| Author | Message | ||
| Ralph Peters (Ralph7)
Registered Member Username: Ralph7 Post Number: 35 Registered: 3-2004 Posted From: 206.251.9.109 Rating: N/A |
My old 5.0, will not hold rpm. Adjusted float several times. Need to have the choke near fully closed. It is a 2 cylinder/1800rpm. Replased points an condensor. It warms up, runs 2-4 min. then, like no fuel, govenor opens full throtle and it my keep running. But it needs the choke on at normal running. This is a 1978 with 410hrs, mid range fuel an carb cleaner. I installed a new fuel pump, no difference. Fuel boul was clean, it has a maual fuel shutoff an engine was run till it quit. AND I do not like to work on small engines.....But I will tinker with it. | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 287 Registered: 1-2009 Posted From: 24.129.232.232  Rating: N/A |
-sucking air in the fuel line before the new (assumed working pump)? - - easy test is to bypass - use a gas can, run a hose from the intake side of pump into gas can, raised at same height as chassis tank. - - - if no difference , then do a pressure / flow test after the new pump. opening the chassis line up might allow air into the gas supply system , if it runs other devices. fuel shut off valves before the pump tend to leak air, after the stem seal drys up with no fuel in it. so bypass this with the test can of gas first. I to dislike them wee engines... but getting beyond my prejuges, they are similar principles for diagnostics. + next guess would be stuck float assuming the spark is good and timed well ( oil on points, shorting out on engine, bad condenser, low oil shutdown stopping power feed to points... may this night be cool for you , take a crack at it in the morning, after a good breakfast. I might have specs & schematics manual at the shop (not till Tuesday) if you need them for a 1975 ck series . | ||
| Jim Wallin (Powderseeker01)
Registered Member Username: Powderseeker01 Post Number: 31 Registered: 10-2008 Posted From: 208.68.48.77  Rating: N/A |
Or you could save yourself some future trouble and convert it to propane. It's pretty easy and the engine will run better and cleaner. | ||
| John and Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 228 Registered: 9-2007 Posted From: 96.42.7.186  Rating: N/A |
I don't know how old your conversion is, but I have had several fuel supply hoses go bad inside and partially block the fuel supply. That is something that may show up in the tests that Clint advised. | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 876 Registered: 7-2006 Posted From: 75.209.65.18 Rating: N/A |
Sounds like an air isue to me..BTDT.   RCB | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 288 Registered: 1-2009 Posted From: 24.129.232.232 Rating: N/A |
.over the long term plan, JW sazzzzs it "write", provided you run enough propane appliances to warrant a big tank. ..one of my concerns on conversion, heard through the grape vine, $ is that propane is not so easily found down there $; any validation or denial of this rumour is welcome. <with a big enough tank, it should be feasible to get home delivery for those times of prolonged parking or immobility. I know this use to be common practice; any update on this practice. <It is always possible to patch in a portable tank or patch in a very large portable tank that they deliver, just make sure any modifications to your system is safe & certified ! There are far too few bus nuts too loose to reckless prevental incidents, and far too many buses getting lost due to our shortage of us(es ), in my biased opinion. ... having done big vehicle propane conversion to dual fuel, I have no experience on small engines as far as advanced timing curves modifications (for efficiency), perhaps someone can share there intimate knowledge on small engine propane conversion and good kit sources to install. Details such as liquid versus vapor , ideal compression ratio candidates,dual fuel systems, etc . etc. .... seems to me the over-sized Onan CK series would be a good candidate , despite its low compression, as it is oversize enough to deal with the reduction in peak horsepower potential. ..... if one were ever inclinded to try heat scavening from the cleaner (but still deadly CO2)exhaust &/or cooling stream; burnt propane condensate is much less of a challange, as it will not carbon up the system as it cools , being almost free of "free carbon particles" unlike stinky gas or diesle exhuast. The technical issues are many, so this ideal is not for the novice macgyvers or tinkers due to the extreme risks with deadly gases, fire issues & system synergy in the "napkin sketch designer". But then the first one of anything is always a challenge to get working well, and in this case the odds are not waisting as much of your 66 % heat. I know , it is just as easy to drive south when there is demand for that heating, but what we do here first does have spin off benifits, not completely unlike all that ingenious effort waisted on created better killing machines in the Ind.Mil.Comlex . -"make good machines that save life, not just killing machines to take life " it makes for a more sustainable economy & more logic, at least in my universe. Peace out & bus on humans ! | ||
| Jim Wallin (Powderseeker01)
Registered Member Username: Powderseeker01 Post Number: 32 Registered: 10-2008 Posted From: 173.14.23.49 Rating: N/A |
My generator runs both gasoline or propane. The propane conversion consists simply of a supply block which admits the propane vapor into the intake air stream from a demand regulator. A second regulator on the tank maintains the 10" water column vapor pressure required by the demand regulator, which is the same as most propane appliances and grills. The rest of the carb is simply not used in propane mode. The main consideration is that the surface area of liquid propane in your tank must be sufficient to supply the device you are running or your tank will freeze. | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1669 Registered: 12-2000 Posted From: 76.69.143.60  Rating: N/A |
I'd be thinking fuel varnish/gumming. Did you do a full tear down on the carb? My small engine mechanic friend makes most of his money simply tearing down carburetors, cleaning them and resetting to spec. The occasional decayed needle valve, but for the most part, its all gum in the tiny passageways. His best advise, all the time, every tankful, use name brand fuel stabilizer in all your casually used gasoline engines, mixed exactly as specified on the container. Cheap insurance for reliability. happy coaching! buswarrior | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 292 Registered: 1-2009 Posted From: 24.129.232.232 Rating: N/A |
yes that is always the next step , once supply is confirmed, as it can often be hard to get to them crusty little breaking bolts on these setups. well actual, being lazy and all about things I don't enjoy, I usually mix a bit of fuel cleaner into the test can first, open the float bowl drain to get it in there and confirm flow (stuck float valve) while flushing it out. ~Not fixed yet, go for tea and let it sit for a while, then try again . Don't burn out the starter either. ~~ As a last resort use corrosive spray can carb cleaner in a can (with eye protection) it may be sprayed into the needle valve chamber and anywhere else you can get into; with the risk of dissolving gasket, seals & float needles along with gum, but not dirt or metal dust, if left to sit for more than a few moments; but then you would probable need to rebuild the carb anyhow, so no big loss. -(if you not sure it is broken, break it and remove all doubt, then repair it and move on to the next bit of doctor like guess work). I guessing you remember that one from your apprentice days BW ? Pass on my appology to your freind along with my way, he might not take as long for repair, but then he could make up for it in volume: less junk thrownout because it is too expensive to fix / more junk that is worth fixing = a more sustainable truth & a better thinking conscience in all our ways. {complement verus compete} is my main point then ! | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1586 Registered: 10-2003 Posted From: 71.58.110.9  Rating: N/A |
How about removing the carb and have a local good small engine shop do a proper cleaning with a new set of gaskets and needle/seat. Sounds like your main jet is partially plugged with varnish. Very common on small engines from the way you describe it. We clean a lot of these carbs from lawn mowers every spring, because the old fuel isn't drained; especially if it sets for a few years. Quite possible that a carb kit may be available from NAPA if you get the correct numbers. They aren't costly since they have few parts in them. Dis assembling and immersing in carb cleaner works best to remove all the varnish in the small passages. | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 980 Registered: 11-2005 Posted From: 208.54.200.45  Rating: N/A |
Ralph, I had the exact same thing happen to my 2 cyl lawn tractor recently. I took apart the carb, sprayed all the orifices with carb cleaner and blew into all them with low air pressure. I was up to running it with almost full choke. My theory is that the power jet was clogged which make it run too lean. I also blew out the fuel line filter using the same system. Works normally now. For future reference. When I first got my bus my same year old Onan would run for a while and then just stop. After a bit it would start again. I found that the points had almost no gap at all, maybe none. I never could figure out how it ever ran at all?? | ||
| Ralph Peters (Ralph7)
Registered Member Username: Ralph7 Post Number: 36 Registered: 3-2004 Posted From: 206.251.12.226 Rating: N/A |
OK Points an cond new last week, adjustment on points was good, but I redid them after a 10min. hot run. Paralled a light on the electric fuel pump, may still need a new relay for the pump, which one there are two. I have done some old mower carbs this summer and it helped them. Have had the top off the carb an cleaned an put cleaner in passages,but next to get gaskets. Needle an seat like new and no sticking, float ok. I was a power house operator, 550KW and 1000KW, some of you may know those units. As for propane it's for my hot water, 24in. apartment stove in bus, cat. heator, and outside grill. | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 297 Registered: 1-2009 Posted From: 24.129.232.232 Rating: N/A |
~fuel good , carberation good & correct calibrations including the float level, spark good ( secondary KV & timing/ dwell), (once had a similar mystery in a ford 360, the points were intermittently grounding where the condenser wire was screwed to them,also had just enough distributor bearing slop to make this possible, easy to find with a scope , but not see easy when you can not even see the primary spark location ) no big vacuum leaks. { you might well imagine why I START with "cleaning the fuel system shortcut" before I introduce other variable to the guess work.) ~~ now it is time to do a compression test and interpret those results (wet & dry). Stuck or rusty rings not sealing, bent valve, dry sticky guide crap on the valve seat. >The biggest problem I have with old small engines in tight places is re-taping those studs holes after I manage to extract the broken studs, and matching up parts , as is the case with all obsolete junk. Just four bolts ehy ?< |