Hi, new here but certainly not new to working on my 10 year old Dixon 4515 ZTR. We use it a bit harder than a homeowner-grade mower probably should be used, but not crazy or abusive. The originaly Vanguard 16.5 (I think) threw the rod two years ago. I ordered and installed a 330000 Intek ELS 21 hp 540cc engine to replace it. Worked great with all the extra power, and in fact still runs great. But now in it's 3rd season the fuel pump got balky. I replaced the pump, figured out how they work after. Momentary crankcase vacuum I guess? Anyway, it is still having trouble. Runs/sounds good, but it starts fading under load, I can see in the filter that fuel supply is still the problem. The pressure for the pump comes from the dipstick tube. The tube seems well sealed top and bottom, no cracks in the hose. For grins I pulled the dipstick out and started the engine, oil came SPRAYING out the tube. This is not normal, I assume? Hard to believe my rings have already failed. Oil consumption is negligible. Any ideas? Thanks.
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B and S 330000 blow-by?
- Thread starter zman
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Export threadWelcome to LMF...
If you had pulled the dipstick at anytime you would have the same big pulse...
The crankcase is small relative to the piston size... every down stroke will produce pressure in the crankcase, every up stroke negative pressure... :smile:KennyV
If you had pulled the dipstick at anytime you would have the same big pulse...
The crankcase is small relative to the piston size... every down stroke will produce pressure in the crankcase, every up stroke negative pressure... :smile:KennyV
Yeah, I think I'm off course on this one. I've spent all afternoon on this and come up with nothing. Pulled the carb apart and it looks perfect. Plug looks perfect, by all indications everything is normal. Filter is good. Drained the gas and refilled with fresh, still pops and backfires under load.
When I first start up, it idles normal. I pull the bars up, bring the engine up to speed and turn on the mower, it goes OK for a few seconds, then starts to miss and backfire. If you go up any sort of hill, the engine starts to die. If you go real slow on level ground, things work more or less normally with a miss here and there. I even made a couple of attempts to bypass the pump and gravity feed under load, with the same result. I guess maybe an ignition problem, but it sure seems like fuel starvation. The clear filter has just a little bit of fuel in the bottom of it. But if you pull the line off the carb port on the pump, fuel squirts out when you crank it.
When I first start up, it idles normal. I pull the bars up, bring the engine up to speed and turn on the mower, it goes OK for a few seconds, then starts to miss and backfire. If you go up any sort of hill, the engine starts to die. If you go real slow on level ground, things work more or less normally with a miss here and there. I even made a couple of attempts to bypass the pump and gravity feed under load, with the same result. I guess maybe an ignition problem, but it sure seems like fuel starvation. The clear filter has just a little bit of fuel in the bottom of it. But if you pull the line off the carb port on the pump, fuel squirts out when you crank it.
taxidermist
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Is the fuel filter made for a fuel pump? sometimes when you replace the fuel filter it does not flow enough fuel to keep up with the demand of the motor.
Rob
Rob
It's the original filter that came with the engine when I ordered it. I tried running it with no filter just to make sure, and it runs the same. I never really paid attention before because I just hooked everything up and it ran, but when I cleaned the dust and dirt off the filter, I could see the filter had just a little bit of gas in the bottom of it. That's why I assumed the pump was bad and not keeping up. But the new pump had no effect. The fitting in the fuel tank just pulls out of a rubber grommet (you can jam a bolt in there to keep the gas from all leaking out). I pulled it and cleaned the screen, although it had no contamination, and checked that the fuel line was flowing freely when I drained the tank. Everything I've read about fuel pump malfunctions said they can often be traced to lack of crankcase vacuum. That's why I got worried about things when the oil came blasting out the dipstick tube. But the engine runs well, seems to have tons of compression and the plug looks beautiful. No sign of oil burning at all. So I assume that shoots down the rings/valve seal theory. I'm still on square one.
taxidermist
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Try a new set of spark plugs. I was working on a ferris z turn and thought I had fuel problems. It would start to miss under a load. I adjusted valves changed fuel pumps filters ect. It turned out I had a plug that as soon as it started to heat up it would miss. But with a twin cylinder you did not notice it until it was under a load. Its worth a shot and a cheep check too. Also take off your line from the fuel pump to carb and turn over the engine. If fuel pumps out at a good flow you know your pump is working.
Rob
Rob