Okay, so my 90 4.9L 4wd went to the shop for the 4th or 5th time in the last two weeks today to get the timing checked.

The problem I'm having is that they set it to 10 BTDC and the truck runs fine at idle but under a load will bog down.

The next problem is that once i park it and let it sit for a half hour the truck then has a hard time starting.

Then if I let it sit for over an hour and try to go start it it wont start.

But, if I loosen the dizzy up and bump it over a little the truck will start fine, sometimes runs like **** sometimes runs fine. Tonight I had to do this and the truck ran fine don't know how its gunna run tomorrow.

What could be causing it to run like complete when the timing is set at 10 BTDC?

Could my timing gears be jumping from being worn out. At a total loss any help will be greatly appreciated.

Thanks.

 

sounds like it could be a spark and/or fuel issue too.

 

From what I have gathered reading on this forum, and with my own expedience with my 87 302.... seems to be a typical problem that occurs from multiple issues. Have you dont anything such as a tuneup recently before it started happening?

check grounds
check the ECT
check/clean the Idle air control valve and EGR
Make sure you are not getting cross-fire from bad wireset routing
if not running copper core plugs, try some if possible
pull vacuum line from fuel pressure regulator and see if it improoves at all, inspect fuel pressure regulator for gas in the line.
have the PIP and TFI checked and replaced if needed (stay away from Remans if possible)
check vacuum at intake with gauge, at both idle, partial throttle, and full throttle. if vac drops down to nothing when throttle is open, inspect exhaust and look for a clogged catalytic converter


and of course, before any of that... the favorite response on the forum... check for codes. hehe. in my case, I ended up having a plugged cat and a bad TFI/PIP