3.5 V8 Help

[Jock The Rock]

Gday

A mate of mine has a '96 Defender with a '91 Disco Fuel Injected V8. Its on gas

Since he has bought it, it has slowly been taking longer and longer to fire when turning the key. When he first bought it it would fire almost straight away.

Last night he rang me up. Not starting at all.

I went down and he said it was parked on a hill with only quarter tank of fuel. I thought this would mean not enough fuel getting to the motor because of the slope. So we put 20 litres in. Didnt make a difference.

Now i tried turning it over while pumping the throttle this should make the tips of the spark plug wet with fuel right? Pulled one out and was dry as a bone tried another was the same.

I never touched a injected petrol engine before so I left it at that and suggested he take it back to his mechanic; as Ive only worked on a series petrol engine and numerous small motors.

What could be the problem? Is it likely to be simply dirty or dirt in the fuel?

Or something far more complicated and expensive?

Thanks

[lambrover]

the spark plugs don't get wet from pumping the throttle on a fuel injected car
as the injectors are controled by the ECU (computer) and tells them when to release fuel, the throttle cable is connected to the throttle body that sensors its position electronicaly and the computer use's these inputs to know how much fuel to deliver. A carby will spray fuel when you pump the throttle though.

[lambrover]

is it hard to start on petrol or gas, if petrol it could be a fuel pressure problem blocked filter or stuffed pump. MAF sensor playing up(air flow sensor) or a air leak after the sensor can cause problems usually rough running though.

[Jock The Rock]

the spark plugs don't get wet from pumping the throttle on a fuel injected car
as the injectors are controled by the ECU (computer) and tells them when to release fuel, the throttle cable is connected to the throttle body that sensors its position electronicaly and the computer use's these inputs to know how much fuel to deliver. A carby will spray fuel when you pump the throttle though.

oh righty shows how much i know about injection systems

only worked on old series' and the like.

he thinks it will start on gas tomorrow so we are goin to fill it up with gas and try again. Personally i dont think it will but hes that kind of bloke im not going to stop him its his car

either or he starts it on petrol 80% of the time. see how we go tomorrow

[lambrover]

I have a 97 v8 disco dual fuel, when the engine runs of gas it bypass' some of the sensors and runs alot like a carby engine by drawing the gas in, as dose a carby knowing this you can isolate it to a area, if it runs on gas it is not a dizzy or coil problem as it runs on gas so it must be working. Let us know what the out come is.

[lokka]

with what you have posted about taking longer and longer to fire id be firstly looking at the ignition set up ..

Being a 91 disco engin it should have electronic ignition BUT being a mix and match it could be anything from points in the dizzy to a aftermarket set up like i run whats the ignition set up it has and have you checked that its getting good blue spark at the plugs ????

The symtons sound like the coil may be geting a lack in power and it could be anything from a dodgy earth at the coil to a dodgy power wire at the coil use a multi meter to check voltage at the + terminal of the coil while cranking if its an electronic set up it should get at least 12V and if its a points set up it should get 12V while cranking at first then drop back to 9ish then once running drop back to 6V electronic should stay around the 12V mark at all times ....

Best of luck with it hope ya get the beasty fired up and running tomoro

[big guy]

Hi

Had similar happen to me.

My pump was not buzzing.
Check if you can hear fuel pump.

Check if its turned to petrol on switch over from gas.
Happened to me also, mate came by and switched it over, hey presto.

Quite often new LPG systems give 2 seconds of petrol when starting on gas. Check wiring for the Gas computer under the hood.


The timing might be out.
Gas likes to run on 12degree before TDC. Prevents backfires etc.

I think a tune up might be in order.


Firstly I would check fuel pressures, pumps often seize.

Best of luck, its usually something simple.

[lambrover]

there shouldn't be any points in that system the efi engine run a electronic dizzy. if he is trying to start on petrol and want go but dose go on gas then you rule out the dizzy or coil as being the problem. I was told 12 degrees is correct for your timing on gas as well, as was mentioned.

[lokka]

with what you have posted about taking longer and longer to fire id be firstly looking at the ignition set up ..

Being a 91 disco engin it should have electronic ignition BUT being a mix and match it could be anything from points in the dizzy to a aftermarket set up like i run whats the ignition set up it has and have you checked that its getting good blue spark at the plugs ????[IMG]file:///C:/DOCUME%7E1/ADMINI%7E1/LOCALS%7E1/Temp/moz-screenshot-4.jpg[/IMG]

The symtons sound like the coil may be geting a lack in power and it could be anything from a dodgy earth at the coil to [IMG]file:///C:/DOCUME%7E1/ADMINI%7E1/LOCALS%7E1/Temp/moz-screenshot-2.jpg[/IMG]a dodgy power wire at the coil use a multi meter to check voltage at the + terminal of the coil while cranking if its an electronic set up it should get at least 12V and if its a points set up it should get 12V while cranking at first then drop back to 9ish then once running drop back to 6V [IMG]file:///C:/DOCUME%7E1/ADMINI%7E1/LOCALS%7E1/Temp/moz-screenshot.jpg[/IMG][IMG]file:///C:/DOCUME%7E1/ADMINI%7E1/LOCALS%7E1/Temp/moz-screenshot-1.jpg[/IMG][IMG]file:///C:/DOCUME%7E1/ADMINI%7E1/LOCALS%7E1/Temp/moz-screenshot-3.jpg[/IMG]electronic should stay around the 12V mark at all times ....

Best of luck with it hope ya get the beasty fired up and running tomoro

Buggered if i know how them extra bits got in there sorry bout that one of the downfalls of late night posting id say

[Jock The Rock]

well wouldnt start on petrol so i towed my mate out to legana. 10ks away. and filled it up with gas.

turned it over a few times and away it went. my mate thought all good so drove it back into town and pulled up switched it off and died again.

so towed him back out to legana to his old mans place. when we got there is started again switched it over to petrol and it ran fine.

mate once again thought oh she be right and took off to his brothers birthday party. wouldnt start again so towed him home again

finally i got a bit fed up because it wasnt going to go so i left it at his mechanics place.

now the last time it wouldnt go he rang up RACT and apparently the bloke thought something was wrong with the switchover between petrol and gas. how could this be when it was working fine earlier in the day



Any ideas?

What are the chances its his injection system? and how much are they to fix/replace?

Thanks

Just remembered we checked the fuel pump and it working