Fuel Problems, HELP!

[jgasca]

Alright first off I have an 84 k10 350 sm465 edelbrock 1406.

Last weekend I took my truck out for wood. We went to some mountains near bye. One we get to the mountains, the truck starts running rough and I see white exhaust smoke, I know white smoke means water, but wouldn't I be burning water all the time........ So we managed to bring a load home in that condition. I noticed once we got down the mountain the truck starts running fine.

So this has me thinking its elevation causing my problems.

Well I started my truck here at home a few days ago and a few seconds after I start it, it starts running rough again, nearly dieing. So yesterday I replaced my fuel filter and opened up my carb. I cleaned the float area and the jets with carb cleaner. I noticed one of the main jets was sorta clogged. I made sure the floats were near 7/16" like the manual says it should.

So I took it for a drive right after and it ran perfect. No problems. Well today I turned it on and it's back to the same old crap, it seems like the idle screws arn't changing anything when they're turned, oddly enough the idle goes high when the screws are screwed in all the way. I'm stumped......not sure what else to try other than getting different jets.....

I apologize for the novel but I really need help. Trying to avoid taking it in to a local mechanic.

The following is the fuel filter I have on at this moment

http://shop.advanceautoparts.com/we...google&utm_campaign=gpla&utm_content=22905603

 

[Boone83K10]

If you can bury the idle screws and it idles, you have a vacuum leak somewhere. The mountains just revealed the problem.

 

[jgasca]

If you can bury the idle screws and it idles, you have a vacuum leak somewhere. The mountains just revealed the problem.

All vacuum comes from the intake correct? I'll look more into it tomorrow.
Thanks for the response!

 

[Jims86]

Idle screws will usually kill fuel too...what carb is this?

 

[Boone83K10]

All vacuum comes from the intake correct? I'll look more into it tomorrow.
Thanks for the response!

vacuum is created by the pistons going down. vacuum is usually readily available from the throttle plate of a carb/throttle body. It can be pulled through the intake by the "couple" of ports on it but not usually.

 

[MrMarty51]

Idle screws, all the way in, will cut off the fuel from the idle circuit.
Sounds to Me like You are having an over gas problem.
Floats are set at 7/16ths but are they really, where are they at when the float bowl is full ???
It seems possible that You just might have a broken gasket or a sinking float that is causing too much fuel to enter into the intake system.
Stock fuel pump or electric, whichever it is, also check Your fuel pressure, might be too high.

 

[Jims86]

Or an internal carb leak...especially if it is an untouched, factory Q jet with leaky plugs.

 

[MrMarty51]

Or an internal carb leak...especially if it is an untouched, factory Q jet with leaky plugs.

E-Brock 1406 EEEEEEEKKKKKKkkkk

 

[Boone83K10]

Ive never had trouble with edelbrock, holley on the other hand...

Sent from my SCH-I535 using Tapatalk

 

[jgasca]

Idle screws will usually kill fuel too...what carb is this?

Edelbrock 1406

Idle screws, all the way in, will cut off the fuel from the idle circuit.
Sounds to Me like You are having an over gas problem.
Floats are set at 7/16ths but are they really, where are they at when the float bowl is full ???
It seems possible that You just might have a broken gasket or a sinking float that is causing too much fuel to enter into the intake system.
Stock fuel pump or electric, whichever it is, also check Your fuel pressure, might be too high.

How else can you test the floats? When I opened her up both floats seemed to move freely....Gasket also looked fine. This carb is only about a year old with very little use

 

[chengny]

I was just wondering (and I'm trying not to sound like a wise guy); how did you became so certain that this intermittent issue is fuel related?

I read that you saw white smoke (or water vapor) at the exhaust one day when you went to the mountains and that while it was making white smoke the engine ran rough.

When you inspected the carb internals you "noticed one of the main jets was sorta clogged".

Since then you have had a couple of instances where the truck ran poorly.

If you only saw white exhaust one time (and it hasn't returned) - I would not use that in the troubleshooting process.

So with the white smoke out of the equation, would it be safe to say that a handful of times over the past couple of weeks your truck has run poorly - and you don't really know why?

You seemed to think that you had a restricted jet and that clearing it made the problem go away. When it ran bad a few days later, did you go back into the carb to check whether the jets had again become restricted?

Adjusting the idle mix screws effects the idle - how is the engine running off idle?

At what rpm do you have your idle speed set? I don't know much about carburetors but one thing I'm fairly certain of is the idle mixture screws lose any control at high rpm.

To adjust a carb you have to slow the idle down as low as it can be and still run. Then you can start opening the screws.

Is your choke opening and staying open?

Have you checked the ignition system? Maybe lay on your back under the engine at night and while it's hot and running, look for stray arcing that would indicate a bad plug wire.

Does the truck have trouble if it is raining or very humid?

It has been my experience that carburetor problems don't come and go. They start off as mildly annoying and just get worse.

Have you noticed any correlation between ambient temperature and poor performance? The about fuel tank level - any connection there?

On the other hand, ignition problems are more likely to be sporadic in nature.


Just offering a few other things to consider as you work through this issue. Intermittent problems are the worst to diagnose- good luck.

 

[jgasca]

I was just wondering (and I'm trying not to sound like a wise guy); how did you became so certain that this intermittent issue is fuel related?

Well thats the thing I'm not sure. When in the mountains, seemed like the only thing that kept the truck running was stepping on the gas......
I'm guessing this is a combination of things.

But after seeing the truck run fine after cleaning the carb, that gives me more reason to blame it on the carb.....

I read that you saw white smoke (or water vapor) at the exhaust one day when you went to the mountains and that while it was making white smoke the engine ran rough.

When you inspected the carb internals you "noticed one of the main jets was sorta clogged".

Since then you have had a couple of instances where the truck ran poorly.

If you only saw white exhaust one time (and it hasn't returned) - I would not use that in the troubleshooting process.

Every time we go for wood up in higher elevation areas, the truck starts running the same, rough idle, nearly dies, white smoke......every time

So with the white smoke out of the equation, would it be safe to say that a handful of times over the past couple of weeks your truck has run poorly - and you don't really know why?

You seemed to think that you had a restricted jet and that clearing it made the problem go away. When it ran bad a few days later, did you go back into the carb to check whether the jets had again become restricted?

I want to open it up again sometime this week. Thats what confuses me, after cleaning it last week, why would it be dirty or clogged again? I guess we could point the finger at the fuel filter.....

Adjusting the idle mix screws effects the idle - how is the engine running off idle?

When not in idle, it sputters a bit until I get the revs up then it runs strong

At what rpm do you have your idle speed set? I don't know much about carburetors but one thing I'm fairly certain of is the idle mixture screws lose any control at high rpm.

To adjust a carb you have to slow the idle down as low as it can be and still run. Then you can start opening the screws.

I dont have a tach, I was taught to do it all by ear

Is your choke opening and staying open?

Choke looks to be working correctly.

Have you checked the ignition system? Maybe lay on your back under the engine at night and while it's hot and running, look for stray arcing that would indicate a bad plug wire.

Does the truck have trouble if it is raining or very humid?

Thats a good idea, i'll have to check that out. But again the mountains were very humid, thats when it was running rough. Any other time around the house it ran fine......

It has been my experience that carburetor problems don't come and go. They start off as mildly annoying and just get worse.

Have you noticed any correlation between ambient temperature and poor performance? The about fuel tank level - any connection there?

On the other hand, ignition problems are more likely to be sporadic in nature.


Just offering a few other things to consider as you work through this issue. Intermittent problems are the worst to diagnose- good luck.

Thanks Jerry for the input. You have a history for solving most of my problems!

 

[chengny]

List of counties in the State of New Mexico that are designated as "high altitude":

You must be registered for see images attach

Changes to be made if a low altitude truck is to be operated primarily in a high altitude county:

To be used for the following 1986 low altitude (NA5) engines used primarily at high altitudes.

^ 4.3L Federal All Except "M" Vans

1. Advance base timing to a maximum of 4~ over specification if little or no detonation occurs at high altitude.


2a. Manual Transmission

Reset idles to original specifications on the Emission Control Information Label.

2b. Automatic Transmission

Set fast idle speed to 1800 RPM in N (neutral).

^ 5.0L/5.7L Federal

1. Advance base timing to a maximum of 4~ over specifications if little or no detonation occurs at high altitude.


2a. Manual Transmission
Do not adjust the carburetor vacuum break.

2b. Automatic Transmission
Reset carburetor vacuum break to 26~.

3. Reset base, A/C solenoid (if present) and fast idles to the specifications on the Emission Control Information Label.

^ Heavy Duty Gasoline Emission Packages

1. Advance base timing to a maximum of 4~ over specification if little or no detonation occurs at high altitude.

2. Set idle speed to specifications in accordance to Emission Control Information Label.


Changes to be made if a truck set up to operate in high altitudes is reclassed as low altitude (basically the reverse of the above):

Procedure II


To be used for the following 1986 high altitude (NA6) engines used primarily at low altitudes.

^ 4.3L Federal All Except "M" Vans

1. Retard base timing up to 4~ from specification if detonation occurs at low altitude.


2a. Manual Transmission
Reset idles to specifications on the Emission Control Information Label.

2b. Automatic Transmission
1. Set fast idle speed to 2200 RPM in N (neutral).

2. Reset all other idles to specifications on the Emission Control Information Label.

^ 5.0L/5.7L Federal

1. Reset base timing to specification on the Emission Control Information Label.


2a. Manual Transmission
Do not adjust the carburetor vacuum break.

2b. Automatic Transmission

Reset carburetor vacuum break to 24~3. Reset base idle speed to specification on the Emission Control Information Label.

4. Reset fast idle speed to specification on the Emission Control Information Label.


DEALERS AND CUSTOMER INFORMATION Owners of the 1986 low altitude vehicles taking up permanent residence in one of these high altitude counties, should be encouraged to have these adjustments performed when vehicles are brought in for service. After performing these adjustments, dealers should advise customers that, IF THE VEHICLE IS RETURNED TO CONTINUOUS, LOW ALTITUDE OPERATION, THE ENGINE SHOULD BE RE-ADJUSTED TO LOW ALTITUDE SPECIFICATION PER THE CORRECT CHASSIS SERVICE MANUAL FOR IMPROVED PERFORMANCE. IF RE-ADJUSTED TO LOW ALTITUDE SPECIFICATIONS, THE SUPPLEMENTAL LABEL SHOULD BE REMOVED.

 

[jgasca]

List of counties in the State of New Mexico that are designated as "high altitude":

You must be registered for see images attach

Changes to be made if a low altitude truck is to be operated primarily in a high altitude county:

To be used for the following 1986 low altitude (NA5) engines used primarily at high altitudes.

^ 4.3L Federal All Except "M" Vans

1. Advance base timing to a maximum of 4~ over specification if little or no detonation occurs at high altitude.


2a. Manual Transmission

Reset idles to original specifications on the Emission Control Information Label.

2b. Automatic Transmission

Set fast idle speed to 1800 RPM in N (neutral).

^ 5.0L/5.7L Federal

1. Advance base timing to a maximum of 4~ over specifications if little or no detonation occurs at high altitude.


2a. Manual Transmission
Do not adjust the carburetor vacuum break.

2b. Automatic Transmission
Reset carburetor vacuum break to 26~.

3. Reset base, A/C solenoid (if present) and fast idles to the specifications on the Emission Control Information Label.

^ Heavy Duty Gasoline Emission Packages

1. Advance base timing to a maximum of 4~ over specification if little or no detonation occurs at high altitude.

2. Set idle speed to specifications in accordance to Emission Control Information Label.


Changes to be made if a truck set up to operate in high altitudes is reclassed as low altitude (basically the reverse of the above):

Procedure II


To be used for the following 1986 high altitude (NA6) engines used primarily at low altitudes.

^ 4.3L Federal All Except "M" Vans

1. Retard base timing up to 4~ from specification if detonation occurs at low altitude.


2a. Manual Transmission
Reset idles to specifications on the Emission Control Information Label.

2b. Automatic Transmission
1. Set fast idle speed to 2200 RPM in N (neutral).

2. Reset all other idles to specifications on the Emission Control Information Label.

^ 5.0L/5.7L Federal

1. Reset base timing to specification on the Emission Control Information Label.


2a. Manual Transmission
Do not adjust the carburetor vacuum break.

2b. Automatic Transmission

Reset carburetor vacuum break to 24~3. Reset base idle speed to specification on the Emission Control Information Label.

4. Reset fast idle speed to specification on the Emission Control Information Label.


DEALERS AND CUSTOMER INFORMATION Owners of the 1986 low altitude vehicles taking up permanent residence in one of these high altitude counties, should be encouraged to have these adjustments performed when vehicles are brought in for service. After performing these adjustments, dealers should advise customers that, IF THE VEHICLE IS RETURNED TO CONTINUOUS, LOW ALTITUDE OPERATION, THE ENGINE SHOULD BE RE-ADJUSTED TO LOW ALTITUDE SPECIFICATION PER THE CORRECT CHASSIS SERVICE MANUAL FOR IMPROVED PERFORMANCE. IF RE-ADJUSTED TO LOW ALTITUDE SPECIFICATIONS, THE SUPPLEMENTAL LABEL SHOULD BE REMOVED.

Alright I'll set the timing to 12 degrees, what RPM should my idle be at?
I'll see if I can hook up a tach this weekend. It goes straight to the distributor right?

 

[chengny]

Wait, wait - I was just showing you the GM recommended changes - I don't believe that making them will solve your problem.

Remember, your truck was running fine until just recently - with the same timing/settings you've always had.

I'm telling you - look elsewhere for the cause. I seriously doubt that altitude or carburetion is your problem. A chevy 350 engine that is in decent shape internally can take a lot of abuse and will still run pretty good.

Think about it, you are in your home town and the truck is humming along for a few days and then all of a sudden it starts running rough - it's not a timing or altitude issue.

Do you have a friend that would let you take his carb off and put it in your truck for a test?

I still think it's either an ignition or fuel flow problem.