Black magnetic gunk in my fuel system

Hi everyone

I have written some posts in the past trrying to fix my rough idle. Over the last 3 weeks it got worse and worse, it even stalled once today. Once i got a Fuel Fail 26 code.

I changed spark plugs, and found no vacuum leak. Today i decided to check the injectors. After pulling them off i saw a LOT of black/rusty gunk on them. Also lots of it was at the exit ports of the fuel rail (see video)

I am now cleaning the injectors and the fuel rail as good as i can. Just now i removed the fuel pressure regulator and on one exit a huuuuge amount of this black (it is magnetic) gunk was falling out. (from the red exit)

barely, if any any dirt or gunk came out from the blue fuel inlet.

I already ordered a new fuel pressure regulator. and fuel filter Hopefully it fill fix it. What do you guys think? Does this magnetic black gunk com from the fuel tank or somewhere else? Could it come from the Fuel pressure regulator since most of it seems to have been trapped there?

I’d love to hear some opinions, cheers!

I just wanted to see whether the fuel coming from the fuel lines is also full of this black gunk.

I attached PET bottles to both fuel lines. After turning ignition on 5 times, the blue fuel line filled about 3dl fuel into the bottle. the yellow line pumped no fuel into the other bottle. Luckily the fuel in the other bottle was crystal clear!

(is it normal that the fuel comes from this side? (sry im a newbie…)

Cheers, and have a good week everyone

The only source I can think of where a ‘magnetic’ material would come from is a deteriorating fuel tank.
Better pull the tank to be sure.

so…you are getting clear fuel from the tank? hope so–then follow checking along–tho seems you found the gook in the pressure regulator. IF…from tank…how would it get past fuel filters…I wouldn’t do the tank pull work until a lot more checking…and do a siphon off the bottom of the tank and see what you get–no filter involved in that…or from an unfiltered place on the fuel line. Even the tank pick up has a filter tho. Do easy things first.

Yea…the inside of the rail has rusted. The rust is not magnetic. The rust is steel that gets picked up by a magnet. It’s inside the fuel rail, as witnessed by your video. SD Faircloth

I also suspect that the inside of my fuel rail is crippled. I cleaned the fuel rail with high pressure water, some solvents and even after the 5th cleaning i could hear rusty flakes inside the tube. I banged the rail against some wood and the force made more rust flakes appear.

I might buy a new rail or cut it open, deepclean it and weld it back up… i hope that will fix my rough idle. hopefully my injectors did not get damaged. from a rudimentary spray testing with brake clearner and carb cleaner, the spray patterns looked thick and vouluminous…

thanks for your reply SD Faircloth

the amount of debris, rust and black magnetic gunk i extracted from the fuel rail, and fuel pressure regulator could fit in a grown mans palm. Theres no way such an amount could go trough the fuel filters, right?

I let out another 5dl bottle of fuel and it was crystal clear. seems like im lucky and i dont have to drop the tank…

Hope the new parts arrive soon, and this will be the fix to my rough idling…

Yes the other port will be the return line to the tank.

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I’m gonna speculate to have a handful of rust inside the fuel rail, that this vehicle sat unattended for a long time. I have looked at your rail design before and thought it might be possible to cut the ends off and run a stiff round wire brush thru the rail to scrape off the rust. Something similar to a shotgun bore cleaning copper wire brush. Don’t know about welding it back together. The rail wall is not that thick and welding may burn/melt more material than you want. Someone may have some advise on brazing or ??? Almost certainly, some of rust inside the rail has passed thru the injector filters and is now at least part of your rough idle problem. With the amount of rust you indicate, some will be very fine powder and will probably have passed thru the injector filters. It is also very possible that with rust in the fuel rail (caused by water) that rust has occurred inside the injectors , which is going to flake off continuously as it is doing in the rail. SD Faircloth

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im also concerned about my injectors. If i buy new ones. Do i need specific 1990 4.0 liter ones? Are there aftermarket injectors somewhere? I saw ridiculous prices of 500$ per injector on one website …

Theres a full set on Aussie EBay for just under $400AUS

do you still have the link? :slight_smile:

You can contact me privately thru my e-mail link at my website. I believe I have a full set of injectors and a fuel rail for your year model. SD Faircloth

im now cleaning out the fuel rail with 25% hydrochloric acid. i also flushed the injectors 2 times with a cleaner (both ways). Next week a new fuel pressure regulator will arrive. Then i will build everything back together.

I noticed that my now bare metal fuel rail rusts fast on the surface, tinting it brownish. I put some plant based oil into the insides to stop the rusting until i can instal the rail. Is there a way to apply something onto bare metal so it wont rust? I actually like the bare metal look, but if it rusts fast i wil have to paint the rail…

Phosphoric acid will convert the rust to iron something-or-other (google it) which is black. I’d be apprehensive of using hydrochloric, it does a number on rubber y’know!

Marmo …

Remember if they’re the original injectors they’ve been spraying fuel for 33 years, so definitely YES the injectors needs attention. Rather than paying a kings ransom for new “Genuine Jaguar” injectors or getting questionable performance from aftermarket units why not have your originals cleaned and rebuilt.

I sent mine away a few years ago and the cost was around $150. I ended up with like new “Genuine Jaguar” injectors that I know matched my engine.

Hopefully it will cure your rough idle, but if not you’ve eliminated a major cause.

Hi Larry

theres no rubber in the fuel rail i cleaned. And yes that stuff is vile. luckily i had a gas mask and goggles on while cleaning the rail with it. Im now painting my rail with spray paint.

Hi Grooveman

I hope there are people in my country who could do something like that. I already saw many such services in the US…

And yea if it didnt fix the rough idle, it at least is 1 problem less…

Marmo …

I used a very reputable company that provided a pretty fast turnaround which included a detailed “before and after” flow figures graph … in color ! (I’m easily impressed). They cleaned the injectors with a chemical bath and ultrasound then installed new filters and “O” rings. Great value for the money in my humble opinion.

After a thorough online search I had previously purchased a set of “EXACT” after market replacement injectors for my year and model car. Ran OK but TERRIBLE idle. Replaced old injectors and all was well again … LESSON LEARNED !

I can’t imagine the shipping would cost very much from beautiful Switzerland to the states.

Grooveman, given your DIY inclination and acumen I’m surprised you didn’t tackle the refurbishment yourself using a kit like this one on eBay:

along with an ultrsonic cleaner like this:

Mike, can you send me the link to that kit?

Oh and by the way, i wanted to share more symptoms of my car.

I noticed my oil smelling like gasoline. Could this also be because of the gunk in my fuel pressure regulator? But what i dont understand is that i got a Fuel Faul 26, which states a lean condition. But then why do i have fuel in my oil? Wouldnt it be too rich then?