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Discussion Starter #1
My generator will not crank. I normally run it at least once a month for 15 minutes, or so. I use standard 87 octane gasoline, which has ethanol in it, with Stabil. A month ago, I went to crank it and it did this.


I've tried:
confirmed that the air filter is completely clean
changed out the gasoline
disabled the low oil kill circuit
removed spark arrestor, which was not obstructed
tried running with the gas cap off (to test for vacuum problem)
disassembled and cleaned the carburetor/jets, which was pristine; no gunk

Might anyone have any other suggestions?
 

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Welcome to the forum! You've checked a bunch of stuff, which is great info, but have you tried just the basics?

- Does adding choke make it better, or worse?
- Have you checked for spark, by laying the spark plug against the engine block (cooling fins, etc), and watching for a bright blue spark while pulling the cord?
- Will it run using starting fluid, carb cleaner, or splashing a little gas into the intake? With the air filter removed, of course.
- Have you checked compression?

Your carb work *should* make sure you're getting a proper fuel mix. But maybe you have a clogged fuel filter, or defective shutoff valve, etc. So giving it a definite fuel supply by spraying/pouring a little into the intake, is a good idea. That way you know you have fuel. Then you still just need compression and spark, to complete the required combo.

Are you getting good fuel flow to the carb, if you briefly pull the fuel line off the carb?
 

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Discussion Starter #4
I'm sorry for leaving out the following info:

- The generator only runs on full choke. Moving the choke out of full choke kills the engine immediately.
- I have checked the spark plug and it has good spark.
- The carburetor does indeed have great flow. Even before disassembling it to clean, I unscrewed the bowl plug and watched a solid stream flow out continuously.
- The shutoff valve works correctly; I used it with the hose pulled off the carb for draining old gas. Closed and open both work correctly.

- I have not tried starting fluid. I will try that.
- I have also not checked for compression. I need to lookup how to do that.

Thank you, RedOctobyr, for the input.
 

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Discussion Starter #5
A bit more info:

The generator has under 40 hours on it (it just looks bad because it sits outside under a shed).

Whenever I run it, to turn it off I disconnect any load and then turn gas shutoff to OFF and let it burn all the gas out of the carburetor.

I've read about compression-checking and found that I need to get a tool to do that. I'll do so on my next trip to harbor freight.

I also will need to get some starting fluid, as I have none on hand.

I will update, and I appreciate your input.
 

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Sounds like you have an issue with the main passage in the carb. & the direct passage (choke) is starting to clog as well. Probably time for a new carb. they can be found on ebay & amazon for cheap just might have to get the part number off the old carb. may even have to do some part number cross referencing...
 

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You can use just a little splash of gas, or a spray of carb cleaner, or some other flammable spray, if you don't have starting fluid handy. I think some people have used WD40, but I've never tried that, not sure how flammable it is now.

If adding a separate fuel source (like starting fluid) lets it run briefly, that's great, then we know you have a fuel problem. But it could still be something else, like low compression, some sort of a valve problem, possibly something less-likely such as an ignition timing issue, etc.

As Matt1097 said, I would make sure that the main jet is clear, and isn't partially restricted due to corrosion, a piece of grit, etc. You can do things like running a copper wire strand through the jet to help make sure there't nothing blocking it.

If the testing points to a fuel problem, and cleaning doesn't help, then a new carb is definitely worth considering, if you can find one at a good price.
 

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Yes you are right, cheapest thing would probably be the compression tester from HF, I have been around alot of high performance small engines & also seen alot of cheap chinese engines, he said when it was running it would only run on choke which is why I was leaning towards carb. issue.
 

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Compression tests are good, but unless the number is *really* low, it doesn't necessarily indicate mechanical problems with the engine. Most engines have a compression-release, to make them easier to pull-start. This artificially lowers the compression reading at low RPM.

So even though an engine might make, say, 100 psi while at operating speed, you might only measure 50 psi at pull-start speeds, since the compression release will be engaged. Therefore the low reading doesn't necessarily mean you have a problem. I have an engine that make around 90 psi using the electric starter, but only measures about 40 psi will the pull-starter. The valves are adjusted correctly, the cylinder bore is good, and it makes good power, so I'm comfortable that it's "healthy".

Do you feel "normal" resistance on the pull cord? And distinct resistance when you get to the compression stroke? A compression tester is a good tool to have around, but I don't want to accidentally make it sound like some $20 item is required to check out your engine. Starting fluid, or a splash of gas, is a cheaper place to start. Especially if this problem suddenly appeared out of the blue, which would seem unlikely to be compression-related (unless like a valve is suddenly sticking).

If you have feeler gauges, you could remove the valve cover and check/set the valve clearances.
 

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Based on what I've seen here it's not getting enough fuel. Try removing the carb bowl then with a small screwdriver remove the jet (up inside the carb). Use carb cleaner (soak it for awhile) and blow it out good and make sure you can see daylight through it. Re install and test run.
 

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Discussion Starter #11
I purchased a new carb on ebay. It arrived today and I swapped it out. With the new carburetor, the engine does the exact same thing.

I'm considering installing some 5.56mm vent holes throughout the entire generator. It probably would not help the problem at all but I feel like it would help me.

Any more suggestions? Thanks again for all of your input to date.
 

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Did you try the starting fluid/carb cleaner/whatever test, to see if it will run from a spray of that? And will it keep running a bit longer with another spray, after it starts?

If it will keep running longer with more sprays (don't do that indefinitely), that implies a fuel-related problem. And if it still dies the same way, even with adding some other spray to run on, that would make me think it's not your carb.

Is it possible that you have an air leak around where the carb attaches to the engine? If "raw" air is leaking into your mixture after the carb (at the intake manifold gasket, etc), that will make your mixture artificially lean. One way to check for this is to spray carb cleaner around where the carb mounts to the engine, while running. If the engine sound changes, you have an air leak.
 

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Discussion Starter #13
I tried adding some starting fluid and can tell no difference at all.

I did find that after it started the first time (and ran like before, in the video) it will not restart. I have to wait for it to for gas to drain outta the carburetor or for whatever happens over the next few minutes to let it start again.
 

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If adding starting fluid doesn't change anything, especially after changing the carb, that makes me think it's not fuel-related. Will it keep running if you get it to start, then spray a bit more into the carb's intake as it begins to stall?

Are the valve clearances adjusted correctly? Are they operating properly, nothing sticking, etc?

I think you said testing the ignition shows a nice bright blue spark. I guess your ignition timing could be off due to a sheared flywheel key, though I'm not sure if that would make it start, then immediately stall. I'd expect it to either not start at all, or keep running, but poorly. And something would have needed to cause the flywheel key to shear, which is less-common on a generator. You don't really have instant-stops, like a lawnmower blade hitting a rock, etc.

A compression test would be worthwhile at this point, I'd think.
 

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I should have mentioned: I did a compression test and got about 42 psi (between the 40 and 45 marks).
That's very low... That engine has an 8.3:1 compression ratio and I would expect to see >60psi pull starting and >100psi electric starting. Was the choke open and throttle set on full? Time to check the valves...
 

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Like I mentioned in post #9 , though, I've gotten readings around 40 psi with the pull starter on a Tecumseh OHV engine that seems to be in good health. Valves adjusted, and cylinder bore good.

What you're seeing may simply be from the compression release. Is there an electric starter? I do agree with at least checking the valves, though.

I guess you could pour a little oil into the cylinder, and test again, see if you get a higher number with the oil sealing things up better.
 

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What you're seeing may simply be from the compression release.
On engines with a compression release mechanism, you're supposed to defeat it by rotating the exhaust valve rocker arm and removing the push-rod before taking the reading, in addition to ensuring that the choke and throttle are fully open to allow full intake of air.
 

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Interesting, thanks, I'd never heard that.

I guess you could also just loosen the exhaust valve's adjuster nut some.

Enough that it maintains a valve gap even as the piston comes up on the compression stroke (when the release engages). There would be no need to remove the rocker entirely, or to remove the pushrod, but you could still accomplish the goal, and the engine would also be able to run in that condition.
 
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