91' 3FE Won't start and no CEL (1 Viewer)

[LhPickle]

I am having trouble getting my rig to start. 1991 3FE 190,000 miles on body and 120,000 on motor.

My family and I were running some easy trails near our house, when we stopped to look at a moose and the engine shut off while we were sitting in park idling. I let it sit for a minute before I tried to restart it (I have had no problems like this before), so after I let it sit while my kids watched the moose I turned the key and it fired right up. About 20 min down the trail (we were 1.5 hours into the trail) we ran into a 25' section of 8" deep mud that we drove through (mud everywhere, but not stuck) and went on our way home with no issues.

When I got home I parked the 91' in the driveway to spray it down and get the mud off the body, knuckles, and undercarriage. When I went to start it 30 min later it would turn over, but not start, it was late so I pushed it into the garage and figured I would deal with it the next day.

Didn't get to it the next day, but a couple days later got to look at it. I figured that somehow water must have gotten into the distributor cap and was stealing spark, but it ended up being dry inside. It did have all what appeared to be the original rotor, wires and plugs, so I figured I would just replace those. So I put in a new rotor, cap, plugs and wires. Still it would not start, so I sprayed starter fluid in the air box and it acted like it wanted to start, so I knew that I had spark.

My next thought was that I am not getting fuel to the motor. I had replaced the fuel filter last summer, so I figured that was good so I went ahead and replaced my fuel pump, figuring it was likely original and ready for a change out anyway. I also changed out the Fuel pump and Main EFI relay under the hood. So after I had it all put back together I tried to start it and it would still not start.

So the other day at work during some down time I hopped on IH8Mud and did some searching and found a thread or two on no CEL=No Start. I did go through @jonheld's diagnostic procedure talking about no CEL, but am not sure what he means by b+ and am not sure where to look next...

Here is what I have done since this started:
1) New rotator
2) New distributor cap
3) New spark plug wires
4) New spark plugs
I know I now have spark

5) New fuel pump
6) New fusible link and main battery ground.
7) I verified that I have +12v at the fuse/relay box in engine compartment.
8) New EFI main relay (engine compartment box).

9)Bueller Bueller?

 

[Tools R Us]

... but am not sure what he means by b+ and am not sure where to look next...

Short for battery positive, also a terminal in the diagnostic box on the firewall, that should have battery voltage.

 

[73tlcv8]

When you turn the ignition key to run but not start, is the CEL on? If not check the fuses that supply the ECU and make sure the ECU is getting power. If you are getting 12v to the ECU then it is likely a bad ECU. But before you replace the ECU try this:

Disconnect the AFM from the air filter housing, with the ignition switch in run, stick something into the inlet to the AFM and move the flapper off the closed stop, you should hear the fuel pump start and stop as you open and close the flapper in the AFM. If no fuel pump start, it may be the circuit opening relay (COR) which you did not mention above (likely), or the micro switch in the AFM (not likely). Also Clean up the connections where the harness connects to the AFM with some spray electrical contact cleaner. If the fuel pump is starting when you do this and you are not getting the CEL with the ignition switch in run, probably the ECU but my money is on the COR.

 

[jonheld]

If you're not getting a CEL with the key in the ON/RUN position before you crank the starter, this engine will not run. No need to crank the starter.
How far did you get in the diagnostic?

 

[LhPickle]

If you're not getting a CEL with the key in the ON/RUN position before you crank the starter, this engine will not run. No need to crank the starter.
How far did you get in the diagnostic?

So far I have replaced my fusible link (which was new last fall) and verified that I have +12v to the fuse box in the engine compartment on the drivers side and I have also replaced the Main EFI relay in the same fuse box.

 

[jonheld]

Have you checked for +12 at the diagnostic connector mounted by the firewall? (Step 4)

 

[jonheld]

When you turn the ignition key to run but not start, is the CEL on? If not check the fuses that supply the ECU and make sure the ECU is getting power. If you are getting 12v to the ECU then it is likely a bad ECU. But before you replace the ECU try this:

Disconnect the AFM from the air filter housing, with the ignition switch in run, stick something into the inlet to the AFM and move the flapper off the closed stop, you should hear the fuel pump start and stop as you open and close the flapper in the AFM. If no fuel pump start, it may be the circuit opening relay (COR) which you did not mention above (likely), or the micro switch in the AFM (not likely). Also Clean up the connections where the harness connects to the AFM with some spray electrical contact cleaner. If the fuel pump is starting when you do this and you are not getting the CEL with the ignition switch in run, probably the ECU but my money is on the COR.

The COR is the fuel pump relay. It has nothing to do with the ECU and will not effect the CEL.
The COR has 2 coils. The first coil is fired from the starter circuit when you're cranking the starter. The second coil is fired from the switch in the flap of the AFM, which is the ground path for that coil.
All FP +12 comes through the EFI relay to the COR.

A simple check of the AFM would be to remove the connector by prying up the spring clip and see if the CEL illuminates with the key in the ON position. DO NOT REMOVE THE 2 PHILLIPS SCREWS ON THE CONNECTOR HOUSING. This will damage the internal wiring of the AFM.

You can also bypass all the FP logic by jumping B+ to FP (pin 8 to pin 1) on the diagnostic connector. THis will fire the FP as soon as the key is in the ON position, assuming the EFI relay and associated logic and +12 is good.

 

[73tlcv8]

"so I sprayed starter fluid in the air box and it acted like it wanted to start, so I knew that I had spark" indicates fuel pump is probably not running, hence check COR or possibly no power to ECU or bad ECU. CEL bulb could be burned out so you would not automatically assume bad ECU if no CEL.

Of course the COR has nothing to do with the ECU, I didn't say it did.

Sorry I tried to help.

 

[LhPickle]

"so I sprayed starter fluid in the air box and it acted like it wanted to start, so I knew that I had spark" indicates fuel pump is probably not running, hence check COR or possibly no power to ECU or bad ECU. CEL bulb could be burned out so you would not automatically assume bad ECU if no CEL.

Of course the COR has nothing to do with the ECU, I didn't say it did.

Sorry I tried to help.

I replaced the CEL bulb a year ago, when I had to replace the engine.

 

[LhPickle]

Have you checked for +12 at the diagnostic connector mounted by the firewall? (Step 4)

View attachment 1566797

I have not checked this yet, as I did not know which one to check, I will check that tonight.

The COR is the fuel pump relay. It has nothing to do with the ECU and will not effect the CEL.
The COR has 2 coils. The first coil is fired from the starter circuit when you're cranking the starter. The second coil is fired from the switch in the flap of the AFM, which is the ground path for that coil.
All FP +12 comes through the EFI relay to the COR.

A simple check of the AFM would be to remove the connector by prying up the spring clip and see if the CEL illuminates with the key in the ON position. DO NOT REMOVE THE 2 PHILLIPS SCREWS ON THE CONNECTOR HOUSING. This will damage the internal wiring of the AFM.

You can also bypass all the FP logic by jumping B+ to FP (pin 8 to pin 1) on the diagnostic connector. THis will fire the FP as soon as the key is in the ON position, assuming the EFI relay and associated logic and +12 is good.

Unfortunately I did remove the two screws on the connector housing, when looking around trying to figure out if something came disconnected...so I may have to replace my AFM, in addition to any other parts not working.

 

[jonheld]

I have not checked this yet, as I did not know which one to check, I will check that tonight.




Unfortunately I did remove the two screws on the connector housing, when looking around trying to figure out if something came disconnected...so I may have to replace my AFM, in addition to any other parts not working.

Ugh. If you pulled on the connector, then the very thin wires soldered on the board have been torn off. It can possibly be repaired, but you would need to be handy with a soldering iron.

 

[LhPickle]

@jonheld I checked the b+ With it my multimeter and was showing +10.5v.

 

[LhPickle]

The FP was also showing 10.5v

 

[LhPickle]

@jonheld do you think that since there is only +10.5v at the B+ on the firewall this is the issue? If so what should I do to remedy this?

 

[inkpot]

Charge the. Artery?

 

[inkpot]

Charge the. Artery?

Charge the battery?
Damn spell checker!

 

[jonheld]

@jonheld do you think that since there is only +10.5v at the B+ on the firewall this is the issue? If so what should I do to remedy this?

What does your meter read across the battery terminals?

 

[jigglebear]

Would the battery not being charged cause this? I’m having the same issues. Blew a head gasket. I changed it and put everything back together and this is not my first time on this engine either. I’m getting no fuel now. BRand new relay no I’m getting power arb B+

 

[LhPickle]

I finally got it all worked out. It was the AFM. There were several small foils of metal inside the AFM that were contacting places that they shouldn't be. removed those and now she starts up like a charm. I am sure that new fuel pump and distributor, spark plugs, and wires didn't hurt either.

 

[Technician1985]

Glad you sorted it out!