well I have a 88 305 auto in my s-10 with the stock computer and a painless wiring harness. when i first start my truck it starts up and idles nice lots of response etc...i have my timing at 9* advanced...im not sure if thats too much? I have headers a brand new 02 sensor...and the maf is suppost to be new. sometimes for no reason when I really lay on it and it downshifts the engine light will flicker on and it will fall on its face. I dont have my vss hooked up and I know I have my firing order right. there are no apparent vaccum leaks.

when I first did the wiring for the engine for some reason the fuel pump would not turn on....I tried about 5 fuel pump relays but still nothing. I do know the oil pressure switch above the oil filter does have a corner missing off it.

would this have anything to do with those problems?

 

The ECM should operate the fuel pump relay for two seconds on ignition power-up regardless of the oil pressure switch. You can disconnect the oil pressure switch (or even run without one) and the fuel pump will work just fine, so long as the relay and circuits are intact.

The Painless harnesses I've used have been clones of the factory harness, color for color. In that case, the large orange wire at the fuel pump relay socket (terminal E) should have battery power at all times. The black/white wire on terminal B should be a ground. The green/white wire (terminal C) should have 12V for two seconds when the ignition is turned on, or whenever the distributor is spinning.

 

I was under the assumption by looking at the wiring diagrams that the oil pressure switch powers the maf power relay?

oh and I also had to end up putting a circut breaker in place of the fuse for the ecm because it kept blowing.

 

The fuse for the ECM is also the fuse for the fuel pump. The oil pressure switch does not power the MAF: