1.8 l-jet fires, but dies within seconds, tried searching :-/ Options

[timothy_nd28]

Great, just wanted to verify that you weren't still in the meg ohm range. I'll assume that you were getting a solid 12volts on pins 14-15-32 and 33?

Never mind the dual relay at the moment. The fact that it turns on the fuel pump when you deflect the AFM flap tells me that it is wired correctly. Also your car does start briefly also says that you have fuel pressure when cranking.

Lets do a few more test. With the ECU plug pulled and the ignition switch at the "off" position, put one meter lead on the +12vdc battery post and the other meter lead on pins 5,16 and 17. The meter should read 12 volts on each pin.

After this, remove all fuel injectors from the manifold and insert into glass jars. Turn the ignition switch to the "on" position. Jump pin 88d to +12vdc on the battery post. Use one of your meter leads (detached from the multimeter) and find a way to ground one side of this cable to the negative side of the battery. With the pointy end of the meter lead, insert into pins 14,15,32 and 33. You should hear an audible click (no buzzing), you should also see one of the injectors spraying. Observe the spray pattern while the FI is engaged and be sure it fully shuts off when the meter lead is removed from its corresponding pin. Do this for all 4 injectors. Make sure only one injector is spraying when doing this test, that others are not simultaneously spraying.

[malcolm2]

Man, I'm stupid. Okay, after testing the correct pins, everything thus far checks out fine.

These guys are smart and they WILL figure this out for you. Let me throw in my 2 cents.

Admittedly, I have not read this entire post, so shoot me if this has been said or ruled out with your electrical checks. EDIT: post 14... (IMG:style_emoticons/default/bootyshake.gif) but I added a picture.

But I recently had the air filter box off of my L-Jet and forgot to plug the connector into the AFM... My car did the same thing. Started then died. (IMG:style_emoticons/default/confused24.gif)



the 2" wide connector on the bottom of this picture.

[davesprinkle]

Oh yeah, the old "leave the AFM disconnected" problem. I've done that...

[Chris H.]

Yep met too. Runs terrible with that thing off doesn't it?

[davesprinkle]

Yep met too. Runs terrible with that thing off doesn't it?

It runs great for about 3 seconds...

[thatguywiththedatsun]

Man, I'm stupid. Okay, after testing the correct pins, everything thus far checks out fine.

These guys are smart and they WILL figure this out for you. Let me throw in my 2 cents.

Admittedly, I have not read this entire post, so shoot me if this has been said or ruled out with your electrical checks. EDIT: post 14... (IMG:style_emoticons/default/bootyshake.gif) but I added a picture.

But I recently had the air filter box off of my L-Jet and forgot to plug the connector into the AFM... My car did the same thing. Started then died. (IMG:style_emoticons/default/confused24.gif)



the 2" wide connector on the bottom of this picture.

That's my problem... I don't have the factory optional afm box duct tape. (IMG:style_emoticons/default/tongue.gif) Setting the tests up now. Feeling the love from this forum so far. You guys rock!

[thatguywiththedatsun]

All injectors fire a nice even spray pattern with their corresponding pins. Nothing out of the ordinary aside from a leaky hose clamp connection. 5, 16, and 17 all show clean path to ground.

[timothy_nd28]

So far so good. Now with your multimeter set to ohms, measure between pins 6 and 9 on the ECU plug. Then measure between pins 7 and 8 at the ECU plug. Measure again pins 7 and 8, but move the AFM flap while staring at the meter. Do the numbers increase/decrease evenly when manually pushing the flap?

When you performed the injector spray test, did any of the injectors or adjacent injectors start to buzz? Are you still having the buzzing sound?

[jim_hoyland]

As an aside: By grounding # 1 ( forward left spade ) on the 4 prong connector at the rear (left side) of the relay board you bypass the dual relays control of the fuel pump. Good for an emergency and testing but runs whenever the key is on. The power relay and fuel pump relay will have to be installed.

[malcolm2]

That's my problem... I don't have the factory optional afm box duct tape. (IMG:style_emoticons/default/tongue.gif) Setting the tests up now. Feeling the love from this forum so far. You guys rock!

That is a proprietary mix or Duck Brand and Gorilla Brand. Please let me know if anyone else would like to use that combo, I'll get my lawyer working on it.... (IMG:style_emoticons/default/piratenanner.gif)

[thatguywiththedatsun]

No buzzing from the injectors during the spray test. They all open and close as they should. Resistance between pins 6 and 9 is a steady 292 ohms regardless of where the flap is. With the flap fully closed, resistance between 7 and 8 is 135.6 ohms, if I deflect the flap it's really sort of erratic. Goes as high as 500-800 ohms briefly, but for the most part stays around 200-300 ohms. Wide open it shows 146 ohms. Doesn't seem as smooth as I thought it would be. Doesn't seem to be much correlation with the position of the flap...?

[timothy_nd28]

How far away do you live from Clark? It would be good to try a known good AFM with your setup. Everything else is checking out good with your Ljet, the only squirrely thing is your AFM

[thatguywiththedatsun]

Not sure. I'm in Memphis. I did see a '74 412 at the junkyard the other day. Thought about grabbing the afm that was in the front seat. Don't recall if it was 6 or 7 pin though. Worth it?

[timothy_nd28]

If it can be had for under 5 bucks, maybe.

[malcolm2]

How far away do you live from Clark? It would be good to try a known good AFM with your setup. Everything else is checking out good with your Ljet, the only squirrely thing is your AFM

We are about 4 hours apart,I'll help if I can?

Clark

EDIT: I put a few feelers out, maybe someone here or even in Memphis will loan you a known good AFM to try for a day. Better to rule that one out without spending big bucks.

If the JY unit is a match, get it. We have 2 914s in a JY here, but one has no engine, the other has no injection, so that's no help.

I'll keep you posted.

Clark

[timothy_nd28]

Pin 6 and 9 on the ECU plug show the total resistance on the AFM resistor plate, this number will not change (except with temperature, only slightly). This part of the test is good.

Pin 7 and 8 on the ECU plug is one half of the AFM's resistor plate. I expected to see 0 thru 200 ohms, or half the total resistance (pin 6 and 9) as you moved the AFM flap. Since you measured up to 800 ohms, (more than the total resistance of the resistor plate), suggests to me that the AFM wiper arm is not making good contact with the resistor plate. It could be dirty, or you could have worn carbon tracks on the plate.

Obtaining a known good AFM would be the easiest way to test. Or, you could clean the resistor plate with some good (hard to get) pot cleaner. If the carbon tracks are worn, the whole plate can move slightly if you were to loosen the screws and reposition the board. I'm not sure how in depth you wanna get with this.

[malcolm2]

Tim, did you give him the ITINERANT link?

http://www.itinerant-air-cooled.com/viewto...f=50&t=7761

only do stuff on here if Tim suggests it. ( or as a last resort, when Tim says you are ready for the last resort) There are a couple serious disclaimers in the document. READ and HEED.

Good Luck

[timothy_nd28]

Black22 found that link, all good stuff. (IMG:style_emoticons/default/beerchug.gif)

[thatguywiththedatsun]

Oohlala. Definitely my cup of tea. I'll probably test the connector on the side of the box to rule out any problems in the harness between the ecu and afm and pop the black box open if I get the same readings. What have I got to lose, right? Anything else I should grab off this 412?

[thatguywiththedatsun]

No dice, gentlemen. Got the afm responding reasonably well to the flapper arm location and the symptoms are the same. After a new cap and rotor (just cuz it's a new to me car) symptoms are still the same... Got wires, points, plugs, and condensor going in next time. Any more ideas?

I'm more and more leaning towards an electrical problem outside of the fi circuit. I've seen the injectors all fire a nice spray pattern, with adequate pressure in the lines as confirmed by a gauge. Checked for proper spark. Afm connector is securely plugged in, as is the cht which reads a nice steady 3.5k ohms. Even with the pump hot wired on all the time, it starts, revs to around 3000rpm, and dies within seconds. Makes me think that my nice strong spark is going away when the key goes back to "run" from "start." What am I missing here....? (IMG:style_emoticons/default/huh.gif)