I have a 91 4Runner 3.0 V6 3VZE with 176,000kms (109,400 miles)

It drives fine but I think it could get better mileage and it has a bitch of a time going up hills... I think I have narrowed it down to the fuel pump, fuel filter, or cat. It doesn't sputter or bog out at all, it's just sluggish... Any Ideas? Any insight will be appreciated. I will probably Change the filter no matter what.

 

Just what are you comparing it with??

After all it is a 3.0

Manual or auto transmission??

A fuel filter and tune up can never hurt.

Fuel mileage how much stuff do you cart around the weight adds up fast .

I had a thousand feet of #01 welding cable That sort of got buried under a tarp I forgot about .

Tire size and pressure also impacts fuel mileage .

Your driving style as well makes a huge difference.

 

The o2 sensor, TPS and timing should be checked out too.

 

Have you checked the air filter in a while? Fuel filter is also a good idea.

Also you could run some seafoam through the brake vac line plug

You said you narrowed it, have you done some stuff already?

 

It is a 3.0, but I think it could go up hills a bit better. There is no weight in it at all. It is an auto...

 

Upgraded to a K&N cold air intake. I seafoamed it. I tested the VAFM... I am trying to avoid the injectors hoping that they are good because they are $420 for six of them...

 

Ya. I am trying to get my hands on a timing gun. I don't really want to buy one just to use it once, but I might have to. wouldn't the O2 sensor cause a CEL? Can it really make that much of a difference in power?

 

O2 sensors can fail over time and not throw a code, but just provide bad info to the ECU. If yours is original, then it probably needs replacing.

I have my timing set to factory 10 BTDC, and it runs like a champ. Powers uphill just fine (empty). You should definitely check to make sure it's in range.

It is also possible that the timing belt is off a tooth. That would definitely wreck your power also.

You could send your injectors out to witchhunter.com for cleaning if you are concerned about them. No need to spend so much cash. You can buy cheaper sets off eBay for less than that.

Good luck with it!

 

Thanks. I really need to get the timing light.... I really hope the belt isn't off a tooth... That would suck. there's no way I can do that job myself $$$$. I suppose I will do the o2 sensor this weekend. I just finished changing my fuel filter and took it for a short drive. I will see how it goes up a decent sized hill tomorrow.

 

If you get the timing light, might as well get the compression check kit as well. That will only help to pinpoint!

Have you looked at the plugs? Do they smell like fuel?

 

I haven't. What will that tell me? I'll pull one out in the morning and see. Should I pull all six, or is one enough?

 

All of em for sure, do it after warm engine. That way if you're running super rich you'll be able to smell the gas on them.

Let us know how it goes. Pics are always useful for forum diagnostics as well!

 

Will do. I'm pretty sure I'm not running super rich though, especially after playing with the AFM. I leaned it out about 8 teeth and I could tell it was too much so I put it back. We'll see though! Also, I noticed nobody has even mentioned the possibility of a clogged cat. Is that not something i should worry about? It's a 23 year old truck.. It's just going to be such a bitch to get off that I have been neglecting it. I'm actually mostly concerned with the timing now. I'm starting to think it might be out. I did my fuel filter today and the gas was pretty nasty, but I really haven't noticed any improvement. Maybe just slightly. Anyways, I appreciate your input. I'm off to bed! Thanks again!

 

Clogged cat is def a possibility. Mine (when I got the car) was bad. It had blown through, though.

No problem on the advice, sharing knowledge and trying to be helpful is one of the keys to being happy imo! Doesn't matter if it's online or in real life!

Best of luck to you, report back with how it goes