Diagnosing power loss

[Lucky]

My 86 3.2 seems to be a bit off its song these days. It runs well, but it just doesn't have the same zing as it used to... it seems to gain revs at a slightly slower rate than in the recent past.

I suspect a fuel pump/pressure problem, but have never diagnosed fuel pressure problems before, so I don't know what tools to get and where to tap into the fuel system to check pressure. A step by step, "checking fuel pressure for dummies," description would be most appreciated!

Thanks in advance.

[Targa77]

When is the last time you gave the car a complete tuneup (plugs, fuel filter, air filter, rotor, etc)? Also, check the timing.

[stlrj]

John,

Are you assuming that the lack of performance is due to a lack of fuel?

It may be just the opposite condition due to a tired old 02 sensor causing your engine to run rich and that can make your car loose all the snap it used to have.

If your lack of performance was due to low fuel flow then I would expect your engine would be sputtering, popping and stumbling whenever you gave it the gas which it clearly is not doing.

Joe Garcia
86 Carrera
92 Grand Caravan
90 Bonneville
86 Olds 98

[Lucky]

The last complete tune up was 13 months, 6500 miles, and two oil changes ago. At that time a complete major service was done.

The reason I suspect the fuel pump (and resultant pressure) is recently my fuel pump became very quiet. I used to be able to hear it run when I first turned the key, now it is so quiet that I can't. Why would that change?

The car does not stumble or sputter or even hesitate. In fact, it may be running perfectly and this is all in my head. Maybe I need a g-tech to make up for my imperceptive backside.

-- John

[ChrisBennet]

A friend's '86 had less zip than it should and it turned out to be a plugged catalytic converter.
-Chris

[Lucky]

My lack of zing was due to #6 plug wire coming loose, again! I had this problem last fall. A close inspection of the Beru revealed two problems: 1) the semi-circular spring which keeps it clipped to the plug is gone!, and 2) the electrode inside is in bad shape (corroded & pitted, probably due to arcing).

I pulled the #6 plug... it is in perfect shape. I also checked the other 5 plug wires with no visible problems.

Replacement Beru ordered (from Pelican, of course) last night!

An interesting tidbit learned from this is that my idle is erratic when only 5 cylinders are firing. It would surge from 800 to 1200 in a second and then fall back to 800 (or just below) in a couple of seconds and then surge again. With all 6 firing, it idles just fine. This agrees with what another 3.2 DME owner experienced recently (on this thread engine "surgeing at idle"). So for you 3.2 DME owners, remember to check plug wires and plugs when diagnosing surging idles.