Cranks but wont fire up after reconnecting battery

[Scallywag]

Hello there my good chaps!!! I've got quite the puzzling issue where the WF won't fire up after having briefly disconnected/reconnected the battery.

Yesterday I got code P0174 and swapped in a used MAF from one of my donors as I'd been experiencing backfiring, poor drivability & reduced MPG since Wednesday. I took it for a test drive after replacing the MAF and felt that it ran better but continued to backfire every now and then. I figured to disconnect the battery(Negative then Positive) for a while to clear a Check Engine light and to reset the ECU to have it relearn the Air/Fuel ratios incase it was all jacked up due to the defective equipment.

I reconnected the battery(Positive then Negative) after about a half hour and to my dismay have not been able to get the car to fire up. The fuel pump primes up just fine and the engine cranks with no problem but fails to ignite. I'm baffled by this as the Mark was turning on without issue prior to disconnecting the battery and am at a loss as to how it wont ignite. I checked the Fuel Pump Shut-Off but it's pressed in and won't depress. Is that normal?

I've read about the Crank/Cam sensors possibly being the culprit but swapping them in with new units did nothing.

Any and all suggestions are appreciated.

Thanks!!

 

[soduka]

I would have started simple; check your MAXI fuses in the engine bay fuse box. Who knows, maybe upon disconnecting the battery you blew the ignition fuse.

 

[slowmkviii]

After fuses check for the basics fuel and spark.
Also make sure the anti theft isn't activated.

The fuel pump shut off should be pressed down.

 

[Scallywag]

Well, the fuses seemed fine but I swapped them around just for the heck of it. I confirmed to have spark by extracting a spark plug while still in the COP spring, hooked it up to the negative jaw of jumper cables to ground on battery and asked a friend to turn the key which displayed a healthy spark at the gap of the plug.

I do not have a fuel pressure gauge to check the psi but surrounded the shrader valve with rags and pressed in the pin while the key was on and got no gas at all. I assume the fuel pump would have to be swapped out after I check the connection to it tomorrow. That just confuses me more because I can hear for a moment what I assume is the fuel pump winding up as I turn the key to the On position and even when attempting to Start it.

Any other tips just incase I may not need to do that project would be greatly appreciated. Otherwise, so be it.

 

[slowmkviii]

Clogged fuel filter.
You can rent a fuel pressure gauge from Autozone free of charge.
You might want to recheck the crank shaft position sensor and it's wiring.

 

[mikemark8]

If you hear the fuel pump when you key on but no fuel at the rail, it is either a very weak pump or possibly the fuel filter is fully clogged like Slowmk suggested-check crank sensor too and another possible problem might be a bad Variable Load Control Module (VLCM), it has relay control for the fuel pump. Because it was running bad prior to all this, I'd do fuel filter, then check pump pressure with a gauge at the rail. If you have very low pressure after the filter change, it's the pump, if no pressure it's a crank sensor or the VLCM. I think if you have momentary fuel pump that goes dead it is a crank sensor, no pump noise at all (ever) it is VLCM.

 

[Scallywag]

Alright, well, I assume it is the Powertrain Control Module.

While I visually inspected the fuses in the power distribution box, I never actually put a voltmeter or Ground Test Light to the fuses.

Today I put both the Voltmeter & Ground Test Light to the fuses of which all of them panned out fine except for Fuse #3, the Powertrain Control Module (EAM Pump Motor-Monitor), which did not give of ground light and displayed a meager 0.000 on the meter whilst all the other slots pushed out 12.2V.

Are there any troubleshooting methods for the PCM to ensure that that is the problem?

Thanks again!

 

[NoLimit95]

You mentioned "donor", so I'm assuming you have an extra PCM? If so, and the years are the same, swap those out and see if it starts. Also, check the plug for the crank position sensor down by the AC compressor. Sometimes just unplugging it and plugging it back up will give it the connection it needs. You can spray it good with (CRC) MAF cleaner to make sure it's cleaned good. I can't really remember if the cam position sensor being bad can stop it from firing up but that plug down by the AC compressor can be dirty enough to keep it from starting. I could be mistaken but I'm sure I've seen this in the past. Keep in mind that I'm making suggestions and I don't even know what year it is you have. Although I probably should...., but since I don't visit here often enough, I don't.

 

[soduka]

I can't really remember if the cam position sensor being bad can stop it from firing up

The car will start without the cam sensor but it will take more cranks than it "should" since the cam sensor is supposed to tell the computer where the cam last was to ID where on the stroke it is faster and thereby speeding up starting with less cranks.

 

[chris2523]

the cam sensor times the injectors.
since injector timing is not crucial, its just a nice piece to have to run sfi.
without it, the car does batch fire, and runs pretty much fine.
ford EEC IV was batch fire for years.

i had mine unhooked for a bit and really didn't notice anything.
you may receive a 214 CID code.

 

[Scallywag]

You mentioned "donor", so I'm assuming you have an extra PCM?

My Daily Driver that's currently down for the count is a 98 LSC White Pearl, WF .

Unfortunately the PCM that was in the 97 donor was sold years ago, I kick myself now for that sale.

I got the voltmeter, put it to the fuses in the engine bay and got some strange readings(may be normal but since I'm not an electrician is strange to me).

Key OFF
Black probe to Negative on battery, Red probe to fuses
Fuse #3: 0.0000V
All others: 12.3V
Red probe to Positive on battery, Black probe to fuses
Fuse #3: 12.3V
All others: 0.000V

Key ON
Black probe to Negative on battery, Red probe to fuses
Fuse #3:0.101V
All others: 12.2V
Red probe to Positive on battery, Black probe to fuses
Fuse #3: 9.86V
All others: 0.147V

Im not sure what this is indicative of, if any, as the fuse never blows and would like to know so that my DD can come back to life. I opened the relay box a bit to get a glimpse of the wires and believe I see a Solid White and a Black with Pink stripe leading into Fuse #3. However, I only see a White with Black striped wire within the bundle of wires leading to the PCM. I just need a diagram to get an idea of what I'm looking at. Online searches bring up diagrams for 97 Thunderbirds/98 Mustangs and am not certain if the pinset is the same as ours.

I'll feel so dumb if it turns out to be something very small and simple, which knowiing my luck it will be simple in the end.



The sensors for both the Crank and Camshaft were already swapped with used units from the donor's engine, the crankshaft sensor being the bigger pain of the two. Maybe new units will work better as the donor engine hasn't been started in years. It wont cost much since they're only 20-some dollars for each sensor.

All this trouble because I disconnected the battery for 40-some minutes..... *sigh*