HELP! Runs perfect then just dies

[johnny]

well it's either giving out of gas - or getting waay too much - or giving out of sparks. Investigate further and report back.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

 

[RF_Burns]

The electronic module on the HEI ignition has a habit of going thermally intermittent. The module heats up and an internal connection opens with
thermal expansion. Let it cool and it will make connection again.

In electronics repair we used to have a can of freon to cool a suspect component. If you have a spare module you can try swapping it in.

The ignition coil can do the same thing.

Fuel problems will usually sputter. Electrical is more a sudden failure but can be intermittent.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

 

[Matt Colie]

Shawn,

I am very much in agreement with our Canadian friend from Mexico.....
This has happened (never to me because I won't have HEI) to three engines I have had experience with, and I would like you to think that I immediately
came to a solid diagnosis. The definition of immediate here has to be a little loose.

You replaced all the rubber lines including those on top of the tank? If you have not, you should.
If it has to crank a while to restart, suspect the fuel.
If you check the accelerator pump and it does not squirt fuel, suspect the fuel.

As Bruce wrote, if it does not sputter just quits, suspect the spark.
If you check the accelerator pump and it squirts fuel, suspect the spark.
If you can wait a while and it fires right up again, suspect the spark.

Next time you are messing with it have a long phillips screw driver handy.
When she quits, pull a plug wire and put in on the screw driver. Arrange the screwdriver to be close to something on the engine and crank.
**Caution** If you crank with a plug wire disconnected, that will often take out the module with a single event.
¿¿Did You see a big spark??

Tell us when you know more.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[tyler]

I agree HEI is more likely than what I'm about to suggest.
Are you sure you got the fuel pick up hoses on correct connection at tank? If you reverse them, you are trying to draw gas from the vent pipe, which
does not run fully into the tank. If you have an auxillary electric fuel pump this is easier to test (pull end and let her rip into spare tank for a
few minutes).

--
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC