I have a 1987 4runner that dles very rough when I start it upand it's already warm. When I start it up in the morning, the idle picks up fine (around 1000 rpms) until it's warm, however after a drive of 10 miles or so, if I turn it off, wait about 30 minutes then restart, the idle can be as low as 400rpms causing the engine to shake considerably. I took it to my mechanic and he checked and verified all the idle settings, but the problem persists. One option he mentioned is that there is a check valve in the fuel line which may be leaking by. This check valve maintains pressure in the line up to the engine.
Anyone have any insights. Replacing that check valve means droping the fuel tank and replacing the whole fuel pump assembly.
thanks

 

If the ignition key is on, the fuel pump would be energized and fuel system pressurized, so the check valve would be immaterial to the problem, wouldn't it? Also, if it were a leaking check valve, the problem would be exacerbated by a long off period, such as overnight, yet according to your post there is no problem the first time you light it off in the morning.

Seems to me the problem is heat related.How hot/cold is it where you live?

 

Thanks for your reponse. Those are good points you make. I live in Sacramento and I have only noticed this problem since it started to get cold (November) time frame. I also noticed that this last week when we had a warm spell in the 70's the problem seemed to go away. I keep the 4runner in the garage at night so it may not be getting cold through the night. The problem occurs when I stop for 15-20 minutes at a store and the truck is parked outside.

So how do I prevent the cold weather from affecting the idle so much. Shouldn't the computer have the engine rev higher to warm it up?

 

Does the problem ALWAYS happen? If itis intermittent, it might be a vacuum leak somewhere. A v-leak will cause low idle and engine shaking. Doesn't happen all the time, either.

 

Need to know if this is a 22re or a 3vze.....

 

Hey bro did have you ever fix your Idle problem ? I have the same issues but mine just the Idle issues where I have gas the pedal to keep it idle until it hot enough to stay idle...Not sure what causing this..

 

Hmm seems like a ignition coil problem have you tried checking it?