Do you bypass the fuel pump with a zenith???

I bought a 4000 SU Gaser. It had some issues with the holley so I talked them into putting a zenith carb on it for me. They did put a rebuilt one from Wengers on it as well as new points and condenser. Ran awesome! Way more power than my worn out 3400.

So they said they had to remove/bypass the fuel pump because it would flood the engine using the zenith. I couldn't find reference to that in the forums but took their word.

I got it home and went to go straight to work with it. Drove it down to get my plow and let it run while hooking up. It stalled out after running a total of 10-15 minutes. Wouldn't restart. Eventually did holding choke full out and limped it back. After dinner I noticed the carb was spewing gas from the top. Drained it and rapped with a rubber mallet. Seemed to work. So next day again went to work with it with it assuming it was now fine and same - died after about 10-15 minutes and couldn't get it started at all this time. (Carb not flooding this time)

[b:2c3a8f9e6d] I'm assuming maybe ignition or coil but I question whether the fuel pump should have been bypassed?? And it's just running out of fuel?? When it runs it runs strong- when it got closer to 10 minutes it really struggled under load.
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It's a 2-hour haul to take it back one way. Which I'm already waaaaay behind in my work without a running tractor.

Thanks for your thoughts and advice.
 
So they said they had to remove/bypass the fuel pump because it would flood the engine using the zenith....After dinner I noticed the carb was spewing gas from the top.

Should not be that way - I'd say there is a carburetor problem - these tractors need the fuel pump since the fuel tank is only slightly higher than the carb. The fuel pump is a low pressure unit and a functioning float/valve system in the carb should hold against that modest pressure.

Often times the engine will run without a pump if the tank is near full and the load is not high - I doubt you'll be able to plow tho.

Maybe call Wenger's and talk to them and see if they will warrantee the carb. I would place no faith in the mechanic that got you into this position. I doubt you'll be using this tractor to plow anytime soon - sorry.
 
My 3400 runs great with the zenith and the mechanical fuel pump..

Im confused why the carb has gas coming out the top of it and why it ran with the choke.

Did they put a fuel filter inline before the new/rebuilt carb?
 
(quoted from post at 05:22:07 05/10/18) My 3400 runs great with the zenith and the mechanical fuel pump..

Im confused why the carb has gas coming out the top of it and why it ran with the choke.

Did they put a fuel filter inline before the new/rebuilt carb?


I am super confused too. I'm guessing the float got stuck and with no pump as a check it just over filled the carb. It was primarily dripping off a screw I believe on the back side top of the carb (toward the engine). Maybe it has a vacuum leak as well?? There was also a smidgen leaking out a pin hole in a circular depression on the top outside of the carb. I'm thinking that the stuck float is a seperate issue and by bypassing the pump it's running out of fuel. No inline filter, They simply put a sediment bowl straight in the side of the carb at the inlet with the gas line straight from the tank to the sediment bowl. The sediment bowl is aluminum so I cant see if it is full. It runs fine for 10-15 mins so I'm not sure a vaccuum leak is the issue but could be a partial issue??
 
Try running it until it has the problem and then loosen the gas cap. If that lets it run good without waiting then the gas cap isn't the proper vented type or the vent is clogged. If loosening the cap doesn't help and you still have to wait before it will start again then it sounds like the coil is going bad.
 
(quoted from post at 07:30:44 05/10/18) Try running it until it has the problem and then loosen the gas cap. If that lets it run good without waiting then the gas cap isn't the proper vented type or the vent is clogged. If loosening the cap doesn't help and you still have to wait before it will start again then it sounds like the coil is going bad.

Forgot to mention i did try to loosen and even remove the gas cap. No difference. I do suspect the coil or ignition and have both to try. I am just very leery and suspect of bypassing the fuel pump. I didn't know if this was common practice with the zenith. I just brought the tractor home from the dealer so can take it back if it's going to be a lot of troubleshooting and carb adjustment. I can bolt parts and wire but usually screw up a good carb.

Thanks
 
there is a screen in the fuel tank on the valve, you could check it and make sure it's clean.

I think it would be a mistake to do anything to the carb - you'll void anything resembling a warrantee. Make the responsible people (dealer/mechanic and carb rebuilder) make things work.

use the archive search and you can find threads about replacing the mechanical pump with an electric - I have doubts you'll be able to do real work with this machine without a fuel pump.
 

The screen is clean, tank is clean. Pump and steel gas line is still on the tractor, just plugged off with screws and a new rubber line from tank to sediment bowl/carb. I've never heard of anyone bypassing the pump and couldn't find anything stated as such in the archives which is why I bring it up for all of your expert experienced opinions. If anyone has done it and it worked ok, let me know. I want to avoid 2 lost days hauling and another week or more waiting without it.

I just got home from work and it started right up. Put it in 4 high on a slope and it took right off. We r getting storms so I just got to some cover. Ill try to replace the ignition and coil when they pass.
 

I bypassed the ignition and then the coil and same thing. Died at about 15-20 minutes at idle. Took the sediment bowl off and while it had fuel in it, it seemed too low to get into the carb. I turned the fuel back on and it ran freely out of the line. After sitting for 5 minutes it fired right off and ran up the hill. So almost has to be the bypassed fuel pump - not enough fuel flowing to keep it running. My guess is that the float was sticking on them and they blamed it on the fuel pump thinking it is a newly rebuilt high flow zenith carb?? So I guess I'm hauling tractors instead of driving them the next 2 weekends.

Still interested in others thoughts on that pump bypass???? If you have ever heard that was necessary with a zenith?
 
(reply to post at 03:07:47 05/10/18)

- When fuel is spewing out the carburetor that is a sure sign the float valve is not closing. I read your post to say you drained the carburetor. If you indeed removed a drain plug (assuming the Zenith has one (?)) in the bottom of the fuel bowl, then you likely corrected this problem. When changing fuel lines etc. there is always a risk of introducing dirt which can get caught in the float valve. Draining the carburetor bowl opens the valve fully, many times allowing the particle to pass through - end of problem.

- When the engine runs better with the choke on it is a sign the carburetor (engine) is not getting fuel. Since you no longer have a fuel pump - fill the tank to the top and see if the problem goes away. Also, I have seen gravity flow fuel systems be sensitive to engine heat. Next time the engine stops, spray the fuel line and carburetor with cool water. A simple spray bottle will suffice - just cool off the carburetor. You stated there is not an inline fuel filter. An inline filter can be problematic however, I don't believe it is required for the problem.
 
(quoted from post at 07:43:32 05/11/18)
I bypassed the ignition and then the coil and same thing. Died at about 15-20 minutes at idle.

Not sure I understand how you bypassed the coil? Did you have another coil?

Yeah I ran a wire straight from the battery to a brand new pertronicss coil. Made no difference whatsoever. I feel pretty comfident now that its just running out of fuel and gravity cant keep up. I picked up a 1-3.5 psi electric inline universal fuel pump(34 gph). Figure if the dealer is right and the fuel pump was flooding the carb I would meet in the middle with a low psi pump. I will run it tomorrow and see what happens. The pump is far cheaper than hauling the tractor back and forth that far. Since it runs great after sitting I don't think it's the carb, just a starvation issue from not enough fuel. I had 5 minutes when I got home from work before i had to pick up my daughter so I hit the key and it fired right off with no choke.
 

Well gentlemen, I am exceptionally relieved to say that the pump completely solved the problem. It is plowing just fine for past hour. I put the inline pump on and bolted it to the outside of the silonoid and grounded it there and ran the hot to the silonoid coil wire. it was the easiest place to put it and it's only on when the ignition is.

Now I can finally get caught up on some things. When things slow down again I can then start to transition over the loader from the 3400. [b:b3d5bed2f7]This site is great and so are all the guys who take the time to help- and with great patience... Thanks to all.[/b:b3d5bed2f7]
 
Glad to hear you got it solved. And thanks for posting back with the solution. Lots of folks come here and ask questions about a problem and we give them suggestions and we never hear from them again so we don't know whether they ever solved it or which suggestion might have been the one that did solve it, so it's good to get feedback on what the solution was for folks who come here in the future who might have the same problem.
 




Also.. a new carb can get plugged up in 10 seconds.... if you have trash in your lines or tank!!!!!! Now who do you blame for that? Its not the sellers fault.
 

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