Crank, no start. Sometimes comes to life then dies.

https://youtube.com/shorts/2jorRYtkzM4?feature=share

Video above with the symptoms.

I bought this thing non running, was running great prior to the starter dying (allegedly)

Replaced the starter, car ran but didn't really like idling much, kinda sputtery. However if I gave it gas it was fine.

I pulled it off the jackstands, dropped it down, tried starting it again, barely idled.

Tried again, cranked but nothing.

Again, sputtered and died

Then I could crank and crank and crank and nothing.


I can hear (A) fuel pump. I have read there may be two?
Spark is beautiful.
I can hear 4 cyls when crankin.
I can smell fuel and can see smoke exiting the open downpipe (not installed yet)
Get a very occasional backfire out of the intake.
Timing seems to be okay

Ideas?? Car is a 91 - US Spec, Digifant.

Car has sat from dec 2022 to now

Got it running, the fuel pumps weren't primed enough I guess. Clicked the key a few times to start and held it with the starter disconnnected and the sound of the pumps changed.

Can keep it running if I set idle high, however in gear its about 6-700 and idles pretty poorly. Have a bit of hesitation on the throttle

sw201444 said

Got it running, the fuel pumps weren't primed enough I guess. Clicked the key a few times to start and held it with the starter disconnnected and the sound of the pumps changed.

Can keep it running if I set idle high, however in gear its about 6-700 and idles pretty poorly. Have a bit of hesitation on the throttle

Posting the Year, and Fuel type in your post goes a long way in getting responses.

Now that I had to open your video, to see what engine you have.  You should of posted 90ish Cabriolet Automatic with Digifant injection, so we could eliminate a lot of guess work. There is the Suction Pump on the intake that is for the automatic transmission.

Digifant 2h probably automatic.

So you have a in-tank as well as an External fuel pump, do the residual pressure tests to validate that you don't have a fuel delivery issue.

It will eliminate the fuel pumps, as well as the (fpr) fuel pressure regulator that is on the end of the Fuel rail.

 If you take the vacuum line off of the FPR and fuel dribbles out of the vacuum hose bad FPR.  If your leak down or residual pressure tests fail as in not enough fuel pressure (bad pumps).  Leaking is usually a vacuum leak on a fuel line or the FPR that is bad.

2. Vacuum leaks cause all kind of bad things.

Check the Idle bypass screw if it can turn freely by hand then your o-ring is CA-CA, and needs replacing.

 It is on the back of the throttle body almost against the firewall as it takes a 7mm open end wrench.

If you replace the o-ring (good hardware store to match it up), I suggest that  you wrap the threads and threads only of the screw with 2 wraps of white teflon plumbers tape.  It will stop all air leaks in to the Throttle body.

Now when you reinsert the screw, bottom it out slightly then back it out about 3/4 of a turn to reset the rest position.

When you have it running, if you hear a whine from the right rear wheel arch, then that is a sign that your in-tank pump may have failed causing the primary external pump to overwork and cavitate (whine) about it.




 

Briano1234 said

Posting the Year, and Fuel type in your post goes a long way in getting responses.

Last sentence of the OP is " Car is a 91 - US Spec, Digifant." It's on 89 octane though, apologies.

Auto, yeah 2h

I did get it running, just won't idle well. I think the pumps needed primed, they're quieter and sound like they build pressure when priming now.

I'll check the bypass screw and for further vacuum leaks.
 

This thing is about to make me lose my sanity. 

Won't start today. Cranks and cranks and cranks. It's getting fuel and I can see smoke from the exhaust and I can smell it. But won't turn over again. 

Taking so long that the starter is overheating and slowing down. 

Ground 0 - where do I start? What do I check and how? If this was a Toyota I'd have it on the road by now and I'm getting super frustrated over this. 

SOS 

It is Cranking, and turning over.  It isn't starting because it isn't probably in correct time.

Fuel Air Ignition are all needed at the proper time.
If you replaced the plugs and wires are you sure that you have them in the correct order

see cabby-info.com for proper timing pictures
There is also a way to statically time your car using but a DVOM and setting the static timing of it prior.

Clean your main grounds battery to frame and frame to engine.

Starter are to run for 30 seconds or less to start a car,  running it for minutes can burn them up.

If you haven't installed the heat soak relay do so.

Do your fuel pressure tests.

We have:
beautiful spark
Fuel
Air




had the opportunity to have it run ONCE today. CCA on battery is low, charged it and it's fine.
Can't get it to start consistently. Feel like I have to crank and crank and crank and crank




even spraying carb cleaner down the throat does nothing.
It's so inconsistent. And when it runs, it runs GREAT. I genuinely cannot figure this out.




edit: got it again.
When running I can adjust the stop screw at the top. Seems to want to idle at 1500ish rpm.
If I back it off to not having any tension idle is super choppy. Moving the brass screw near the firewall (by Hand, which is bad?) moved idle a little but not much.

Can't find any compatible fuel pressure testers locally. But runs fine when it runs (higher than idle)

Here's an update:

Here's it running again. I replaced the o ring on the idle bypass screw, no change. It's screwed all the way in right here. Screwing it out does raise idle a little.

However, here's what pulling the throttle does: 

Idle screw all the way in. No throttle response - YouTube

Bogs the car down and wants to die. I've sprayed carb cleaner around vacuum fittings I see and none have caused the idle to go up. 

I did manage to stall the car messing with the throttle. Here it is cranking without starting again, right after the above video:

Cranking again :) - YouTube

Do the tests people are telling you to do!

It's got the symptoms of an air leak, if it starts when cold  and then won't go at all when it's warm even more so.
Have you had a look at the plugs after cranking it to see if they're soaked in petrol or bone dry.
The small blanking off caps that VW use on unused take off spouts are a good place to look, the tops crack off.

cedar said

It's got the symptoms of an air leak, if it starts when cold  and then won't go at all when it's warm even more so.
Have you had a look at the plugs after cranking it to see if they're soaked in petrol or bone dry.
The small blanking off caps that VW use on unused take off spouts are a good place to look, the tops crack off.

It doesn't matter if it's hot or cold. I've gotten it to fire both ways. No difference. 

Plugs aren't wet but aren't bone dry. See my next post regarding the fuel system 

Small update. 
Have confirmed no vacuum leaks. 
The in tank fuel pump passed the flow rate test. 
However the holy Bible (Bentley) appears to be useless in checking the external fuel pump's fuel rate. Page 5-51 states to check 4.3 in fuel system and upon doing so it's strictly CIS after the in tank pump test. 
Going to get a fuel system pressure tester in coming days (bad weather) and will check pressure. 
Also waitijg for it to warm a little bit more to check the blue coolant sensor. 

sw201444 said

However the holy Bible (Bentley) appears to be useless in checking the external fuel pump's fuel rate. Page 5-51 states to check 4.3 in fuel system and upon doing so it's strictly CIS after the in tank pump test.

Wrong.
5-12 has the tests for flow rate of the main digifant fuel pump.



Then if you refer to the residual pressure tests
5-61 7.6  you will see the pressure rate of 44 psi and the regulator is capping it at 36 to the injectors.




In actuality the In-tank pump and the main pump are both rated @ 45psi and same delivery rate of 9-10 US GPH.



So both pumps in a digi produce the same flow and psi.

Which is why you can convert it (digi) to a single pump it.  single pump conversion.
A VERY big thank you to Tolusina | VW Vortex - Volkswagen Forum

Caveat: Hard cornering less than 1/4 tank may cause fuel starvation.

Briano1234 said

sw201444 said

However the holy Bible (Bentley) appears to be useless in checking the external fuel pump's fuel rate. Page 5-51 states to check 4.3 in fuel system and upon doing so it's strictly CIS after the in tank pump test.

Wrong.
5-12 has the tests for flow rate of the main digifant fuel pump.



Then if you refer to the residual pressure tests
5-61 7.6  you will see the pressure rate of 44 psi and the regulator is capping it at 36 to the injectors.




In actuality the In-tank pump and the main pump are both rated @ 45psi and same delivery rate of 9-10 US GPH.



So both pumps in a digi produce the same flow and psi.

Which is why you can convert it (digi) to a single pump it.  single pump conversion.
A VERY big thank you to Tolusina | VW Vortex - Volkswagen Forum

Caveat: Hard cornering less than 1/4 tank may cause fuel starvation.

I don't have the Bentley next to me at the moment, can I test fuel pressure by cranking on these? The residual test states to start it - and that's what I m trying to figure out  

Yes you have to have a running car to check the residual pressures.

I would do the static tests to make sure your car is in time.

Set the time, that is crank finger on 0, make sure that the cam is at O on the front or that the dimple on the back is at the place of the valve cover tin and that the diz goes from 0-11Vdc.

It only uses a DVOM to

Then if all aligns and your wires are 1342. It should start.

http://cabby-info.com/Files/AdjustingTheTiming.pdf

Also when timing it Statically, you will hear the fuel pumps run when your rotor engages a sparking wire with the cap on.
If you pull the vacuum hose for the Fuel Pressure Regulator off of the throttle body and fuel dribbles out the FPR is bad.
 

It maybe if absolutely no help, but my Gti would crank forever and a day and not start, but sometimes just catch and start as I released the ignition key from cranking position. At first I was getting suspicious of a bad ignition switch, but then put a jumper lead from the negative on the battery to the engine and from negative to the chassis, fired straight up. Just bad earth leads/connection

GAMMYGOLFGTI said

It maybe if absolutely no help, but my Gti would crank forever and a day and not start, but sometimes just catch and start as I released the ignition key from cranking position. At first I was getting suspicious of a bad ignition switch, but then put a jumper lead from the negative on the battery to the engine and from negative to the chassis, fired straight up. Just bad earth leads/connection

Yes, I have a Thread on Grounds, in the archive section.
But there was also a time when I had a Crank gear shear which caused a few weird things.  But I didn't want to go there yet.

Timing is in. 

Rechecked spark plugs, all are getting nice clean spark 

Fuel flow rate is correct. Tests in manual for pressure state car should be running, so I haven't tested it as I have no idea what pressure should be when it won't run. 

AFM tested good 

Replaced the blue coolant sensor, it would start a little and run really poorly, see below. 

Pulling the throttle did nothing.

https://youtu.be/1rdawvcAbMk

Idle was poor

https://youtu.be/hagttZTX3po

Nothing changed though - because today the car won't start again. Smell fuel, see spark. 

Going to do the Bentley ECU tests and wiring tests soon, the fuses it recommends are all fine.