proteus Posted June 28, 2006 Posted June 28, 2006 I have a Briggs 8hp #191700 motor on a '72 Broadmoor 728. Not too long ago I installed one of those clear NAPA fuel filters with the pleated paper inside. After riding for about 20 mins. the filter runs dry and the engine begins to sputter and die. If I take it out of gear it will recover but begins to die as soon as I apply load to the engine. I let it sit for a few hours and the filter fills up. Yes, when I choke it, she stays running better but not perfect. The other day I pulled the fuel line between the filter and tank and the flow was great even with the cap on. I took the tank off and unscrewed the elbow from the bottom of the tank to inspect it. The screen on the elbow was clean. I blew compressed air into it and it was clean. A month ago I found rust in the carb bowl and cleaned it out with steel wool and made sure it was perfectly clean before reattaching. Do you guys think this engine should not use a fuel filter? Am I using the wrong type of filter (nothing in the manual)? Do I need to pull the carb again and clean it out? How do I prevent the bowl from rusting inside if this is the problem? Or, is something going on that I'm just missing?
jlasater Posted June 28, 2006 Posted June 28, 2006 If you unhook the hose from the carb end, with the filter in place, does fuel freely flow out as well? I don't run a filter on my 716H and haven't ever had a problem. I'm more concerned with super clean fuel in fuel injected engines than carburetted ones.
proteus Posted June 28, 2006 Author Posted June 28, 2006 No, fuel doesn't run out when I disconnect hose at the carb end. I use a filter because I didn't trust the screen in the fuel tank. Now that I've inspected it, I guess I should trust it. Looking on the B&S site, I see that there are specific filters for gravity feed and engines with fuel pumps. The gravity feed is a 150 micron filter which probably lets fuel flow better. I'll bet NAPA gave me a filter meant for an engine with a fuel pump and the fuel can't flow thru it fast enough to keep up with the demands of the carb.
IronPony Posted June 28, 2006 Posted June 28, 2006 After having read this thread, I think you have found your own answer. Buy car parts from Auto Parts stores and small engine parts from small engine dealers/stores. Also find them at ACE Hardware and others like Lowes, Home Depot, ranch and farm stores and etc. Dan aka IronPony P.S. I looked at those same filters at a NAPA store and just thought they did not seem right for my AC716?? Could not put my thumb on why I thought that. Now I know^
HubbardRA Posted June 28, 2006 Posted June 28, 2006 The problem is that most automobile filters use a very fine mesh, since the fuel pump is able to push the fuel through it. A gravity flow system does not have the pressure to push much fuel thru that type of filter, so it flows very slowly and will starve your engine of fuel. I use the little B/S filters, only about one inch diameter and 1/2 inch thick. They seem to work fine. They are made for gravity flow systems.
D-17_Dave Posted June 28, 2006 Posted June 28, 2006 The talk of a diffeerance in fuel filters is right. However you should see fuel inside the filter on the tank side of the mesh even if the mesh won't flow the fuel well. Sounds to me as if you have a flake of trash in the fuel tank floating around partially blocking the flow after running for awhile.I've seen it take several atempts of blowing a tank out to remove the built up debris in a tank.
proteus Posted June 28, 2006 Author Posted June 28, 2006 The tank is clean. No floaters. I think the carb is using up the fuel in the filter and it is getting displaced with air which is pushing back on the fuel trying to flow in from the tank via gravity. Basically the filter is becoming a big bubble in the fuel line. If the flow is faster, air from the gas and back from the carb do not have time to displace the gas in the filter and therefore the bubble never forms.
D-17_Dave Posted June 28, 2006 Posted June 28, 2006 An air bubble isn't uncommon and can be trapped in the filters and not hurt anything. What we can't see is how well the flow is going through the filter under load. So if your comfortable that the tanks clean, I'd put a small engine filter on it and go. That should fix you up good to go.
dirtsaver Posted June 29, 2006 Posted June 29, 2006 I'll add my vote on the type of filter also. Strange as it seems, the larger filters just don't work on small engines,for the reasons stated above. If you read the package on the little red B&S filters they tell you they work on engines up to 16hp without a fuel pump. Take that to the bank! Coming from one who's been there and has the teeshirt!
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