Rebuilt Engine won't start
 

I just finished rebuilding and installing a rebuilt motor in my 944. I checked everything, filled all of the fluids to proper levels, etc. I primed the oil pump and with the DME relay out cranked it over until I saw good oil pressure. I replaced the DME relay and cranked it over again. This time when the rail filled with fuel it caught and fired on what seemed like one or two cylinders. I checked spark on the #1 plug and it was strong. The motor sounds perfect spinning over. I double-checked timing when I installed the timing and balance belts. I gave up for tonight, but tomorrow I will recheck timing, spark on all 4 plugs, and test the injectors. I used the same AFM and Throttle body from the old motor that was running days prior so I know those are good. I used the fuel rail and injectors from the rebuilt motor so those may be plugged. I am also getting wiggle on the tach and with spark and some fire I know the reference sensors are gapped right. I will also check compression. Any hints or suggestions? I need to get this motor running ASAP.

is the dme relay new? other things always seem to not work after other things have just finished being repaired...... :D

Yeah, I replaced it last year, I also know fuel is getting to the rail and I saw spark. I also just checked timing this morning, dead on. I also checked the fuel rail and tried again. Still it sputters like it wants to start but never catches. For referance, you turn the idle screw CCW for a higher idle?

My list of things to do;
-Change fuel rail+injectors back to the set I know work
-Check for spark on all plugs
-Regap the position and speed sensors
-Check compression
-stick my foot in a bear trap

Strongly suggest skipping that last step...

I think your first step sounds promising. If it's trying to start, the fire may be ok just doesn't have enough fuel. I take my injectors out and attach clear plastic hoses to them routed to a container and watch what kind of fuel flow I see.

Fuel, air, spark!
Your first two items will tell you what it is that's missing. Did you try disconnecting one of the injectors and seeing if that makes a difference?
Good luck!

Well I got an update for ya. I checked compression and got wonderful numbers. While I was taking the plugs out number 3 was wet and the others were bone dry and clean. So I swapped the fuel rail and injectors with the old ones. The car fired up and ran strait to 3k, it was lean because the threaded fitting on the fuel rail was not tight and leaking. After fixing that and cleaning up the mess, i tried it again and lowered "I think" the idle because it had been bumped up earlier. Know the car will start but not idle. If i give it gas it will make it to 2.5K and then run fine from there but if I let off the gas it immediatly drops, a single backfire, and will die if I dont give it immediate gas. I am thinking vacuum leak. Any other ideas?

Lean mixture....maybe a vacuum leak...still may be a fuel problem.

Vacuum leak, the ISV to intake was not even close to being connected. It runs and idles fine.......but...........there is a loud tapping, kinda sounds like lifters, it has not gone away yet. The motor sounds ok other than that, and seems to run strong. The only other thing it could be is an exhaust leak, can one sound like a loud clicktap?

Well it calmed down. I'll post pics later.

you are correct, the lifters just needed time to lubricate. the fuel injectors make their own share of clicking noise as well. good to see a fellow pelicaneer bring another 944 back to life. ;)

Yeah, my cars been running great for 4 years, ive put nearly 50K on it and done just about everything including a clutch. The old motor needed an overhaul but still ran great. This forum has saved my butt a few times along with clarks garage.