help help??? 1987 TBI change over

[plowguy]

ok need some help did a tbi change over that I was told would be easy and now have a big problem ...
it started as a 1986 chevy k 20 with 350 carb

ALL I change over was from a donor truck was the TBI and computer, intake dist.. new howell wiring kit
however I did take the fuel tank from the 1989 donor suburban because it had the fuel pump and all (maybe this is the problem I was thinking same fuel pump but now maybe not!!

ok now it runs but wont go up a hill and it back fires out of tale pipe back when letting off of gas however it runs great in a parking lot all day like a brand new truck what did I do wrong??? starts right up runs great will do 60 mile an hour down the road if you go slow getting up to speed but when slowing down she backfires bad PLEASE HELP

[ChevyTech]

Welcome to the board.

The 1989 fuel pump is compatible with the 1987 system.
Test the fuel pressure with it running. The pumps get bad. The rubber hose in the fuel tank often fail, and the fuel regulator spring can rust and break. If the tank sat for a while it is common for the hose in the tank to fail.

Did you unplug the set timing wire when you adjusted the ignition timing? If not the timing will be way retarded.
Did you clear the code after setting the timing?

[Palf70Step]

Sounds like the timing is off. I am not real good with TBI, but I know on the 94 version you have to disconnect some wire before you time it.

PS NOTE: The smart guy got it typed before me.

[mountie]

when troubleshooting, remember a simple thought....

Backfire out of the intake is low on fuel, ( lean)

Backfire out of exhaust is too much ( or unburned ) fuel, ( rich)
,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,
..... Yea, that wire is a brown wire attached with a 'fused looking' link, to be disconnected when checking timing. it should be seen - or found just to left-view of distributor cap / near firewall / next to that plastic wire harness cover that is mounted on firewall.