NEED HELP: 1974 1.8L Will Only Start with Brake Clean, Runs with AFM disconnected only Options

[Nor.Cal.914]

Hello everyone,

I have a 1974 1.8L that needs a new fuel pump and the customer purchased this pump from Pelican:

https://www.pelicanparts.com/More_Info/0439...59&DID=4630

I have already figured out the line routing in terms of inlet and outlet, but I do have a few questions about some other aspects. Being that the stock pump is a 3-port pump, first question is, what was the reasoning behind the 3 ports instead of just an inlet and outlet? My first thought was maybe an internal FPR, but I see there is a one in the engine compartment so that doesn't seem to be the case, but please correct me if I'm wrong! Second question involves mounting the pump. I have a 1975 so I'm not as familiar with how the 1974's were setup. This car has the coil style ring bracket around the pump which I'm now trying to figure out if I can utilize to mount the new pump. Main issue of course is the fact that all 3 lines came out on one side of the factory pump, whereas this pump has inlet/outlet on either side.

So my question is, what have you guys done to mount your pumps either in the same location or where did you place it instead of the factory location? Thank you in advance for the help! (IMG:style_emoticons/default/beerchug.gif)

-Christopher

[Nor.Cal.914]

A few thoughts that came to mind when reading your posts. Hopefully these will be helpful....

Here's a thread from another L-Jet owner with a similar problem. One problem was a loose connection at the AFM that wasn't evident until he "wiggled" the wire. The other problem (not in the thread but known from private communication) was that there were multiple vacuum leaks.

http://www.914world.com/bbs2/index.php?sho...342895&st=0

Here's a link to the "914 Tech Notebook" section on Jeff Bowlsby's website. There are multiple L-Jet manuals in this section. Just scroll down through the list and you'll see them, with clickable links. Jeff's website is worth exploring whenever you have the time. Lot's of links to resources there.

https://bowlsby.net/914/Classic/TechNotebook.htm

I had a several week education in L-Let when I revived a 1979 VW Super Beetle from a 16 year nap. By far the best explanation of the system that helped me was in the Bentley manual. There is a section at the rear of the manual dedicated to explaining the system. It was clear and concise, but also probably duplicative of the resources on Jeff's website. PM me with an email and I can probably scan that section for you and email it to you. I might be local to you, depending upon where you are in NorCal, so I could just lend you the manual. I'm in the East Bay. Also, sounds like you have eliminated the dual relay as an issue, but if you are local and are still concerned I do have a known good dual relay you can plug in to confirm.

@fiacra Thank you for the link! I just read through the thread you linked about the loose connection. I will have to look into that as well. Only difficulty for me right now is I'm at a dealership and the foreman is trying to keep things moving so doing the in depth diagnosing is getting difficult now. I am trying to check as much as I can. I am out in Texas now, I used to live in San Jose/Morgan Hill area, but moved out here in October 2020 so long ways away from the Bay Area now. Thank you so much for the offer!

here is a direct link to the L jet troubleshooting guide jeff bowlsby has on his website that fiacra is talking about.
you can download it as a PDF.
save you a bit of trrouble searching his site.

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


there is also a bit here on the type 4 club website.
but this is for the type 4 sedans (411/412).
these were all auto gearbox L jets.
tiny bit different.
but its a good resource.

https://www.type4.org/manuals/ljet/index.html

believe it or not there is a whole detailed L jetronic manual on this website.
i stumbled over it years ago and downloaded it page by page.
but the search function on the website is hopeless.
it was somehow contained in a members file from memory.
i'll try and google search that and see if i can uncover it.

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also on link a couple of posts up i left to factory manuals,
in the electrical volume you will find all the wiring diagrams for the 74 and 75 L jetronic 914s - inclusive of the EFI system. possibly handy to have.

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speaking of your engine photos. (IMG:style_emoticons/default/idea.gif) (IMG:style_emoticons/default/blink.gif)

ok it looks intact.
a couple of questions.
there is a green coloured hose in second photo.
it is diving down the side of the throttle body facing the front of the car.
is this hose then continueing from there to the fuel pressure regulator which is located underneath where the air cleaner box is.' it should be connected. normally this hose is routed around the rear side of throttle body and across tin to FPR, but it appears to be correctly hooked up at other end where it goes into a T connector with the hose from the decel valve. that end looks right.


secondly there is no hose from the vacuum advance can on the distributor to the the advance port on the throttle body. the advance port on throttle body will be on ther rear facing side of throttle body (to rear of car) and sticks up at a 45 degree angle. normally that advance can on dist is connected to that port with a vacuum hose similar in size to the green one i was talking about above. normally that is if its a 1974 49 state car.
however the 74 californians did not connect the throttle body to the advance can. they just tucked the hose of the advance can under the inlet plennum and left it there open.
and there was no port on the throttle body. this car could be a 74 californian model?
have a look at that throttle body and see if that is the case. because if its a 49 state car then it would have an open vacuum leak if that hose is missing.

(another way you can tell if it is a 49 state car or california is see if it still has the emissions sticker in the engine bay. it will be on the left side above the fuse board near the air cleaner. its white with red writing. if it says EC-B its a 49 state car if it says EC-A its a california car.

someone has definitely "restored" this engine or shall we say, dressed it.
the tune up sticker on the fan housing casting is incorrect. its a repro sticker i suspect and its meant for the earlier D jet cars. the L jets had a white sticker with black diagrams and text on it. so someone has been playing around with the engine at some point. to what extent hard to say.

the other thing you want to check is that the vacuum retard hose is there from the distributor to the throttle body. all the different L jets had this.
the retard side of the vac can is the flatter part close to the distributor body.
should be a little port sticking out of it down low. standard it has a green hose runs off it and connects to the throttle body on the forward facing side. the port is down low on the throttle body. the hose is routed under the inlet manifold pipes from the dizzy to the TB.
check that hose is there. photos are too dark and don't show it or i can't see it.


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the manuals i have linked to will tell you pretty much everything you need to know to test methodically.

questions i have - have you pulled the injectors and made sure they are working correctly.

you can find all the tests for fuel pressure itself in the factory manuals and the other manuals linked to.

another point of difference you will find from the 74 to the 75 is that the 74 has a six pin connector to the AFM. 75 has 7 pin. with the 75 they separated out the intake air temp sensor and you can test for that. not so in the 74.

i'd suggest unclipping the EFI harness at the ECU and make sure the pug pin connectors are all clean. clean with eletrical fluid cleaner. same at other end where connects to AFM.

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whats the story with the car. did it run before it came to you?
did someone just think it was the fuel pump that was kaput.
has it been sitting for a long time?

@wonkipop Thank you again so much for all the information you're providing! I will be reading through the repair and operation manuals as I can!
In terms of your questions, the green colored vacuum line going to the FPR is hooked up properly.

The vacuum line for the distributor is something I'm not entirely sure about. The emissions label is actually there and it claims to be an EC-B car. So by what you mentioned, there is supposed to be a vacuum port on the back side of the throttle body, but this one does not have one. There is a vacuum port on the front side of the throttle body that does go to the distributor vacuum retard.

The customer said the engine was "rebuilt" at some point, not entirely sure when, but it seems like it was a long time ago if that is actually the case as the vacuum lines are very stiff, but maybe they were not replaced at the time of the rebuild, I'm really not sure.

I have not pulled the injectors out yet, my foreman has a fuel injection tester that I used to activate each individual injector and the cold start injector. I could audibly hear the injectors buzzing and I was getting fuel into the cylinders based off of a slight difference in cranking after activating each injector. The cold start injector didn't buzz, but I could feel it vibrating when I put my hand on it with it activated so it seems like it's at least trying to function. Will have to pull them out to actually see the flow, if I'm allowed the time to do so.

Pins at the AFM look clean, I haven't checked for continuity as the thread fiacra linked. Still need to get the ECU harness off to inspect as well.

The car was towed in, no start. Fuel pump was not working, as we talked about earlier. So I started with replacing the pump and was able to get it run under the conditions that we've been talking about. He claims it was only sitting for 8-9 months, but the fuel smelled like varnish so it really seems like it was much longer than that.

The connection there at the double relay is a butt splice that has two wires going into the one side so it looks as if it's disconnected, but it's not. Granted the splice is very poor, but they are connected. Will be something to fix.

Some other things I found this morning while testing things:
If I have the AFM connected while cranking, there is no fuel pressure. If I disconnect the AFM while cranking, I have fuel pressure. I can move the flap inside the AFM and get the double relay to activate and run the fuel pump. It's almost identical to the thread fiacra linked, but mine also won't start at all unless it has brake clean sprayed into the intake. It stumbles at least with the AFM disconnected, but I've only had it close to starting like that a couple of times.

I will see what I can find with some other tests. Thank you all so much for the help! (IMG:style_emoticons/default/beerchug.gif)

-Christopher

[wonkipop]

Some other things I found this morning while testing things:
If I have the AFM connected while cranking, there is no fuel pressure. If I disconnect the AFM while cranking, I have fuel pressure. I can move the flap inside the AFM and get the double relay to activate and run the fuel pump. It's almost identical to the thread fiacra linked, but mine also won't start at all unless it has brake clean sprayed into the intake. It stumbles at least with the AFM disconnected, but I've only had it close to starting like that a couple of times.

I will see what I can find with some other tests. Thank you all so much for the help! (IMG:style_emoticons/default/beerchug.gif)

-Christopher
[/quote]

ok, this is good detailed info you have given.

first of all. with AFM connected, if all is well, cranking there should be fuel pressure.
is none, the pump is not running.
so that is fault #1.

secondly , with AFM disconnected you can get the fuel pump to run and pressurize while cranking. this would accord with the situation in my stock unmeddled L jet. if i disconnect the AFM, cranking the engine will run the fuel pump and it will fire (likely on its cold start injector) which will move the flapper in the AFM to take over the pump, except its not connected so nothing happens which is why mine dies. but yours will keep running (sometimes) and basically idling. what tells me is your fuel pump also keeps running. when it should not. so something is amiss in the wiring and connections somewhere.

the way the engine keeps running in your case is i think off the throttle position switch which is under the throttle body. at idle this switch is activated and it sends a signal to the ECU to tell the ECU the engine is at idle and requires the idle fuel mixture load. the AFM is not actually telling/commanding the ECU to idle, but it is telling the fuel pump to run when its connected. the flapper moves just enough to open the pump switch contacts but not far enough to go into its enrichment settings. you see pulling out the AFM plug still leaves the TPS plugged in lower down along the loom. the AFM really runs the engine at throttle openings above idle. thats when it takes over letting the ECU know how much air volume is entering.
its pretty simple old thing in the L jets.

so that is how it is running. you caused it to fire with the starter fluid. and its just enough to make it keep running sometimes off that idle mixture signal from the TPS.
and it can do that because the fuel pump is also running when it should not (because normally it cannot run the fuel pump if the AFM plug is out).

so you should not get confused by that. it is possible. but only because the fuel pump running is what is abberent or wrong.

and.........what is the one bit of work you have done.
you have replaced the fuel pump.

so rather than rushing all around the place thinking this or that.
i would return to the fuel pump.

you say the owner said it ran before he put it away and stopped driving it.
lets believe him.

are you sure you wired in the fuel pump exactly as per the connection to the three port.
normally you have to muck around with that plug that went into the 3 port and make new connections/plugs for the modern pumps.

we seem to have a situation where the AFM is both preventing the fuel pump from running at crank and also a situation where it won't allow itself to run the fuel pump after the engine fires. and its the fact that its preventing the fuel pump running at cranking that is kind of interesting! its almost like its functioning back to front if that makes sense?

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now the other thing i noticed reading your posts you report a fuel pressure of 68psi.
this is way too high.
i assume that is from the guage positioned where it is in the line in one of your engine bay photos which is in the right spot.
that reading ought to be 35psi +/- i psi.
thats the factory requirement anyway.
other L jet guides can be a bit looser saying somewhere between 30 and 35.
now when you get it running it should actually be 28psi at idle and it should drop pressure to that when you snap close the throttle. then when you raise reves it will rise to 35psi. the FPR will do all this automatically using the inlet manifold pressure from the vac line connected to it.
given the state of the fuel you describe in the tank and elsewhere it sounds like maybe the FPR is gummed up too. like its stuck and its not releasing pressure at the required level.

i would not want to drive an L jet with an injector line at 68psi. thats going to blow hoses off. and burn.

so at some point you are really going to want to get the fuel pressure down.
and i think that will be a new FPR. but wait until you can at least get it to run.

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with that fuel pump correctly wired in - what you should be able to do is push the flapper in on the AFM - with the AFM plugged in and with the ignition in the on position and make the fuel pump run. forget about the double relay clicking thats not enough.
the fuel pump must run and pressurize the line to 35 psi.
if thats not happening then something is wrong with the wiring connection to the pump i believe or the dual relay.

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i am not there to see the car. (IMG:style_emoticons/default/biggrin.gif)
i'm on the other side of the world.
and i am not an electrical genius to begin with.

but given all you have really done is replace the pump then i would return to that and ensure it was connected correctly.



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something else i notice with yours is the relay board is jammed full of the round relays.
we only use one of those in an L jet and its to run the engine bay blower fan.
the rest are not required. their functions were assigned to the dual relay and the resistor block etc on an L jet which are under the battery tray. so someone has loaded that relay board full of relays when they are only needed for a d jet. i can see the all important yellow wire which is on an L jet is there and it is connected looking at your photo. so that is probably not the problem.

this is a great vid on the relay board by Dr. 914.
about half way through he gets to what the relay board should look like in an L jet.
and whats different from a D jet. its a quick vid so worth a look.

https://www.youtube.com/watch?v=YLgQxpNHzIU


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artfrombama has raised the white wire to coil.
when i look at your photos i can't see it but that does not mean its not there and its not connected. it leaves the EFI harness around about where the battery is and you run it up to the coil.

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looking close at your photos i did another double take when i was looking at the side of the ECU and the plug in connector. it may be no big deal. but its all upside down.
someone has had the ECU out and put it back in the other way around?
the ECU slides out of its outer holder so if someone has had it apart its possible they have slid it back into its outer holder the wrong way.
normally the harness comes in at the bottom of the plug. it may be no big deal but when i look at mine the harness is not hugely long in that area and i wonder if this could be stressing connections at the top of the plug when its fitted this way. stretching the harness?

i've attached a image from the factory manual which shows how the ECU is normally mounted.

might be worth taking a very close look at that plug and how it is seating into the ECU.
because to flip it upside down means it also rotates front to back. so you really have to twist the harness at that point to get the plug aligned socket to pin from plug to ECU.
i'd sniff a bit around that plug and just make sure its all sitting nice and comfortable.




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i can't offer much else.
but i do believe in always returning to the notion of "what has been done to the car".
and thinking that over.