rough running 4.3 v6

jeepcj3a

Well-Known Member
Joined
Jul 13, 2006
Location
winston salem
just picked up a truck, and the carbed 4.3 v6 has a very rough idle(shakes the whole truck). when it gets to around 2000 rpm is starts to get a little smoother. when i put it into gear today and backed up slowly it died twice, and not until i kept my foot pumping the gas pedal would it stay on.

stock toyota fuel tank w/ a purolator pro12s universal electric fuel pump. says it pumps 4-7 psi and 35 gal. an hour.
(http://www.marketworks.com/StoreFro...ail.aspx?sid=1&sfid=78392&c=613659&i=14046324)

holley carb, ill post up the model soon

complete newb at this. what should be the first thing i try to get the engine running smoother?

thanks
 
It could be nothing more than carb idle is set too low or timing is a touch low.

If bumping the idle up a bit on the carb adjuster (should be an idle scew somewhere around the acclerator circuit, post a carb model and I could be more specific) smooths the idle, it will probably also cure the choke out syndrome.

Either way if its a new to you vehicle, a couple bucks in a few filter is a great starting point also, especially with the sludge we are pumping for gas these days.
 
read up on adjusting the holley carb. and went out today and found muddy looking fluid in my radiator, and since i just drained it and refilled it sat. i believe i have a blown head gasket or cracked head. not real happy so now ill be turning my attention to learning how to replace the gasket
 
hold on....
not so fast

Water in the oil will show up chocolate milkshake, usually it takes quite a bit of oil to sludge up an entire colling system. Easy check would be to check oil level, but thats no guarantee.

What you are probably seeing is the rust/gunk build up from the cooling system. All your fitted hoses have thin metal wires in them that form the hoses.

Over time they rust and your cooling system in general will look rusty or almost red. 1 flush probably wont get it.

One of the Prestone quick flush deals is ok, But I generally end up running a motor for 10-15 minutes with a water hose stuck in the radiator and the drain cock open to completely flush one.

Chad, I don't think a head gasket is your problem from what you are describing. I would concentrate on carb, timing and vacuum as mentioned. Hell Id even go as far as clogged cat(s) before Id look to a head gasket.
 
alright then ill try the carb then tomorrow. When got it i pulled the dip stick and found a little water in the oil. So i drained it, replaced the filter, and refilled. And changed the radiator fluid becuase when we checked it it looks justl ike it did now, like muddy water.
so when i started looking up why those issues were there, i kept getting people saying that it would be a blown head gasket.
 
well now water in the oil is a lot more indicative of head gasket.
muddy antifreeze, not so much.

But a possibility.

Is it an original carb motor or an aluminum head late model 4.3?

The aluminim heads were much worse to eat head gaskets
 
i believe it is an original carb motor, but im not 100% sure. The guy said he found it in a junkyard. I can post a picture if that helps.
 
could these things be caused by a blown head gasket?


water in the oil when i got it, not now after i changed the oil/filter
oil in the coolant
 
A blown head gasket can cause your oil and water to swap spit.

It COULD be your rough running but it wouldnt have been my first guess.

Here is a quick and dirty test (if you dont have a compression tester)

Start the truck and get it idling.
Take a standard test light and connect it to the ground post on the battery.

1 by 1 pierce the plug boot of each cylinder at the plug. This will serve to temporary ground out that spark plug. If the engine has a noticeable stumble then that cylinder was firing and grounding it has caused a difference.

What you are looking for here is the cylinder that will cause no change in rpm. Specifically if its a head gasket you will have 2 cylinders that will cause little or no change and they will be side-by side.

Thats a dirty shade tree trick.

But for $25 you could buy a compression tester and check each cylinder, it would tell you the same thing.

Truck in WS or SC?
 
jeepcj3a said:
truck in winston salem. hope to have it ready for school in spartanburg in sept.
ill try to pick up a compression tester tomorrow
Click to expand...

Im gonna be in Spartanburg all day tomorrow hence the Question.
;)
 
well just ran my first compression test and got these results.
Rear
188 180
182 175
187 170
Front

and from what ive read these are fine becuase they arent more than 10% diff from one to another.
Is that correct?

thanks
 
Chad none of those jump out hard at me.

But it is interesting that the only two that are low at all are side by side (1,3).

With it running more are you getting any more oil and water mixing?
 
Back
Top