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MG MGB Technical - Fuel system cleaner- does it work ?

As I continue to try to reawaken a 1978 MGB which has been on axle stands since 1993 I have drained all the very nasty stale petrol which has left the carburettors and fuel pump gummed up and (I believe) perished the fuel hoses.

I have replaced the fuel pump and freed up the carburettors (everything was stuck). When I have the correct fuel and hose and clips in place I hope to try to start the engine.

I feel the fuel system could do with something to remove the remaining residues. Do fuel system cleaners work and can anyone recommend one?
sam christie

They do indeed. I was never a fan of majic potions, but the steady downslide of fuel quality led me to this. Starting mid 80s, I try cleaners first for any strange running maladies. Works great on Norton, fuel injection systems that leak down when sitting, and anything that sits any great time. I now run a can through everything once a year or so as prevention.
There are a million brands, I use something in the mid price range. Typically from $2.95-$15.00 US, I'll buy the $5 or $6 stuff, and try to get one that says "absorb water" for PM.

FR Millmore

I use various fuel tank additives a couple times a year and have suffered no ill effects. I think they work pretty good to keep the gunk clear. Bob
Bob Ekstrand

Bear in mind FRM and Bob are from the USA, which has very different fuels to the UK, with very different effects on plastics and rubbers. If you've replaced the pump and cleaned the carbs then apart from replacing the fuel filter just drive it.
Paul Hunt

Paul's comments are true, but since you say that stuff was gummed up, there can be deposits all through the system that may cause problems. I would guess that cleaners/conditioners there suit the fuels there, if there is in fact any difference. A point is that high priced "premium" fuels tend to have a much better additive package than el cheapo discount fuels.Many times a couple of tanks of the "good" stuff will help out.

FR Millmore

Well here's my 2cents...

I've used fuel additives for many years, some are more universal and can be used in the oil for few hundred miles just before changing oil.

My by far preferred brand (in the U.S.) is Seafoam. Comes in a 16oz steel can, which is added to a tank of gas or to the oil, depending upon what one is trying to clean.

I've observed it freeing up stuck lifters as well as clean out fuel systems.

As I recall the main ingredient is Stoddard solvent or something like that.

Seafoam ($4-6 per can) is the only one I can recommend. Justice Brothers makes another but harder to find.

R.W Anderson

One potential problem with the type that you add to your gas tank is that they can free up all of the crap and corruption that has settled to the bottom of the tank over the years causing more problems as this stuff gets into the fuel system. I put a bottle of methyl hydrate into my tank to remove water contamination and the whole thing got bunged up with released crud. I ended up removing and reconditioning the tank.

Rich McKIe

Seafoam is an excellent product and there are probably others. Not sure if you can find it in the UK. I recommend you make sure your fuel filter is reasonably clear and be prepared to replace it after you run a tank or two of fuel. In fact, might be wise to put a new one on before you add it as well. I noticed rusty sediment in the filter after adding Seafoam to my 80LE just after I purchased it. You don't want fine particles of rust in your cylinders wearing the rings and walls. Make sure you have a proper filter on it also. Mine had a little lawn mower filter on it from the previous owner.
Rick Penland

I don't want to hijack the thread, but just which fuel filters are the best ones? I thought they were all pretty much the same.
George Phillips

Actually, that's a good question. My 80LE had one of those inch diameter lawn mower filters on it. I replaced it with a larger capacity fuel filter, but there was nothing in those "hanging" catalogs that you see in your auto parts store that showed it for the MGB, so I chose the right fitting and of larger capacity. My LE has the Weber DGV on it. The fuel filter should be for 5/16 fuel line connectors. Your question piqued my interest and I went to Fram's site and they show the G2 as the proper filter for an MGB (used 1980 for year). It's 3.67 inches long and 1.91 inches in diameter. Maybe some of the others have suggestions.
Rick Penland

I have heard of the fancy glass and chrome ones coming apart, which is pretty disastrous, I just use bog-standard plastic.
Paul Hunt

Just a thought, but I always use a clear filter. After installing a new filter on a "new to me" TR6 and having the car stop running less than an hour later, the filter was clogged almost completely from goo and rust. If I had used a metal filter, I would not have been aware of the problem and searched in the wrong places for the lack of fuel. I was able to replace the tank and lines without further issue.


Hard to know if they are really usefull or snake oil these additives. I used them monthly in my EFI Jag., but it may be more a matter of faith.
For carb. carb, I never notice a real improvement. One thing for shure it is mandatory to have a clean thank and fuel system to have a trouble free MGB. A 10-15 years old tank is most of the time rusted inside...


Jean Guy Catford

I was turned on to Techron 20 years ago by the parts man at what used to be an MG dealership. At first I was scepticle, but it increased my idle by 200 rpm. The car ran much smoother. The one warning, at that time, was that after running a tank full of fuel through the engine: change the oil. It dislodges a lot of crud. RAY

Hi Folks:

I strongly agree with Ray; regarding Chevron Techron, this is the only fuel additive I use and it loves to eat carbon deposits. I use it on my Camry and my 67 B roadster prior to oil changes. Cleans the fuel injectors on my Camry.

Good luck: Ricb Boris
REich Boris


I've spent the spring and early-summer rekindling my love affair with my '79 LHD roadstar, which I'd neglected for the past decade. She's currently at garage having dual HiFs installed in place of the HD6 which itself had replaced the sole Z-S over ten years ago.

The high-end brand that seems to be favoured in Europe is Liqui Molly, a German brand of additives. I've been quite happy with the fuel system additive, that also helped bring emissions under control. Liqui-Molly sell primarily to professional mechanics, but you can order through their national web sites (they have one for the UK.)

I must confess that, since I knew I was shortly going to be putting the HD6 out to pasture, I gave the car somewhat of an "Italian tuneup." I put the additive in the tank, and then drove the car like the blazes for a few miles. It smoked and ran ragged for a couple of miles, and since then has run much more smoothly.


DJ Roussel

This thread was discussed between 22/07/2009 and 03/08/2009

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