2005 Toyota 4 Runner Flooding out.. This is a tough one…
When I first arrived, the engine was severely flooded with fuel. Dripping wet plugs. It took several minutes to clear the flood, but I did get it running. After blowing the engine out with a few snap throttles, it ran fine. Went into closed loop and fuel trims were +/- 2%… both long and short term. Coolant temp and Air intake Temp were accurate. MAF reading appeared to be correct, hot idle about 650ish RPM it was about 4 grams/sec. Fuel pressure was 41 PSI while running. Removed the hose from the pressure regulator and the purge valve, no leaks, no signs of fuel. Shut the engine off, and fuel pressure maintained 38 PSI. I restarted the engine several times with no problems.
I ended up leaving and told the shop to leave the fuel pressure gauge on it, Wait till it cools off and see what happens. They called back later that day and said that fuel pressure never dropped below 38 while the engine was sitting for over an hour, but when they tried to start it, it would not start and was flooded again. I had them clear the flood and blow it out again and leave the fuel gauge on it and I'd come back the next day. They ran the engine for about an hour, then shut it off for the night.
When I arrived, I first looked at the fuel pressure gauge which was 38 PSI even after sitting all night. I removed the vacuum hose from the pressure regulator (I actually think its a pulse dampener, not really a regulator…but it has a hose attached to it.) No signs of fuel. I removed the line from the purge valve, no signs of fuel Before cranking it, I verified coolant temp, intake air temp, TPS, KOEO MAF reading, etc.
Attempted to start the engine, it cranked, but did not start. I tried a few times and almost got it to start but didn't quite catch. I decided to stop here an remove a plug. It was dripping wet with fuel… definitely fuel…not water or coolant. I removed the radiator cap anyway, the system was not low on coolant.
I attached an adjustable spark tester to the coil and opened it up most of the way to make sure I had a strong spark. Connected one channel of my scope to that coil and another channel to an in cylinder transducer (WPS) to verify spark timing, which is occurring about 5 degrees BTDC during cranking.
Cranking compression is about 175 and there is no exhaust backpressure.
No codes and as I said, once you clear the flood and run it for a minute or so, fuel trims stabilize near zero. Also, it may be worth mentioning that it will also happen even if the MAF is left disconnected (I was thinking something may be affecting start up air flow somehow…not sure exactly how…but I was grasping for straws by this point)
I have a theory, but don't want to taint the suggestion pool.
Tanner, I did. Put it in a graduated cylinder. Smelled normal..about 5% alcohol. HOWEVER, I did smell a bit of turpentine smell while clearing the flood. So from the exhaust, it did smell like old gas, but when I took a sample…it smelled very normal. So My best is “inconclusive” on that front. I do think the problem is fuel volatility…whether it be old, or maybe a summer blend instead of a…
My thoughts are probably diesel mixed with the gas. Remove the fuel pump relay, tie into the fuel rail with an injector cleaner set up and fill the injector cleaner with hood fuel. I use the otc7448a. I remove the fuel line from the tank and hook the otc tool to the fuel line and pressurize it that way. You want to disable the fuel pump but not the injectors that way it will still be running off…
I would put a torch to dripping plug to see what happens.
I have gotten severely bit by one of these purchased at an auction. It was coolant. I Diagnosed as head gaskets. Teardown-cracked block. Exact same symptoms you describe. Drain coolant. Fire it up. Check again. I too thought fuel smell on the plugs was the key to a repair. Drained the tank, refilled with fresh. Chased my tail.
I have a 2017 Hiace doing the same thing but mine is worse cold. I’ve check everything you mentioned and more but still haven’t been able to nail it. If I get a fix before you I will post the fix 👍
Are all the plugs dripping w/fuel? If not, let the truck sit. Take all the plugs out and crank it over. You'll then see if its coolant or fuel blowing out of the cylinders.
Ain't got a ton of choices here: either the fuel isn't fuel that's combustible, or there isn't any real spark happening, possibly ‘blowing out’ under compression when cold. Summer blend fuel, especially e10 has no shelf life at all, (less than thirty days before it starts its degradation) would do it, depending on ambient temps. Winter blend has higher volatility to assist in starting in cold…
Spark is super strong, It would jump my adjustable gap tester opened up nearly all the way… about an inch or better. I agree that the fuel volatility is the issue. I told them to drain the tank and refill it with fresh fuel and we would go from there. I probably won't hear anything until Monday.
I have to agree with the diesel in fuel thoughts. I have seen those symptoms with a 5% mix diesel in gasoline. Temperature made a huge difference!
Anytime I have a severely flooded engine I check then change the engine oil.
One quick thought- check near the MAF and see if someone put a “AIR Delete Kit” in line with the MAF, I had a 4 Runner that came in with same symptoms and it turned out that device somehow failed and it went pig rich. HTH
One other suggestion if you find that it is not a contaminated fuel type issue, is check a couple injectors with the scope to see if they are being kept on way to long for some reason. It is unlikely but the injectors could be being commanded on for a long time by the PCM. I think the bad fuel is more likely, but just wanted to give another option in case it does not pan out.
You could also remove the brake booster hose before the cold start. If it starts okay, then you don't have enough air or you are rich on start up. Normally when i find diesel mixed in, the exhaust is smoking and the plugs get a sooty covering. Not saying this isn't your case. Are you graphing scan data during cranking and what does LT fuel pid say KOEO cold ? Long shot but have you scoped an…
So the shop drained and refilled the tank, which fixed the issue. They had the gas in a bucket and took samples, I agreed that it looked and smelled normal. I usually have a very sensitive nose for diesel fuel. The only hint I got of bad gas was from the exhaust fumes when trying to cleaar flood….that is when it smelled like old gas, but out of the glass beaker, it smelled normal. So I'm not…