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