REALTIME: No spark after PM items

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Fergie

Fergie

SILVER Star
10 Year 15 Year
Joined
Oct 16, 2007
Threads
59
Messages
330
Location
Flagstaff, AZ
1991 LC, stock.

OK, vehicle running fine prior to today.

I'm doing PM stuff: Dizzy cap, wires, plugs, PCV grommet and valve, oil change and filter, cleaned up air filter and housing.

Went to start the vehicle after double checking all connections and nothing.

Did all the diagnostics in the FSM for the coil and everything checks out fine as far as the ohms go.

What else could it be?
 
Okay, checked B+ and had +12.

Checked the EFI relay and it is good.

Checked voltage at brass terminal screw and it as +12.

My guess is the igniter.

Can this go bad from the time I changed the oil and everything else until I tried starting it up?
 
Fergie said:
Okay, checked B+ and had +12.

Checked the EFI relay and it is good.

Checked voltage at brass terminal screw and it as +12.

My guess is the igniter.

Can this go bad from the time I changed the oil and everything else until I tried starting it up?
Click to expand...

It is unlikely it will go bad when you are changing it, but things happen sometimes. Hopefully you find the problem and remedy soon. Good luck
 
Fergie said:
Went to start the vehicle after double checking all connections and nothing.
Click to expand...

Describe "nothing".

Sounds like a battery connection if you are getting nothing as in no voltage to the starter.

-B-
 
Well, we wouldnt be able to get 12V to the coil and fuse box if it was a battery connection.

This is a no spark issue, just dont know what exactly the specific issue it.
 
jonheld said:
Does the CE light come on when the key is in ON position?
Click to expand...
No it does not.

We used the FSM and your diagnostic page as guides.

Firedog- Before we did all the diagnostic procedures, we tried using the old wire to no avail. It doesnt matter though as there is no spark at the coil.
 
Step by step of what all has happened and what the conditions were.

Vehicle has a known EGR issue causing a CEL and code 71. CEL was on when I pulled into the driveway and shut her down.

Got underneath vehicle and drained oil. I sprayed some degreaser on the oil pan, tranny pan and other misc. parts to clean them up.

Jacked the body of the vehicle up to allow front axle to drop. This was done with the intention of replacing the pan gasket. I discovered the bolts were all loose, so I tightened them to spec rather than reaplacing the gasket right away.

I then removed the airbox assembly, including what I am guessing is the AFM(dont have the manual infront of me). When we removed the airbox, we disconnected all the vacuum hoses. When removing the AFM(?) I unscrewed the two small philips head screws from the housing, thinking this was the attachment method for removing the plug. When I started to remove the plug, and realized I was removing the entire sensor, I stopped and reassembled the plug. I then saw the wire clip that held the plug in and removed this.

The air cleaner assembly(bottom) was washed down and cleaned up. The top portion was very carefully washed off, not letting any water get on the the AFM(?) section. These were set out to dry.

I then replaced the fuel filter.

I then started pulling each plug and wire from the vehicle. I replaced each plug accordingly. I then removed the distributor cap. I then removed the rotor. This was done by simply pulling the old one off, and pushing the new one on. I installed a new dizzy cap with dielectric grease. The orientation of the cap is correct. I then installed all the plug wires, orientation is correct. I then installed the wire from the cap to the coil, with dielectric at all connections.

I then reinstalled the airbox assembly, reconnected the vacuum lines and plug to the AFM.

I then removed the PCV valve and grommet and replaced with new.

I then filled the engine with oil.

Removed vehicle from jackstands.

Checked all my connections and went to fire the vehicle. I cycled the key to the on position several time thinking this would bring the fuel through the lines from being drained by the filter changed. I made sure the gas cap was on tight too.

No start. It cranked and cranked but nothing. I listened for the fuel pump, and heard a low whirring that sounded like the pump, but am not sure if this was the under dash fan or not.

The CEL is no longer on. To my knowledge, the battery was not diconnected.

We pulled a plug wire and checked for spark...nothing.
We pulled the dizzy cap wire and checked for spark....nothing.
Checked for spark with old wire...notihng.
We checked for spark at the coil...nothing.

We then performed the FSM check on the coil/igniter and got Ohm values within the range.
We checked the EFI spade fuse and it was good.
We checked the the main EFI fuse for continuity and got continuity on two prongs, notihng on the other.
We jumpered both prongs in the fuse block and still had no start.
We checked the brass terminal screw per Jon's site and got the +12V.
We checked B+ and got +12.
 
Common problem. No check engine light = need new EFI relay. Try to get a plastic one from Napa. Lasts longer than metal ones from my experience.
 
Fergie said:
When removing the AFM(?) I unscrewed the two small philips head screws from the housing, thinking this was the attachment method for removing the plug. When I started to remove the plug, and realized I was removing the entire sensor, I stopped and reassembled the plug. I then saw the wire clip that held the plug in and removed this.
Click to expand...

Bingo.

I'd say 99% chance this is your problem. You likely pulled the end of the sensor far enough to break a connection or two inside. Not all that uncommon of a mistake. Good news is that almost everyone here who's done that has been able to simply solder the connections back together.

The process for getting into the guts of the AFM is to *carefully* cut through the caulking around the edge of the top cover and then *gently* pry it off. There are a few very good threads, with pic's, detailing this procedure.

Curtis
 
Beretta Vertec said:
Common problem. No check engine light = need new EFI relay. Try to get a plastic one from Napa. Lasts longer than metal ones from my experience.
Click to expand...
Not the relay. Installed new one and still a no go.

CJF- The AFM shouldnt cause a no spark situation. This may be a separate issue once I get to it though.
 
CJF said:
I knew you were going to say that.

At the very least, do the onboard ohmmeter tests on the pin connector.

Curtis
Click to expand...
Which onboard ohmmeter tests would these be; I'm confused.

From my other readings, my pulling the plug on the AFM could have broken the solder on the 3 tabs inside. The AFM sends a signal to fire the fuel pump too.

When I replaced the EFI relay today, I cycled the key to the ON position several times, and never heard the fuel pump like I hear it on other vehicles. So, I may not be getting fuel either.

So...

1. No spark for sure.
2. Possibly screwed the AFM
2A. Possibly don't have fuel due to #2.
 
Going to jumper the fuel pump tonight and see if I can get it to cycle then....that should narrow it down to the AFM...

Would a bad AFM cause a no spark, no CEL issue?
 
Fergie, got your PM.

IME, the AFM can, in fact, cause a no-CEL issue, that was the case in my buddy's truck. There was a piece of metal lodged in the AFM causing a short....how it got in there is still a mystery to me. When I removed the offending piece of metal, the CEL lit up like it was supposed to.

Also, the fuel pump on these trucks is pretty much whisper-quiet. I cannot hear mine for the life of me.
 
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