Hello all,

I have been browsing the forums for a while and have been working on a problem in my head for a while and can't think of any problems so I am turning to all of you for help. I have a 1996 Trooper with the 3.2l v6, when I drive it for, lets say about an hour (only on the freeway) it starts to struggle before it ends up having me flooring it to keep it going 60, the only times I have noticed it is driving from Phoenix (AZ) to Payson or Flagstaff, so it is going uphill and it is definitely better going downhill but when I am driving uphill, its not that steep and it still slows me down rediculously, and ruins my fuel economy while its at it. Heres some things I have done


Replaced muffler (Old one was rusty)
Had shop replace transmission filter and fluid
replaced oil filer
Replaced o2 sensor
replaced IAC
replaced timing belt
replaced waterpump
replaced alternator
replaced A/C Compressor
replaced battery
Checked backpressure (at intake manifold) and all looked good
Just passed emissions so I think the cat is good

I know some things on that list aren't related to my problem, I just felt like I should say it all in case something is weird that I don't know about, I am out of ideas. One other thing that happens (that I think (MIGHT) be related, but I'm really not sure, is that whenever it's time to fill up on gas, I open the filler cap and it sounds like my gas tank was pressurized, without fail, every time, I cant tell if its pulling air in but I think its pushing it out, I think the cap is good however because they check it with emissions. I would just like to have this problem solved because so far, its really my biggest issue with the Isuzu overall.

Thanks for the help

 

While I'm tempted to say it's a fuel related problem it could also be one of a number of other things. The next time you're on the freeway and it starts happening again, put the tranny into neutral and note how fast the car slows down while coasting. It could be a wheel bearing getting hot and increasing drag. It could be brake related.
If it still looks fuel related you should do a compression check with the motor cold and again warm. Have you had the injectors cleaned or replaced?
When you mentioned that you checked the back pressure I assume you meant the fuel back pressure regulator but were you able to check the fuel pressure after an hour of driving when the problem started occurring? It could be the fuel pump getting tired. Have you changed the fuel filter?

 

Need help. While in drive I have no power. Not getting gas. Replaced oxygen censors, fuel filter, plugs and they are getting oil, fuel pump, and ignition coils. Still having same issue. 96 Trooper 3.2