[RidingRoadsAndTrails]

RidingRoads, I wish it was as simple as the pump getting too warm, but at 21degrees that is definitely not an issue.

The image below shows temperatures I recorded while troubleshooting. Specifically, note the ambient temperature. The readings were taken just prior to the 129 fault code. What is missing from when I originally did this image is the reading where the output port meets the pump body, when it reached 80°F the 129 fault would occur, even when it is really cold out. Note that the perspective of the photo is confusing and the exhaust pipe was nowhere near as close to the pump as it looks but was still part of my problem. Both are in different locations now.

 

[RidingRoadsAndTrails]

On the first test with partial blockage of the output was positive. Ran through the start cycle for the first time at 36F ambient. Can't believe this hasn't been common knowledge for all the heaters with no output ducting. Will take time to verify but looks promising.

Awesome news that you now have a definitive cause & solution, even if the solution is a bit of a hack. Maybe bring this up in the automation thread to develop a temperature activated baffle on the heater warm air output since anyone that installs the heater in this location is likely to have the same problem.

 

[RidingRoadsAndTrails]

Can't believe Espar isn't aware of this issue????

I updated the Espar troubleshooting post on my website and sent a note to Mike on this. Hopefully, we can get the word out for other folks dealing with this and maybe Espar will address it. This seems like a worse issue than I experienced since the fault codes in this situation are actually misleading and detrimental to the troubleshooting process.

 

[RidingRoadsAndTrails]

I went back & forth with Mike a bit yesterday. He's not buying the working theory we have here. His first explanation is that on the cold start mornings, the heater goes into boost mode and boost mode is more susceptible to the fuel cavitation. On warmer mornings, the heater doesn't go into boost mode and can better tolerate the cavitation bubbles in the fuel line. He's trusting the fault codes and still believes that it is a fuel supply issue (cavitation).

So why would the warm air exhaust back pressure affect this? The heater heats up faster and gets out of boost mode.

With our very small sample, we see a correlation of folks with the cold start issue that have no warm air duct and those with ducting not having the issue. He didn't have an explanation for this.

Anyway, I don't know that we'll get to the bottom of this unless someone with the issue gets hooked up to the EasyScan diagnostic tool to watch the sensors in real time. In my case, this was very enlightening.

At least there seems to be a workaround.

 

[RidingRoadsAndTrails]

Here is a video of what my fuel line looks like between the pump and heater, lots of bubbles and no errors (anymore). Does yours look better or worse?

 

[RidingRoadsAndTrails]

How do I load an MP4 file?

I uploaded to Vimeo.com and posted that link. I'm not sure if this platform can handle a file that size as an attachment. (paperclip button below)

 

[RidingRoadsAndTrails]

Check out my bubbles.

That looks much better than mine. I shared it with Mike, I'll let you know what he comes back with.

 

[RidingRoadsAndTrails]

Tell Mike to send me an EasyScan and I'll show him what's going on. Espar Parts has them, $1463.86 each.

If it was only that easy. Do you have a van upfitter in your area that has one? If you have a Transit specific upfitter that has experience with the gas heaters, that would be even better. I got lucky with Adventure Vehicle Concepts near me.

 

[RidingRoadsAndTrails]

Did the heater put up any error codes?

I would check the electrical connection on the pump itself is properly clicked into place. If that is OK, I'd disconnect the electrical connector and check the voltage on the connector to the pump with a multimeter to see if the heater is trying to activate the pump. If you see voltage on that connector and the pump is quiet, then likely the pump has failed.

I recently started mine after not running it all summer and fortunately for me, it fired right up.

 

[RidingRoadsAndTrails]

Try a factory reset. I know that doesn't make sense... but it's resolved issues for us (and others) in the past. 🤷‍♀️

Just curious, what issues have you seen resolved by this? I haven't run across this as a solution before, but I can add it to my troubleshooting guide if it will help others.

 

[RidingRoadsAndTrails]

Have you inspected the fuel line for cavitation bubbles on startup? Cavitation is more prevalent at altitude. The fuel line connections, if they are not butted right up against each other can add to the cavitation.

Fuel pump angle must be within spec.

I don't think we've solved this by replacing the fuel pump. I do have a spare that I used to rule that out for my issue. If you are near Evergreen, you are welcome to try it.

 

[RidingRoadsAndTrails]

Long thread... I ended up ordered a webasto air top. Are the recommendation in this thread (small diameter gas intake straw) only for espar, or for all gas heaters? I know they are finicky. Just want to make sure its installed correctly the first time. cheers.

This recommendation would be for any gasoline heater.

 

[RidingRoadsAndTrails]

Do they all use similar pulse-style dosing pump technology? I assume that the issue is tied to that technique.

I'd say that it is more about the fuel pump pulling the fuel causing negative pressure in the fuel line which enables cavitation. The thinner standpipe helps to mitigate cavitation since there is less space for the gas to expand and vaporize. In contrast, the vehicle fuel pump is located within the fuel tank and pushes the fuel causing positive pressure and does not have such problems.

I don't know enough to say whether the pulse vs continuous flow type of fuel pump has an effect on this.