BlaineBug
Full Access Member
Test with a replacement from the junkyard first?
Tahoe won't restart after getting gas - Not the usual issue
- Thread starter OffRoadN
- Start date
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Test with a replacement from the junkyard first?
Thought I would provide an update with the solution to my problem. Many thanks to everyone who provided input!
It took a long time to get my Tech2 back, then with the holidays in the mix everything got super busy. Since there weren't any noticeable drivability issues (outside of starting immediately after refueling), I let it go till recently. Thankfully, though, I finally, had the time, and the tools, to get back on it. Here is what I discovered:
Fuel trims values were acceptable. Nothing crazy, but they would go negative from time to time. My assumption was it was during times when the purge valve was commanded to open.
I had previously pulled the lines off the charcoal canister and didn't find any beads (very thankful that was the case), or any liquid gasoline. Everything appeared normal. I retested both the purge valve and the vent valve solenoids and they were in perfect working order. I also tested the tank's pressure sensor and that too was working well.
My next move was to go get gas. While at the station I removed the purge line from the solenoid under the hood and had a buddy hold the end of it while I pumped gasoline. Sure enough, as soon as I started pumping he said that fumes were pouring out of the line as though it was the primary tank vent.
At that point, I returned home and removed the charcoal canister. Using a vacuum gauge, I tested the large outlet (to the vent solenoid/canister). I discovered that it took an incredible amount of vacuum to draw even the smallest amount of air though the charcoal from the (disconnected) inlet. Further inspection revealed that both the inlet and the purge line seemed to be internally connected. Thus, the internal blockage between the inlet and outlet was forcing the fuel tank to vent through the smaller purge line.
I wasn't certain of the restriction specification, and couldn't find it anywhere, but ordered another charcoal canister (the actual GM product). When it arrived, I performed the same tests on the new one as I did on the old one. The new one also had the inlet and the purge line connected to what appears to be a common plenum. However, unlike the old one, there was very little restriction between these two connections and the outlet (to the vent solenoid and canister).
A quick 10 minute swap and another trip to the gas station proved that the problem was solved. Since it wasn't triggering any codes/MILs/CELs, there was nothing to reset. Been a few weeks now and there hasn't been even the slightest hiccup when restarting after adding fuel.
Hopefully, this helps someone else with this fueling problem where the purge valve tests okay.
It took a long time to get my Tech2 back, then with the holidays in the mix everything got super busy. Since there weren't any noticeable drivability issues (outside of starting immediately after refueling), I let it go till recently. Thankfully, though, I finally, had the time, and the tools, to get back on it. Here is what I discovered:
Fuel trims values were acceptable. Nothing crazy, but they would go negative from time to time. My assumption was it was during times when the purge valve was commanded to open.
I had previously pulled the lines off the charcoal canister and didn't find any beads (very thankful that was the case), or any liquid gasoline. Everything appeared normal. I retested both the purge valve and the vent valve solenoids and they were in perfect working order. I also tested the tank's pressure sensor and that too was working well.
My next move was to go get gas. While at the station I removed the purge line from the solenoid under the hood and had a buddy hold the end of it while I pumped gasoline. Sure enough, as soon as I started pumping he said that fumes were pouring out of the line as though it was the primary tank vent.
At that point, I returned home and removed the charcoal canister. Using a vacuum gauge, I tested the large outlet (to the vent solenoid/canister). I discovered that it took an incredible amount of vacuum to draw even the smallest amount of air though the charcoal from the (disconnected) inlet. Further inspection revealed that both the inlet and the purge line seemed to be internally connected. Thus, the internal blockage between the inlet and outlet was forcing the fuel tank to vent through the smaller purge line.
I wasn't certain of the restriction specification, and couldn't find it anywhere, but ordered another charcoal canister (the actual GM product). When it arrived, I performed the same tests on the new one as I did on the old one. The new one also had the inlet and the purge line connected to what appears to be a common plenum. However, unlike the old one, there was very little restriction between these two connections and the outlet (to the vent solenoid and canister).
A quick 10 minute swap and another trip to the gas station proved that the problem was solved. Since it wasn't triggering any codes/MILs/CELs, there was nothing to reset. Been a few weeks now and there hasn't been even the slightest hiccup when restarting after adding fuel.
Hopefully, this helps someone else with this fueling problem where the purge valve tests okay.
Awesome job it getting this troubleshot and corrected.
