New to the site with an 80 series LC, it cranks, but does not start. Having fun chasing the issue. (1 Viewer)

[jonheld]

Please see the diagrams from the 1994 EWD below that I have stitched together for you.

 

[raijinbu]

Jon, thanks for the links and tips.

C8 is the Circuit opening relay behind the foot rest.

Circuit opening relay

My 1994 FZJ80 was having an intermittent no start issue. Engine would crank and CEL light would illuminate but would not start, after a few tries it would start and then run perfectly. The no start occurred infrequently, maybe once per month. I tracked the problem down to the Circuit Opening...

forum.ih8mud.com

 

[jonheld]

Jon, thanks for the links and tips.

C8 is the Circuit opening relay behind the foot rest.

Circuit opening relay

My 1994 FZJ80 was having an intermittent no start issue. Engine would crank and CEL light would illuminate but would not start, after a few tries it would start and then run perfectly. The no start occurred infrequently, maybe once per month. I tracked the problem down to the Circuit Opening...

forum.ih8mud.com

You really need to take a step back and start from the beginning here. I feel like you're going down the primrose path. Why are you concerned with the COR at this point?

In one of your first posts, you said that the CHARGE lamp doesn't illuminate with the ignition key in the ON position. That screams fusible link AM2 or the 7.5 amp IGN fuse. Look at the current flow chart in the power source section of the EWD.

In an earlier post, you said that you were getting +12 to ECU connector E7-13. Then you said you weren't getting +12 to E7-13.
How are you testing this?
Is the key in the ON position while testing?
Is your meter set up to read voltage?
Does your meter have a good ground for the negative lead?
Is your meter lead making good contact with the pin in question?
Are you checking fuses with your eyeballs or are you pulling them individually and checking them with your meter set to continuity?

There can be no guesses here and I can't see what you're doing. I'm trying my best to help, but I can only go by what you're telling me and it's not making sense.

 

[raijinbu]

You really need to take a step back and start from the beginning here. I feel like you're going down the primrose path. Why are you concerned with the COR at this point?

In one of your first posts, you said that the CHARGE lamp doesn't illuminate with the ignition key in the ON position. That screams fusible link AM2 or the 7.5 amp IGN fuse. Look at the current flow chart in the power source section of the EWD.

In an earlier post, you said that you were getting +12 to ECU connector E7-13. Then you said you weren't getting +12 to E7-13.
How are you testing this?
Is the key in the ON position while testing?
Is your meter set up to read voltage?
Does your meter have a good ground for the negative lead?
Is your meter lead making good contact with the pin in question?
Are you checking fuses with your eyeballs or are you pulling them individually and checking them with your meter set to continuity?

There can be no guesses here and I can't see what you're doing. I'm trying my best to help, but I can only go by what you're telling me and it's not making

I borrowed another voltmeter with thinner leads and got 11.76 V for E7 pin13 with the ignition switch on.

For the charge light, I re-checked AM2 which showed +12 V and the 7.5 IGN fuse shows conductivity and +12 when connected.

I rechecked all fuses in the box next to the battery and by the kick panel for conductivity and voltage, all check ok.

Trying to understand the schematics makes my head spin. Getting pretty close to selling the LC as is.

Thanks again for the help.

 

[raijinbu]

Latest update, I replaced the circuit opening relay and got the CEL. I tried starting it, ran for a few seconds then stopped. I noticed the cable was still unplugged from the MAF. I plugged it in, the CEL went away, but now it cranks with no start. With the MAF sensor cable off, the CEL does show now.

Got codes 31 and 24 which seem related to the MAF being disconnected.

Jumped pins FP-B+, with MAF disconnected, it starts, idles at 1k RPM for about 5 seconds now, then dies.

Checked fuel pump relay for conductivity = pass

Checked fuel pump power connector while cranking = getting voltage

 

[jonheld]

Latest update, I replaced the circuit opening relay and got the CEL. I tried starting it, ran for a few seconds then stopped. I noticed the cable was still unplugged from the MAF. I plugged it in, the CEL went away, but now it cranks with no start. With the MAF sensor cable off, the CEL does show now.

Your AFM is likely the issue.
The switch for the flap in the AFM provides the ground path for the secondary coil in the COR that fires the fuel pump. That's why the engine stalls shortly after you stop cranking the starter. The primary coil is fed from the starter circuit.
The fact that you get a CEL without the AFM connected and it goes out with the AFM connected tells me that someone removed the 2 Phillips screws on the connector housing and pulled internal wires off the traces inside the AFM housing. This can be repaired if you're very handy with a soldering iron and know what you're doing. If not, pick up a used unit from the classifieds section. There are several trustworthy sellers that part out 80 series.

 

[raijinbu]

Your AFM is likely the issue.
The switch for the flap in the AFM provides the ground path for the secondary coil in the COR that fires the fuel pump. That's why the engine stalls shortly after you stop cranking the starter. The primary coil is fed from the starter circuit.
The fact that you get a CEL without the AFM connected and it goes out with the AFM connected tells me that someone removed the 2 Phillips screws on the connector housing and pulled internal wires off the traces inside the AFM housing. This can be repaired if you're very handy with a soldering iron and know what you're doing. If not, pick up a used unit from the classifieds section. There are several trustworthy sellers that part out 80 series.

@jonheld I will check if the AFM can be repaired, else will shop for one, thanks!

 

[jonheld]

@jonheld I will check if the AFM can be repaired, else will shop for one, thanks!

Test the AFM according to the FSM first. Be certain that's the issue.

 

[raijinbu]

Test the AFM according to the FSM first. Be certain that's the issue.

@jonheld you were right on the money! I popped open the AFM and noticed the 3 broken connectors. I took my time with solder. Placed it back in the LC and I now have a running truck. Drove around the block a couple of times. Now have to put it back together and do baseline maintenance.

I had tested the resistance on the AFM yesterday and the values were within the limits according to the FSM.

Thanks again for your help, you da man!