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.

[wonkipop]

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.

[wonkipop]

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.

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?

[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.

[Van B]

@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 (IMG:style_emoticons/default/slap.gif)
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.

[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.

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?

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.

[wonkipop]

@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 (IMG:style_emoticons/default/slap.gif)
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.

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.

[emerygt350]

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.

[Van B]

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.

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.

[wonkipop]

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.

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?

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.

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.

[Van B]

@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 (IMG:style_emoticons/default/slap.gif)
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.

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.

@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…

[emerygt350]

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

[wonkipop]

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.

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.

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.

[emerygt350]

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.

[914Mels]

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.

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.

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.

[wonkipop]

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.

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.

[wonkipop]

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.

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.

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.

both of them.

[wonkipop]

@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 (IMG:style_emoticons/default/slap.gif)
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.

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.

@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…

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.
(IMG:style_emoticons/default/beerchug.gif)

[914Mels]

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.