86 MGM Wagon fuel problem

86, 5.0liter injected, tranny works fine in all gears. Unsure of last tune up. I have been told to check the fuel filter first. Nobody knows where it is located. Any ideas?

I have been reading over the messages about MGM's with fuel problems. Most talk of the white cresent hissing vacume leak. I am dealing with one that had no vacume leak.

This one simply dies as soon as it starts. Turn the key, it fires, runs for 2 or 3 seconds and dies. Pressing the gas pedal causes it to instantly die.

I read the messages about the Idle Air gizmo that cost $72, it doesn't seem to be the same kind of situation.


I am sure it needs a full tune-up, but the car was running rather well, and simply died while driving under load on an low incline. Was towed and parked.



I was also reading about a computer checker (STI) is this a special device, or is it something simple like Chevy uses (i.e. a paperclip stuck in the data module to make the check engine light blink out the code). I found a good page explaining all the codes but I have never heard of this STI, never worked on Ford/Merc cars before.

I'd definitely check the fuel filter first.

I was told there might be one near the gas tank. I'll check there.

Is there one inside the air intake chamber where the two gas lines come in?

I don't think there's one in the air intake chamber, I haven't had that apart....yet. I do remember a filter back near the tank, replaced my tank last year.

Def sounds like a fuel filter or fuel pump issue.
You car is old like my '87.

You need a voltmeter and a paper clip.
Get the book Haynes Computer Code Techbook.
Cover all makes and models.

Only GM cars up to certain year can be read from the dash engine light.

The Fuel filter is inside the frame on the right near the middle, locked in by a case that has 2 bolts mounted to a bracket. I know this because I just replace mine and we both have the same vehicles 86 GM Wagon.

You might also want to check the coil and coil wire since I had to replace both on mine because the coil stated arcing out to the body and the wire was fried where it plugged into the coil, it was probably the cause of the failure of the electronic ignition module on mine (which is what killed the engine and wouldn't restart after).

The best way to determine if you are having a fuel problem is to run a pressure test then a flow test to make sure that you have the appropiate fuel pressure which is between 35-45 lbs base pressure from the factory setup, as for flow well if it is just tricling out of the line I would say you definitley have a restriction with the pump putting out 35 to 45 psi you should get a steady stream shooting all the way out of the vehicle.

Marco Mollison Sr.

86, 5.0liter injected, tranny works fine in all gears. Unsure of last tune up. I have been told to check the fuel filter first. Nobody knows where it is located. Any ideas?

I have been reading over the messages about MGM's with fuel problems. Most talk of the white cresent hissing vacume leak. I am dealing with one that had no vacume leak.

This one simply dies as soon as it starts. Turn the key, it fires, runs for 2 or 3 seconds and dies. Pressing the gas pedal causes it to instantly die.

I read the messages about the Idle Air gizmo that cost $72, it doesn't seem to be the same kind of situation.


I am sure it needs a full tune-up, but the car was running rather well, and simply died while driving under load on an low incline. Was towed and parked.



I was also reading about a computer checker (STI) is this a special device, or is it something simple like Chevy uses (i.e. a paperclip stuck in the data module to make the check engine light blink out the code). I found a good page explaining all the codes but I have never heard of this STI, never worked on Ford/Merc cars before.

Hey Marco, Welcome to AF. Please check the date on the thread prior to replying...this thread has been dead for almost 2 years. Thanks.

Sorry about that, I looked at the month and day, didn't even look at the year ACK.

I'll be more careful in the future, but the info is still valid.

Marco Mollison Sr.

Hey Marco, Welcome to AF. Please check the date on the thread prior to replying...this thread has been dead for almost 2 years. Thanks.

Not to worry, we've all done it! Thanks for the info.