Fuel Cap Light?

Mike Cork · May 20, 2022, 09:53:03 AM

Got a "Fuel Cap" light on my 2016 Ram 1500. In the past when the cap wasn't tight enough I would get a check engine light, tighten the cap and it would go out. So it strikes me odd to get the Fuel Cap Light.

The first step according to the wise inter web is to tighten the cap. That didn't work. Next step, replace the cap, that didn't work. Next step, pull the battery cable and reset the system. Wha-la that worked.

Well for about 350 miles anyway. It came back on? I plan to reset the system again but if it comes back on, and with my luck it will. What am I looking at now? I read that the sensor is part of the fuel pump. So that's drop the tank, bla bla bla.... Is there any way to prove or troubleshoot that I need to do before getting into all that?

oldjim · May 20, 2022, 10:43:16 AM

low pressure from fuel pump air or clog, check filters
oldjim

J.W. · May 20, 2022, 11:00:35 AM

Could also be the evap cannister or a leak. It'll run fine if it is, but that annoying light/message will stay on.

Mike Cork · May 20, 2022, 03:01:25 PM

All the google help says it will be one of two valves. Fortunately both are simple enough. I might try one of them Sunday.

J.W. · May 20, 2022, 03:53:19 PM

Quote from: Mike Cork on May 20, 2022, 03:01:25 PM
All the google help says it will be one of two valves. Fortunately both are simple enough. I might try one of them Sunday.

If those purge valves are cheap (I think they are), that'd probably be the best thing to try next since you already tried the gas cap. If that ain't it, it'll probably take a smoke test to check for leaks.

Mike Cork · May 22, 2022, 04:20:11 PM

$30 for the valve. I'm gonna give it a go first and see what happens. The truck only has 60k on it so I'd hope there wasn't a hose issue already.

Mike Cork · May 24, 2022, 08:24:42 AM

I purchased the "Evaporative Emissions Leak Detection Pump", the guy behind he counter just looked at me funny when I asked for it

He looked it up and chuckled, "Yep I have one but I've never sold one. It's gonna take me a minute to find it..."

It doesn't even take tools to change. Pull off one hose, one quick disconnect electrical connector. Then, like and bilge pump, pull the tab and turn and it will pop out. Replace the seal, install the new one, line and connector.

My old valve was slopping around. Meaning it was rattling bad and the actual valve appeared to be broken free from it's plunger. According to all the You Tube mechanics it would take several drive cycles to clear the Fuel Cap Light, however mine went out immediately. I assume because my valve was broke versus just leaking.

So for now it's fixed and with the poor condition of the old valve I think we got it.

Princeton_Man · May 24, 2022, 09:14:47 AM

I dealt with that purge valve a few times. The real PITA is that anytime it throws a code, the remote start is disabled. I have a Diablo Sport tuner and the OBDMX +2 with AlphaOBD on board, so clearing the codes wasn't a problem, but they were always popping up. I built a vacuum leak detector, didn't find anything. Replaced the purge valve, that helped for a while, but still didn't resolve the problem. Then I read that topping off at the gas pump causes fuel to go into the purge valve line which prevents the purge valve to sense vacuum. I quit topping off at the pump and no more codes.

J.W. · May 24, 2022, 09:31:02 AM

Quote from: Mike Cork on May 24, 2022, 08:24:42 AM
I purchased the "Evaporative Emissions Leak Detection Pump", the guy behind he counter just looked at me funny when I asked for it He looked it up and chuckled, "Yep I have one but I've never sold one. It's gonna take me a minute to find it..."

It doesn't even take tools to change. Pull off one hose, one quick disconnect electrical connector. Then, like and bilge pump, pull the tab and turn and it will pop out. Replace the seal, install the new one, line and connector.

My old valve was slopping around. Meaning it was rattling bad and the actual valve appeared to be broken free from it's plunger. According to all the You Tube mechanics it would take several drive cycles to clear the Fuel Cap Light, however mine went out immediately. I assume because my valve was broke versus just leaking.

So for now it's fixed and with the poor condition of the old valve I think we got it.

Good deal. Glad you didn't have to go chasing it down too far down the rabbit hole.

Mike Cork · May 24, 2022, 09:52:38 AM

Interesting about topping off... I quit topping off about a month ago and started getting fuel cap issues LOL... But the damage may have been done, this valve was like a marble in a box....

Princeton_Man · May 24, 2022, 10:03:02 AM

Quote from: Mike Cork on May 24, 2022, 09:52:38 AM
Interesting about topping off... I quit topping off about a month ago and started getting fuel cap issues LOL... But the damage may have been done, this valve was like a marble in a box....

That's how mine was as well. Fuel destroys them over time, but even one topoff can screw them up enough to throw a code.

Mike Cork · May 24, 2022, 10:30:30 AM

At these prices I'm afraid to spill a drop so I don't push it anymore.

Hopefully this one will last. If not it wasn't hard and they gave me a lifetime warranty...

Princeton_Man · May 24, 2022, 10:50:47 AM

Love a lifetime warranty, but it would be in the shop for three weeks or more waiting for parts to be ordered, received, then returned because the were the wrong parts.