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Posted by: CYCPYT Mar 25 2024, 07:42 AM

Any advice on a forum article I should go to, or advice on how to troubleshoot this would be appreciated.

I have replaced the fuel filter and fuel pump, as I originally thought it was a fuel issue. Now I am not sure.

Thank you!

Posted by: FlacaProductions Mar 25 2024, 08:23 AM

This thread here is a good start. If you can do a complete list of what you've done, specifics about the car, etc...

Are we talking literally one second or?

And welcome to 914World - this place will get you set up...

Posted by: rfinegan Mar 25 2024, 10:23 AM

I had a similar symptom on my 2.0 DJet( know is different ) but crank start and die....If I continue to pump the pedal in different location of open while staring and running the engine wold continue to run "like pumping and an accelerator pump” the root cause end up being the CHT sensor on/ @ 3 cly. I replaced the sensor and starts and runs great after the change.
GOOD place to start looking...

Posted by: Geezer914 Mar 25 2024, 10:45 AM

I had a similar issue when I rebuilt my 1.8L to a 2056. It was a huge vacuum leak. Do a smoke test. You can make a smoker for under $10.

Posted by: dr914@autoatlanta.com Mar 25 2024, 11:55 AM

good call.

Posted by: fiacra Mar 25 2024, 01:42 PM

I gather you are looking to be directed to a troubleshooting thread? The search function on 914World is not the most efficient. Best to use Google. Type in "914World" and then your question/search terms. That will usually get you where you need to be on this site.

If you are looking for direct advice, there are so many questions.....Give more information if you want help.

1) What made you think it was a fuel problem? Did you check fuel pressure/flow first? Just replacing the fuel pump and filter is not a guaranteed fix for a fuel problem. There are many other components to the system. Given that it runs for a second and then shuts off it could be that the double relay is initially firing the fuel pump but then the fuel pump is not being given power after the ignition is turned to the run position. Check your repair manual for how to test the system. Very briefly, push open the air flap at the AFM and see if the fuel pump starts to run. That's only one quick example of part of the diagnostic procedure for the fuel system on an L-Jet car.

2) What's the background on the car? Was it a good running driver before this happened? Has it sat for years?

3) Did you do any work on the car and now it won't start?

4) What have to do so far to diagnose the problem?

You'll get lots of advice here. People are very willing to help and the hive mind has a lot of collective knowledge. Can't argue with starting with a smoke test as the L-Jet system relies on vacuum.

Good luck!!! I'm sure you'll get this fixed.

Posted by: technicalninja Mar 25 2024, 01:57 PM

Quicky technician tip...

Can you run it for more than 1 second on B12 carb spray?

I'll try that early on to prove I have capable ignition and compression.

I once bought a ratty 99 Miata that had sat dormant for 10 years as an organ doner.

Opening the gas cap would make you retch...

Completely destroyed fuel system!

I disabled fuel pump, popped air inlet off, fired it on B12, and got it up to temperature.

Proved engine good.

And, when the car was parked the AC was left on.

Proved AC function as well!

If it will run on an alternate fuel source you have ruled out many things...

Posted by: StarBear Mar 25 2024, 02:27 PM

Make sure the harness plug is attached to the AFM. The cold start valve I think gives it a shot then then stops since no AFM circuit. When working on it, we often forget to reattach it as it slips down into the engine compartment.
Agree that more background would be helpful.

Posted by: CYCPYT Mar 25 2024, 04:31 PM

Thank you so much! I have not done anything to the car other than the fuel filter and fuel pump. Bought the car out of Cali, put about 1500 miles on it and this happened... It will stay alive for 2-5 seconds before it dies. It starts relatively easily, just won't stay running.

I was thinking about doing the plugs wires and coil, since I don't know their age.

Any advice is greatly appreciated.

Posted by: CYCPYT Mar 25 2024, 04:33 PM

Thank you, I will put this on the list of things to check.

Posted by: CYCPYT Mar 25 2024, 04:35 PM

Thank you, I think that this is probable. I think I am going to just replace all the vacuum lines, again as I do not know their age.

Posted by: CYCPYT Mar 25 2024, 04:35 PM

Thank you, I will check this out also.

Posted by: CYCPYT Mar 25 2024, 04:37 PM

I will give this a shot as well, thank you.

Posted by: CYCPYT Mar 25 2024, 04:42 PM

Thank you, I have a lot of testing in front of me. I just did not know where to start. I thought since it starts and dies, I went immediately to fuel in my mind, that may have been shortsighted. I figured I would knock out some of the easier things that I thought I would be replacing anyway not knowing age or true condition. And then rather than reinventing the wheel, ask the jockeys that have been here before me and better at it.

Posted by: CYCPYT Mar 25 2024, 04:43 PM

I am going to start here! Thank you...

Posted by: emerygt350 Mar 25 2024, 05:09 PM

Good idea to start with a vacuum leak search.

Posted by: wonkipop Mar 25 2024, 05:38 PM

is this

A) a car that has been sitting for a while/long time and not been run.
and you are attempting to start it and bring it back to life.

or B) has this problem suddenly developed in a running car.

if its A) then then the symptoms fit this scenario.
its starting and running off the cold start injector. it will run 5-10 seconds on the squirt it gets from that. but then it dies because the 4 main injectors are not opening.
they are clogged or corroded closed and cannot spray. to check, pull an injector and crank the engine - confirm they are spraying.

if not A) and its developed suddenly let us know. can think further.

Posted by: wonkipop Mar 25 2024, 05:47 PM

ah - i see the problem developed suddenly.
as @http://www.914world.com/bbs2/index.php?showuser=10753 has noted - its firing off the cold start injector.
thats the 2-5 seconds bit.

a bit more info needed.
take a couple of good shots of the engine bay and post them up here.


you need to be methodical with the old fuel injection systems.
but its surprisingly simple. esp these early L jets.

the correct vac hose diagrams for the 74 1.8s (both USA and Calif) are here.
scroll down the page - towards bottom.

http://www.914world.com/bbs2/index.php?showtopic=357407&st=40

the 75 1.8s are not very different and if you have one i can let you know what is changed from 74.

its probably a good idea to down load these - you may as well.
from jeff bowlsby's website there is this little guide to L jet troubleshooting.
helps you be methodical and gives you a reference to read if you can't understand what might be suggested by members here.

https://bowlsby.net/914/Classic/zTN_Man12.pdf

and of course these are super handy.
pdf files for the entire 914 factory workshop manual set.
the fuel injection stuff is group 2 (4 cylinder cars).
but if you have the ability with internet connection download the lot.
tells you just about everything you might need to know to do anything on the car.

http://p914-6info.net/Manuals.htm

Posted by: jhynesrockmtn Mar 26 2024, 08:02 AM

I'll offer this. I bought my 70 1.7 a few years ago. It had sat for a long time. I refreshed fuel lines, filter, pump, etc. It ran fine for a while. Then it started to die after starting. My fuel tank was rusty inside and the sediment was plugging the in tank screen. The only thing I can think of is the more I drove it, the more things broke free in the tank. A tank reseal and new sock solved it.

Posted by: fiacra Mar 26 2024, 09:41 AM

I STRONGLY recommend you don't start replacing parts BEFORE you diagnose the problem. That will just muddy the water and potentially make it much more difficult to figure out what is going on. I get the impulse to start doing all the work you had intended to do before this problem happened, but it won't be productive to do it before you figure out what is causing your current problem. Figure out what is defective first, get the car running, and then start on any deferred maintenance. Once you start firing the parts cannon at the problem you are on a very slippery slope....

Posted by: CYCPYT Mar 26 2024, 10:43 AM

The car was running. I bought it, and ran about 4 tanks through it and then this happened... I will put that on the list of things to check, thank you!

Posted by: CYCPYT Mar 26 2024, 10:44 AM

A slippery slope indeed, sound advice, thank you again.

Posted by: CYCPYT Mar 26 2024, 10:45 AM

I will check this as well, but when i did the fuel filter and pump, I looked in tank and it looked pretty clean. I will add checking it thoroughly to my list, thank you.

Posted by: CYCPYT Mar 26 2024, 10:46 AM

Awesome info and thank you for the links. I will post some pics of the engine bay later this evening or tomorrow and appreciate the look!

Posted by: wonkipop Mar 26 2024, 05:25 PM

so
did it suddenly stop while you were out driving and not restart.
or
did you drive it one day, park it in the garage and it would not start the next time you went to drive it?

Posted by: CYCPYT Mar 27 2024, 08:10 AM

parked for literally a day, got in it the next day and then would not run. I probably drove it 10 days in a row prior to this.

Posted by: Frankvw Mar 27 2024, 08:22 AM

my bet : CHT or the injectors do not get operated properly and stay closed, providing no fuel.
If your CSV plug is not connected in teh FI harness then forget the second part about the injectors, then it will also not run for 1 second (otherwise it will run with fuel provided from the CSV and dies after no geting new fuel from injectors)

Posted by: brant Mar 27 2024, 09:28 AM

the 4 wire loom that plugs into the distributor points
is a very fragile connection that often fails or breaks first due to heat
I'd check that connector...

I once used an ohm meter to check all 27? wires from the ECU

brant

Posted by: rfinegan Mar 27 2024, 10:08 AM

Confirm a good connector to AFM/connection at the Air flow Meter. I had a loose pin /connection that gave my L jet symptoms like this and well as intermittent symptoms and stumbles and stalls

Posted by: brant Mar 27 2024, 10:26 AM

Sorry
My comment was djet specific and not helpful

Posted by: CYCPYT Mar 27 2024, 11:46 AM

Everything is helpful as I learn to work on and maintain this car, so thank you!

Posted by: wonkipop Mar 27 2024, 02:06 PM

yes the CHT could be it.
and a few other things.

thanks @http://www.914world.com/bbs2/index.php?showuser=27149 for info about how problem surfaced.
since it ran the day before and not the day after problem its likely a EFI harness issue (elec connection) or a failed EFI electrical component.

stick up those photos of engine bay when you get time.
lets have a look at the state of the engine bay.

further question. where is the fuel pump? still in original location under the engine on passenger side inner long? reason i ask is to work out whether your L jet is still all intact. a lot of l jets or 914s have had their fuel pumps shifted up front under tank and the wiring to the pump changed (in the case of an L jet this is relevant).

the L jet fuel pump if everything is original does not run with ignition on but engine not running. its an early safety feature that D jet did not have. with L jet the fuel pump runs when the starter is cranking - then when engine fires the flap in the AFM (air flow meter) is moved by intake air drawn in by engine and sends a signal to the ECU to keep the pump running. another component under the battery tray called the double relay is is involved. If any one of those things is not behaving correctly the fuel pump will not keep running and the engine will die after the initial hit from the cold start injector.

how to test all this is laid out in the L jet manual i gave link to from Jeff Bowlsby's site.
see if you can find the page in that which lays the tests out.
its under the heading - engine starts but then dies.

Posted by: Dave_Darling Mar 27 2024, 02:07 PM

I suggest starting by looking around in the engine bay. Look along all of the wires in there for any visible breaks or kinks. Check the connections for loose plugs. Make sure ground connections are clean and tight.

Then check all of the hoses. Are any broken? Any disconnected? Any of them soaked with oil and cracking?

Generally a sudden loss of power is caused by something getting disconnected. This isn't exactly that scenario, but it's close. So look for stuff that may have gotten disconnected.

--DD

Posted by: CYCPYT Apr 12 2024, 02:49 PM

Hallelujah!! Vacuum leak for the win! Back on the road and running like a top! Thank you all again for your assistance, I truly appreciate it.

Posted by: Spoke Apr 12 2024, 03:11 PM

Good to hear. Can you provide any more detail as to where the vacuum leak was and how you repaired it?

Posted by: Geezer914 Apr 12 2024, 05:23 PM

Yep, vacuum leak or the AGM is unplugged.

Posted by: Van B Apr 12 2024, 08:55 PM

Posted by: CYCPYT Apr 15 2024, 09:39 AM

For whatever reason it will not allow me to upload the picture. Basically I just took the time to go through the engine bay and look at every possible vacuum connection. Found one that was kind of hidden and it turned out to be the culprit. Started right up and purrs now!

Posted by: wonkipop Apr 16 2024, 12:11 AM

good stuff.
nothing beats being methodical.