howitz91

Hi Guys

I just bought a 1980 D100 stepside. Like any 40 year old truck, it has its quirks. First, when I try to put fuel in, the pump immediately shuts off. I get like an ounce in before the pump shuts off. I see online a lot of people talking about a clogged vent, and I crawled under there and I see a rubber line going up to the filler neck (It looks like a new tank installed under the bed) - but I also noticed its a pretty shallow angle into the tank from the filler neck. Has anyone had to try to wedge something between the bottom of the bed and the rubber filler hose to try and create some more angle into the tank so its not just sitting in the filler hose? Or I could be completely off here. If you guys think its the vent, do I just take the little vent hose off and blow some air through?

Thank you for your help

Iowan

Fourty year old trucks can have bad fuel pumps rubber hoses with cracks that only draw air. So see it the pump will draw fuel from a gas can and after fourty years I would just replace all the fuel rubber line and inspect all the steel lines for rust holes.

howitz91

Hi Iowan

Thank you for your help. I apologize, what I meant by "fuel pump" is like at a gas station. The fuel pump on the truck works fine, and gets fuel up to the carb just fine. But when I try to fill my gas tank at the gas station, something is stopping the pump there from letting fuel flow into my tank.

Iowan

Sounds like a pluged vent hose to me, I can’t remember if it goes to an evaporative canister up front or not but that could be plugged as well.

howitz91

Ok thank you - so I checked and it looks like all lines have been cut from the canister up front (i'm assuming its the canister in the front left wheel well kinda by the blower motor) - so is the vent hose the smaller hose that attaches to the filler neck? Or is there another vent hose hiding somewhere on top of the gas tank that I cant see when I crawl under the truck?

RacerHog

The Fuel Filler Vent Hose is spliced in just under the gas cap... You should be able to unloosen that hose clamp and remove the hose and blow air through it and hear is come back out the filler neck with the gas cap removed. I believe it is a 1/2 hose? If that is clear and the problem still exists...

Check to make sure the new tank looks like it is mounted in the correct spot, and not mounted to high... Note: may have some other witness makes for mounting?
Some of these had different size fuel tanks... 18.0gal or a 28.0gal... So you could be on to something when you say its mounted to close to the bed and a wrong angle for fueling at the gas pumps...

Are we all together so far?

howitz91

yeah this is great info, thanks Bob - I'll blow some air through the vent in the next couple of days and if that doesnt help i'll come back and bug you guys some more, haha

RacerHog

Sounds like a plan..... Also look and see if it looks like the hose is going "up hill".... My thought is someone my also have replaced the hose and did not cut it to the proper lenth.??? The filler hose that is....

Talk to you soon.... Cheers

howitz91

Hi Guys - sorry for the slow update - SLC finally got the snow that has been due, so that slowed me down. I got under there, pulled the vent hose off, put some compressed air through it, and immediately got a gallon of gas sprayed back in my face...so I dont think its clogged. I took the truck down to the gas station, and the problem was still 90% there (though I was able to turn the pump handle a certain way and just barely trickle gas out in a way that didnt shut off the gas pump). So i'm getting the impression that the filler neck is at too shallow of an angle, and fuel is resting in the neck too long, thus shutting the pump off. I'm thinking I should try to wedge something between the filler neck and the bottom of the bed to create some angle. Thoughts?

RacerHog

Could help with the issue......
But, If you have a BoreScope? you can look down inside the fuel filler neck and pipe and make sure that someone has not left a rag in it at some point before you took ownership.... Just a hunch...