280z Cranks but won't start

BenjEtch

Club Member
Hi all, wondering if anyone can shed any light on the problems I'm having with my 280z!

My 280z was running great on Friday, then on Saturday it wouldn't start and I had to jump start it a couple of times throughout the day. I gave it a good blast throughout the day as there is still some old fuel in it (as well as new). Then it ended up cutting out on me at a set of lights and I had to get a recovery truck to pick me up!

Today I had a good look over the engine, disconnected a few of the fuel hoses in different places to see if there was fuel in the filter/rails etc (seemed to be fuel in ther). Found a split section of hose, which had been dripping petrol so swapped that out (photo attached). But it still wouldn't start.

Finally got it to fire for a few seconds with starter fluid, but it would cut out almost immediately.

I'm thinking it is a fuel-related problem and that I potentially need to empty the tank and start again. Any thoughts?
 

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jonbills

Membership Secretary
Staff member
Site Administrator
you said it wouldn't start so you had to jump start it - whats the situation now? does it start with a jump start?
what condition is the fuel filter in?
 

BenjEtch

Club Member
you said it wouldn't start so you had to jump start it - whats the situation now? does it start with a jump start?
what condition is the fuel filter in?
I'm pretty sure it would start again if I jump it, however, I'm afraid it will cut out in a place that I then can't jump it from.

Digging back through Mike's post about it here: https://zclub.net/community/index.php?threads/resurrection-cali-280z-hybernation-in-1987.27319/

I can see he had the fuel tank drained and cleaned too: https://zclub.net/community/index.p...li-280z-hybernation-in-1987.27319/post-313326.

He mentioned he was having problems with the AFM so perhaps it's either that or like you mentioned the fuel filter? As there's nothing said about it in the original posts.
 

jonbills

Membership Secretary
Staff member
Site Administrator
If it jump starts, but won't start on its own battery, its probably the battery or the alternator.
Have you got a multitester? what voltage at the battery with everything off, and with it running?
 

BenjEtch

Club Member
If it jump starts, but won't start on its own battery, its probably the battery or the alternator.
Have you got a multitester? what voltage at the battery with everything off, and with it running?
I'll check this tomorrow, it cranks easily and pretty fast too. It also started almost instantly with starter fluid for a few seconds then cut out.
 

Robotsan

Club Member
I'm pretty sure it would start again if I jump it, however, I'm afraid it will cut out in a place that I then can't jump it from.

Digging back through Mike's post about it here: https://zclub.net/community/index.php?threads/resurrection-cali-280z-hybernation-in-1987.27319/

I can see he had the fuel tank drained and cleaned too: https://zclub.net/community/index.p...li-280z-hybernation-in-1987.27319/post-313326.

He mentioned he was having problems with the AFM so perhaps it's either that or like you mentioned the fuel filter? As there's nothing said about it in the original posts.

He said he did change the fuel filter in that post Ben:
Screenshot_20220524-045632~3.png

Deffo sounds like you should look at the AFM again as that was just cleaned rather than replaced, if that was causing the injectors to not fire last time? Maybe a mouse has moved back in..
 
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Huw

Club Member
Hi

It is unlikely the AFM will cause a non start. Poor running yes but not normally a non start. There is a long list of other more common potential reasons why before pulling the AFM.

I would suggest looking at the attached EFI bible and running through the various testing sections. Basis such as fuel supply, is the pump running, power to the ECU, power to the injectors, timing not slipped etc. Then move on to the starting sequence (checking water temp sensor, oil pressure sensor, various relays, thermotime and cold start injector).
 

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Robotsan

Club Member
Sounded from Mike's post on Ben's thread that the AFM was stopping it from starting when Mike still had the car though. Maybe give it the mallet treatment Ben! 😂

Screenshot_20220524-051058.png
 

Huw

Club Member
Yeh, read that and thought it was odd as the AFM doesnt actually control the fuel pump
and doesn’t provide any input to the ECU for start up until the car is moving. Unless it’s electrically dead it won’t impact starting at all.
 

BenjEtch

Club Member
Hi

It is unlikely the AFM will cause a non start. Poor running yes but not normally a non start. There is a long list of other more common potential reasons why before pulling the AFM.

I would suggest looking at the attached EFI bible and running through the various testing sections. Basis such as fuel supply, is the pump running, power to the ECU, power to the injectors, timing not slipped etc. Then move on to the starting sequence (checking water temp sensor, oil pressure sensor, various relays, thermotime and cold start injector).
Ah yes, I've got this doc, I'll go through all the troubleshooting this weekend. Thanks!
 

Faster Behr

Club Member
The EFI bible is a good place to start As Huw has said.

280Zs up to ‘77 had a fuel pump switch in the AFM. ‘78 did not. If your unsure then unplug the AFM and look to see how many pins it has in its socket. Early cars had 7, later had just 5. I’d start by looking for fuel pressure on this one given your concerns about the tank and the symptoms you describe. You should be getting 37psi at idle with the vacuum reference disconnected from the fuel pressure regulator. Machine Mart do a cheap fuel pressure test kit if you don’t have one.
 

SacCyclone

Club Member
So i learned from my mechanic last year that the AFM has a breaker point type switch in it which activates the electric fuel pump.....a couple of taps on the AFM with the end of a screwdriver handle did the trick on more than one occasion with your car Ben.

The other area is a box under the seat which again send electrical to the fuel pump.....my mechanic jumped that pin connector on another 280 and was able to get the electric fuel pump to light up.

Best if it will not start is to have someone listen to the fuel pump while cranking the engine over to see if it is sending fuel down stream. Use caution when someone is under the car while cranking the engine over!!!!!!!!!

These old EFI systems are problematic after 40+ years and best to look for a modern alternative.

Mike
 

BenjEtch

Club Member
Hi all,

Had a good crack at the Z today and have found a few things.

AFM flap was stuck in the open position, it was getting caught when all the way open, so managed to get that to move more freely - I get what the gentle tap is for now!

Once I'd addressed the AFM, it still wasn't starting, so I put an inline fuel pressure gauge after the fuel filter, cranked the engine and nothing (0psi). So I then removed the filter (photo of what came out attached was some right gunk in it!) and installed the pressure gauge before the filter - still no pressure at all.

I also tried just cranking the engine with the fuel line directed into a tub, absolutely nothing came out.

I now think either the pump isn't getting any power or the lines might be clogged.

So I used the "engine won't start" section (page 32) in the FI Bible to do some testing. From that, I'm pretty sure the fuel pump and regulator aren't making any noise so I jumped to step 6 (page 33).

The power relay definitely clicks so I did the circuit checks in 6b, all resulted in the desired outcome, so I'm a bit stuck really now.

I will go looking for the box under the seat as Mike suggested, but I'm wondering if the AFM is affecting the fuel pump from activating.

Any thoughts?

Thanks all and have a great weekend!
So i learned from my mechanic last year that the AFM has a breaker point type switch in it which activates the electric fuel pump.....a couple of taps on the AFM with the end of a screwdriver handle did the trick on more than one occasion with your car Ben.

The other area is a box under the seat which again send electrical to the fuel pump.....my mechanic jumped that pin connector on another 280 and was able to get the electric fuel pump to light up.

Best if it will not start is to have someone listen to the fuel pump while cranking the engine over to see if it is sending fuel down stream. Use caution when someone is under the car while cranking the engine over!!!!!!!!!

These old EFI systems are problematic after 40+ years and best to look for a modern alternative.

Mike
 

BenjEtch

Club Member
So i learned from my mechanic last year that the AFM has a breaker point type switch in it which activates the electric fuel pump.....a couple of taps on the AFM with the end of a screwdriver handle did the trick on more than one occasion with your car Ben.

The other area is a box under the seat which again send electrical to the fuel pump.....my mechanic jumped that pin connector on another 280 and was able to get the electric fuel pump to light up.

Best if it will not start is to have someone listen to the fuel pump while cranking the engine over to see if it is sending fuel down stream. Use caution when someone is under the car while cranking the engine over!!!!!!!!!

These old EFI systems are problematic after 40+ years and best to look for a modern alternative.

Mike
Is this the box you meant Mike?

I presume it's another relay? As it clicks when you turn the key to start.

IMG_0385.JPG
 

Huw

Club Member
Tried tapping the pump with the ignition on or failing that’s putting 12v across the pump? With that much crud that’s come out of the filter it might be stuck.
 

Faster Behr

Club Member
There may also be a small wire strainer within the inlet of the fuel pump. Unless it has already been removed. It only has a small surface area so it’s easily blocked. It’s easy to find.

I would be checking for power at the pump itself then working backwards if there’s nothing there.
 

SacCyclone

Club Member
My mechanic told me that the electric fuel pump is activated in 2 ways and they both need to be operating properly to send voltage to the fuel pump. The first one is a relay from the AFM and the second is a relay when in the crank position. I believe that the AFM won't send a signal to the fuel pump until the car is running......the cranking relay sends a signal to the fuel pump so it will start, I believe it is possible to jump the crank relay under the seat also.

I tried calling my mechanic today but he won't be back to work until tuesday.

One other thing to do is send a direct 12V wire to the fuel pump to confirm it still works......at least you will know if the pump is good.....it probably will be.

Mike
 
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BenjEtch

Club Member
My mechanic told me that the electric fuel pump is activated in 2 ways and they both need to be operating properly to send voltage to the fuel pump. The first one is a relay from the AFM and the second is a relay when in the crank position. I believe that the AFM won't send a signal to the fuel pump until the car is running......the cranking relay sends a signal to the fuel pump so it will start, I believe it is possible to jump the crank relay under the seat also.

I tried calling my mechanic today but he won't be back to work until tuesday.

One other thing to do is send a direct 12V wire to the fuel pump to confirm it still works......at least you will know if the pump is good.....it probably will be.

Mike
Thanks for that info Mike, good to know that there's two ways the pump is switched on.

I wired the pump directly to the car battery this morning and here is a video recording of the noise it was making. https://www.dropbox.com/s/1cggpuljbxpzgdk/IMG_0391.MOV?dl=0

When I tapped the wire on the contact, it would make a clunking noise, but then nothing. The odd time it sounded like something was moving slightly but then stopped again. I'm guessing there's a clog in the pump/it's faulty perhaps?
 
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