No power 1991 Toyota pickup, 3L V-6

[RacerX]

I have a 1991 Toyota pickup, 3L V-6, about 150,000 on present odometer. Might have another 30-50k on top of that.( Dad was previous owner and had to replace odometer). Had a problem with idle on cold starts. But now it seems that it doesn't have any power. After motor is warm I can floor the accelerator, and nothing really happens. Eventually it will pick up speed and go down the road. There is NO check engine light on. Pulled plugs, looked normal. Motor doesn't appear to have any misfire in it. This problem has gotten worse over time. Tried injector cleaner in the tank, (BG44K), still don't have any power. Truck has had all regular maintenance done at the prescribed intervals. There is no smoke exiting the exhaust pipe, exhaust also doesn't smell rich either. Will try to test fuel pressure once I can locate the correct adapter. Any other ideas as to where to look? Or what to look for??

 

[toyotafan]

Ok, so it's running and idling just fine or not?

 

[RacerX]

It seems or appears to have a small miss at idle. But it has NO power at all. It is still drivable, but if trying to enter the freeway, it takes a while to get up to speed. I can mash the gas pedal to the floor and it really doesn't do anything.

 

[tbplus10]

Since it's the 3.0ltr engine my first recomendation would be doing a compression test.
Yea I know you dont have excessive oil burn, coolant in oil, oil in coolant, or any of the other standard signs, but I also know plenty of others that had the same complaints from that model engine right before it started to show those issues and needed new head gaskets.
Also dont know your future plans for the truck, but if they include keeping it a long time I'd look into dropping in a 3.4 or even a GM 4.3, anything but keeping the 3.0, because even with new head gaskets it'll still be low on power and the heag gasket issue will return at some point in the future, it always does with the 3.0.

 

[RacerX]

Will try to check compression after doing the fuel pressure test. Head gaskets were done some time ago. Can my problem be caused by a bad O2 sensor? As far as I know, the O2 sensor has never been changed. From the research I've been doing, that was one of the things that could be the issue. There are NO check engine lights on.

 

[tbplus10]

Normally an O2 sensor sets off cel's, but one thing I've learned in life is never expect normal.
So yes an O2 sensor might cause this issue too.

 

[RacerX]

Here's an update. I've changed plugs, cap, rotor, O2 sensor, and I also did a compression check. The compression check showed about 125psi in all cylinders +/- 3-5lbs between all 6 cylinders. Still NO power. Still no CEL. However it seems that when I am driving and need more speed, it will automatically downshift a gear when I push on the gas pedal. Also sometimes it will make a real throaty noise, like when you floor a carburetored car. But it still seems to have no power. Any ideas??? I'm at a loss as to what could be causing this.

 

[jazz]

I am thinking it is lacking fuel pressure, either fuel filter is the culprit or possibly failing fuel pump. Can you check fuel pressure?

I had similar issue however the problem that seemed to be lack of power was the rented car hauler trailer brakes were dragging!