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Mazda 2.2L \  No acceleration

No acceleration

Mazda 2.2L Mazda Engine Mazda Tech
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hey_you   +1y
OK, long story:

I got this '87 carb'd b2200 that had been sitting for a while without a carb. I put a rebuilt carb on it and it ran OK, just had a tick in the head. (Some of the vacuum lines were clogged with dirt; I believe I got most of them clean.) I changed the fluids, plugs, wires, fuel filter. That didn't help so I pulled the head off and had it rebuilt. After I put everything back together, it won't accelerate or increase RPMs. It idles rough, like it's got a miss, and as soon as I open the throttle blades, it'll die.

I've been fighting this for a while, but I remember having a problem with the EGR valve when I got the head back, clogged or stuck open, I don't remember. I think I started it up once and it idled high. I pulled the vacuum line of the EGR and it went to normal, so I ended up pulling the intake off and cleaning out the passages. I don't think it had any effect on my current problem.

As far as I know, cam timing is good, ignition timing is good. I don't have any means to check dwell, but if it was fine before, it should be OK now, right? I still have an HLA that won't pump up.

What can I check next?
Thanks
dan woodland   +1y
I'd check all the vacuum lines and set/verify timing. You put the head on after it was rebuilt, did you double check the head bolt torque settings?
hey_you   +1y
Sorry, I don't get to work on it very often.

I had matched all the vacuum lines to a '90 model, but I double checked them none-the-less. None were clogged. I did replace the PCV hose and crankcase ventilation hose. After all that, it wouldn't start unless I held the accelerator to floor, which means zero vacuum.

I watched the machinist put the head together, he pulled a vacuum on all the combustion chambers, so that seems right. Perhaps the camshaft sprocket is installed incorrectly? But then I wouldn't have any compression, right?

I've attached a picture of the camshaft sprocket with the crank at TDC. Sorry for the quality, hopefully, it's clear enough to see details.
post photo
dan woodland   +1y
As long as the dowel is in the alignment hole in the cam gear you should be okay.

Did you check the crank position timing? That has to be set to TDC (top dead center) on the proper stroke - the crank must be turned twice. Also the distributor has to be set properly after the timing is set.

The timing should be set withOUT the vacuum line attached.

Also be sure to align the two marks on the distributor (hole and mark) are aligned when you insert it.

hey_you   +1y
I have double checked the cam timing and it is correct. The head bolts are torqued correctly. Everything checks out.

I ended up talking to a race engine/hot rod builder and all things being equal, he thinks a piece of trash may have gotten into the carburetor and is holding the needle open to flood the engine. I believe that as two of the spark plugs were covered in soot and two were wet and looked like they didn't even fire.

I will verify compression and ignition before having him look into the carburetor.

If anyone is interested.
dan woodland   +1y
Of course, post your findings it will help others.
hey_you   +1y
So, I took the carburetor off and had it inspected. Nothing blaringly wrong with the needle or seat, but, there was a bunch of trash at the bottom of the bowl. There was an o-ring that seemed loose but, on reassembly, fit pretty snug.

After I reinstalled the carburetor, I double checked all the vacuum lines for correct routing. All of the symptom persist. I fiddled with the mixture and idle screws and it'll start on its own, just won't accelerate.

The dwell appears to be stuck at 0*. I'm beginning to think that even though the camshaft marks are aligned, it's not correct. I think there's no vacuum in the manifold so the computer thinks the vehicle is under acceleration and dumping fuel into the carburetor. I'll try to get some better quality pics of the camshaft sprocket and crankshaft pulley.

I didn't have a chance to double check compression.
geterdun   +1y
All else fails, CHECK THE COMPRESSION. The rings may be the problem, if all the timing marks line up.
Is there any oil film inside the distributor cap?
Drain the fuel tank (should have plug in bottom), that may tell it all.
Being new to the B trucks, not sure, does the 87 have fuel control involvement from the computer. I do not think so.
hey_you   +1y
Just to clarify:

When I got the head back from the machinist, I checked compression. All cylinders were at 140#. The guy checking my carburetor suggested that if the HLAs were not pumped up, I could've gotten an erroneous reading. If the rings were the problem, I wouldn't have gotten 140#, right?

The truck didn't have any fuel in it when I started putzing with it, the fuel is only a few weeks old, at most.

The carburetor has a few electrical connections and the engine has an O2 sensor, so I'm sure there's a computer controlled feedback loop of some sort.

So I guess the question becomes, how do I know where to set the camshaft if the timing marks are incorrect? At TDC, are both HLAs supposed to be on the base circle? The intake valve just closing, and by how much? If I have no vacuum, is the cam retarded or advanced?

Thanks for all the help.
geterdun   +1y
I went back to check, I can not find where you told us the compression earlier? Just that the mechanic pulled vacumn on the head. With that compression, which is good, there should be plenty of vacumn in the intake. Connect a vacumn gage to the intake, hold the carb open and spin the engine, you should have vacumn. I am not sure how much, with just spinning with the starter. Someone should know here. If yours falls short, cam out of time, or valve held open.
I can not tell from the picture, do you have both the crank and the cam marks straight up, aligned with the marks, not ninety degree toward the driver's side? That is what this manual is showing, straight up, have pointers there to align with.
Human leukocyte antigen (HLA) or hydraulic lifter adjuster? With seven lifters pumping up, it would run, and have a click, probably a miss too.
I understand the engine runs, or will run independent of a computer that year. All this input is based on engines in general, I know just enough about Mazdas to be dangerous.

And yes, if you do not know what is in the tank, check it. An empty or nearly empty fuel tank, over time ("setting for a while") of warming and cooling can inhale enough moisture to have a puddle of water in it. If nothing else, disconnect the fuel line from the carb, BEFORE THE FILTER, and stick into a two litre soda bottle. You may need to supply a longer length of fuel line to accomplish this. Crank (you can bypass the fuel pump relay to do this without spinning the engine so much, unless this engine has a mechanical pump, then it is spin it.) until you have a pint or so in it. If it looks like the gas you put in it, then problem is not water in the tank.
If muddy or watery, another tale.

Too bad you did not check the compression before pulling the head, but it is ruled out now, compression is good, move forward. Not like any of us have not errored in the past in something, shoot, I sold my Smokey & Bandit 6.6 TA.