[HerbMarshall420]

I have a Chevy 350 in a 88 s-10 blazer.

It runs perfect in the garage. Nothing wrong.
When I pull out onto the street it runs great for awhile.
Sometimes 50ft or other times two hours. Then it starts to misfire.

I have changed the distributer, fuel pump, carb, intake, plugs, and fuel filter.
Checked all vacuum lines and all look good. My guess is that it's either in
the ignition or the carb.

I also have checked the cam, timing, and fuel pressure. All are fine.

When it decides to go from good to bad its instantly.

Any ideas?

Thanks.

[racecar100]

Is the plug wires touching any metals? I've seen them arcing to headers or any other matal parts. The best way to fund out is check it while running at night with no light and watch for any blue arcing.

[beaker60]

Here's one for ya,,,try replacing the ignition module in your distributor,,,that's what it sounds like.A lot of people will tell you that when they go bad the engine just dies,,,not so.What happens is they start creating a random misfire first and then they die.If you are unfamiliar with where the module is,,,it is located underneath your rotor inside the dist.It has four prongs attached to it.Make sure you coat the bottom of the new one with the supplied silicone grease,it keeps it from overheating.Now,,,also I have had the distributor washer go bad and cause your simptoms.It is located underneath everything,rotor,pickup ring,,,everything.I have had those go bad and cause the entire unit to short to ground.

[HerbMarshall420]

Ok, I just complete swapped out the distributer and nothing changed.

However, my carb is an Edelbrock model 1406. I removed the top of the carb,
filled the bowls with fuel and ran the motor. The motor ran just great.

Could this be the problem? Does this imply a mixture problem, metering rods, or are the floats getting stuck? How can I test each problem?

[beaker60]

Ok,,,I have the exact same carb on mine,,,if the bowls were empty,,,then you have a supply issue or a leak down problem,,,but I don't know,,I've never seen one of these carbs leak down,,,not to say it couldn't happen,,,but I would be more likely to go with the supply problem.Instead of testing,,I think I would just go with a re-build,,you know a good thorough cleaning and replace whatever comes in the rebuild kit.I know that this is a pain ,,,trying to locate a misfire,,I have to do it everyday,,,,it's just very time consuming,,,but it sounds like your on the right track,,,But again,,keep an eye on that dist.they can fool you.

[HerbMarshall420]

I've noticed the problem is only when driving down the street. In the shop the truck runs great. Even if it's running like crap, when I get back to the shop it starts the run good again.

I also noticed that it looses all its power only when I press the throttle.

[alvto65]

i always build s-10 350s ive had that problem to try running it with out the hood see if that helps. then ull know if thiers to much engine heat. hope this helps