I have a 1991 Chevrolet silverado with a 5.7 TBI 350 engine it has 130000 miles on it. Over the last week or so the truck has a lot of trouble starting. I have to crank it over several times and it barely fires. Once it is about running I can get it going be snapping the throttle just a little bit and it smoothes right out. The idling is good. The engine misses intermidintly when under a load getting off the gas when this happens seems to erase the problem and you can feel the engine have all kinds of power when I get on it. I got a service engine light that comes on shrtly after the engine is running or down the road. Having an adld connector ans obd1 system I retrieved my codes by jumping the adld terminal. I got a code 43 which is the electronic spark control module failure malfuction. I also checked the I ac unit and found a little carbon build up on the pintle. Adjusting the looseness and tightness of the iac made the engine respond at idle. I replaced it. I recently replaced the cap and rotor and about a year ago needed to replace the ignition module and coil. I seem to have good fuel pulse at all rpm ranges, but I cannot completely rule out fuel issues. Ran a fuel pressure check and got varying pressures. I know fuel pumps either work or don’t work, but if it was working half right like I heard. That can make the engine run ruff or die, but it would do that all the time wouldn’t it? Any help that can be given would be helpful and appreciated.
I’ve posted a few times to the Yahoo GM TBI group about my 93 305 TBI and they have been helpful. There’s not a lot of activity on the group at the moment, but you could search the message archive for similar problems.
http://autos.groups.yahoo.com/group/GM_TBI/?yguid=288452351
Ed B.