JackDanson

I performed an engine swap from my old 94 into a 95 body, both 3.4L V6 engines, both ran fairly well before the swap. Now when I try starting the 95 with the 94 engine, it will crank but not start and will usually start to backfire. I’ve replaced the coils and checked the spark plug wires and I know it’s getting good spark. I’ve also tested the cam sensors and even tried replacing them to see if it makes a difference: it doesn’t.

I imagine it has something to do with the timing, but I’m not sure what else to do for that. If anyone here has had similar problems, I’d appreciate any insight you’re willing to offer. Thanks.

jetech

How is the fuel pressure? Try a squirt of starting fluid or a squirt of gas in the throttle body before you crank it?

B52bombardier1

I don't like using starting fluid as a crutch to get an engine to start - its tough on the cylinder wall oil film. But . . . as advised above, its a very good diagnostic tool if used in moderation. You will know very quickly if it is a fuel delivery problem or an ignition spark problem.

Rick

jetech

my thoughts also. I would never use starting fluid by the directions on the can. "Spray 2-3 seconds" Not me! Even if the starting fluid has "lubricant" in it.

JackDanson

I don’t think it’s fuel pressure, since I can hear the fuel pump running when the ignition switch is on. It also appears to get strong spark from the plugs. The coils are new and I believe all the grounds are good, but it’s possible I’m missing one somewhere I suppose.

to clarify, the engine ran smoothly after the swap, then progressively got worse each time it was run. It started with bad misfiring, so we replaced the coils and checked the timing system. Now it will crank but not start.

I’m looking into the VATS system, though the security light seems to function normally, so I feel like I’m off the mark. I took the computer out and noticed no change when I turned the ignition if that helps.

01CamaroSSTx

iTrader: (3)

Very important to make sure you have good chassis grounds. I had a similar issue after a 5.3 swap with our 05 Tahoe. My scanner said no crank signal so I re-used the crank sensor from my original engine and it started after that.