nicksmith18vt

I have brought my 4runner to 3 different mechanics and none of them can diagnose the problem. My truck does not want to start. When i turn the key, it will sometimes start and sometimes not, when it starts it will go from 1000 rpm's to 0 and keep doing this every couple of seconds and then just stop. It usually does this series of going from 1000 to 0 rpm's around 2-8 times before it stops. But when I keep trying to start it sometimes it will start and run fine for a couple of miles, then while I am driving it does this same thing and I will lose all power steering and power brakes and it will shut off. I know what isn't wrong with it, the battery, ignition, alternator and other electrical has been checked by the mechanics and they think it is either the wiring harness or the computer that is the problem, but since it is an intermitting problem, they can't seem to pinpoint the problem. Has anyone ran into this same problem with a 1986 turbo 4runner?

Any help would be appreciated,
Nick

tried4x2signN

Have you checked the timing

Is the check engine light on

Can you jump the fuel pump and listen and see if it's running fine

Have you changed the fuel filter recently

Wonder if the fuel pump's ever been changed and they put a RE pump in it? It takes the same as a V6 BTW...

TPS is notorious for being off in these trucks and causing problems. IIRC, a bad TPS won't even come up on the CEL. Mine was bad and had a small rust hole in it and the CEL didn't turn on.

Check as many components as you can with a multi meter.

nicksmith18vt

yeah, the check enigine light is on, but when the engine stops going from 1 to 1000 rpm's a few times, sometimes it will run smooth for a minute or even 30 minutes and the light goes off. I don't know if the mechanic has checked the timing or fuel pump, but I will ask them to do that. The fuel filter was changed last year. My truck burns gas a little rich too. What is TPS? Sorry, i'm not very knowledgeable about mechanics. Thanks!

75k5toy

Howdy Nick. I had an 86 p/u turbo, some years ago and one day it started to act loco, the idle was fine but when it reached the 2k rpm's. it chocked, and didn't passed that point, I un-plugged the tps and temporary solve my problem, won't hurt to try, p.s the tps is on de d/side of the t/body, top of the thermostat housing. good luck.

tried4x2signN

if the CEL is on, check the code...

Ignition off, jump the T to E1 and turn the ignition on but not to the start position.

annoyingrob

To me it also sounds like either a fuel issue, or a TPS issue. If the fuel pump is bad, or the filter is clogged, you would get a drop in pressure. If you can, disconnect teh cold start injector, and install a fuel pressure gauge. Monitor the pressure when it runs bad, if it's low, it's a fuel problem.

If it's an auto transmission, what you can do is use it to check the TPS. Look it up in the FSM, but you can hook a multimeter up to the auto tranny ecu's check connector, and verify that the TPS is outputting the proper signals.

Edit: sorry, it's a 4Runner, OF COURSE it's auto.