1986 Other GMC Models

MAZDI

MEMBER
1986 GMC
V8
2WD
AUTOMATIC
57,690 MILES

Is there a difference in the micron specifications of the in line cannister fuel filter and the fuel filter in the carburettor?

i have had problems wihen gas tank is somewhat less than half full

the carburettor (and the fuel pump) do not get gas due to suspected gunk in the gas tank

the downstream side of the in line fuel filter is wet indicating fuel has gone through but the fuel pump (in one case) was not getting fuel and the fuel filter in the carburettor (in the second case) was not getting fuel

problem was solved after tow bills by air pressure being sent from fuel line to fuel pump connection backward into gas tank in one case and replacing carburettor fuel filter in the other

so apparently whatever was blocking the fuel line did get through the in line fuel filter but did block the line between the fuel pump and the line downstream of the in line fuel filter, BUT IT IS STILL IN THERE SOMEWHERE!

do I need to replace the gas tank?

1 Reply

HMAC300

MECHANIC
48,601 POSTS

You will probably hae to drop the tank and get it cleaned out as long as there is no rust in it and the tank is weak. The sock that is the pickup fuel filter is probably shot and needs replacing as well. Check for blockages in the vent line as long as you have it off.