73 2.0 Has Issues, Ran GREAT and then it didn't Options

[Minerva's 914]

1973 914 2.0 restored and motor rebuilt by Fat Performance and installed by Black Forest Racing. We've driven her off and on for about 750 over the past year with no problems, in fact she ran fantastic .... until she didn't. Driving around the neighborhood last week the engine bucked a few times with the tach dropping to zero before bouncing back to normal, downshifted and it seemed better only to return again while cruising along at 2800 RPM, down shifted again and since we were only a block away from home made it with no drama. Was thinking maybe an electrical issue shorting out the ignition.

I started the car yesterday evening and backed out of the garage and it stopped dead in her tracks. Turned the key to 0 then back on again and no fuel pump buzz. Proceeded to engage the starter and after several seconds of cranking I returned the switch off, then back on again. No fuel pump buzz.

Checked the relay in the circuit board, switching out the relays, no change. Checked the fuses and connections seem clean so I jumped directly from the battery to pin 12 on the circuit board, turn the key to 1 and got the fuel pump buzz, turned off and back on again got the fuel pump to work.

What do you guys think should be my next step? I planning to get on it early tomorrow and start chasing the wiring but hope someone here might help me narrow down the possibilities. Plan to remove the circuit board, turn it over and check the connections and double check the grounds and then check continuity from the brain, then work my way to the inside fuse panel and wherever else the electrons are circulated before reaching the fuel pump.

As always THANK you guys for all you do to help the 914 live on!!!

Brady

[ottox914]

Had a similar problem with my car.

Ignition switch. There is a small plastic piece that is sort of an interface between the mechanical turn of the key cylinder and the electrical contacts that sent power here and there when the key is turned position 1 or 2 Give away for me was no fuel pump buzz and no spark when turning over. I checked fuses and relays finding nothing wrong. Was thinking ecu issue as well, but couldn't believe that was it. Pull a plug wire and put an extra plug in it, have someone spin the motor over. The part is not all that $$ and can be swapped out in 30 min or less.

NOTE- my car us running SDS ecu, not stock, and the ecu controls both fuel and spark. So no fuel or spark had me thinking of what would prevent ecu from doing, well, anything. Its been awhile since I messed with a stock system, but I expect the same clues might lead to the same solution.

[Minerva's 914]

Had a similar problem with my car.

Ignition switch. There is a small plastic piece that is sort of an interface between the mechanical turn of the key cylinder and the electrical contacts that sent power here and there when the key is turned position 1 or 2 Give away for me was no fuel pump buzz and no spark when turning over. I checked fuses and relays finding nothing wrong. Was thinking ecu issue as well, but couldn't believe that was it. Pull a plug wire and put an extra plug in it, have someone spin the motor over. The part is not all that $$ and can be swapped out in 30 min or less.

NOTE- my car us running SDS ecu, not stock, and the ecu controls both fuel and spark. So no fuel or spark had me thinking of what would prevent ecu from doing, well, anything. Its been awhile since I messed with a stock system, but I expect the same clues might lead to the same solution.

Excellent advice and makes sense! Thanks, I'll get on that and report back. Rob-O had suggested the ignition switch earlier but I got sidetracked chasing the ECU theory so thanks to R-O as well.