Need advice...carb related...

XStang302x · Aug 24, 2004

Alright...first off, I can only assume this is carb related...if it is, I'm tempted to toss the ancient holley back on and send this carb back to edelbrock.

Carb is set with stock jets, and pink secondary springs. Choke is operating fine, the valve is fully open when she warms up. I'm currently using that triangular edelbrock sponge-type air cleaner (may be the root of my problem, I'm going back to a paper element tomorrow). Floats havent been touched...factory setting. I also have an inline fuel filter, only a couple weeks old...see through and does not look clogged.

But here is how she runs...

Start her up cold, let it warm up for about 5mins and drive to work. Runs great till I start getting closer to work...then she wants to start backfiring a little bit if I open the throttle up too much. Bear in mind it's much cooler out this time of morning.

On the way home, same startup process...but once I get closer to home...she really starts running like ass. Sometimes in heavy traffic (like today) even barely tapping the throttle will bog it to the point of stalling. I assuming this is due to the hotter temperatures?

On a side note...If I'm making a run to the store...2-3mins away tops...spend about 10mins there and get back in the car, she starts running like this all over again.

I've checked the choke valve...all seems ok. If I look at the inside of the airfilter. There appears to be almost a wetspot above the front two barrels. I've had the same results with regular and premium gas. Carb has all new hoses and a vacuum cap. No power brakes so the brake booster plug is in (Hmmm might need to check and make sure there isn't a leak there...but I would assume that would make the car run like ass from startup).

I have no idea where to even begin getting this right. Are stock jets normally too rich, hell is it even a rich condition im expeirencing? Secondary spring changed yield no difference. Idle screw adjustments yield no change. Choke is operating properly as far as I can tell. Car idles great. New plugs and what not. I don't see how this is a float issue...but very well could be.

Any ideas would be GREATLY appreciated...This is the worst my car has ran in 7 years and it's pissing me off quite badly.

-Frank

jikelly · Aug 24, 2004

To me your problem sounds like a choke setting problem. You can adjust that by loosening the screws on the choke spring cover. It will say on the cover which way is rich and which is lean. I'm betting that the choke is opening up and making you car run to lean as it warms up. The factory setting on the carb I have found to be pretty close to the ideal settings. Of course it may not be depending on your engines intake, cam, and heads.

Please see the following post http://forums.stangnet.com/showthread.php?t=482402&highlight=carb

There was a guy who had questions about tuning his carb and some of the information might be helpful.

Ozsum2 · Aug 25, 2004

It does sond like it is running too rich to me, not lean like kelly said, but you said you checked the choke. If you warm it for 5 minutes and all is well, the choke should begin to open up. Think of it this way............by the time you get to work it is fully warm and the choke if still on will choke it. Make sure it is opened when it is up to operating temp. If it is still choked, it may be fouling the plugs.

mustang70 · Aug 25, 2004

You might want to check your needle and seats. Make sure they're not clogged. That wet spot you're talking about shouldn't be there. I had a similar problem where mine started running rich for no reason. Pulled the air cleaner and the top of the carb was wet. Turned out a piece of dirt was keeping the needle from closing completely.

XStang302x · Aug 25, 2004

I usually check it before I leave, the valve is almost completely open in the morning. On the way home from work before I leave the lot, the valve is completely open. I'll see where it's at when I get to work in a bit.

By open I mean the choke is off.

-Frank

Ozsum2 · Aug 25, 2004

XStang302x said:
I usually check it before I leave, the valve is almost completely open in the morning. On the way home from work before I leave the lot, the valve is completely open. I'll see where it's at when I get to work in a bit.

By open I mean the choke is off.

-Frank

Yea, it will be. It will be at wherever it was when you shut it off. It won't close until you depress the gas pedal to set the fast idle cam. But, that tells us it is opening.
Try what 70 suggested.

One more thought. it may not be opening fast enoiugh. It may only open fully when you park and the heat sink sets in.

351LX · Aug 25, 2004

If it idles fine but the problem occurs off idle chances are you can rule out vacuum leaks and float problems as these would tend to affect idle as well.If it is carb related it is probably in the accelerator pump.Next time it happens check to see if the accelerator pump shot seems strong but also do a quick check of the choke position and whether or not gas is dripping out of the boosters just so you can rule it out.Does it get worse under load,will the engine rev freely in neutral but bog in gear?This could indicate an ignition problem.I had a Ford truck once that would start running like crap about half way to work.It would idle fine at a light but as soon as I took off the problems would begin.The problem ended up being a faulty ignition coil that worked fine when cool but would misfire when hot.

XStang302x · Aug 25, 2004

Checked the choke before I pulled out this morning...it's definitly opening fine. I'm going to change to a paper element today just for piece of mind.

You guys definitly gave me some areas to start troubleshooting with. I will definitly look into some of this tonight. Interesting note on the Ignition coil...I do remember looking at it a week or two while the car was running. Looking at the terminal where the tach was hooked up, looked like a little piece of dirt/metal was glowing, but in a pulse fashion....not a constant glow. That very well may mean it's bad. Any way to test one of these? Like a good definite yes or no test?

Ran the situation by one of the techs here at work (bike shop, so they have carb knowledge), mainly the airfilter and he said it sounded like that wet/dark spot on the element is probably from backfires though the carb hitting the element. It does look 'eaten' a way a tad...but no black sooty deposits.

Again thanks for the posts...I'll have to dig through these when I get home and read them a little more in depth. One of the links that were posted someone had the same problem I was having last night. Give it some throttle and it feels like it's stumbling/misfiring...you can give it more throttle and the condition won't change unless you back completely off of it.

-Frank

351LX · Aug 25, 2004

You can test your coil with an ohm meter.Here is what it says in my Chiltons book :Turn ignition off,detach coil wire,measure resistance between batt and tach terminals,should be .8-1.6 ohms,measure resistance from batt to coil wire terminal, should be 7700-10,500 ohms.If any are higher or lower then replace coil.these numbers are for a Duraspark so yours might be slightly different.They are fairly easy to replace so if you have a spare laying around or if you can pirate on from another vehicle you might try that as well.

XStang302x · Aug 25, 2004

Also, in answer to your question, it is only when the car is in gear. Clears right up in neutral. What difference is that going to make in what I should look at first?

-Frank

351LX · Aug 25, 2004

If it only happens when there is a load on the engine it is probably either related to a weak spark or not getting enough fuel.

XStang302x · Aug 25, 2004

Hmmm...come to think of it, I forgot I had a few days of hell on the Holley when I decided to put an inline filter in. Can't remember if I have a fuel pressure tester at home, will have to dig around and look. Only a few years old though...Autozone crap though hehe.

-Frank

XStang302x · Aug 26, 2004

Well after thinking about the possible problems that were mentioned all day. I personally felt the coil was the best option to just go ahead and replace, old as dirt anyways. Made sense that once it would heat up things would go wrong, and would take a quite a few hours of sitting and cooling for it to run somewhat decently again. Plus on the way home when it was getting to the point of dieing, I kept it at a steady throttle opening for a mile. About halfway through that mile it started to stutter/misfire with no throttle change at all with no acceleration/decceleration. Plus the stutter happened at all the same intervals. Even with throttle change the stutter was always the same rhythm, I figured with a carb prob there would be a little bit of change in the rhythm.

So....just got done tossing a new coil in and air cleaner on and took her for a 5-7mile romp. All seems well at this point. However, it is pretty cool out at 2am hehe. Made a stop for gas and she ran just fine after that as well...started like a beast too which was nice to hear. The real test will be tomorrow with traffic when the heat sets in too hard to tell at this point if shes cured or not (temp guage isnt working for some reason hehe) .

Anyways....keeping my fingers crossed for tomorrow!

-Frank

XStang302x · Aug 26, 2004

Woohoo! Looks like the coil was the problem! Guess I need to add 351LX to the beer tab list lol. Now I just need to try different springs again, and I think I'm all set! Wooohoo!

Thanks for all the replies all....greatly appreciated.

-Frank

jikelly · Feb 19, 2007

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