Super fuel causing problems?

[Rissy]

On Sunday, I chose to add about £35 of Momentum 99 super fuel to the existing 1/3 of a tank of E5 Premium I still had left.  This was a choice over moving the car on to the Premium E10 replacement we've otherwise been forced to adopt.

2-3 weeks ago, the car was running all weekend flawlessly during the Silverstone event and the car has not been used since, until yesterday after refuelling on Sunday evening.

Now; as of yesterday with a 50:50 mixture of Premium and Momentum 99 in the tank, the car seems sluggish, especially at the upper end of the speed limit, and the car starts juddering, like mini bunny hopping at about 66mph in 5th gear.  If I push harder on the accelerator, it seems to push through this, but not to great avail because I'm having to have my foot hard down to try and maintain 70mph, particularly when going uphill.

Like I said, the only variable which has changed, is the fuel in the tank since the last time the car was running perfectly 2-3 weeks ago.  So i'm blaming fuel, and nervous at what 100% super fuel will bring me.  Will it even run at all!?

So I was wondering if anyone else has experienced this, and if so, how they've overcome it.  My thinking right now is that the super fuel has altered the timing of the combustion, meaning I may have to retard, or advance my timing at the dizzy to compensate.  Not sure which way right now, even if this is the solution.  At this point I'm just hoping the super fuel mixture hasn't cleaned and dislodged any "crap" in my fuel lines and deposited this into my injectors instead?

Any thoughts anyone?

[Chris Williams]

As mentioned on the phone I (personally) cant see the fuel being an issue (unless you had some bad fuel, it happens) but do think it is fuel related.
Test your fuel flow as before and as Rich suggested and the jam jar test and go from there.
Chris

[Guinney1971]

I remember Malc Lomas years ago saying that he put BP Ultimate in his car, and basically it 'cleaned'
the fuel and dumped crap in the injectors making it run like a bag of poo.

The 'jam jar' test will check the injectors and you can go from there.

[Rich H]

(31 Aug 2021, 22:55)Guinney1971 Wrote: I remember Malc Lomas years ago saying that he put BP Ultimate in his car, and basically it 'cleaned'
the fuel and dumped crap in the injectors making it run like a bag of poo.

That was me. Way back in 2007

[Rissy]

So I started knocking off tests last night.

I checked the operation and conductivity of the idle speed switch, and followed on with a confirmation that the advance solenoid is operating, and plumbed the correct way around. This all checked out ok.

I checked the timing using my timing light gun and observed it hovering around the 10-10.5 degree mark (pretty consistent). This is ok for the Volvo set up.

Then I started dismantling what I had to to access spark plugs and injectors.

All spark plugs look good and healthy, leading me to believe that the mixture is also ok. Before I removed anything, I checked that everything was seating correctly and tight i.e. ignition leads on top of the spark plugs.

I then went on to doing the jam jar test (I used cooking sauce jars, is that still acceptable?). All 6 injectors are performing in the same manner, and equally. Atomised fuel in a jet pattern, increasing in severity as the Venturi flap is depressed. I depressed it down as far as it would go to check full travel. I also checked that none of the injectors were leaking. None were.

After putting it all back together again, I fired the car up to make sure it did so ok, as would be expected, and as it was before. All ok, so at least I've not made anything worse.

Tonight's plan is to concentrate of two flowrate tests. I'm going to repeat a test I did in June. The flow rate to the fuel dizzy. In June, I got 1.45ltrs in 30secs. The manual states a minimum required of 800ml. So at that point, my pump, fuel lines and inline filter were producing nearly double the minimum required. I was very pleased with that, and didn't do any other checks. Tonight, I'll get a comparison test done. Next I'll do the same test again, but at the return to tank end down at the front of the car. I've never checked that before, so I have no comparison to make. I'll just observe. I'd expect it to be the same as the input to the dizzy without any injectors firing (what goes in, must come out).

I'll be emptying most of the tank during these tests and continuing to run the pump to do so.

I'll report after that.

My plan is to leave just enough in to go for a drive along the motorway to retest for the symptom again. Then I'll put E10 Premium in the tank to bring the octane back to what it's always been until Sunday's fill up.

I'll also be changing the fuel filter, but depening on time of arrival (it's on order) I'll either be changing that out before, or after the test run and refill. If I do it after, and I have the same problem before, but not after, then I know it was the old filter causing my issue. If I change it before the test run and refill, and I have the same problem before fill up, but not after, then I'll know it was the fuel causing my issue. (still keeping up?)

[Rissy]

It's not been a nice night at all.

I did the first fuel flow test again, to repeat the same as I did in June. I got 1.5ltrs in 30 secs. I think I spilled less fuel this time measuring it, so I think probably I was getting the same in June, but lost more.

Then I went on to do the same test again, but this time at the return to tank hose next to the pump. I got 860ml in 30 secs (close to minimum required). This screws with my head. How can that be? It's not going anywhere else...! I didn't start the stopwatch until I saw fuel leave the hose into the portable fuel tank, which was basically immediately anyway. I did the test twice to make sure. Same result both times.

Then I proceeded to use this line to continue to empty out the tank, one portable fuel tank at a time. About 15ltrs worth into this exercise, the pump started making some horrible noise, like cavatation or something, and the fuel flow out of the pipe reduced in response. Then fuse no. 7 operated, cutting power to the pump. I replaced the fuse, and tried again, and managed to get more fuel out, but had to do it in fits and starts because the pump would start making that same noise again, followed by a rest, then go again until noise etc etc. Until I thought I had enough out of the tank. the petrol warning light was on, so i left it there (as it turned out, I've still got maybe 2cm of fuel left in the tank).

I went into the tank, digging out EVERYTHING, and noticed that there are some small flakes of shiny metal shrapnel floating around in the tank. Not many, maybe around 30-50 very small pieces, less than 0.2mm in size, each of them.

Where is THAT coming from!? What's the noise from the pump!?

I assessed the "?" hose. Although quite sticky and soft feeling, it wasn't blocked, and due to the coil, couldn't collapse along most of its length. However, at the 90 degree bend right at the pump nozel, there is a section without coil, and feeling quite soft. This *may* have started collapsing, but there's no way to be sure. There is also now a small torn gap in the plastic filter from the other end of the "?" hose which sits in the baffle at the bottom of the tank. I'm wondering if this has been sucking through some shrapnel like the stuff I've seen floating in the remaining fuel. or is this shrapnel FROM the pump!? Who knows.

So now I'm finding myself having to clean out the tank to remove the shrapnel, fit a new pump and "?" hose (to be safe) and try to repair or replace my plastic tank filter (I don't have a new one to hand).

Then I can think about starting over with the whole bloody fuel system to get it tuned again. sigh.

[Chris Williams]

Certainly would explain why you were having issues then, if nothing else may again also point to the filter being bunged up as well. If nothing else certainly does need replacing once you have cleaned the tank and sorted your pump out. What's the condition of your filler neck? is that breaking down? Or the pump itself breaking down and the internals rubbing against the side?
Chris

[Rissy]

(03 Sep 2021, 16:49)Chris Williams Wrote: Certainly would explain why you were having issues then, if nothing else may again also point to the filter being bunged up as well. If nothing else certainly does need replacing once you have cleaned the tank and sorted your pump out. What's the condition of your filler neck? is that breaking down? Or the pump itself breaking down and the internals rubbing against the side?
Chris

All good questions. I've now got the tank dry and clean, and have been messing with the pump out of the car. It now seems to work "ok", but tbh, it's under very little load outside with my setup. I proved it was only drawing 80mA with the load I was giving it, which is nothing, and considering I operated a 20A fuse last night with it, it just goes to show how much power it drew at one point to do that!

I'll maybe make a point at looking at my filler neck a bit closer. From memory, it's not too bad actually, at least where you can see down to put the fuel nozzle at the station. There was very little debris in the tank, but there was some bits. Some were shiny (0.2mm maybe), and at least one was a bit rusty (0.8mm maybe). There was a bit of really really small debris in the fuel, which i've now syphoned out of the fuel ready to put back in the tank again.

I ran the pump forwards and backwards. I never got any debris from the pump running it backwards, but I did get a tiny little bit running it forwards.

I'm now awaiting the arrival of my new inline filter...

[Chris Williams]

TBF, based on what you had found in the tank (size and how shiny) I cant see it being anything other than pump debris, combined with the '?' hose degrading possibly collapsing I think there in lies your issues. Unless of course they (the small shiny flakes) were introduced from filling your car from cans whilst it was off the road?
Chris

[Rissy]

So just a quick update before I rush to work.

Over the weekend, I changed out the pump for a brand new unit and cleaned all the fuel out of the tank to get rid of any debris and replaced the "?" hose for a new one off the shelf. I had a lot of trouble trying to get the fittings to seal properly on the new pump. Petrol kept spraying out from around the banjo fitting on the top of the non-return valve. I had the pump in an out of the tank several times! When I did get it running leak free (more or less), it was making the same horrible noises as the original pump was, even though on the bench test before fitting it, it was fine. I actually also tried the old pump in the same bench test conditions, and although a little noiser than the new one, it performed without the horrible noise too.

At this point, I was confused, and decided it was making noise due to not enough fuel in the tank, so filled the tank up to nearly half way again (way off the petrol warning light which it was before). THEN, the new pump was sounding ok (Now i'm wondering if this was the whole problem with my old pump, and it's actually fine after all!?) I've still left the new one in simply due to it performing more quietly, no other reason.

I then went for a repeat fuel flow test, at the tank return. I did this test twice. 760ml in 30 secs, followed by 750ml in 30 secs. So worse performing than the original pump.

At this point, I had access last night to a new fuel filter which arrived in the post yesterday. After a LOT of hassle trying to fit that, and get it to seal fully, I again did another fuel flow test. Twice. The results were 860ml in 30 secs and 800ml in 30 secs. So now I'm finding myself roughly back where I was before I changed out anything!!!?? All that took me up to about 11pm last night, and I'm knackered.

How can all this be? What's going on? My only thought now, trying to think of my thermodynamics from university, is that pressure and flow are related. Am I simply exhibiting low flow due to low primary pressure? The last time I checked remember, in June, with old pump and old fuel filter, I was measuring 4.75bar primary.

So I have two choices now (that I can think of).

1. Button up the fuel pump assembly on the top of the tank and take the car for a drive, and see how it's performing now (at speed) with the new pump and inline filter fitted.
OR
2. Tonight, go straight for the fuel pressure tester and measure the primary pressure with a view to increase this at the regulator with a shim or more, then remeasure the fuel flow (easily since the pump assembly is all still open at the top of the tank).

Any ideas, and recommendations?

[Derfel]

Funny enough my car started running funny after putting in the new fuel. It hesitated really badly on the way back from the petrol station and when I got home - it refused to start.

After a lot of diagnosis - I found that the O rings on my pressure regulator were a bit worse for wear. The front one looked ok but was slightly crushed.

£3.50 for the hot start O ring kit from DeLorean Go and she started right up and revs really smoothly!

For the money, it's worth changing them!

https://www.deloreango.com/uk/hot-start-o-ring-kit.html

[Rissy]

Thanks Derfel. I have a newly refurbished fuel distributor, so all the o rings are new anyway.

[Rissy]

Right. So after taking the car for a pummel along the motorway, I can say the car is driving a lot better now. 5000rpm in 4th, 82+mph in 5th etc. Perhaps a very slight jitter, but so minimal you wouldn't really notice if not super sensitive to it as I am right now.

I think it's probably not far off performance of how it was before, if not the same.

My fuel sender was playing up though, and not giving an accurate reading, leaving me thinking I was going to run out of fuel on the M6!
I didn't though.
I went to Tesco again, and filled the car up with Super fuel again too.

I don't want to mess with it again right now if it's going to satisfy my requirements for this weekend, but I do have the intention to still further investigate fuel flow (with fully charged battery etc) and do a fuel pressure test (with my gauge kit, and someone elses so that my kits accuracy can't be questioned. Once it's not in doubt, I think i'll attempt to raise my fuel pressure at the regulator. But at I'll be doing it under much calmer, less time sensitve circumstances as I have been dealing with for the past week.

Thanks for everyone's input and support, it's much appreciated, and I'll follow up with my fuel distributor adjustments when I finally go to do that at a much less time critical time with demands looming for the car to be working. Perhaps over winter once I've taken it off the road for the rest of the year...

[acmetowers]

I have a calibrated gauge, happy to drop if off if/when you need it.

[Rissy]

Thanks Richard, that’s much appreciated. I might take you up on that offer.