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Walbro primer bulb appears to work, but no fuel is going to carb

Posted by Tipiford none (My Page) on
Sun, Aug 4, 13 at 11:48

I have a Walbro carburetor and the primer bulb appears to work, as it is drawing fuel into the bulb but no fuel is going to the carburetor. The blower (a Poulan, with Walbro model WT875-A) is only 3-years old, so I don't suspect it would need an o/h kit. I have taken off the bulb and blown compressed air through the top orifice and the two lines going into the fuel tank, as well as cleaned the fuel filter to no effect. Any ideas on this issue?


Follow-Up Postings:

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RE: Walbro primer bulb appears to work, but no fuel is going to c

Does your carburetor have the orange or black rubber check valve under the primer/purge bulb installed in the primer base assembly?


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RE: Walbro primer bulb appears to work, but no fuel is going to c

1.See if the youtube info at the link below will help you troubleshoot.

http://www.youtube.com/watch?v=uCC1qO75zDk

2. I f you find resistance there is a small fuel screen inside the carb that could be restricted. Attached. One screw will let you into the area with the carb off. Personally, I cln the screen with Compressed Carb Cleaner vs replacing which has been a challenge for me. While you are there you might as well flush all openings to know they are open. Mark and lightly seat your carb settings to know references. Digital pics are helpful if you are not real use to the setup.

Here is a link that might be useful: Check this info


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RE: Walbro primer bulb appears to work, but no fuel is going to c

Do not use high p.s.i. compressed air to do ANY cleaning inside these carbs as you could easily blow out or dislodge one of the sensitive check valves. That will end the carb's ability to DRAW fuel using the primer bulb as it performs on vacuum and that is lost with a bad check valve. A look at these carbs and HOW they operate is a must see read if you are going to work on them. The Walbro web site has lots of good info on function, parts and repair.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

homegrown55,
It has a black valve. When pressing the bulb it just blows air into the tank, so I now suspect the check-valve. Can these be purchased separately? Or do these come as a part of a carb kit?

homegrown55 (message 2),
We used very low air pressure in cleaning.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

homegrown55,
It has a black valve. When pressing the bulb it just blows air into the tank, so I now suspect the check-valve. Can these be purchased separately? Or do these come as a part of a carb kit?

homegrown55 (message 2),
We used very low air pressure in cleaning.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

You can get just the check valve for the carb. Problem is, that may NOT be your problem. If fuel is making it to the primer/purge bulb, then fuel is ALREADY in your carburetor. A weak vacuum in the carb would cause the engine to burn off ALL the fuel that the bulb was able to siphon and die lean. Do as Loger said and clean up the mini screen and all the little ports. There is another check valve in the carb Idle circuit. If it is not closing as it should, the action of the primer bulb will be inhibited and it won't draw enough fuel to keep the engine running...due to a lack of vacuum.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

  • Posted by baymee LehighValleyPA (My Page) on
    Mon, Aug 5, 13 at 15:39

With the water in the fuel or water absorbed into the ethanol, I've begun to see the tiny springs on the check balls become rusty and stop working. This in addition to the clogged screen. I learned the hard way....never blow compressed air into that area unless greatly reduced. The ball seats against a thin round disc of rubber and can be blown away.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

homegrown55,
Fuel is not coming into the primer bulb, just blowing air into the tank, which is why I'm suspecting the check-valve. Is there a difference between the black and orange valves? The only one I've seen offered so far is the orange. And, I will take it apart and do a thorough cleaning.

baymee,
I'm not seeing any signs of rust, But as stated above, I will take it apart and watch for that.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

Baymee....On what carbs did you observe the tiny springs and check balls? On the diaphragm carbs I only observed those on the nylon choke levers. An end user that owns a machine with these carbs only learns of check valves when it is too late and they have failed it seems.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

The orange or black check valve do the same thing. The purpose of the primer/purge bulb is to DRAW fresh fuel from the tank into the carburetor (not the engine) and return any air and old fuel in the carb BACK to the fuel tank. Ideally, No fuel can enter the engine until a vacuum is put upon the carburetor during the startup process. From what it sounds, you have a failed or sticking check valve in the primer base assembly below the bulb. The symptoms are it just won't draw fuel. I would suggest saturating the primer base ports top and bottom with some carb cleaner and/ or some WD-40. Then there is the issue of a leaking or stuck check valve in the Idle circuit of the carb Do you HEAR any air or gurgling or get ANY fuel in the throat of the carburetor when you push down on the bulb?


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RE: Walbro primer bulb appears to work, but no fuel is going to c

Did you see the testing and experimenting of the fuel systems? If so, what were your results? I feel that testing verified fuel in the carb or not. Proper passage and firing could be another chapter/challenge. The bottom line, there is always a solution or why the sys etc is not working. The question is, is it worth your time not to mention others? Minor or Major Problems, Experience or Not Related To Repairs. I send my want to be customers to the Best I know, I Have Retired !


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RE: Walbro primer bulb appears to work, but no fuel is going to c

I agree with Baymee within the ethanol issues being the basic if not contributing cause of your prime / purge bulb issues. These lower end Walbro GT Models on Poulan Units are very sensitive to ethanol fouling issues . Much like the Old Tecumsehs Carbs that Baymee services regularly on his blowers some equipment just does not run on ethanol fuel without regular servicing lol . The small checks just don't function well when stored for prolong periods or run more than 3-5 yrs on this new corn fuel . I has a few Weed-Eater units that were manufactured by Poulan in the mid 80's that had the GT series carb and they ran well for decade,s on Regular fuel and even unleaded . They would have not lived long on ethanol . Proper fuel treatment for storage is critical , All the Best !


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RE: Walbro primer bulb appears to work, but no fuel is going to c

  • Posted by baymee LehighValleyPA (My Page) on
    Tue, Aug 6, 13 at 6:09

homegrown...the checks in the primer section of the carb is where the ball and spring rusted. One symptom is that the primer bulb doesn't return when pushed in.

I know I have pictures of this, but I can't find them.....and I took them recently.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

loger,
I did see the video, and the primer bulb is not drawing fuel. I have ordered a new check-valve which comes with the top fitting or base it sits in (I don't recall, but I don't think the primer bulb comes with it--but the original bulb is sound).
Great idea about pix, more folks should be aware of this routine, I do this in breaking down laptops.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

Baymee Your pics are legendary on here.Could you try to find them and post them? I hope the OP Tipiford is paying attention...he seems to be. Do you find that the ethanol inflicted fuel causing the damage equates to a bigger problem with the ball check OR do you see some damaged valves themselves? Aren't they made of mylar or something like it? Pics of the primer base internals would shed a LOT of light on this common problem. I am seeing and hearing about it more and more from folks with diaphragm carbs on their lawn equipment. I hope a new primer base assembly cures the ills with Tipiford's Walbro carb. Many of those blower carbs do not even have a main nozzle, just the 2 or 3 ports in the throat.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

I finally have gotten around to replacing the carburetor (the check valve was $16, so I bought a new carb for $25--and have been too tied-up with other issues, so just now getting back to this repair project). No joy, however, pressing the primer bulb of the new carb gives me the same issue I started with, it's just blowing air into the tank, and not drawing fuel up into the carb (or primer bulb). I took out the tubing and checked that and it has no leaks. I now am wondering if the new carb is bad. I'm stumped.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

I finally have gotten around to replacing the carburetor (the check valve was $16, so I bought a new carb for $25--and have been too tied-up with other issues, so just now getting back to this repair project). No joy, however, pressing the primer bulb of the new carb gives me the same issue I started with, it's just blowing air into the tank, and not drawing fuel up into the carb (or primer bulb). I took out the tubing and checked that and it has no leaks. I now am wondering if the new carb is bad. I'm stumped.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

What is the make and model of the new carb? I presume it is a Walbro. If the new carb actually is NOT drawing fuel, then there probably is a stuck check valve in the Idle Circuit or the Main Nozzle. These are very small and unlike the one under the bulb. A valve stuck open causes this and the primer cannot produce the necessary vacuum needed to draw fuel because of it. If a carb has had a long shelf life, the check valves could be stiff, but they should still function after fuel hits them.

This post was edited by homegrown55 on Fri, Aug 23, 13 at 20:06


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RE: Walbro primer bulb appears to work, but no fuel is going to c

did you replace the fuel lines and the filter in the tank or at least clean the filter? If not you may have small crack or collapsed fuel line. if there is crack line it will suck air and not pull the fuel up to the carb.? E85 will eat fuel line up in 4 years or so. Crumble in in you hands what submerged in the alcohol in few short years.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

homegrown55,
"What is the make and model of the new carb? I presume it is a Walbro?"
Yes, same model no. as original, Walbro WT875-A.

rcmoser,
"did you replace the fuel lines and the filter in the tank or at least clean the filter? If not you may have small crack or collapsed fuel line"
Yes, cleaned filter, and as I posted, "I took out the tubing and checked that and it has no leaks"


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RE: Walbro primer bulb appears to work, but no fuel is going to c

I tried a hodge podge elixir of different fluids in the past to clean and/or remedy stuck check valves. The last one I did was an OLDER Zama Rotary carb on an Echo Power Edger. It had the RB-75. I used a combination of carburetor/choke cleaner, WD-40 and Liquid Wrench. On that carb, when you pressed on the bulb, it became hard as a rock and like yours no fuel entered the carb. I did not install a rebuild or gasket and diaphragm kit on this one. I had fuel supply line and fuel return lines connected and liberally sprayed inside them. I let the carb absorb the mix and let it sit. Push bulb, spray...let sit.Over and over I did this UNTIL, the primer/purge bulb started picking up the fuel and pushing it back out. The Echo ran great! If this method worked on an old Zama, it couldn't hurt on yours (if you care to try it).
A picture of your carb seems to show a brass main nozzle. Inside the nozzle is a check valve. If that valve is leaking; as I have stated befor the symptoms will be identical to what you are experiencing. The primer/purge bulb will NOT function correctly. All I can tell you is take apart the NEW carb and make sure all the parts inside are there and the gaskets are sealing it up. You could pressure test the carb with some compressed air too if you wanted. I think the check valve in the main nozzle is stuck open.
If all else fails, return the carb as faulty and get another one!

This post was edited by homegrown55 on Sat, Aug 24, 13 at 16:25


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RE: Walbro primer bulb appears to work, but no fuel is going to c

homegrown55,
"What is the make and model of the new carb? I presume it is a Walbro?"
Yes, same model no. as original, Walbro WT875-A.

rcmoser,
"did you replace the fuel lines and the filter in the tank or at least clean the filter? If not you may have small crack or collapsed fuel line"
Yes, cleaned filter, and as I posted, "I took out the tubing and checked that and it has no leaks"


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RE: Walbro primer bulb appears to work, but no fuel is going to c

Tipiford We received that post earlier today...this morning as matter of fact. Is there anything else you care to mention? Annoyingly, I find in THIS and other forums on here that the problem the OP has is NEVER resolved and that the OP (you Tipiford) leaves us all hanging as to what the final outcome is. If you don't post back in the future with an update we will NOT know why the Walbro carb malfunctioned.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

I guess when I went back to see if a reply had been made (this forum doesn't seem to alert you to updated posts) I guess I refreshed the page which caused the duplicate post, please forgive me, I've been around computers for a long time--as a programmer back in the DOS days--and should have been cognizant of the page I was on, and known better than to have refreshed at that point.
I will try the aforementioned 'lubricants' and report back as to the outcome. As to taking the carb apart I am hesitant to affect the warranty if it is, indeed, a defective part.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

Good point about the warranty, but it will probably be OK to open it up and take a look. Nothing personal about posters not posting back; but it helps users like me to understand what happened along with others that search for answers on the forum. I am still with you though, and would like to see this thing through.


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RE: Walbro primer bulb appears to work, but no fuel is going to c

I gave this machine away. Tinkering with it at 2-week intervals, I find I just don't have the time right now. Thanx for all the advice.


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