Nissan Repair: Problem w/1990 Nissan P/U, new distributor cap, nissan motor

Question
QUESTION: Recently replaced the alternator after it went out - right after that is when I started having problems with how the truck runs.  It almost runs like the exhaust is plugged up.  I did a tune up/replaced plugs,condensor, fuel filter - just a basic tune up. There's still no change in the way it runs. Someone suggested that it might be a burnt valve.  The truck runs like the timing is off - it misses at about 35 mph on up.  There's no power, but it will idle.  Any ideas???

ANSWER: Hi Mick -

A high speed miss, or if it misses going up a hill, one should check the fuel pump output. As far as electrical, it could be the distributor cap or rotor. Take it off and inspect it for carbon tracks. Also check the ignition wires really carefully, especially if they were touched when the alternator was replaced. If it is a steady regular miss, then I suspect it is electrical.

What kind of engine do you have?

Aloha

Calvin

---------- FOLLOW-UP ----------

QUESTION: Hi, Calvin.  Thanks for your input.  To follow-up, the engine has a new distributor cap and rotor just replaced this week. Has a V-6 3000cc Nissan motor.  Was running fine after installing the new alternator.  Two weeks after replacing the alternator, is when the the engine started "missing."  It has a steady miss when idling.  What do you mean by suspecting that the problem is "electrical?"  Should I reinstall the alternator?

Once again, thanks for your assistance.  Look forward to hearing your answer.

Mick Jaramillo

Answer
Hi Mick -

I apologize - I thought you said it only misses at 35MPH up. So, it misses steadily at idle?

Please check the plugs once again. One by one, noting the color of the electrodes. Run the engine for about 3 minutes (not too long), and remove the plugs one at a time, and note the color and condition of each electrode. If one of them is black, or wet, then either a plug or wire is defective. There is a chance that a faulty plug was put in.

At the same time you can check your firing order, which is 1,2,3,4,5,6.

Please do this, Mick, and get back to me -

Thanks
aloha
calvin