77 911 2.7 to 3.0 Swap Won't Start

[dschloe]

I'm in the last stages of a motor swap in my 77 911 to 1980 3.0 with MSD 6A Ignition with Blaster 3 coil. The car turns over and sputters once or twice but will not start. I have spark, and hear the fuel pump running. If i leave the key turned to the run position for a min or two is when I get the sputter. I did add all the Lambda equipment for the 80 motor but I'm a little stumped. I've tried to adjust the timing but it doesn't seem to change anything. Any pointers would be great. will the 77 fuel pumps work with the 3.0 motor.

Thanks

[schumicat]

I would check the fuel pressures. you need a CIS pressure test kit. google jim CIS primer for the procedure. you could also try spraying some starter fluid into the air box blow off valve (hopefully you have one).

[dschloe]

Thanks I'll give that a try and will check out the link as well.

[timmy2]

Did you change over to the '80 style fuel accumulator and plumbing?
With key in run position and fuel pump running, ( jumper the relay so pump runs) do you hear the injectors squeal if you lift the airbox arm for a few seconds? (Short duration only, don't flood the engine!)
Have you checked the injector flow of all six injectors?
Have you adjusted the throttle body air bypass screw or adjusted the richness in any way?
As Schumicat said, get the gauges and start testing the fuel system.
Have you tried it with the O2 sensor disconnected?
There are many more questions and adjustments but this is a good start.

[racerboyrt]

How's the starter? I had a 3.0 that would almost start but wouldn't, starter sounded a bit slow, it'd almost catch. Replaced starter and fired right up.

[spuggy]

Originally Posted by dschloe

will the 77 fuel pumps work with the 3.0 motor.

My '77 fuel pump supported a 930 making 330HP just fine. Only changed it (for an 044) on general principle when it went over 400HP.

If you used the 3.0 motor harness, you might want to cross-check the pins on the 14-pin plug; they're different between the 930 and the 2.7 - you may find something not wired the way the 3.0 wants it as well...

The fuel pump should NOT run on a '77 with only the key turned to run (unless either the relay is jumpered or the air flow meter switch is disconnected). If neither of these is true, that's a clue right there.

[dschloe]

Thanks for some ideas to check. I will try these and see what happens. and will try to get the gages and check out the fuel system.

Spuggy do you remember what wires you changed on the harness? I did notice that my oil gauge was showing good oil pressure when I was cranking it then it started jumping all over then back to normal. When I checked the harness against the wiring diagram only the tach wire needed to be pulled but maybe I missed one.

Thanks

[spuggy]

Originally Posted by dschloe

Spuggy do you remember what wires you changed on the harness?

PO swapped the motor in, so I don't really know what was done; the 14-pin plug is so old/fragile I've been avoiding breathing on it for years unless I really have to...

I know my fuel pump isn't supposed to run though without air flow plate moved off rest (and it does). So likely a similar problem there...

I'm also not convinced my CSV is operational (makes no difference if TTS hooked up or not), but it starts well enough when icy that I've never bothered to trace that either.

I did notice that my oil gauge was showing good oil pressure when I was cranking it then it started jumping all over then back to normal. When I checked the harness against the wiring diagram only the tach wire needed to be pulled but maybe I missed one.

Thanks

Think the SC's had a 10 bar pressure sender, so that should match the '77 gauge fine. Unless you swapped the temperature sender, you will find the SC sender doesn't match the 0-340 '77 temp gauge though - this needs the sender from the 2.7, 930 or the 3.2 (the SC temp sender matches the 0-300 numbered gauges used in 74-76 though).

[LakeCleElum]

The instructions to wire in a MSD 6A Ignition with Blaster 3 coil are printed for an American made car.....Forget how, but needs to be different to work in a 911.....

[spuggy]

Did you by any chance re-do the plug wires and perhaps forget that the SC rotates the same way as the 930 (the opposite way to the 2.7 and 3.2s)?

Another thought - was the 2.7 using the MSD, or did you just fit this?

Seem to recall there's a classic "no-start" problem with the MSD if you don't wire it correctly?

These might help:

msd ignition recommendations
Any way to trigger a MSD CD?
MSD Ignition to Distributor - What are you using?

If I recall correctly, the MSD-6A (as opposed to the MSD-6AL) doesn't have a limiter? And you can't (or shouldn't) use the rev-limiting rotor with the MSD, because the extra current will burn out the floating part; should use the solid VW rotor instead.

This leaves you with no rev limiter, if neither the MSD-6A (nor the original '77 Bosch CDI) box) do it. I had a similar problem; my 930 expects the CDI to limit the RPM...

[Flat6pac]

An 80 Sc will plug right in with the exception of the tach wire on the 14 prong.
You need the 10 atm pressure sender or change the guage to the SC 0-5 atm
The 77 used the 911 temp sender that is chrome and matches the 3.0.
Why you would swap the MSD in to a running engine that you havent started doesnt make a lot of sense.
You need 12 volts to the 2 red wires on the lambda to run the frequency valve.
If youre running the fuel pump with the key on, youre wires are reversed between the cold start valve and the air flow sensor

[spuggy]

Originally Posted by Flat6pac

The 77 used the 911 temp sender that is chrome and matches the 3.0.

Please check; '77 has a one-year-only, 0-340 temp gauge. The sender needs to match gauge or it will read off (30-40 degrees high, if you use an SC sender).

According to PET:

74-76, 75-76 930's & SC use 901.641.632.00 sender.
'77 2.7, all 77-up 930's and 3.2 Carrera use 911.606.112.00.

[dschloe]

Flat6pac thanks for the info on the 14 pin connector. The reason I'm adding the msd is because I don't have the 6 pin cdi box for the 3.0 motor. 2.7 is 3 pin. I'm trying to change as little as I can until I can get the car running. Is there any way to jump wires to make the 3 pin cdi to work with a 6 pin motor? The 2.7 ran fine in the car besides the very low oil pressure and all the burning oil.

[boyt911sc]

The wiring for the '77 is very similar to SC's 14-pin connector. The difference is only in the location of the circuits. Plus you don't need the pressure or oil gauges to start a CIS engine.

Below is an '83 SC on my engine test stand made from scrap metal I found in my yard. Note that the engine does not utilize gauges from the dashboard and that's my next project (tach, oil pressure and oil temp. gauges by the engine test stand).





Tony

[dschloe]

Thanks Tony. This is what I found out today. The fuel pump is running and I can hear the buzz from the injectors but still no start. I pushed up on the throttle plate and I can hear fuel spray in then the car will start and run for a few seconds then shut off. So I know I'm getting spark and fuel if I manually push the plate up. I checked all my lambda connections and I have power to the six pin connector but the plate isn't moving on it's own. So now I'm not sure what to check. Is it the relay near the lambda box that isn't working or the cold start valve?

[boyt911sc]

Test run the FP by jumpering terminals 86A and 30 (FP relay socket) with ignition switch @ ON (not start). With the FP running, touch the FV behind the engine. It should be vibrating when the FP is running.

Are you getting good ignition sparks? Battery fully charged? What's your cold control fuel pressure? Are you sure you don't have an air/vacuum leak some where? There should be power (hot all times) for terminal #30 (OXS/VF relay). Check and confirm all these conditions.

Is the MSD ignition system properly wired? This is my main concern at this point. These CIS engines are very easy to test run or start. Keep us posted.

Tony

[dschloe]

Here's a little update. Spent sometime looking for vacuum leaks and didn't find any so I went back over my wiring and it all appeared to be correct too. So out of frustration I removed the WUR from my 2.7 and swapped it with the one on the 3.0 and disconnected the ECU. I pushed the plate up for a sec and the car started and ran perfect. So now I'm even more confused. I wasn't able to drive it still have a few things to do before I can do that. I did read a post where it was suggested that you could use the 2.7 WUR and fuel distributer on the 3.0 and disconnect the lambda. Any thoughts on that?