Weird fuel issues

[Brand]

TLR - car stutters going forward after a batch of bad fuel. Pulling over and turning the engine off solves it for ~50km before happening again. Opening the fuel cap and releasing pressure from the tank also solves it for a period of time. All the bad fuel is gone and its no longer a problem.

So we've had this issue in the past but not on level. We would stutter forward when we put the foot down, it feels like it has full power then none for half a second then full power again, this repeats till we got to 100km/h and there wasn't as much load on the engine. We narrowed down to bad fuel, (this is the 3rd time we've got bad fuel from this station, convinced my dad to avoid it completely now even though its the cheapest around!) We topped off with some good fuel and some fuel stabilizer and the issue was gone, we could put the foot down and it would rev off as usual.

We started to stutter again ~50km down the road, we pulled over and had a look under the bonnet and inspected temps and fluid levels, everything was normal so we pulled back on the road and the issue had resolved itself. Another ~50km down the road it returned and we pulled over turned off the engine for 2 mins and it resolved itself, next time this happened we pulled over and opened the fuel cap and released the pressure without turning the engine off and we pulled away without and issue despite having stutters 30 seconds ago. We tried pulling away with the fuel cap half off and it felt like the car had 0 power. The issue stopped entirely once all the bad fuel was out of the system.

I'm trying to diagnose the issue and I think its the fuel pump. Wanting to hear your opinions on and see if anything has happened to you guys. Fuel injectors and fuel filter were changed with the new engine ~15,000km ago. We've had this issue with the old engine aswell.

Its a 00 NL Escape Auto around 330,000km on the clock with about 190,000km on the engine. We've owned it since new and haven't seen a fuel pump replacement within the the last 150,000km

[erad]

Problem sounds like a blockage in the fuel system. The fun part is now to determine where the blockage is...

I am assuming that your vehicle is a petrol model. I had my wife's TF Magna with this problem. It ran mainly on gas, but the fuel pump was running all the time anyway. The fuel pump has a sock type filter fitted to the inlet. The sock was filled with a red mud type substance. It was rock solid when I removed the pump. It took a lot of bashing and soaking in petrol until it started to move. Eventually I got it 90% clean and fitted it back into the car. No more problems. I wondered about the rest of the fuel tank - what was it like? I couldn't see into the tank to confirm my fears. I fitted a new fuel filter and all was good thereafter.

I had a NL Escape Pajero as well, and the fuel pump arrangement was exactly the same. It never gave me any problems with the petrol pump

[Pushbike]

Weird fuel issues

Hi Brand,
I had a fuel line problem caused by a section of flexible fuel line delaminating for some reason? It resulted in a flap of rubber acting as a valve and blocking the flow. So check the bits of flexible hose in the line and replace if suss.

[bundyjr]

You need to drop the tank out of your rig and pull the fuel pump. its highly likely that the mesh filter on the base of the fuel pump will be chokkers full of crap. ive had the exact same symptoms happen to me. and the base of the fuel pump looked like a mud bricket.
Invest in a new pump and main filter if this is the case.

[basil]

Check your charcoal canister is breathing as it should, because once they start to block it will cause pressure to build in the fuel system which will cause similar issues to what you are describing. I know of two people that this has happened to and both had the same symptoms your describing and in both cases the problem was solved by removing and cleaning the canister, which was not breathing.
The symptom was cured by removing the fuel cap which allowed it to run well again until vapour pressure built up again, usually half an hour or so before removing the fuel cap again.
Both vehicles have had no problems since being cleaned and breathing properly. Easy to check and fix.

Cheers,

[pharb]

The memory is a bit hazy but I had a similarish issue on my Mums Camry about 20 years ago. This was an imported hatchback Toyota sold alongside the Corona before the Corona was replaced by locally produced Camry. All of which is not really relevant except to point out it was very early generation EFI so knowledge and parts were rare and not cheap.

Car would just run out of go sometimes. Let it sit for 5 or 10 minutes and it would come good. Sometimes would occur once a week. Sometimes once every month or so. Very frustrating.

Over a year or 2 replaced spark plugs, leads, distributor (fluked a second hand unit, no aftermarket, genuine super expensive), fuel filter, injectors cleaned, inspected pump pick up, bench tested pump (also a super expensive genuine unit).

Fuel pressure and flow always tested ok, but could only ever check when it was running ok. When ever it faulted it had always come good by the time I hooked up diagnosis gear.

Ended up getting a simple mechanical pressure gauge and fitted into the fuel pressure line so I could immediately see fuel pressure when the car faulted.

Lo and behold when it faulted no pressure. Wait 10 minutes or so and try again. Pressure was fine, car ran.

Replaced pump. It never played up again.

I have never seen or heard of an intermittent fuel pressure issue like this in a petrol EFI car since.

[erad]

Not related to this issue, but too many years ago, a friend had a VW fastback with EFI. The engine used to stop and after 5 or 10 minutes would go for another 20 minutes or so. He came to me for help. I fitted a pressure gauge to the cold start injector and we drove off in mid winter with me holding the gauge out the window. Freezing cold. Sure enough, after 10 minutes, engine died. Fuel pressure had dropped from 28 psi to about 10. That was the cause of the engine dying.

He took it to the dealer and they finally found that his grandchildren had found the fuel filler flap and had put lots of sand from their sandpit into the fuel tank! Cleaned it all out, no more problems.