Keep that sediment bowl clean

[PFord]

So late last week I decided to begin to address my battery situation on the 75 Cub. Posted about it here. Got the battery turned around, hooked everything back up and she started and then died. Add a bit of choke, same thing. Full choke, same thing. Uh oh. What did I screw up? Pulled the battery back out, took a look at my ground, took a hard look at the positive cable. Both were suspect but voltmeter showed I was getting good flow. OK.

Anxiety starts to set in. Did I fry the voltage regulator trying to polarize the generator? Did I fry the generator? Both seemed unlikely but possible. So I got all new stainless bolts for the battery box mounts, cleaned everything, sanded the grounding spot, put a new post terminal on the positive battery cable. Made sure everything was tight. Meter shows everything OK. Cranks great, but falls over unless I get the choke into JUST the right position. Runs at any engine RPM as long as the choke is withing 2mm of being fully closed. OK. If I need to nearly choke off all the air to get it to run, but it runs at any throttle, tells me I have a fuel blockage somewhere. Do some light tapping on the carb but nothing. Anxiety starts to set in again. Do I need to do a carb rebuild (yes, but maybe not now).

So then I start eyeing that dirty sediment bowl that I hadn't tackled. I hadn't wanted to take it off because I was afraid the gasket was toast. But I couldn't even see through it because it was so cloudy. So today on lunch break I decided to take it off. No amount of pliers or other stuff would budge it. Now I know why it was so filthy. Likely no one had been in that thing in years! Finally had to resort to a hammer and flat blade screwdriver to tap on the knob and finally got it to break free. Once I got it off, there was what looked like 1/8" of clay in the bottom. Just CAKED in there and dried. Took 4-5 applications of carb cleaner and vigorous towel scrubbing to get that crap out of there. Finally got it all out. Looked at the screen and could see that was pretty dirty too, so I'll order a new gasket and screen. Put the bowl back on, opened the petcock, and noting flowed. Lossened it off some and the clean glass showed flow. Once it was full and overflowed a touch, I tightened it back up.

Moment of truth. Fired it up, and she came to life and ran pretty strong. I looked over to adjust the choke only to see that no choke had been applied. So it was running with zero choke. Went through most of the choke and it only wanted to die on nearly full choke. So good sign. Ran strong at all throttle positions, but it's stumbling just a bit everywhere in the range. So maybe a flow issue or maybe a spark issue, but she's running strong enough to work.

So, keep after those sediment bowls! Happy to have mine crystal clear again, and an order going in tomorrow for a new screen and gasket.

[staninlowerAL]

You could still have some obstruction within the petcock. The OEM style that I have dealt with in the past does not have a straight through passage so a rod will not pass through it if you try to dislodge any obstruction that way. You can blow air through it from either direction if it is not plugged. JMHO, Stan

[PFord]

:hattip: You could still have some obstruction within the petcock. The OEM style that I have dealt with in the past does not have a straight through passage so a rod will not pass through it if you try to dislodge any obstruction that way. You can blow air through it from either direction if it is not plugged. JMHO, Stan

Thanks Stan,

My guess is there is crap in the filter screen, and probably all throughout the system. I intend to re-plumb the entire thing over the winter but for now I'll just try a couple things to see if they help. Tomorrow, I am going to drain the carb bowl, and then pull the main jet screw and see if that's restricted. I'm guessing it's probably not been cleaned in many years. When I re-plumb I'll full rebuild the carb but don't want to get into all that right now. I have an ultrasonic cleaner so everything will go in there eventually for a thorough cleanup.

Even if nothing improves right now, it's running well enough for me to finish my summer work, so that's some consolation.

[inairam]

There should be a screen at the inlet to the carb. I have seen carbs where that screen was clogged or missing.

[staninlowerAL]

I made a quick search of your posts and didn't find it but if you have a zenith carb the inlet filter should look something like this (without the debris):

[PFord]

There should be a screen at the inlet to the carb. I have seen carbs where that screen was clogged or missing.

I may have a look at that later today if work permits. Thanks for the advice.

[PFord]

I made a quick search of your posts and didn't find it but if you have a zenith carb the inlet filter should look something like this (without the debris): filter.jpg

It's the IH updraft carb, not the Zenith.

[Stanton]

PFord--that's good that you probably found the main culprit to the issue. If you're like me, you don't want to touch it now that it's running good, but I agree, a thorough fuel system cleaning is probably in order. If the sediment bowl was that bad and you haven't cleaned the carb and rest of the fuel system recently, then it may be time to do that too.

Happy running of your nice late-model Cub for the rest of this summer (as long as you need it)!

[PFord]

PFord--that's good that you probably found the main culprit to the issue. If you're like me, you don't want to touch it now that it's running good, but I agree, a thorough fuel system cleaning is probably in order. If the sediment bowl was that bad and you haven't cleaned the carb and rest of the fuel system recently, then it may be time to do that too.

Happy running of your nice late-model Cub for the rest of this summer (as long as you need it)!

Every system in this tractor needs going through. Job 1 was just to make sure all the fluids and everything were OK so I could do the work I bought it for this summer. But It needs to be re-wired, because all the wires are old and stiff. The fuel system needs going through. I tried to get the oil filter lid off yesterday and it was stuck shut. So I know no one has been in there in a while. But the oil was fresh, so maybe they changed it and left the filter. It's got a miss and it's not charging, so I need to look at the charging system at some point.

Mechanically, it seems to be OK, so I'm thankful for that. But this is the nature of things I guess. I'm just trying to be patient, and keep it running for the next couple months!

[Stanton]

...I'm just trying to be patient, and keep it running for the next couple months!

I may have a look at that later today if work permits...

Yeah, I know how that can delay what you want to do. Why does WORK get in the way so much?!!!

[inairam]

I made a quick search of your posts and didn't find it but if you have a zenith carb the inlet filter should look something like this (without the debris): filter.jpg

It's the IH updraft carb, not the Zenith.

My IH carbs have a screen.

[Dale Finch]

Something to remember for when you DO change the oil filter...clean out the filter housing by removing the drain cap on the short pipe extension coming out the bottom. It may be plugged up, so you might need to use a long screwdriver from the bottom to poke through the sludge.

If you reinstall the filter bolt all the way, you can pour some kerosene in the filter housing without it dumping into the engine oil pan. With the pipe cap on, swish it around with a screwdriver or brush, then open it up to drain it.

[staninlowerAL]

IH updraft carb filter screen in the fuel inlet, it's a bit hard to see.

[PFord]

Something to remember for when you DO change the oil filter...clean out the filter housing by removing the drain cap on the short pipe extension coming out the bottom. It may be plugged up, so you might need to use a long screwdriver from the bottom to poke through the sludge.

If you reinstall the filter bolt all the way, you can pour some kerosene in the filter housing without it dumping into the engine oil pan. With the pipe cap on, swish it around with a screwdriver or brush, then open it up to drain it.

Wow, that's a great tip!

[PFord]

IH updraft carb filter screen in the fuel inlet, it's a bit hard to see. IHcarb inlet screen.JPG

I see it in there. Does it stay in there or does it come out?