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Discussion Starter #1
Hi Bronco Tech.

I introduced myself the end of last week with the post Got me a Bronco witb a problem. I got some feedback that it might be the choke and so I took it into the local tunex and had it adjusted... let's just say that I'm getting my money back. I guess it does start better, but when it runs... well, read on.

I bought a 1984 FSB from a guy. This particular FSB got a new engine about 515 miles ago (I have the papers, it's pedigree!). The engine is a 351w with a Holley 4bbl carburetor. Well, when I got it, it had a very hard time starting and would flood out sometimes. I heard it might be the choke, and tunex told me that the choke was too tight. after adjustment, it does start better, but it's still got a problem:

First, it doesn't high idle very well. Tunex adjusted the high idle, and I guess it does kick in but once every 5th start or so. It's still not great.

Second, it seems to idle really low. In park, it idles about 600 rpms, and when put in gear, it drops to about 400 rpm or lower causing it to sometimes stall. Something tells me that is too low. Should I get it adjusted higher?

Finally, when driving, it runs ok, but if I come to a stop, it'll drop down to it's 400rpm idle. (here's the kicker), when I press the gas to go again, it revvs up to about 800rpm and then stalls out.... Almost every time whether cold or not! this is why I am getting my money back from Tunex.

This morning, I started it and let it idle in the driveway for about 10 minutes. This got it up to full operating temperature, so it should run just fine right? Nope! I got to the first stop sign and stalled out in the middle of the intersection because of the aforementioned problem. Now, I have heard that the Holley is a temperamental carburetor and the dude at tunex suggested getting an Edelbrock for the job.

My questions are these, Is there any indicator to any of you what the problem might be? I'm going to turn up the low idle tonight as a temp fix, but i'm sure that's not the real underlying problem. Is it too lean? Is it too rich? should call the company that installed the engine and have them fix the problem?

Any help would be greatly appreciated...
 

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Double check your float level should be a plug on each float bowl. Unscrew plug be careful if it is to high gas will spill out. On top is your needle and seat a screw with a nut underneath with truck running adjust float so gas is right under sight plug hole. Also check accelerator pump or pumps located under float bowl if it isnt leaking press arm you should see gas come out your squirters. Hollys are actually pretty simple carbs they just take time to adjust
 

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Discussion Starter #4
Thank you both! I'll crawl up under the hood tonight and see what i can find. I'll check out those Holley videos too and start with the first to get the carb totally tuned... might be up all night, but if it stops this problem, it'll be worth it!
 

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Discussion Starter #7
Does anyone know where the idle should be on an 84 FSB? I called the Tunex and told him I idle about 600 and he said it was low. what should I adjust it up to?
 

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IIRC there are two idles. a hi and a lo. i think they are like 1200 and 900, but they are in the haynes and on teh EGR sticker on the radiator frame support (beside hood latch)/
 

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Suggestion get a good vacum gauge and tachmoter and pressure gauge.

Adust the idle first before doing anything with the main, but you have to check the float bowl fuel level and pressure. From the sounds of it, you might be flooding the carb out. Are you seeing black smoke? Do have a holley or some other regulator in place? How's your fuel filter ?
 

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Discussion Starter #10
I took it back to the Tunex and the guy upped my slow idle to about 750 (which is about where the sticker under the hood said it should be). I then drove it around and it worked like it should, not shuddering or stalling out. So, I hopped in this morning and drove it.

For the first 10 minutes of the drive, coming to a stop and then going again stalled the engine out, but after 10 - 20 minutes, it ran like a top, just like the guy who sold it to me told me it would.

No black smoke. I get a grey, fuel smelling smoke after it floods and I have to open it up to clean it out, but it hasn't flooded since I had the carburetor adjusted.

The carburetor itself is a Holley, but I don't know what else is under there.

Now, every now and again, the truck smells like fuel, like after it's been driven and is sitting in the garage... like it's running rich. Now, I don't know what kind of gas mileage to expect from this thing (about 10 to 13 is my guesstimate), but I think this morning down the freeway I was getting about 6 (I'll know better when I fuel up on the way home). could this be a symptom of over rich fuel mixture + cold car?
 

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Yes it sounds like you might not have got a carb setup for that engine very well. Before you spend your hard earned money on a new carb you might think about a Holley projection fuel injection unit. The kits are not very much more than a good carb. off of Craiglist I've found them used for about 200. I've used them on three trucks and a boat and WOW what a difference. the basic 670cfm two barrel is great for daily driver. In Anchorage life is all about cranking every time and a smooth throttle for the driving conditoins. Just a thought

John
 

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Discussion Starter #12
Thank you. It's running better, but still stally sometimes. I have another issue I need support on. I'll open a new thread.
 

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Discussion Starter #13
Ok, I know it's been a while, but I finally answered my problem here.

So recap, the most annoying symptoms I was dealing with were: Stalling when cold, Stalling when hot and when the engine was hot, the starter wouldn't spin. Turns out that all three problems were starter related. The starter finally went out this week, and I replaced it, now all my problems have simply gone away.

So, I guess the starter didn't spin freely enough, causing extra strain on the idling engine that it would stall. When hot, the starter's innards would expand and seize it up, causing the hot stall (that acted just like Vapor lock), and causing it to act like a dead battery, but only when hot.

I've been driving it since the starter replacement, and it drives more smoothly, it starts better and it doesn't stall out anymore. If I had only replaced the starter earlier, I'd have saved myself a lot of stupid stress.
 
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