1989 fuel system issues

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Dec 21, 2017 | 08:05 AM

wharthog

Thread Starter

More Turbo

Joined: Feb 2008

Posts: 516

Likes: 3

From: Michigan

1989 fuel system issues

New tanks, new pumps, new pressure switching fuel valve on the frame rail, and now the front tank wont feed the system. Before I started, the front tank worked, rear did not work. Took the bed off and found the rear tank was rotted and the inside was like a rust desert. After new rear tank and pump it worked. Then the front sprung a leak. So I put a new tank and pump in the front. Also found the fuel switching valve was missing when I did the rear tank, so got a new one and installed it. I'm guessing a bad (new) fuel pump up front, unless the dash switch went bad at the same time I put the new pump in the truck. Don't have a break down on the switch so I will check for voltage at the front pump. No power goes to the dual tank valve so I'm guessing switch or pump. I have been playing with three pick ups 2 "89" and a "90". They all had fuel tank problems. I should be writing it down so I will stop having to second guess myself on where I am on fuel issues.

Dec 21, 2017 | 02:38 PM

rla2005

Fleet Owner

Joined: Oct 2005

Posts: 20,786

Likes: 1,751

From: Kentucky

Quote:

Originally Posted by wharthog

Don't have a break down on the switch so I will check for voltage at the front pump.

A diagram from Subford:

It would not be the first time someone has installed a brand new pump and have it fail within minutes. Verify the power is getting to the in-tank pump using the diagram. Just remember power is applied for 1-2 seconds when cycling the key from Off to Run. You can disable that by jumpering Pins 2 & 6 on the diagnostic port/datalink/STO connector. Now when you turn the key to the Run position the fuel pumps will always be energized.