Excessive Cranking on start-up, Assistance request Options

[Van B]

Hello scholars and masochists.

I’m requesting help on solving the issue of excessive cranking on start-up. Not once since I bought the car has it ever fired right up like others described for their cars. I had hoped that this issue was related to the other issues I’ve solved with the help of my friends here, but no luck. The behavior remains unchanged.

To start this off, I rigged a little hidden fuel pressure gauge to the car so that you all can see for yourself. For the context of this attempt, the engine is cold at around 60F, I did not touch the throttle and the ignition was in the on position prior to cranking.

https://youtu.be/DTTQ1zQJkJo


https://www.youtube.com/watch?v=DTTQ1zQJkJo


Edit: moving on to a new phase at post #152

http://www.914world.com/bbs2/index.php?s=&...t&p=2995793


Please advise and thanks in advance.

Van

[914Mels]

First, I'd energize the fuel pump a couple times with the key before going all the way to the cranking position to build up fuel pressure. If you still have trouble starting after that I'd shoot some carb cleaner into the intake once you have fuel pressure built up and see if it fires off of that. If so you probably have a thermo time switch circuit problem or clogged cold start valve. Of course there's more but I'd start with this.

[Van B]

First, I'd energize the fuel pump a couple times with the key before going all the way to the cranking position to build up fuel pressure. If you still have trouble starting after that I'd shoot some carb cleaner into the intake once you have fuel pressure built up and see if it fires off of that. If so you probably have a thermo time switch circuit problem or clogged cold start valve. Of course there's more but I'd start with this.

Ignition was on. Fuel pump doesn’t run until cranking. I traced the wire and it is patched into the black/red wire on the aft relay board plug.

I’ve previously verified the CSV works, but after this attempt I pulled it to see if it would spray, it did not. But, I think that’s because the engine was mostly warm. I’ll leave it unplugged and confirm with a legit cold start next chance I get.
As far as the TTS, I replaced it recently. However, I do know the CSV can function even with a bad TTS.

[Superhawk996]

Ignition was on. Fuel pump doesn’t run until cranking. I traced the wire and it is patched into the black/red wire on the aft relay board plug.

Not clear what you're indicating here. Is the fuel pump is hot wired to the black/red wire that feeds the coil + (pin 7 of the 12 pin engine harness connector?). Why would this "patch" have been done? Maybe I'm misunderstanding your description of "patch" or your description of "aft" which I assumed to mean rear of the car.

If so . . .

I'm going to go way out on a limb. (IMG:style_emoticons/default/sad.gif) Fuel pump in-rush current may be stealing some voltage from the coil preventing a nice hot spark when you first start cranking. Once fuel pump motor in-rush current reaches steady state, voltage to coil pops back up and now you get a hot spark. I'm so far out on the limb that it's about to break but the bottom line remains the fuel pump should be fed off it's own circuit and not shared with the coil.


Fuel pump feed (which is also black / red to further confuse things) should be fed by 12v coming off Pin 13 of the 14 way connector at the front of the relay board that runs perpendicular to the voltage regulator.

I'm also going to note that if you start disconnecting and reconnecting either the 12 pin or the 14 pin connectors -- BEWARE-- they can be installed while shifted 1 pin. The 1970's era error proofing of a plastic guide pin on one end is basically a defective design and can't prevent the connector from being improperly installed in a shifted condition.

Shifting the 12 pin connector WILL result in a shorted coil negative wire that melts the wire insulation.

[wonkipop]

Ignition was on. Fuel pump doesn’t run until cranking. I traced the wire and it is patched into the black/red wire on the aft relay board plug.

Not clear what you're indicating here. Is the fuel pump is hot wired to the black/red wire that feeds the coil + (pin 7 of the 12 pin engine harness connector?). Why would this "patch" have been done? Maybe I'm misunderstanding your description of "patch" or your description of "aft" which I assumed to mean rear of the car.

If so . . .

I'm going to go way out on a limb. (IMG:style_emoticons/default/sad.gif) Fuel pump in-rush current may be stealing some voltage from the coil preventing a nice hot spark when you first start cranking. Once fuel pump motor in-rush current reaches steady state, voltage to coil pops back up and now you get a hot spark. I'm so far out on the limb that it's about to break but the bottom line remains the fuel pump should be fed off it's own circuit and not shared with the coil.


Fuel pump feed (which is also black / red to further confuse things) should be fed by 12v coming off Pin 13 of the 14 way connector at the front of the relay board that runs perpendicular to the voltage regulator.

I'm also going to note that if you start disconnecting and reconnecting either the 12 pin or the 14 pin connectors -- BEWARE-- they can be installed while shifted 1 pin. The 1970's era error proofing of a plastic guide pin on one end is basically a defective design and can't prevent the connector from being improperly installed in a shifted condition.

Shifting the 12 pin connector WILL result in a shorted coil negative wire that melts the wire insulation.

thats a reasonable limb to climb out on.

i was thinking yesterday is there something affecting spark.
coil?
but couldn't think that through further.