bobpat

I have only had my 85 for 3 weeks now been working on it the whole time. It runs awesome cold, but when it warms up and it had serious idle surges and would bog and die at times when you are just cruising and try to accel. I did note that when it bogs if I turn key on/off/on real fast it will come right back to life for a little bit. Looking thru this forum I found lots of threads with similar problems, Most had no resolution to them and were several years old.
Thought I would rewarm the problem up and hopefully help anyone else that might be starting in on a similar problem.


First off let me say I have the idle problem fixed it runs smooth as butter now...till it bogs and dies lol .
I had two different problems 1) wild surging idle 2) bogging and dyeing


Idle problem:
afm cover had seal broken on it and serious rust on innards. replaced..
throttle position sensor had no readings on 3 of 4 of the resistance checks I found on this forum. replaced tps...
Idle air screw was loose and wobbles in throttle body housing and had heavy coking on set end of it. pulled throttlebody cleaned whole thing put new "o" ring on idle set screw...
all these and it idled great cold but warmed up surged a lot
found on here that aac? or cold idle valve? (believe mine is an acc
no electrical connection to it) but could have this wrong,could be problem. deactivated valve ( left unit in truck with water lines hooked up just capped the vacuum ports .) AANND boom idle problem gone. man idles so nice now.

Now the bogging and dyeing problem:
Did not have a fuel pressure gauge at first, so tried a o2 sensor from my grandsons 85. no help
while waiting for fuel pressure gauge to arrive I thought maybe fuel regulator was bad while looking around for one I pulled the fuel return line off the regulator while It was idling and had large amounts of fuel pouring from it. when the bogging and dyeing starts pulled same line and no fuel at all coming from it.
bad pump? or fuel reg? or something (ecu?) cutting off fuel?
this where I am at right now.
pulled bed off today and will install new pump in the morning. I will give an update hopefully and a fix. Should the pump not fix it I have my new fuel pressure gauge in now so I will hook it up and see what I see.
Very long winded here I know but this seems a problem with these engines. Would welcome any ideas, notes, thoughts ect.. love the looks on the 85 yotas trucks and 4 runners just need to get it working so I can run in the mud trails against grandsons 85.







.

bobpat

ok installed new pump, ran truck for an hour and had no issues at all ran great would had bogging several times in that length of time before so more driving required to say for sure but was nice to drive it that long with no problems.

bobpat

after 3 weeks or so of intermittent driving no bogging or dyeing so im gonna call this a fix !!!.

thefishguy77

iTrader: (1)

Rock on. Glad you seem to have gotten it handled. I love one step fixes.

bobpat

yea the surging idle problem was harder for sure.