Did Techron Fix my Coldstart Issues?

[SwampSurvivor]

I'm sure I will jynx myself and the problem will come back.

But my truck (2001 F-350 5.4 with 125K on the engine) had a bit of an odd issue. When I would cold start it, it would run good for 10 or 15 seconds, then as soon as it would go closed loop - confirmed with scanner - it would get an awful multiple cylinder misfire for a minute or 2. Once it would figure itself out, it would run and restart smooth.

I checked fuel pressure and it was good. Couldn't find any intake manifold leaks - long term fuel trim for bank 1 is at 10% . It also has a blown out passenger side exhaust manifold, but this problem was around before the exhaust manifold blew out.

The fuel gauge got stuck at 3/4 tank. I dumped 2 bottles of techron in so I could get the recommended amount for my 35 gallon tank. I heard it works on some vehicles. After 2 days with the techron in the tank the cold start issue went away. The gas gauge is about as good as it ever was, now. That is to say that it was never great to begin with, but it at least reads more than one position.

The exhaust manifold will be replaced soon.

I'm just having a hard time believing that a fuel system cleaner actually did something

 

[KCJeep]

Techron is "da bomb". Your story does not surprise me one bit.

I have fixed (in reality cleaned back into correct operation) faulty fuel gauge senders twice with Techron. Also had the fuel pump on the KIA start whining badly. Wife complained about it several months before I really looked into it. Decided it was the fuel pump whining and realized I had never used Techron in that vehicle. Gave it a good shot of Techron and the fuel pump whine disappeared. That was about 15,000 miles ago.

Yes it can work. None of the issues ever returned either.

I am so convinced Techron is effective I now run a shot every now and then in my vehicles as preventative maintenance, usually right before an oil change.

 

[Patman]

Techron is the go to additive for Corvette owners when they have sticking fuel gauge senders. The dealers want to drop the tank and replacing the sending unit, at a massive cost ($1500 I believe, most of that is labor) But those that are smart enough to try dumping in a tank or two of Techron first, often report the problem to be completely solved afterwards. For lack of a more technical explanation, the sending units get gummed up with crud and Techron removes that crud

 

[Duffyjr]

I have to park my Sierra in the street that slopes towards the passenger side. When the tanks gets below 3/4 it starts showing me it's only 1/4 full until I drive it and it get on level ground then it will come up to read the correct level. I noticed it was getting slower and slower to come up to the correct level so I dumped some Star Tron in there and after about half tank it was working normal again but it still only reads 1/4 when it's parked on the slope, must be the way the tank is designed.

 

[VeryNoisyPoet]

If you had gummed injectors with poor spray pattern, that would cause rough running on a partially warmed up engine that just went into closed loop. Computer cuts back fueling, and the poorly atomized fuel fails to burn properly with a leaner mixture in a still-cold engine. Techron cleared out the nozzles, so your injectors now meter and spray fuel correctly so the engine doesn't run like crud when cold but in closed loop.

As for the fuel sender, exact same thing as what other people said before. There were deposits making it hang up that the Techron dissolved, allowing the float and sender to work again.

With a big 35 gallon tank I'd guess that it can go a long time on a single tank, allowing the fuel to degrade and moisture to accumulate. If this is the case, consider using fuel stabilizer and dosing it with Techron again maybe once a year.

If there were that many deposits and you've never done so, now would also be a good time to change your fuel filter because a lot of gunk from the tank could now be stuck there instead, in addition to whatever naturally made its way to the filter over the years.

 

[SwampSurvivor]

Originally Posted By: VeryNoisyPoet
If you had gummed injectors with poor spray pattern, that would cause rough running on a partially warmed up engine that just went into closed loop. Computer cuts back fueling, and the poorly atomized fuel fails to burn properly with a leaner mixture in a still-cold engine. Techron cleared out the nozzles, so your injectors now meter and spray fuel correctly so the engine doesn't run like crud when cold but in closed loop.

As for the fuel sender, exact same thing as what other people said before. There were deposits making it hang up that the Techron dissolved, allowing the float and sender to work again.

With a big 35 gallon tank I'd guess that it can go a long time on a single tank, allowing the fuel to degrade and moisture to accumulate. If this is the case, consider using fuel stabilizer and dosing it with Techron again maybe once a year.

If there were that many deposits and you've never done so, now would also be a good time to change your fuel filter because a lot of gunk from the tank could now be stuck there instead, in addition to whatever naturally made its way to the filter over the years.


I got it from my father March of last year. From 2009 to 2017 it would get driven once or twice a year. So it has done a lot of sitting. I guess that didn't do too much for the injectors or fuel level sensor. One year it actually had only 70 miles on it.

I put exponentially more miles on it than he did, 5000 for the first year I had it.

Neither of us are big fans of running with the tank low. It would always get parked with a full tank. Same for myself, I never run it low and always fill it up before it sits for a few weeks.

I do have a new fuel filter for it ... just need to get time to change it .

 

[Nick1994]

Did you swap the injectors from the original engine or use the ones that came with it?

 

[SwampSurvivor]

Injectors are from the original engine. The "new" engine did come with 2 fuel rails and all the ignition coils. But didn't rust them.