I’m looking for technical help or recommendations on: Fuel problem
Hi,
I have a problem with my car in that when I have filled up to a full tank, there is a grinding sound(Might be bubbling) when I accelerate. This sound get quieter when the fuel tank gets more and more empty, and with a quarter of a tank it sounds fine. I don’t think it is weight based because:
It is about under half, so a little noise left, and I chucked in 2x20kg plates in the boot and the sound didn’t change at all.
If I leave the car for a week or two (Quite often with lockdown at the moment) it struggles to start, almost if there is no fuel in the lines. Leaving it a day or two and it starts fine, the battery is also fully charged.
It really has trouble starting on an incline, even turning it off for 15 seconds on a hill means it will have a little trouble starting.
Sometimes if I stop the car when the sound is quiet, open the fuel cap and immediately start the car again the sound will be really loud for a short period of time.
Does anyone know what this could be? I thought it could be a small leak in the fuel line, but I didn’t know if that would cause the grinding sounds when there is a full tank of fuel?
Could be the evaporative control system, but I’m not sure about the noise. Can you describe again.
Also, do you fill your tank right up?
I have heard of fuel getting in the evap system and and overfueling the engine. That might be why the car is hard to start, but I’m really not sure, just guessing.
If you have a scanner, it might be worth having a look at the fuel trims.
I assume you don’t have an engine management light on.
The noise is like metal bolts in a can being shaken, I can rev the engine fine stand still with no effect, but under load it doesn’t like it so much. I thought maybe transmission, but it gets better once the fuel goes down.
If you have a scanner, it might be worth having a look at the fuel trims.
I do have a scanner, there are no codes at the moment, but I didn’t look at the fuel trims. I will have a look at those tomorrow.
I assume you don’t have an engine management light on.
Nope, engine runs nice, just when accelerating under load it makes that noise.
Clutching at straws here but could it be the fuel pump or more precisely could the fuel pump filter be blocked and scavenging for fuel.
Do you know of a way to check? This one makes sense, it rough idles for maybe 30 secs after startup and they make a grinding noise when they are dying. I want to check more before I take it to a mechanic, right now they are super expensive around me.
EDIT: Although more fuel in the tank would usually ease the load on the pump, not increase it
If there is a problem with the fuel pump you will find it behind the passenger seat after removing all the plastic covers.
Before going mad and stripping everything down i would go in the boot and remove the plastic trim in front of the metal fuel filler pipe and with an engineers stethoscope (a long screwdriver pressed to your ear and the pipe) run the car and see if you can hear a definite noise, do this at start up.
At least this would be a cheap way to diagnose a faulty fuel pump, this would be my next step on the way to eliminating possible faults.
Good luck in your quest.
Dave.
As far as your problem with the car starting, I had the same problem about two weeks ago. It must be twenty years since I checked the gap on the spark p[lugs of any car, but I did this and found the gaps were all different. I scraped the inside of the plug and set the gap to what it should have been and using an airline blew it dry. With all the plugs out and cleaned I turned the ignition on to clear any residue of petrol, only once mind you and then put all the plugs back in and it started up first time. The batteries on my Mk1 don’t stay charged for more than 6 days , even with new ones, so I have one of those chargers you leave connected to the batteries all the time when not using the car, especially in Winter time.
Had a mechanic friend look at it today, looks like a combo of a very tiny hole in the fuel pipe with cold weather. The hole meant that it wasn’t holding a vacuum after a few days.
Had a mechanic friend look at it today and he said both Anti-roll bar ball joint dust covers were badly disintegrated at the rear. This might let dust in and causes a rattling sound, does this sound plausible? I need to get them changed before my next MOT anyway, but a second opinion never hurts.