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Been having issues with my 1979... on cold startup it runs fine.. once warm it idles great but you give it a liitle gas just above idle and then it sputters. The coil (just replaced to a new internal resistor) is very hot and the ignition and light switches seem to be warm... just took apart the carb, cleaned and installed it, i noticed the old ballast resistor was super hot while it was running... what could be the problem? Help.... thanks

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... Good, you've located the problem; step 2 is washing it off.

If you are saying that you replaced the coil with one that has an internal resistor, you then don't need the stock resistor any more.
The stock resistor will get hot in its normal operation.

What is your voltage at the coil while the truck is running?

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Certified pilots, looking down on people since 1903.

Ok, that makes me feel better. Been wanting to replace it with an internal resistor type coil anyway. That still leaves my sputtering problem just above an idle. I am waiting for a new set of points (not wanting to change over to electronic points just yet; expecting it to be a hassle), I noticed that the points were burnt and the timing is off. I got in a hurry the other night and forgot to set the timing with the vacuum line unhooked. Hopefully this solves my sputtering issue. It has been running like a champ until recently. The problem has been getting progressively worse. Any other thoughts? Thanks for your reply... Much appreciated.

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... Good, you've located the problem; step 2 is washing it off.

Not sure... I have a Dwell/ Volt Meter, how would I check the voltage from the coil? I have only used it to set the dwell.

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... Good, you've located the problem; step 2 is washing it off.

Hook up the volt meter to the power side of the coil and use a chassis ground. Start the truck and read the voltage, I am wondering if you have a over voltage issue.

I am guessing all of your problems are with the carb, these carbs are junk and very very few have had success of rebuilding them.

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Certified pilots, looking down on people since 1903.

What baffles me this is that when it cold, it runs great right after I start it. The second the needle hit the "C" on the temp gauge it won't idle up smoothly. I know these carbs are junk but surprisingly enough I have had zero problems with the carb. Can't really tell what it is until the points come in. Will check the voltage on the coil when I get off work... I hate electrical...

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... Good, you've located the problem; step 2 is washing it off.

Sounds like as soon as the choke starts to come off is where your problems start. Again it sounds like a card issue.

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Certified pilots, looking down on people since 1903.

I thought that might be the issue, so I disabled the choke... Tried again the next morning and the same thing happened

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... Good, you've located the problem; step 2 is washing it off.

Check the vac lines. There is a vacuum switching valve for the EGR valve that opens when the truck warms up, and I think another valve in the air cleaner that opens based on temp. Those combined with a leaky vac line could make a problem that only appears after the truck starts to warm up.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

Ok... sounds like a plan. I just installed new lines coming from the intake to the vacuum pods... the ones under the air cleaner are newer will check those to be sure... thanks everyone for your help.

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... Good, you've located the problem; step 2 is washing it off.

You can plug off the ones to the air cleaner as a test. They are not essential. The flapper valve that is out on the intake of the air cleaner has a diaphragm in it that could fail and leak.

_________________
95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

Good to know... So I can just plug the intake port. I'll check the flapper too. Everything on this ride is original... Slowly having to go through and replace everything

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... Good, you've located the problem; step 2 is washing it off.

Another thing I haven't seen mentioned--make sure the vacuum advance is working properly. If it has a hole/leak it will cause a sag or hesitation right off of idle. #1 it will not advance the timing quickly enough and #2 it will be a vacuum leak just above idle.

Vac leaks are a likely cause of the poor running. That hitachi carb actually has some vac diaphragms that can leak too. My 76 had one that just split in half for the vac secondary.

There still is something going on with the coil perhaps though, it shouldn't get extremely hot. The resistor will warm up a bit if its still being used.

_________________
95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

While checking for vacuum leaks, I noticed the advance plate in the dizzywasnt moving like it should. So I pulled and disassembled it and found that the advance plate was gummed up pretty good. So I hosed it with carb cleaner and worked it around for a bit to get the ball bearings freed; then I dropped some machine oil around the edge. When I put it back in, it ran better, but still not advancing like it should, which is the cause of my problem. I noticed that there was virtually no vacuum pressure coming from the intake. I'm used to working on SBCs where the vac line sticks to your finger while it idles, and my 1973 Opel Manta 1.9L did the same thing. I think I will check the secondary pod, like you said. I do hear a hissing noise inside the cab when I accelerate. Any other vac switches I should know about? Thanks

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... Good, you've located the problem; step 2 is washing it off.

P.s. The igntion had two wires shorting out. Coil is fine now, 5.3 volts going to the contact set. Yay

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... Good, you've located the problem; step 2 is washing it off.

There will be no vacuum to the distributor at idle. Vacuum is applied when the throttle is opened by design. At that point the timing should immediately jump ahead about 10 degrees. This is while looking at the mark with a timing light.
Another way to check it is to apply a vacuum source--either from the manifold somewhere or an external pump source--and listen for the engine to speed up. This checks the vacuum advance operation quickly.

Good deal on the coil wiring. One problem down!

Eggxactly. The vac advance should have almost no vacuum at idle, then pick up as the throttle is open. It should be hooked to "ported vacuum" on the carb not "manifold vacuum".

_________________
95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

Looked at the underhood vac diagram while i installed the new lines... they are all where they are supposed to be. Going to crack open the secondary diaphragm. I believe it could be torn and i am losing vacuum... it hisses when i accelerate. No bueno

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... Good, you've located the problem; step 2 is washing it off.