Gasoline vapor deposits left in fuel injector nozzles after an engine is shut down form hard varnish. Over time, it can build up and clog the injectors. Gasoline additives and detergents already mixed into the gasoline you buy help reduce this problem, but they can’t eliminate it entirely. Injectors periodically need to be cleaned. Some experts recommend cleaning the injectors every 25,000 to 30,000 miles to keep them flowing at peak efficiency.
Preventives
But first, a word on prevention. In the U.S., most of those generic gas stations with names you’ve never heard of purchase their gasoline from the lest expensive source, sometimes including refiners who, to save a few pennies, may skimp on the engine-protecting detergents added to their product; name brand gasoline filling stations on the other hand are more reliable, many use their ‘special’ additive cocktail in their sales pitches. A special caution for those driving south of the border: just about the only gasoline you can purchase in Mexico, Pemex, is notorious for not only skimping on detergent but also selling dirty (and even watered-down) gasoline.
In addition to using top quality petrol, be certain to change your car’s fuel filter at least once a year.
But if you definitely feel the need to add additional injector-cleaning detergent to your gas tank, two such products that have been recommended to us are Chevron Techron and BG Industries 44K.
Other than using preventives, we do not recommend cleaning fuel injectors as a do-it-yourself project. But, if you insist on cleaning the injectors yourself…
Non-Invasive Cleaning
A faster and easier method than removal and cleaning.
Benefits:
- Running a commercially available cleaner through the injectors while the engine is running removes many of the deposits on the valves and inside the combustion chambers as well as in the fuel injectors.
- It takes only 15 minutes to determine, by running the engine, whether the treatment resulted in resolution of the symptoms of the fouling problem (poor idle, etc.).
Tools:
- Fuel injector cleaning kit; the cost will be around $100 at an auto supply outlet.
- Long screw driver.
Procedure:
This is the basic procedure – you will still need to follow the instructions that come with the kit.
- Either disable the fuel pump and plug the fuel return line (doing this on some cars may set a fault code which must be cleared after the job is completed), or
- Install a U-tube so the fuel will return directly to the tank.
- Disconnect the pressure regulator.
- Connect the cleaning kit to the fuel port on the fuel rail.
- Remove the fuel cap from the gas tank to ensure that excessive pressure does not build up in the system. Cleaning kits deliver a large burst of pressure to the fuel system.
- Turn the ignition to ensure that, with the fuel-pump shut off, the engine will not turn over.
- Open and continue to open the valve on the kit until the fuel pressure reading matches the one appropriate for your vehicle. (See your vehicle’s owners or service manual.)
- Start the engine to run the cleaning solvent through the injectors and let it run until the solvent is exhausted in about five minutes and the engine shuts down.
- Reset the fuel-pump switch and replace the gas cap.
- Reconnect the pressure regulator.
- Start the engine and check the fuel injectors for proper operation using an extra-long screwdriver as a “stethoscope.” Listen for clicking sounds in rapid sequence to indicate a properly operating injector.
Limitations and Considerations:
- Badly clogged injectors may not pass enough solvent during a normal cleaning cycle to be thoroughly cleaned.
- You may have to do some additional tests such as checking HC and CO levels in your emissions or an injector pressure drop test to confirm that the injectors responded well enough to your cleaning efforts.
- Strong solvents may attack rubber and plastic components in the fuel pump, regulator, and fuel lines.
- Because of the flammability of the gasoline and solvent you’re working with and the fact your engine needs to be running during this process there is some risk of injury attached to using this method.
Removal and Cleaning
This is not really an option open to the do-it-yourselfer because it requires special equipment that can cost anywhere from $4,000 to $8,300. Because of that and the labor involved, a shop may charge you $40+ per injector for removal and cleaning. (Makes you long for the good old days of carburetion, doesn’t it?)
But it’s a lot cheaper than spending at least twice that to replace ruined injectors with new ones, which is what happens when an injector becomes hopelessly clogged. And injectors can be tested, observed, and compared off the car. An injector that’s not passing as much liquid as the others can be re-cleaned. If that doesn’t work and the injector must be replaced, the injector that needs to be replaced is easily pinpointed.
Cleaning Other Components
When cleaning injectors, fuel varnish should also be removed from the throttle body and intake tract with an aerosol cleaning solvent. Intake valves and combustion chambers should also be cleaned using a “top cleaner” type of product, especially on engines that burn oil. Replace the spark plugs after performing any kind of engine cleaning; also change the oil and filter.
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adding Dextron/Mercon ATF one quart to 20 gals of gas before a long road trip will safely clean dirty throttle body injectors for a price below five dollars.
Bryon, are you saying add transmission fluid to your gas? I have never heard that before.
Never use transmission fluid in gas tank. There is an old product on market since I was a teenager, it is called Marvel Mystery Oil. When you get a quart low on oil, add can less less 8oz. to the crankcase. The remaining 8oz. should be added to the gas tank. Take a long trip and you will certainly see increased power. Have a great trip!!
I definitely agree with Bryon the transmission fluid works OK. Mysteri oil is good too.
Transmission fluid
Ya, it works good I used and WOW my 1987 k-car runs like it just came off the show room floor. Thanks for the tip guys keep them coming.
Thanks Kenneth
Seafoam?
I’ve heard a LOT of people recommend “sea foam” online… supposedly it cleans everything.
You add 1/3 of the can to your tank, 1/3 to your oil (crankcase?) or the last 1/3 ….. I can’t remember where, lol. And it’s supposed to clean out your injectors, oil, etc.
But personally, I just go with the over the counter fuel injector stuff.
If you pay the 20 bucks at Walmart, they have an “IV drip” type system, in which they put some solution in the tank, and some in an IV drip type thing, and feed it directly into the engine or something to thoroughly clean the injectors.
Best left to an expert lol.
Plenty of hokum to go around
BG products are only available at dealerships and are overpriced. I have no clue where to get Chevron’s products. The process described above is far different from the process we used at the dealership I worked at. We poured a can of BG 44K in the tank, used a spray to clean the throttle plate, and used a vacuum port to suck BG’s Engine Treatment into the plenum at a steady rate for 5-10 minutes while the engine ran at 2000-3000rpm.
MMO and ATF are both good at loosening up carbon deposits, but may foul your oxygen sensor.
The gas market is pretty open, and most any gas station, name brand or not, buys from whoever’s selling at the best price. Some of the better brands may add their own additives that may help reduce deposits, but I’ve been using 7-Eleven gas for decades now and haven’t had a problem yet.
The fact is fuel standards are higher than they used to be and fuel injectors are a lot more resilient than they used to be. If your injectors clog within the expected life of your vehicle, then it’s likely you got some seriously old gas that turned to varnish or somebody put something in your tank.
Or your mechanic doesn’t know what’s wrong and is just selling you something.
20 dollars at Wal-Mart
Wal-Mart uses Gumout injector cleaner for their injector service. The canister with the cleaner that they hook up to your car, connects to an intake vacuum line like the brake booster hose. The cleaner just gets sucked into your fuel system where the air and fuel ar mixed. Some people think it helps but I think it’s a waste of money. I’ve seen Wal- Mart techs sell this service to people that don’t even have fuel injectors on their car. I think a good fuel additive like Seafoam or Marvel Mystery Oil is more effective. Just my opinion, I’m a Wal-Mart tech.
Transmission fuel
Does it also work for diesel engines? I mean can we add ATF to diesel engines safely?
TIA
Special Equipment
The Best off the car fuel injector cleaner I have found is the ASNU system. http://www.asnu.com. The Best on the car fuel system maintenance chemical and equipment isn’t available to “man on the street”. MotorVac is about $4000 for their on the car system, quite pricey. I have been using the ETECH chemicals and tools for 10+ years and I know they work. Most of the “professional only” chemicals work to some degree, ETECH is just my personal choice. Tell your mechanic to ask his NAPA man about it.
ATF in diesels
I had a 2003 dodge Cummins. Fuel pump kept messing up. I told an old timer about it he said to add automatic transmission fluid – about a half to a whole quart per fill up. He said new diesel and the bio diesels dry out seals. He was right, I’ve put 100,000 miles on since then with no problems.
ATF additive to gas
ATF is a good additive for diesel engines. It has detergent and would clean out the fuel system. It also provides some lubrication to the today ULSD (Ultra Low Sulfur Diesel), which is detrimental to diesel engines built prior to 2006.
I use ATF and TW-C3 2-stroke engine oil alternatively in my fuel tank for my F250. It smooths out my engine nicely.
Through the vacuum line
Walmart guy, the stuff that goes into the vacuum line is top engine clean / induction system clean, not injector cleaner. A fuel system can’t “suck” anything in. Top engine clean is good for carbonated or injected engines.
Adding oils into gas
Oxygen sensors are sensitive to oil contamination. One of the main reasons why fuel injected 2 stroke engines don’t have this sensor. Could this Excess oil damage it? Just a thought.
I have a 1995 Aurora and I was getting a Hesitation that felt like it was miss firing. I had replaced all the gaskets, plugs and plug wires, nothing helped.
I got pushy one day, filled up my gas tank, put half a gallon of Ethanol racing Fuel into the fuel tank, and 2 standard bottles of STP Fuel Injector Cleaner.
Ran my car at about 4000 RPM’s and wallah.
Although I do NOT recommend doing this, but if you have tried everything it’s a decent alternative.
I have been told , by an oil company executive, OTC inj. cleaners amount to “mouse milk”, because even if they have an effective cleaner, there isn’t enough to do any good. RE: fuel quality, is there some posting that shows which fuels have good cleaning properties?
Really “mouse milk”…well I used a OTC fuel injector cleaner on my 2001 ford expedition because I was running it on low fuel a lot & it helped matter of fact it was… Gumout…for 2 bucks @ a retail store.. it quit trying to stall on me… Iast for me – I would never trust an oil exec they are crooks…
hi guy’s. i own a 80 series land cruiser diesel. i started using atf [ clean atf straight out the bottle] in my fuel . 500 ml to a full tank [ 93 ltr ] the result is amazing. lot less diesel clatter, no smoke, a hell of a lot more power, and over all it is running very smooth, there is no change in running temp it runs nice and cool as always. as for an engine flush, i buy nulon diesel engine flush[ Australian made] two bottles every oil and filter change[ 5000 kilometers] idle for 30 min drain well till pan stops dripping. put the plug back in and your new filter and you back on the road with with a perfectly clean engine. done it for years. cruiser now has done 300 000 klm, and runs like a brand new cruiser. cheers ferry, Australia.
Umm… I know it’s been a while since anyone has posted, and this may be a little off topic, but what would an oil company executive (or any executive for that matter) know about working on cars? In fact, most of the executives I’ve met don’t really know about anything and are actually quite proud of their ignorance. To be honest, I don’t know how they even get their shoes tied in the morning.