No throttle response

[andywehrle]

A little over a month ago I posted a question abt a minor engine surge and lack of throttle response. Several of you were kind enough to respond with several suggestions. Thanks for that.

Unfortunately my vocation overrode my avocation right after that. At any rate I finally got the time to drain the fuel filter and remove and clean the carb. Reinstalled the carb this past weekend and the engine started.

But now, where before I experienced some small surge, then engine RPM increase with no change in throttle setting, and eventual shut down with popping - now the engine starts and runs at 1000RPM but does not respond to throttle. The throttle lever on the carb moves in response to the movement od the throttle so the cable is good to go. And the choke works - the engine smooths out after starting and closing the choke.

Electric fuel pump.

Hmmmm.....

[hanleyclifford]

When you say the throttle does not respond do you mean in neutral or in gear? When you increase the throttle does the engine bog down or backfire?

[andywehrle]

After reinstalling the carb I ran the engine in neutral. The engine did not respond to either throttle or choke. After about ten minutes the engine stumbled and died with a small pop.

[hanleyclifford]

That suggests fuel is not being delivered to the main jet. Remove the drain plug and note contents of bowl. Be careful not to drop the plug.

[andywehrle]

OK. Will do. Will post results as soon as I can. Thanks.

[andywehrle]

OK. Drained the carb bowl and got about two ounces of clear, clean fuel. Reprimed engine and started. Any time I put it in gear the engine died.

I'm thinking I didn't get the carb completely clean when I pulled it. So I'll pull it again, take it to a local garage and get them to put it in a bath of cleaning fluid and then completely rebuild with new jets and seals.

Results to follow.

[hanleyclifford]

If you got two ounces of clean fuel out of that chamber then your needle and seat are functioning. Next look at the main jet and discharge nozzle. It may require compressed air to clear them but I doubt if you need any kind of a rebuild but you may need a new gasket after several disassemblies.

[sastanley]

Andy, you can buy a gallon of cleaning fluid with a basket at the local parts store for about $20...Any Napa, Autozone, Advance or similar should have it.

When I was cleaning my carb, I was not able to get the jet out, I just put on some safety glasses, checked out the Moyer carb diagram and sprayed liberally!!!

[CalebD]

I am really no expert. Sounds like you have clean fuel, which I do not have at the moment and causes similar symptoms of fuzzy throttle response.
You wrote: "and eventual shut down with popping - ". I hope it is just a carb issue for your sake and one of your 'jets' are clogged or partially so.
Another system to consider is the exhaust system. If there is a blockage in the exhaust or water lift muffler there could be enough back pressure to cause some unusual operation with eventual shut downs.
Fuel pump? I am also not an expert in this area. If you had a few ounces of fuel in your carb that sounds normal to me.
Another idea to consider is if you inadvertently took on some diesel fuel in your tank which would also cause some smoky exhaust, most likely.
Another remote possibility is that there is a leak of gases from your exhaust system that could help to shut the engine down once most of the O2 has been burned up.
Do you run your blower normally?
Do you routinely smell engine exhaust smells?

[andywehrle]

Thanks so much for all the helpful suggestions.

I decided to rebuild the carb. Did so, to inclement immersion in a cleaning bath. Reinstalled today and...drum roll please...throttle response is still weird.

The engine starts fine but throttle response is nonexistant. The engine runs at 1000 Rpm no matter where the throttle is.

I let the engine run just to get it up to operating temp and twice it surged to 2000 rpm - with no change in throttle setting - and then settled back to 1000 rpm.

So carb is good, fuel filter has been drained with no sign of crud - so I pulled the electronic fuel pump and will replace next week -- I hope!

Looks like my goal is to get it running before I have to winterize the dang thing.

[hanleyclifford]

The time has come to have a check of exhaust system. Test back pressure with gauge if you have one. Otherwise it will be necessary to work thru system looking for blockages or possible collapsed inner wall of hose. First place to look is just where the water is injected into the exhaust.

[ndutton]

Along HC's line of thought, you could remove the exhaust hot section at the manifold flange and give her a test run. It'll be noisy and wet but it will instantly confirm or eliminate the exhaust as a problem.

Are you sure the carburetor butterfly is working properly??

[Bill Litke]

I found once that closed points act a lot like a faulty carb. Pop off the cap and check the gap. I have since switched to electronic ignition. It's wonderfully maintenance free.

[sastanley]

Bill,
I can recall this as well...the car would just slowly die like a carb problem.. My '78 Honda Civic had points and they liked to periodically 'close up' on me (stripped adjustment screw) - I got to be pretty good at road side repairs to get going again..

[andywehrle]

Really appreciate all the help.

If replacing the electronic fuel pump doesn't help then I'll check out the coil and exhaust system.

But help me out - how in the world is the exhaust system related to what appears to be a fuel or ignition problem?

The carb was just rebuilt so the butterfly is good and I'm running an electronic ignition so there are no points.

Thanks again. More as I can report.