I have a 1988 Toyota pickup with a 22 re 4wd manual. The past year or so it has had not much for power. Basically it starts right up and idles fine but when u go to accelerate it (hard to explain) you push the gas and go to take off and it revs up and goes slow and hardly any power and when it is about 3/4 of the way through the "power band" it gains a sudden burst of power until you have to shift and then does the next thing for the rest of the gears. It always ran like this the past year and just recently for a few days it ran WAY worse, it took all it could do to get up to 30 mph.....then all of a sudden it started running better than it ever had before for a day or so. When it ran great, every time I shut it off you could hear air coming out of the gas tank cap for a solid 30 seconds and when I would go to pop the gas cap a big surge of air would come out due to the tank being mega pressurized.


In the past year I have replaced the following to try and solve it:
Plugs
Wires
Rotor and cap
TPS
MAF
O2 sensor
Clutch


All of these did not help the problem....any ideas? or tests I can run?


Thanks!

 

Where is the ignition timing set? An easy (and very basic) check you should do before you start replacing parts.

The pressurized tank is normal (on a warm day gasoline evaporates in the tank); the hissing from the gas cap is not. The gas cap is vented to allow air in (so the tank doesn't crush as you pump fuel out), but not to allow fumes out. Replace the cap.

 

Fuel pump. When mine went out it did the same thing. It's grabbing too much air and not pushing enough fuel to the motor.

 

The fuel systems in these trucks get neglected. Is the return line clogged?

 

How do i test if the return line is clogged? Also i did run It without the gas cap and it still ran crappy....

 

When you hit the gas pedal, do the RPMs increase but no increase in speed? If so I would say clutch. A symptom I currently have with my 94 pickup 3.0 4x4 manual is that the truck drives fine until under load and/or going up a step hill, when gassing, the RPMs will jump, but the speed won't increase...Mechanics I have talked to as well as on other threads, they all say clutch. It doesn't help that I supposedly have a misfire in cylinder 2 which I need to further diagnose, according to one mechanic. Anyway, back to pieps57....maybe fuel starvation? Change the fuel filter? What about the fuel pump? Have you checked fuel pressure?

 

Try driving it with the gas cap off. If it runs fine then you know that is where your problem lies. Are you talking about positive pressure or negative pressure (vacuum) in the tank? If you have too much negative pressure then your fuel pump will not be able pull fuel efficiently (kind of like trying guzzle a beer out of a glass bottle - if you don't let air in, you aren't going to get that yummy deliciousness out). You should have a return line going back to the tank, but that is for excess fuel provided by the pump so that it doesn't force feed the engine. I'm not sure about the later models, but the 79-83 pickup tanks are vented through the charcoal canisters. A vented gas cap can help the situation too.

 

I did drive it with out the fuel cap and it made no difference, I also have replaced the fuel filter. As far as negative or positive pressure....Im pretty sure it is positive pressure as in it is extra air in the tank trying to get out.

 

I think have it narrowed down to my fuel pump or the equalizer tube in the gas tank....I am replacing my whole tank, sending unit and pump this weekend and will keep everyone posted. Thanks