Fuel issue, not entirely sure

D

Dion kereopa

New Member
Hi

I have a CE 1.5 Lancer 2000, I purchased this in mid 2023, it had its fair share of issues, but I've been crossing them off as they come up.
So recently it's been running rough and smooth.
So it starts ok, and then after 5-10min it starts spluttering, even a little black smoke came out the back.
Still drivable its struggling with power to get through the gears, like it's not giving me enough fuel. So I get the car up to crusing speed of 100k and it was going great. Now for context, recently I had the fuel sender replaced about two months ago, and it hasn't worked since, I've taken it back and its still not given me correct readings. So I will be going back at some stage, so as a back up in running the trip metre to gauge fuel consumption. So I know on long trips I can get at least 700km on a tank. From a full tank from Mackay last week, I started the trip metre and I'm just south of home hill and all of a sudden the car just dies, I slow down and it seems ok, but I'm travelling at 60km now. I don't know why if it should have at least half a tank as I've only used 300km of a full tank of 700km. I make it to Home Hill, I get roadside assistance and RACQ turn up. Just before he did, I checked the air filter, and it looked like it was in the wrong way, I put it in proper and it ran really smooth, but after a couple minutes it started idling rough again. RACQ checks a few things and then he puts in 20ltr of fuel and the car is running good again. So I stayed in Ayr for the night, next morning I went to Burdekin automotive and long story short, he gave me some fuel injector cleaner, I've used it before, it helped but it wasn't the source of the problem. So I head about 130km north to camp overnight. Next day I'm getting ready to head to work, start the car and it's idling rough again, get up the road same thing happens again it's like it's ran out of fuel, although it had a full tank when I left Ayr which is only 140km from where I am, so at least 3/4 of a tank still in there!
Same thing, RACQ turn up, he does his checks, then taps the tank and says it sounds empty, he puts in ten litres, I have 20 litres in a Jerry can which I used later, because I figured I needed to have fuel on me when it runs out at that certain point and that's what actually happened. When I drove from Balgal to work, about 100 km in, I started running out of fuel, so I topped up with what I had left and it got me to work so, there's a problem. It sounds like fuel at the moment.
Anyway would appreciate any help
 
Hi Dion,
Perhaps it'll be worth emptying the tank to see if there is gunk or grit in the tank and the fuel lines. These cars are pretty forgiving with parts, so dont be too nervous about taking them apart. I think it sounds like either a fuel leak, or running extremely rich. If its just rich, then a replacement O2 sensor shoul help fix that (dont forget to unplug the battery for 15mins, and then go for a 20min drive, as a power cut & gentle drive will reset the fuel usage requirement). If its a fuel leak, that will depend on where the leak is, and needs further diagnosis.
 
If it's running poorly and blowing black smoke it may be misfiring. Loads of things to look at.
Start with seeing if it idles smooth when warmed up. Leads plugged in properly, spark plugs in good condition.
If it's an intermittent could be a sensor. These can be scanned for codes.
 
Thanks Donki,
donki said:
Hi Dion,
Perhaps it'll be worth emptying the tank to see if there is gunk or grit in the tank and the fuel lines. These cars are pretty forgiving with parts, so dont be too nervous about taking them apart. I think it sounds like either a fuel leak, or running extremely rich. If its just rich, then a replacement O2 sensor shoul help fix that (dont forget to unplug the battery for 15mins, and then go for a 20min drive, as a power cut & gentle drive will reset the fuel usage requirement). If its a fuel leak, that will depend on where the leak is, and needs further diagnosis.
Click to expand...
donki said:
Hi Dion,
Perhaps it'll be worth emptying the tank to see if there is gunk or grit in the tank and the fuel lines. These cars are pretty forgiving with parts, so dont be too nervous about taking them apart. I think it sounds like either a fuel leak, or running extremely rich. If its just rich, then a replacement O2 sensor shoul help fix that (dont forget to unplug the battery for 15mins, and then go for a 20min drive, as a power cut & gentle drive will reset the fuel usage requirement). If its a fuel leak, that will depend on where the leak is, and needs further diagnosis.
Click to expand...
"(don't forget to unplug the battery for 15mins, and then go for a 20min drive, as a power cut & gentle drive will reset the fuel usage requirement)"

I went ahead and tried it this afternoon.
It felt like it struggled to get to 100km so I backed it off to a comfortable speed at 80km. I stayed on that for a bit then I noticed the acceleration started to pick up so I backed off some more until it got to 100km and it was with hardly any effort, the acceleration point adjusted to being right under my foot.
Also noticed that the idle has reduced to 500rpm from 1000rpm. It stalled a few times at intersections during the drive, but it seemed to be running smooth. I think it's done something, could be a good start.
 
frosty7 said:
If it's running poorly and blowing black smoke it may be misfiring. Loads of things to look at.
Start with seeing if it idles smooth when warmed up. Leads plugged in properly, spark plugs in good condition.
If it's an intermittent could be a sensor. These can be scanned for codes.
Click to expand...
Thanks frosty7,
It travels and runs smooth from this afternoon when I took it out for a run.
I've also filled the tank up, but it seems to be consuming alot of fuel.
 
Clean your throttle body and map/maf sensor. Run 98 and injector cleaner for the next 2 tanks of petrol.

That's the easy/cheap starting point.

Also check your spark plugs for oil.
 
4g15 has no MAF, map sensor only. Map sensor probably wont need cleaning but its low cost to try.

It kind of strikes me as Maybe being a throttle position sensor related issue. As in the car doesn’t know where the throttle is and it’s only guessing at how much fuel to throw in.

Worth mentioning as well I had an odd issue with an 80s Celica where the fuel tank had a bunch of gunk in it. It meant the car would run fine for about 20 minutes and slow slowly block the fuel pick up during that process. Then with a blocked fuel pick up it would stall. You leave it for an hour or two and it starts up fine because all of the gunk has receded back into the bottom of the tank.

I don’t think that is your issue if you are using so much fuel. Just with sharing an anecdote may help you get thinking about other ideas.
 
donki said:
Hi Dion,
Perhaps it'll be worth emptying the tank to see if there is gunk or grit in the tank and the fuel lines. These cars are pretty forgiving with parts, so dont be too nervous about taking them apart. I think it sounds like either a fuel leak, or running extremely rich. If its just rich, then a replacement O2 sensor shoul help fix that (dont forget to unplug the battery for 15mins, and then go for a 20min drive, as a power cut & gentle drive will reset the fuel usage requirement). If its a fuel leak, that will depend on where the leak is, and needs further diagnosis
Click to expand...
 
Dion kereopa said:
Just curious to know: what determines how much fuel is put into the injector rail and injectors?
Click to expand...
Primarily its a voltage related amount, however the Engine Control Unit (ECU) assumes its at around 43.5psi, and will adjust the miliseconds needed for the injectors to open based on engine RPM, o2 sensor reading, air intake amount pressure (if its 1.5L, or air flow rate if its 1.8L), amongst about 10 or 15 other operating variables.

Dion kereopa said:
What's the 02 sensor?
Click to expand...
Oxygen sensor, it plugs into the exhaust manifold and provides a variable feedback voltage into the ECU to allow it to adjust more or less fuel spray timings
 
"(don't forget to unplug the battery for 15mins, and then go for a 20min drive, as a power cut & gentle drive will reset the fuel usage requirement)"

I've done that part and the car is running excellent, however the fuel consumption is very high, I'm getting 327km to 40 litres and the fumes have rich odor.
So what's the next step to get the fuel consumption right?
 
Dion kereopa said:
"(don't forget to unplug the battery for 15mins, and then go for a 20min drive, as a power cut & gentle drive will reset the fuel usage requirement)"

I've done that part and the car is running excellent, however the fuel consumption is very high, I'm getting 327km to 40 litres and the fumes have rich odor.
So what's the next step to get the fuel consumption right?
Click to expand...
I'm usually getting 700km
 
Blocked exhaust.
Blocked air filter.
Fuel injectors need cleaning. Poor flow.
Map sensor problem or a hole in the vacuum hose to the map sensor.
 
I didn't do anything to it, it's been like that since I bought it. It used to be a petrol heads car, I replaced air pod, mags all the racing stuff and got it back to a normal vehicle.
I have had the injectors replaced about two years ago, but other than that nothing that modified the fuel.
 
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