Major 350 Tpi Issue

thesargster · February 27, 2011

Hi all, i am new to the forum and cant wait to start giving advice but i will ask for everyones first as im in dire need!

I just did a 4.3 v6 to a 350 v8 tbi swap in my '93 K1500. Freshly re-built 350 out of a donor 88 tbi suburban. The ECM is number 16168625 and i ordered a new PROM for it being call code BDKP which all checks out according to the books.

The engine starts, runs for about 3-4 minutes very strong; then starts to loose power, and then eventually stalls out as if someone shuts the ignition off. Keep in mind the SeS light is staying lit DIRECTLY from the point of the engine starting. Once the engine stalls, it has to sit almost as if i have to wait for the fuel pump to prime for the engine to restart, sometimes having to start it WOT then waiting for it to catch it self. Eventually its like this bug just crawls out of the truck, and it starts to run perfectly strong again.. then everything just starts over again. I was told that the V6 was having the exact same issue before it threw a rod and i bought the truck!!\

I have replaced the following:

ECM/PROM

Fuel pump/relay/filter/regulator diaphragm

Oil pressure sender/fuel pump shut off switch

Injectors (55lb)

Distributor (including all accesories)

Cap/rotor/wires/plugs

Coil

TPS, MAP, IAC

Theres a few others ive replaced but i cant think of them off the top of my head. Keep in mind like i said the SES light comes on the second the engine starts.. and i dont know anyone that has an OBD1 scanner, nor do i have the cash to pay a shop $65 an hour for them to plug a diagnostic computer on to it.. Any advice much appreciated!

thesargster · March 2, 2011

I managed to get the truck up and running without stalling, i pulled the engine codes and turned out the knock sensor had a bad pigtail, the temp sensor was bad, along with the fuel pump had a bad ground.

Now it runs, but it has a SLIGHT lag in the beginning of accelerating when you just barely touch the pedal, but goes away as you give it more pedal. Seems like the timing is very touchy with this system, i have it set right to where it seems it wants to be as far as how it runs WoT and at idle. Whats odd is it seems like its not advancing when i give it more throttle; as it should correct? Ive had plenty 350's and they all had much more get-up than the way this one is treating me.

As far as the o2 sensor goes, when i had the exhaust done the mech at the shop didnt re-install it in the new custom y-pipe, and told me i should be okay without.. which i have had plenty of chevys and cut the o2 and didnt have issues.

Let me know what yall think,

Thanks

John