sure surface to dizzy and back of ampo is clean smear of grease and bolt on and replug plug and see.

CTS - Coolant sensor, when these fail (front of the top of the manifold sort of in a piggin stupid place under top hose joining manifold ) they tend to make the think run horriblt rich, they are about £10 new from genuine parts so frankly if you can afford it change it and see

Fuel pressure, tricky as you need kit to test, has anyone you know got the kit to do this ?...also I would maybe change the fuel filter for again around £9 genuine, coopers or fram parts even cheaper, dirt blockin the filter can cuase probs as it takes a while from starting to have all the bits suck back up and jam the flow

I would suggest you print off and read the Hotwire disg manual I have posted in tech from, we can them jointly guide you through the tests should you get stuck

lastly, are the cap rotor arm and leads all GENUINE and known newish and goos, pattern parts are reknowned for causing odd and difficualt probs to track down, if you replace ONLY GENUINE !

Hope the above makes more sense and helps

Nige

[DC_]

Cheers Hybrid, really appreciate the input. My gut is telling me Amp on side of dizzy for some reason.

Does anyone know the part number for this as i have scoured through craddocks and paddocks with no luck.

when you wrote

"remove plug from top, I think 2 screws to body of dizzy and off it pops, can be done with dizzy in place (although your learnt this bit !!) make sure surface to dizzy and back of ampo is clean smear of grease and bolt on and replug plug and see."

Do you mean make sure it's clean of grease or put a little on the back of it?

CTS=

Is this it?

Again if anyone has a part number that would be brill.

I don't know anyone at the moment with a testing kit for fuel pressure.So kinda stumped for now on that one.

Cap is after market i think but new.Leads are lucas and new, arm is lgenuine and cleaned up in the last week.

Did make more sense.