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

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.

i'd call 7 cranks when i count.
or what i call cranks.

noticed when it fired, it part fired and then fully fired.

different behaviour to mine.
week standing, 2 cranks, no part fire, full firing and going.
leave it a day and i barely need a crank.

fuel pressure builds fast in vid.'
believe mine fires the minute the fp hits - after watching the vid and seeing what looks like 35 on your gauge arrived at. like 1 to 2 seconds.
in abut the same time your gauge says yours got there.

so cancel my thoughts previous partly at least on it being fp or fpr.
i think in that department it is reasonable.

hmm.

i like the way you are going after perfection.

i know its colder in the USA.
but a winter start for me here is the same as a summer start.
winter temps at coldest here are 45 - 50 F.
so i'm not doing starts below that temp for comparison.

----

how long had it been since last start in that vid.
i have a feeling that mine is holding fp higher than that for 24 hours believe it or not.
but i have not done it with a gauge to know.
i also have a new turbine pump in original location, which i do think builds fuel pressure faster than the old roller cell pump.
but i'm splitting hairs because the fp in yours comes up fast anyway.

L jets don't turn the pump on until you crank.

- correction, they shouldn't if stock.
but some are now wired up to come on with ignition.

but i'd go with the cold start injector as a hunch.
think van has tested that and also has replaced therrmo time switch with new one.


spray pattern in cold start valve?
like its not making it down all those inlet tracks.
or shooting it all to one side and staying down one end of plenum?

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.

@wonkipop
My fuel pressure drops to zero as soon as the engine is shut off.
I had just started the car yesterday while working on the AAV upgrade.

When I last filmed the CSV (before I replaced the TTS) it was a perfect mist… glossed the whole engine bay in fuel lol
I want to see it work though as I’m not sure why it didn’t fire a few minutes ago when I started again… I’m thinking it’s because the engine was warm… maybe.

Forgot about the l jet fuel pump circuit going through the air flow meter. Sometimes the flaps stick shut or bind. With the key on try moving the flap by hand and see if it moves without binding and the pump comes on right away. The contact is under the black plastic cover and easy to inspect.

ok - well that is not right dropping off to zero.

probably be the check valve in the fuel pump causing that.

here is another thought.
to knock it off list.
vac retard on distributor.
car is designed to start on 7.5 BTDC
immediately it fires then manifold vac retards dist so its around 3-4 degrees (for emission). but the car does not try and fire on that retarded setting.
its harder for it to fire at that retard emission setting.

could there be something wrong with can and its stuck at retarded idle setting.
not sure how.
when i look at distributor it seems to me its designed to fail in safe mode.
ie 7.5
but......

easy test.
get car warm, idling steady.

turn off. pull vac hose off retard side of can.
plug hose.
if you really want to double check pull advance hose off can as well.
(but i don't believe you have to as its on other side of closed throttle).
plug hose. dist is neutral.

start it. see if it will idle.
i think i have that right.
it will idle higher with the vac hose on?
anyway, see if any difference.
should be if dist is functioning correctly.

That sounds like my car the other day when the pump died. My car doesn't really hold pressure long but starts right up (when the pump is running).

Have you tried retarding your timing? Did that make a difference?

I like the idea of adding some gas, wonder if you could send 12v to the csv without hurting anything.

No binding on the AFM barn door. And I can see via the gauge that pressure begins rising as soon as I turn the key to crank the engine.

I just pushed on the flap with the ignition on, pump ran and fuel pressure came right up to 35psi, and then dropped to zero as soon as I let go.

yeah, it won't be that.
pump goes while cranking, then when engine fires flap opens contacts and takes over.
if it was the flap binding the car would start then die i think.

the hard starting is something else i think.

i also think my starter cranks slightly faster than vans.
but thats academic maybe as i would not call mine a fast crank.
not when compared my newer fine french machinery.

@wonkipop
I’ve timed the car several times now and I’m 100% certain the distributor vac can is a-ok. Idle climbs the moment I pull the hose and drops when I plug it in. Several months ago, I remember trying to start the car with the retard side unplugged and it wouldn’t start. Not sure what that means, but I guess it’s a thing that happened in the world lol…

Hmmm. I wonder if that pressure drop is ok. You would think it would hold pressure for a little while.

you can get away with this in the 914 with the f p in orig location near engine.
its such a short fuel circuit that it pressurizes easily even with a crook check valve in the pump. be a different matter with remote pump. a bit of a delay pressurizing a long fuel line.

you can take the top off the pump to try and fix that.
i have put up a thread in originality section and i think sir andy might have shifted it to classic thread. my tear down of pump and rebuild. but........
as mr. p would say, why not buy a new pump. however the top off the pump is not a tear down. but lets leave that aside for now as its building pressure and holding it while the pump runs.

Could it be something with the regulator? I can't see how it could be. If there is 35 at idle than there is 35. Even if it is pushing more back to the tank than it should... The pressure is still 35psi according to the gauge.

I don't think you should lose pressure that fast. I can't remember if its the pressure regulator or fuel pump that holds the residual pressure in the lines.

its bound to be the check valve in the fp emery.
i think van still has a 3 port on the car?
there is a little rubber tit seal in there and a spring that pushes the valve closed when the pump stops. prevents back flow. that tit will either be perished or stuck with gunk and won't seal if its an original and/or older pump. be losing the pressure back down the fuel line rather than past the regulator.

its definitely a different weaker start than mine.
video is good. instant clear comparison.

both of them.

great. its not that. strike off list.

i am heading into the workshop now to work on the falcon.
i'll tell mike about your work of genius on the AAV.
the smile i get out of him will allow me to ask him about this at lunchtime and see what he says.

might even be able to watch your vid on his phone.

+ i have a fair idea of all the things you have done to the car.
so i can yes no him on what he suggests.

Maybe someone with an l jet could comment what their fuel pressure holds at when turned off. Our D jet holds around 20psi for a long time.

Says you can, but it’s not real helpful…. I don’t know which prong on the CSV should get positive and which should get ground.

If you could fire it, and know that it was firing, and your engine roars to life...

@wonkipop confirmed that it is a three port relocated to the front. FP Reg looks old but appears to function as 35psi is the target value per the service manual.

I want to see it work on its own again before I jump it… I’m a little scared of burning it up.

I know it worked previously even with a bad TTS.

yes 35 is the target.
think the f p regulator hooked up to manifold vac drops it to 28 or something else (need to go back and look in manual again) when you close the throttle. a sort of an emission related thing where it drops off fuel pressure. thats probably not a very exact description but its something like that.


mike said you should not lose pressure. confirmed from his photo memory that mine was tested by him2 years ago when i wasn't there and it held 20 psi ages after switch off.
like morning start, end of day test. so its probably holding 20 the next day too? - or something maybe just under. def got pressure for long time as per
@914Mels remark re d jet.

i reckon my fp, in the close location to engine, and because its a new pump is almost instant at building pressure. perhaps that has something to do with the very fast start compared to yours.

he said one thing to test on csi is spray pattern on cold start. does it spray or is it just kind of dribbling out. its got to deliver a huge amount of fuel relatively speaking as atomised as possible. but it is a denser spray than the normal injectors.

while you are at it, does it close and not leak any drops. even the smallets amount. you can pull it and turn on the ignition and crank. need someone to work the key for you while you watch. its messy. you can try and catch it in a bucket and observe it.
watch to make sure it does not drip, even a little bit long after switch off.

when i rebuilt the two 3 ports i had and bench tested them, i saw just how vigorous they are. they sure pump a torrent out of them fast, instantly.

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. 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.

Thanks for the confirmation on the fuel system holding pressure. Clearly I have a problem there... and the correct fix will be a grand or more since I should be replacing those 49yr old plastic fuel lines.

I plan to reconfirm CSV function on a cold engine. I didn't have time this morning, which is a shame because it was a bit chilly this morning. It worked beautifully a few months ago. And I'm confident the reason it didn't fire last night was because the engine was warm. but, you never know.

@Superhawk996
The answer as far as I can tell is yes, and I don't know. I don't know what the Black/red wire does, or why they spliced there when the fuel pump was relocated. The reason I mentioned it is that I was afraid it was probably robbing current from what should be getting power from that line... the limb you climbed out on is the one I'm already sitting on lol! Welcome!

I want to find the original wires for the fuel pump in the OE location but no luck so far. I'm hoping they weren't cut back and are just tucked away somewhere.

Thanks for the warning about incorrect fitment of the plug, but no reason for concern there. I try to avoid doing things that are simultaneously dumb, dangerous, and different.

It looks like the search for the original fuel pump wire is something I can pursue now as opposed to a new fuel pump and lines to deal with the pressure drop.

Van,
This is very similar behavior to what I experienced with my 75 1.8. Put a timing light on the coil. I bet it doesn’t flash until you get those partial hits. Then it will flash intermittently until it fully starts and flashes at a regular interval. I never did get this problem fully solved. I just figured out how to live with it. Never did fail to start, but would always take a bunch of cranking with intermittent hits just like your video shows. I think the large initial draw on the starter would not leave enough voltage to charge the coil. Could have been a weak battery or upgrading to a high HP starter would help.

@troth
Great tip, thanks!
Did you notice that starting was improved when the engine warmed up but still never hit the instant key bump response others describe?

The large current draw to the starter motor can certainly drop system voltage with a weak battery.

@VanB

In looking at the schematic some more the later 75-76 current flow diagrams are useful because they also contain the wire gauge.

Fuel pump motor is supposed to be on 2.5mm wire (14 AWG equivalent). The coil + is 1.5mm (16 AWG).

Why does this matter:
You're going to get more voltage drop across a wire that is too small of a diameter. The fuel pump was put on an independent circuit with 14AWG wiring. The coil was put on it's own independent circuit with 16 AWG.

Now you're trying to pull both current draws through the same circuit of 16 AWG wire.

Probably low priority to chase after fuel pressure but this definitely isn't the correct set up.

Adding this relay board picture you might appreciate. Not sure who created it . . . nice addition of circuit names.

Click to view attachment

yeah and it's a long wire running nearly the length of the car to the new fuel pump location.

Alright, it's settled:
First thing, reconfirm CSV is still alive just for peace of mind.
Second, find the original fuel pump wire, and get the fuel pump connected to it.

Also, thank you for the size translation of wire gauge. The wire that was run to the fuel pump is definitely not 2.5mm in diameter. So, I'll need to deal with that as well.

Looking at this, it seems whoever redid the fuel pump got baited by the same color wires.

It sounds like weak spark to me. You have pressure and it runs once it fires off. Mine had a similar problem when my distributor had points. Just too weak to create a good spark. I put in an electronic ignition and it went from what you have to two maybe three cranks and vrrroom. If you already have it, check to see if it is getting proper voltage. Good luck

Yes, definitely try that timing light trick. I would do that before mucking with the CSV at this point. So easy and a problem you want to address (should be very easy to fix at that). Leave the fuel stuff for after you verify if you have dropped spark.

For what it’s worth: after sitting for several days mine cranks 3-5 times then starts. If sitting a long time like 2+ weeks it takes 5-10 cranks. If only 2-3 days it pops to start right away with only 1-2 cranks. So, me thinks it holds the pressure for a while but not forever. BTW I replaced all my fuel lines only a few years ago.
I like the fp spring/tit explanation.

It definitely improved after warming up. It always seemed worst after sitting for more than a couple days. Seemed easier on warmer days. Don't know if I ever got instant lightoff, but it certainly wasn't anything to complain about when doing hot starts.

I had something similar awhile back and was due to a weak ground strap connection from the transmission.

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.

sounds reasonable.

i have left mine on occasion for two weeks.
what you describe as a 3-5 crank start is needed.
probably all pressure has drained by then. but its still a fast start. never 10
but f p in original position likely pressurises very short fuel circuit.
you have a pump in front don't you @StarBear ?

the only time i have to do a 10 crank start is a hot start on a hot day.
thats fuel boiling in the fuel line run from tunnel outlet to fuel pump in my case.

van can fit an inline check valve easily if he felt the urge.
just after the fp.
that will at least confirm his pressure loss location.

i retract my earlier view that it isn't the pressure regulator.
it could be.
if it had gunk stuck under its valve.
but i doubt it because his loses pressure instantly so i think it would have a great deal of trouble holding it in the first place. and it does hold pressure.
the other way they fail is more spectacular, sending fuel through vac line to plenum.
you would know about that, be more than a 10 crank start going on.

good suggestion too.

@Van B. i had the gearbox on mine out to do the clutch.
went over all the starter connections, cleaned them etc.
and cleaned up the transmission ground to the body.
so all that is tip top.

Yep; in the front. Replaced all the fowl lines at the time. Braided stainless (I don’t race).

you running your car on roosters instead of petrol.
is that some kind of secret racing fuel?


---

sitting here thinking how my car is still running on lots of old fashioned stuff.
points.
orig dist.
very likely original coil (i've never changed it and its prehistoric looking black coil).
etc.
and it starts bam. go figure.

its days are numbered but. they are vintage points i have and the box is going to be empty soon enough. and the aav is almost ready to fall out of its wheel chair.

when we dropped the gearbozx to do the clutch we found one of those stoopid rubber core clutches in there. so we knew it was the showroom clutch. funny thing is it wasn't worn out. but the rubber had turned to something that wasn't rubber anymore. the stuff was probably not rubber but an evil compound invented in WW2 as a substitute for truck tyres on the russian front.

always been suss on the shift fuel pump to front of car move.'
a million people tried to get me to do it back in the 90s.
i didnt. mostly because i never suffered from a vapor lock problem with the car so why fix something that wasn't broke.

seeing van's problems there sure seems to be some ways you can mess with power supply to pump with 1,8s that doesn't matter so much with d jet.

van's going to have a pretty damn good car the way he is going at it.


side benefit = following all this research.
i'm already out on the trail of BMW aavs to go with the SAAB one.

I was watching my pressure today and my 2.0 holds 20 for a little while but not over night or even a few hours, however, I wonder about the difference between holding pressure and having fuel in the lines. The lines can be full but under no pressure and the lines can be empty. At start up that would make a difference.

Evening Gents.

My lines are not draining, I know that. And given the relative incompressibility of fluids, the speed in which my fuel pressure builds supports that claim.
But, I also think that there is a hidden cost to that bleed down on pressure. It must be happening all the time which means the fuel pump is working against the pressure bleed constantly. So, I'd bet my fuel pressure is way low under acceleration because the pump will be losing pressure to the system and to itself.

Well, I found the actual fuel pump wires... Uncovered and laying on the rubberized coating in the hell hole... M F'ing PO! He should've paid me for saving this car from his dumb ass!

Also, I verified that the CSV hasn't broken on me so, that's good. Although, I'm not happy with what I'm seeing with the Nissan TTS. After putting it in the freezer, I only get a lil' puff while cranking. And when it's warm, I get nada. I want that sucker to spray like aqua net while I'm turning over.

Any way, now that I've dug the wires out, it's time to get things hooked up properly.

That makes sense. Although mine loses pressure and goes to zero within 10-20 minutes, that is a much different thing to a pump than instant zero. I wonder if you haven't found a pretty deep problem (cold start stuff too).

Dude, everything I do on this car I so out and say, “oh so that’s what 76hp feels like”.

When I first got the car and it had those unseated spark plugs, I couldn’t understand why the engine was so noisy. I fixed that, instant power improvement… “oh that’s what 76hp feels like!”

Then the injectors: “oh…”

Then the ignition: “oh…”

But this fuel pump thing must be costing me.. probably both in spark as superhawk said and in fuel pressure under load.

I was at least able to see that those wires merged back into the main loom so, I don’t think they were cut elsewhere up the line. I should be able to cut em back brighten them with some phosphoric acid and then run them up front.

Can anyone tell me why on earth someone would cut and dump those wires only to splice into the coil????

You'll probably never know. The joy of 50 years of DAPO's.

My best guess would be can't read a schematic, didn't understand how the relays work, and just went to a known power source. I'm sure having both the coil + and fuel pump being black / red was part of it. Probably figured it was mis-wired from the factory.