Whac-a-mole Wednesday: stumbling cold start (resolved*) (1 Viewer)

[ElHefe]

For the past couple mornings, the 100 has cranked strong then stumbled for half a second before roaring to life. Stumble does not repeat with subsequent starts and truck runs great otherwise with a smooth idle. Any ideas?

More info:
-It has been freezing over night for the first time past couple days.
-Went through power car wash for first time ever day before issue started.
-The truck has a new fuel filter and pump (in last 500 miles).
-Sitting at 150K.
-I put BG44K into the last tank. It ran through the system with no noticeable impact on performance or efficiency.
-Currently doing a Seafoam crankcase cleanse (last 120 miles).

UPDATE: I was concerned that it might be water in my fuel so I added Heet and a full tank of gas. Two cold sink starts, including another 28f over night, and no hesitation since. Putting an asterisk by the resolved note since it has been a short post-intervention period. I’ll update if anything changes.

 

[Mike NXP]

When it gets below 20degrees my rig has a slow gurgling start, and kind of has a goose sounding honking noise for a split second. The weak start clears up after about 2 seconds and I could never pinpoint. I keep my battery on a tender and also have it wrapped in a heated mat.

Fuel system and everything performance / electrical related on this truck is in tip top shape, I've always just summed it up to it's really cold out and it's normal, since after the first few seconds it purrs like a lion.

 

[AlpineAccess]

^ Mine sounds the same with the "honk". I've had it before on other Toyota's (FJ Cruiser and Tacoma) for a much longer duration - chalked it up to sleeved blocks and cold, dry cylinders. The stumbling not so much, other than a little bit of a struggle two days ago at a whopping 3* when it was parked outside (we moved the boat into the garage as I hadn't had a chance to winterize it yet).

When you say its been freezing overnight, how low is the temp getting? Have you experienced this stumbling start before?

 

[ElHefe]

When it gets below 20degrees my rig has a slow gurgling start, and kind of has a goose sounding honking noise for a split second. The weak start clears up after about 2 seconds and I could never pinpoint. I keep my battery on a tender and also have it wrapped in a heated mat.

Fuel system and everything performance / electrical related on this truck is in tip top shape, I've always just summed it up to it's really cold out and it's normal, since after the first few seconds it purrs like a lion.

This is good to know. It did feel like gurgling but I don’t recall a different sound (like a goose). I decided to check if it might be water in the fuel since the fuel is old. I put Heet into the tank + a full tank of gas. Hasn’t hesitated since (two cold sink starts) and the start up is strong and immediate. Temperature got to 28f last night. Hoping this resolved the issue.

^ Mine sounds the same with the "honk". I've had it before on other Toyota's (FJ Cruiser and Tacoma) for a much longer duration - chalked it up to sleeved blocks and cold, dry cylinders. The stumbling not so much, other than a little bit of a struggle two days ago at a whopping 3* when it was parked outside (we moved the boat into the garage as I hadn't had a chance to winterize it yet).

When you say its been freezing overnight, how low is the temp getting? Have you experienced this stumbling start before?

Thanks Alpine. It got to 28f the coldest night when this was happening. But I tried a fuel additive to eliminate water in the tank and it has not stumbled in the last two cold sink starts. Last night it got down to 28f again. No issues with the start up this am.

No stumbling (or weird noises) ever before during similar conditions which is why I was concerned. We live outside of Chicago, so cold weather is a way of life.