June 5 I put some Gumout One N Done in my 05 H2, thinking I was doing some preventative maintenance for the fuel system. The very next day I started hearing a knocking coming from underneath, sounded like muffler or the cat. I took it in and Midas couldn't find the cause. It pretty much went away within a few days but I started to notice a slight hesitation when accelerating and the engine sounded like it was revving at higher rpm than it was. This increased until last weekend I was driving up a long incline on a highway when a car merged in front of me. I let up on the gas then tried to accelerate when the car got enough ahead of me. NOTHING!! NO POWER. She wouldn't accelerate and within a couple seconds the flashing CEL light came on. As soon as I let off the gas and coasted, the light went off. I managed to make it home without further incident. The next day I drove over to my buddy's house to have him check the code. On the way over, same thing...CEL came on steady, then flashing, then back to steady. Code was "random misfire". He's a former air force mechanic and said he thinks the Gumout had kicked loose a bunch of debris and ethanol and it was clogging the fuel system. He recommended Octane Booster and Ethanol treatment, which I did right away. The next day the CEL was back and I barely made it back to his house. This time the code said random misfire, O2 sensor, and EVAP sensor. We replaced the EVAP sensor and found a sticky yellow oil around it (burnt ethanol byproduct??). He cleared the codes and told me to get the gas tank down to 1/8, try the octane booster and ethanol treatment again, and fill up. Still no luck. So off to Midas I go. They have spent the last 3 days trying to diagnose the issue but to no avail. They also found moisture in the engine. The plugs were fouled (after being replaced just 2 months ago during 100K service) and were replaced (still misfire but giving #2 and #6 this time). Head gasket was checked, no leaks. Exhaust manifold, no leaks. Fuel injectors, cleaned. CAT works, no blockage. Coils checked, all fine. MAFS is fine. They went down a list of 15 different possible causes but still no luck. Luckily they are only charging me 3 hours labor because I'm a long time customer but they are almost out of ideas and told me if they cant find it the cause tomorrow they don't know what else to do. My buddy thinks the Gumout caused the gas tank to "sweat" since its fiberglass and the detergent cleaner in the Gumout reacts to the fiberglass interior, thus the water. My last hope is dropping the tank, draining it, checking the fuel filter, and trying a new tank of gas. I don't want to give up on my yellow beast but I'm at a loss. 1)Anyone else had issues with Gumout One n Done? 2) Any thoughts on what's causing my baby to misfire and run REALLY rough?

 

Side note, I found out the parent company of Gumout has had over 2000 damage claims from this product alone, almost all from large trucks and SUV's with the same engine issues after using the product. I contacted them, and without even asking for it, they gave me a refund of the product I bought and referred me to the damage claim link on their website.

 

So....$3000 later....cracked cylinder head due to excessive heat. Thanks Gumout.

 

Ouch! Are they going to help with the costs through the damage claim process?

 

MixManSC.... I don't know if they will own this. They were really quick to refund me the cost of the product and refer me to the damage claim link. They said they might send someone out to look at everything. My mechanic/attorney buddy is going to help me write the claim so that it's very clear what their product did. I can only hope they do the right thing. My H2 had just had a 100K mile service a month earlier and was running perfectly. Everything started the day after I put in the Gumout. Midas said the chances of this issue starting DAG (day after Gumout) and being coincidental are slim to none. Their mechanic even blamed Gumout for causing my engine to overheat and crack the head. I'll keep you posted although I'm sure the claim process will drag on.

 

They might wanna see those fouled plugs if still around. Wasn't there any temp gauge warning the engine was over heating? prior to the fail.

 

Lennylexx, there was no warning light. The shop is saving all of the parts that were replaced so Gumout can send someone out to look at them. So far, they've been pretty cooperative and apologetic.