# Vermeer 630b Stump Grinder Question: Bad fuel Pump or Other?



## StihlRockin' (Jul 17, 2013)

This 630b has been giving me problems. Sometimes it won't start or even fire. To get it going I have to open up the hose to the carb and put gas in manually. This most always works, then when it's warm and I have to turn off the machine, it will start up with normally no problems. It's the cold starts that kill me. Choking using the choke lever doesn't work. It works the butterfly in the carb, the flap that turns, just fine.

Also, sometimes when I put gas in manually I get it to fire and run for a few seconds, then it will die, but I fight it by using my hand to cover the carb opening. I disconnect the hose to the air cleaner and turn it straight up and this is where I pour the gas in.(about 2 table spoons) After engine fires and starts to run, then starts to die, I put my palm over the hose entrance and use it like a choke, except I can completely block all air creating more of a pull from the fuel line. 

The other day I put in a new inline fuel filter. This idea was installed several years ago and when I did replace the old filter for the new one, the filter actually filled up to about 90% capacity. I can see this because the filter is not metal but see-through plastic. My other filters almost never filled beyond 50-60% capacity and normally running with about 10% fuel capacity inside filter. However, after about day 3 of using the grinder, it is running(filter) and sometimes has less than 3-4% and it's so low and can't believe the engine is still running.

I thought since because I can see no air leaks happening it could be the pump. When I have had air leaks in the gas line, I can see a wet dusty spot where it's at, but see no evidence of such a leak now. Is it possible to have a leak in the line or connection somewhere and see no wet dusty spot?

This problem goes back to last year, but not sure when. I can get a new fuel pump, but it will be an electric one and would also have to get a pressure regulator all for about 1/2 the price of a new Vermeer fuel pump. I can also rent a pressure tester for the pump to see if it's pumping at the correct level. Having me ask these questions now can help me diagnose and troubleshoot the problem(s) better.

What do you think the problem is?

Oh, almost forgot to add... when the grinder is finally started and is running, it runs fine. It has stopped while in the middle of doing a grind about 4-5 times in the last 45 days. Recently it did this twice in the last week. I think the last episode of engine cutting off was due to lack of fuel in the fuel filter and not getting enough gas. 

Thanks,

*Stihl*Rockin'


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## Mowingman (Jul 17, 2013)

This is a long shot, but, check your fuel cap. It may not be venting properly, thus starving the engine for fuel. Try starting and running the machine with the fuel cap loose, or off. I have seen this problem on many engines.


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## elmostump (Jul 17, 2013)

I agree with mowingman I was having similar issues with my Rayco 1635 I'm on my 3rd fuel pump, last time replaced fuel cap and have not had any issues. I have also had to do the same on a blower and mower............I hate guessing and chasing problems but it will be an inexpensive part to replace. Plus I ALWAYS run non ethanol fuel plus seafoam and change fuel filter every oil change.


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## johncinco (Jul 17, 2013)

Pull your carb, clean the bowl, check the jets for obstructions. The filter does not have to show 100% full to be allowing enough fuel to get through, you can't see it but fuel is passing through. Check the needle to make sure it is not worn out, and slides into the shut off cylinder smoothly. Check the float to make sure it is sliding up and down freely.
I ran into the same scenario. I even went so far as to add an electric in line fuel pump that came on with the key. Small particles were passing through the filter, and jamming up the carb and surfaces. I got my fuel tank cleaned up, a carb re-build kit, and she runs great.


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## StihlRockin' (Jul 18, 2013)

johncinco, I was afraid someone would say that! I believe that could be a problem, but one I'd have to hire out. It'd be worth it though.

Others... Come to mention it, I lost my gas cap some time ago and bought one that fit from the automotive store. It seems to me it's seals up tight... no venting at all. Most every time I open the cap I hear a sound, but thought it was the vapor escaping. It could be suction. ??

What does a venting cap do anyway? And how can I be certain I get the right one... without ordering direct from Vermeer? Not worried about cost, just the time. I'd like to change it tomorrow if you'all think it's a problem?

What are your thoughts gentleman?

Thank you for the replies and help.

*Stihl*Rockin'


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## MSgtBob66 (Jul 19, 2013)

*Sounds like you need to vent the fuel cap*

StihlR,

That sound you hear is either pressure build up from gas fumes or suction from running the machine. You can vent your cap by drilling 3 small (1/16") holes in the cap until you can get the right one.

If you are hearing suction, then venting will help as you are starving your engine for fuel.

If you are hearing pressure, the vented cap will help save your fuel system from too much pressure.

Venting will help!

Semper Fidelis & Good Luck!

BOB


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## StihlRockin' (Jul 20, 2013)

MSgtBob66, Yes, I did talk to two people yesterday and showed them the cap and they say it's vented and explained to me how it works. I thought I was hearing suction, but it's pressure release. Thanks for the help and info!

==============

2 days ago it was hot... upper 80's and was grinding for hours. A mechanic mentioned it may have been vapor lock. Yesterday it ran sweet. Since then the machine has been starting cold without gas prime help.

The issue of the pump condition is still unknown. I will keep you guys updated as to what I find for follow-up and educational info, etc.

Thanks!

*Stihl*Rockin'

P.s. "Also, mechanic told me the amount of gas that was in the tank(1-1.5gallons) when the problem came up shouldn't make a difference. However, I filled tank and that seemed to me, again, that it did? Do any of you think it helps the fuel pump if the tank is more full than empty? If so, why?)


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## CalTreeEquip (Jul 20, 2013)

What happens with the Wisconsin engine is ethanol in the gas eats up the aluminum in the fuel pump and the carb. This can cause a hole to develop in the diaphragm chamber of the pump. Also aluminum power will start to clog the jet in the carb. The more it sits the worse it gets. Open the carb float bowl, if there is a white power in there then this is your problem. Replace the pump and clean the carb. Some people will install an electric pump, this will permanently fix the problem. I try to keep a spare pump on hand just because this is such a common problem.


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## StihlRockin' (Aug 1, 2013)

Pump has been working well lately, but it is the original that came with the machine, so realize it's probably on it's last leg. The electric pump idea is about 55-60% of a regular pump and am considering it.

Also found the gas cap was indeed a vented one.

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Thanks for the help gentleman. Will keep you updated when I get a new pump... if I do... as the engine is now going bad. :msp_sad: Will post on that for questions later.

S*tihl*Rockin'


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