RichieN

My Feedback: (5)

I have two DL-50 engines, both with WT-889 carb, one of them was purchased directly from DLUSA. They both run very reliable over years.

During the “spring” maintenance on one of them, I’ve discovered that material that was blocking high speed nozzle check valve was dislodged and loose within the metering chamber.
In the other carb, the "plug" is still in place, but it is loose and could be removed from its location. Never less, in both carbs the high speed nozzle check valve was blocked on purpose.
I’ve tested the check valve by blowing air through it and it appears to be working.

Should I try to run the engine with high speed check valve unblocked or it will be just waits of time?

If this port has to be blocked, what is the best way to do that?

Thanks,

Truckracer

My Feedback: (19)

That appears to be an accelerator pump equipped Walbro and that check valve is the inlet to the pump. Don't confuse this check valve with the HS nozzle check valve as they are different though accessed through the same opening. In a normal, non-accelerator pump equipped Walbro, this opening is just blcoked off with a welch plug. The material that was loose in the carb was blocking off the accelerator pump inlet and would make it inoperable which seems to be the goal of whoever placed the material there in the first place. If you want to keep the area blocked off you have two options. First, you could replace the glob of "stuff" with a proper welch plug provided in any Walbro repair kit but this will only work if there is enough recess in the carb housing to accept the plug. Or .... you could clean the area very well and replace the glob of stuff with a glob of JB Weld though JB Weld will deteriorate over time when immersed in gasoline. Maybe someone else can suggest a better material to block off the opening. I guess you could just go with a third alternative and just leave the glob of stuff out in which case the accelerator pump would function if all its parts are still serviceable. If the pump needs service, none of the necessary parts are included in a standard Walbro repair kit and they are difficult to disassemble for service.

When I refer to pump, don't confuse the accelerator pump with the diaphragm pump on the other side of the carb. The accelerator pump injects a bit of gas as the throttle is rotated much like a similar pump works on automotive carburetors. This allows the low speed needle to be run leaner than normal while still providing decent throttle response when the throttle is opened. Franky, I think these accelerator pumps are a huge pain in the a** on a Walbro and avoid carbs that have them.

RichieN

My Feedback: (5)

Thank you for your detail explanation. I like your idea of using Welch plug to block the accelerator pump, but I have not tired that yet.
I bought current DLE-55 carb from Tower and I’m going to use it on one of my DL-50. The other engine I will try to run it first with accelerator pump unblocked. If performance is worse or/and tuning difficult with the pump in use I will work on blocking the port starting with Welch plug idea.
In the long run, if current version of the carb sold for DLE-55 appears to work better, I just buy another one.
Thanks again,

Truckracer

My Feedback: (19)

The carbs used on the 55 all seem to work very well. DLE has at times used both Walbro clones and genuine Walbro carbs and all seem OK. The common Walbro numbers are WT-918 and WT-664 and some have stated over the years the 918 being the best of the bunch. I have (2) 55's, one being 8 seasons old and the other going into its second season. Both run perfectly with zero carb issues.