Multiple misfire after fill up - coincidence?

[1955moose]

Coincidences don't make sense. Pull your fuel filter, take a small sample, you'll see water floating if it's there. Beyond that, do the usual, fuel pressure test, smoke motor, etc. It's possible your pump was going out, or that hose near the pump went south, deteriorated and refueling just triggered it. I've seen stranger crap just unplugging things to do something else. How do you tell a customer their stator on their Kawasaki isn't charging now, but I was nowhere near the area. I was fixing a misfire at 5,000 rpm. Sh## happens!

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[bobmbx]

Coincidences don't make sense. Pull your fuel filter, take a small sample, you'll see water floating if it's there. Beyond that, do the usual, fuel pressure test, smoke motor, etc. It's possible your pump was going out, or that hose near the pump went south, deteriorated and refueling just triggered it. I've seen stranger crap just unplugging things to do something else. How do you tell a customer their stator on their Kawasaki isn't charging now, but I was nowhere near the area. I was fixing a misfire at 5,000 rpm. Sh## happens!

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My point is that the gas affects all cylinders, not just two. If fuel was the cause, no matter the manner (water, pressure, flow, etc...), all cylinders would be misfiring. Since they aren't, the common cause of fuel is ruled out.

The OP is left with plugs, COPs, or injectors on the misfiring cylinders as the culprit. Since he swapped the COPs and has new plugs and the problem remains on the same 2 cylinders, whats left?

I doubt the fueling at a COSTCO is related to the failures. Coincidental at best.

 

[Trainmaster]

I can't count how many times I wanted to blame my crappy running cars on bad fuel. But I can count how many times I really did have bad fuel: Never.

 

[1955moose]

I 100 percent agree with you guys, it seems next to impossible. What about if dirt in the fuel plugged 2 injectors? Those 2 injectors. He's done the first steps of misfires plugs and coils, next is testing injectors for pulse, then pulling injectors themselves. What's left, his motor? His cylinder miss is side by side, #1, and #2, a head gasket would trigger those 2. Hopefully for our friend, that's not the case.

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[bobmbx]

I 100 percent agree with you guys, it seems next to impossible. What about if dirt in the fuel plugged 2 injectors? Those 2 injectors. He's done the first steps of misfires plugs and coils, next is testing injectors for pulse, then pulling injectors themselves. What's left, his motor? His cylinder miss is side by side, #1, and #2, a head gasket would trigger those 2. Hopefully for our friend, that's not the case.

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A chunk of debris that could clog an injector would be caught by the fuel filter. Its possible the filter itself has disintegrated and some of the paper has lodged in the injectors.

The misfiring cylinders being side-by-side means the cabling to the COPs for those cylinders run together for most of their lengths. Its possible that something damaged those wires and is causing a short, which would cause a misfire. That would explain the sudden onset of 2 misfiring cylinders.

I will also assume the injector cabling is laid together, and that wire loom could be damaged and result in misfires.

Fuel quality is almost always the last thing on my list, unless the age of the fuel is a factor....like a chain saw that hasn't been used in a couple of years. "Why won't this damn thing start!"...[cuz the fuel has turned to tar, *******]

 

[1955moose]

Cleaned out my share of clogged motorcycle carbs. If the owners would have put stabil in the gas tank before storage. But glad they didn't cause that was 50 percent of my spring work in my shop. We'll see what our friend comes up with, when he drops it by the shop. Just so weird how all was well till he visited Costco. Weird coincidence. My brother lives in Mexico, they deal with dirty fuel problems all the time.

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[Matticus]

Well, the verdict is in: Stuck valves on those cylinders. Unfortunately, I think this is the end for this expy. If the valves are stuck open, do they ever get unstuck? I would imagine that if they are stuck closed, the cam and its associated parts would be toast.

 

[1955moose]

Well that blows. And your SUV is only 9 years old. How did they come up with that? Did they use a scanner, a compression test, or pulled that valve cover. Depending on how the valves are stuck open, it's doubtful you can get those 2 cylinders back to normal. Either way that head, and the intake and timing chains have got to come off. Sorry about the bad news. I was hoping for bad gas!

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[bobmbx]

Well, the verdict is in: Stuck valves on those cylinders. Unfortunately, I think this is the end for this expy. If the valves are stuck open, do they ever get unstuck? I would imagine that if they are stuck closed, the cam and its associated parts would be toast.

That sucks. If the piston isn't damaged, you could probably get away with replacing just the upper end.

 

[1955moose]

How many miles on your SUV? It's the newest one here that had motor problems.

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