Been awhile since I've been around. Between family and work I'm running on 30 hour days.

1987 toyota p/u 4x4 22r 2bl carb.

Last week the truck started acting up while driving. If you hold the speed at 30, 40 or 50 mph you start to feel a slight stumbling or misfire. Its hard to describe. If you give it gas it stops, if you take your foot off the gas it stops. During trouble shooting I discovered the distributor vacuum advance wasn't working. The vacuum inlet nearest to the block allows air to move in and out. The one nearest the radiator doesn't. I replaced distributor and reset the timing. Road tested, same problem. Double checked the carb setting and checked the timing, same problem. Next I changed out the spark plugs, wires and fuel filter and Checked for any rotted vacuum lines, replaced a couple. The spark plugs had a lot of ash build up as seen in the pic. I never used any fuel or oil additives, just high test gas and 30w oil. Road tested same problem. Next I ran a compression test (#1) 215psi, (#2) 215psi, (#3) 215psi, (#4) 210psi. .
When I rebuilt the engine I had it bored 40 over and matched with new pistons and rings. Before its started acting up it ran great. Idle was always a little bit off but not bad.
I'm really at my wits end..

From right to left 1,2,3,4

From right to left 1,2,3,4

 

New plugs with only a coupe of hours on them.

 

Pulled the valve cover and checked the timing to see it maybe the chain had slipped. Everything looked good. Also replaced the PCV valve and gourmet.
Next step I'm gonna take the carb off and look at it.

 

Traffic TechII did you ever figure this out? I am having a hell of a time with my '86 Pickup. I'm not incredibly mechanically inclined but so far I have changed the fuel filter (frame), alternator, battery, carb (had it rebuilt), spark plugs, and the tranny had to be replaced with used one. My truck idles all day long, then I go to put it in gear and drive and put put put and dies out. The other morning I actually drove it about a mile then had to be towed home by my wife in our other Toyota Tacoma. It seems to cut out right about 30 MPH when it does get going usually right around 3rd gear. Also new to the forum so I hope im not "hijacking" your thread

 

i
i suggest you start a new thread it gets confusing when you start diagnosing and testing things... when two different vehicles, two different owners and several people giving input

 

James - Not yet.
I took the carb apart and cleaned it blasting out all the ports. Didn't find anything wrong. Fuel level is always 1/2 in the sight glass.
Still stumbles or bucks at a steady speed but not during acceleration or de-acceleration.

Maybe a crack intake or the carb is crap? I rebuilt it (stock carb) a couple of years ago.

 

Check and make sure everything under the hood is tight and sealed. My truck stumbled like that on the trail; I had to tighten all the intake air fittings due to years of trail abuse without ever thinking about them. Also, try spraying starter fluid around any potential air leaks. My truck is injected and won't run well with un-metered air, but any air not mixing with fuel thru the carb will make an engine stumble.

Here's some cheap ass starting fluid:
https://amzn.to/2H2gLHY

Also, here's the best penetrating oil money can buy:
https://amzn.to/2E9OEDQ

And if all else fails, Seafoaming your engine is always a good idea:
https://amzn.to/2Eyzc5H

 

Thanks Bigsalty

Have to wait til the frigging rain stops to check the intake.
Wish I would have thought about that while I had the carb off.

 

Checked the intake, everything is tight.
Looked back over the Vacuum lines, nothing found.
Nothing on-line that's the same problem I'm having.

Last ditch I guess is to take to the dealership......

 

Could the fuel pump cause the problem I'm having?
(stumbles or bucks at a steady speed but not during acceleration or de-acceleration.)

 

Not the fuel pump.

To date I have replaced the following:

Distributor (with new cap and rotor)
Spark plugs and wires
Fuel filter
Fuel
Harmonic balance
All old vacuum lines
I have check the carb (rebuilt 1-2 years ago). (adjusted several times)
Compression is good
Fuel pump is good
Timing chain is good
Adjusted timing several times set to 0 unplugged, 8 plugged in. Tried retarding and different advancements.(from 5 to 14)
I will say with each part change the engine is running better at idle.
Read some interesting posts on different sites about a "Flat spot" that almost fits my problem that's carb related.
Before I head to the dealership I'm gonna check the carb again.

 

Off to the dealer in the morning if nothing then the crusher!

 

You mentioned ot raining... is the O- RING on your distributor... they DON'T LIKE even the slightest amount of moisture...

 

How about adjusting your valves? I don't see that mentioned in your list. Is your EGR system hooked up? If so, is it working properly?

 

Thank you for your replies.

The rain remark was just being able to work on it...The barn had the boat in it.
Checked the valve setting (cold and hot) also took the egr off, didnt see anything wrong. Cleaned anyway.

Went to the dealership. The first tech was looking for the computer port to pull codes from...(not a good sign)
Older tech said it could be something wrong with the carb and suggested I buy a cheap one off amazon to see it it changes anything. If so then to replace it with a Weber.

Thanks again for the replies. At this point I would try anything like a toyota voodoo spell or something to figure it out...lol

 

***UPDATE***

Took the EGR off again after cory asking if I checked it out. Before I just glanced at it with 1/2 ass cleaning.
This time I let it sit in carb cleaner overnight and took ,40cal and 5.56 gun brushes to it. I went to blow out the vacuum line toward the bottom when it clogged up. A chunk of crap was stuck inside. Got it REALLY cleaned out this time and the truck runs 80% better.

 

Thank you for updating... good work

 

Thanks,

One step closer to a weber...