1990 4 Runner engine underpowered

[ymme111]

Hi. I previously owned a 1990 4 cyl 4 Runner. Loved it till it finally gave up the ghost a year ago. It was rusted out and not worth the fix. I bought a 6 cyl because I thought it would have more power and better gas mileage. And I could keep my 4 cyl for any parts I might need Wow!!! Big mistake. I know they are underpowered and get bad gas mileage but I think mine is way below average. I get 8 mpg and have real low engine power. It slows down and struggles going up overpasses and small hills. When I try to pull away from stop signs it feels like it's going to stall. A real bitch when trying to get onto highways and beat the traffic. It take forever to get to speed. When I floor it it sound like I'm tearing up the road but I'm barley picking up speed.

This is the second engine in it. The head gasket blew 1 month after I bought the truck and the bottom end let go a month after replacing the head gasket. This new engine out of a parts truck I bought performs exactly like the first. So I'm thinking something else is making it run like that. I took off the headers that were on it and installed factory manifolds and a new exhaust system 2 1/4" pipe and no change. I upgraded the spark plugs and cables. Changed the O2 sensor and fuel filter. No change. Threw on a K&N air filter and took it into the guys at Toyota to run diagnostics on it and they tell me that they can't find anything wrong. Come on!! Anyone out there help?

[Brian R.]

How's the compression?

What do the plugs look like. Are you running lean? May be a fuel supply problem.

Check your ignition timing.

Away from the engine - are your tires larger than stock? Larger will trash your torque at the wheels.

[ymme111]

The compression is normal. Plugs are clean. And I'm running stock tires. I'm leaning toward a fuel supply problem too. Like I said I changed the filter and it seemed to run a little better for a day and then it was back to the same problem. I going to check the fuel pressure this weekend and go from there. The truck seems to be worse just after start-up when it has sat for 3 or more hours. When you step on the gas to pull away is almost stalls. It takes a few seconds and then slowly pulls away. But slower than my grandma in the morning. Thanks for the tips Brian.

[Brian R.]

Try cleaning the injectors - either Cevron Techron or something like

http://www.storesonline.com/site/598452/product/DI208

Check your ignition timing

[ymme111]

Thanks. I'll let you know if it works.

[corbinwaterski]

Dirty fuel filter, or possibly a dirty or contaminated gas tank??

[PagosaJeremy]

You need to check your fuel pressure regulator. Remove vacuum line to regulator see if raw fuel is present. It sounds like it because you have a thermal vacuum switching valve on your regulator.

[Northern Sun]

check ur distributor mine looked like that full tank of gas=180km :22yikes: i gain at least 50km by changing distributor, hope it help, N.S

[Brian R.]

Please don't ressurect old threads. It is not likely that the OP needs the help any more.

[Northern Sun]

hmm.... u right, forgot to check post date Northern Sun