Rebuilt Engine Won't Start - Advice?

[SonomaPete]

Just finished my first ever engine rebuild -- of my '69 911E engine -- capably guided by Wayne's book and Bruce Anderson's engine rebuild class last December.

Everything went surprisingly smoothly (given that I'm a complete novice), but now that the engine's back in the car, I can't get it to start. The starter turns over, I'm getting a spark on all the plugs, and I'm getting fuel TO the injectors (I unscrewed the metal fuel lines running from the MFI pump to each of the injectors, slipped a glass under each, and watched as fuel pulsed out when the engine turned over). However, I don't appear to be getting fuel FROM the injectors -- when I pop them out, screw them onto the metal fuel lines, and turn the engine over, nothing comes out).

My (highly uneducated) guess is that the fuel injectors are clogged, after sitting around in a parts box for a year. Before I send them out for cleaning, though, can anyone confirm or dispel my suspicion?

[kstylianos]

The injectors open under pressure. I know with CIS, if air gets trapped in the fuel lines, its hard to build enough fuel pressure to open the injectors until all the air is essentially 'pushed' through. CIS injectors open under less pressure than MFI injectors, so this may be even more true in your case.....this is just a thought. With CIS, you can manually lift the plunger to increase fuel pressure to the injectors w/o cranking the engine.....maybe there is a trick with MFI, but doubt it since the pump is driven off the cam....

If you think your injectors are clogged, try soaking them in Techron over night and agitate

[Wayne 962]

It's unlikely that your injectors are clogged. I'd say 95% of the "engine won't start" problems are caused by timing issues (when there's a spark). Even if a few injectors were clogged, the engine would still start to fire on the other ones. It's unlikely that all of them are clogged.

Is the engine trying to fire at all? Recheck your plug wires - they are very easy to confuse. The 911SC plug wires are different than your car, so make sure you're not looking at a layout for the SC...

-Wayne

[SonomaPete]

Thanks Wayne, and thanks for the fantastic book too.

I think the engine is trying to fire -- I say that because as I crank it, a thin plume of exhaust comes out of the tailpipe -- and I've gotten two very loud backfires. Does that give any additional clues?

[Wayne 962]

Backfires typically means ignition problems - check the wires first...

-Wayne

[Groesbeck Hurricane]

Also, did you bleed the air out of the CIS? This was another of the reasons my re-build did not start...

[SonomaPete]

I didn't bleed the air out of the injection system -- does one need to do that for the mechanical injection system?

[rcwaldo]

I would put money on ignition timing. I always double and triple check. No matter how careful one is when installing plug wires, some get crossed etc.

Good luck, hope you get it started soon!

Chris

[BURN-BROS]

I KNOW THAT ON DIESELS WITH MFI IT IS BAD TO RUN IT OUT OF FUEL. AIR IN THE LINES MAY NOT LET SYSTEM PRODUCE THE HIGH PREASURE TO SET THE INJECTORS OFF.

[fallonmi]

I had the exact same problem you are describing when trying to start my rebuilt engine. I followed Wayne's distributor wiring diagram, but mine ended up being the exact opposite. I ended up checking it by turning the engine over by hand a little bit with the engine at TDC and the distributor cap off. I checked the rotation of the distributor. Starting with plug wire 1, plug them into the distributor cap (going the same way the distributor rotates) following the firing order. This is what helped me.

[Tim Walsh]

It does take time for the engine to build pressure in the MFI hard lines. When I started mine up after a a strip down to a longblock it took awhile for it to fire and then it was a whump.. whump,whump... whump whump.... etc until it fired on all six and ran.

[BURN-BROS]

SonomaPete, what is status on the no start? .....any luck?