91 5.7L fuel delivery problem

[Arctic Fox]

Attempted to start my 91 with a 5.7L and it cranks and sputters but doesn't run. Pulled the air cleaner off and looked at the TBI and it is spraying, but it appears weak. Checked the spark and it was good. I poured a little gas down the throttle body and it started immediately, then died.

With the help of another person I had them turn the key to the run position while I got under the truck to listen for the fuel pump. When the pump runs it sounds like fuel is flowing into the tank. Is that normal?

I changed the fuel filter since it hasn't been changed since I've owned it, but that didn't seem to make any noticeable difference.

I ordered an adapter online so when that arrives I'll see if I can figure out what the fuel pressure is.

I guess my question is, am I on the right track or are there some other things I should be doing/looking for?

Thanks.

 

[Drunkcanuk]

On my 91, the little hose inside that connects the pump to the fuel line was like Swiss cheese, holes everywhere. Would fire up, rev but as soon as starting to drive, would sputter and throw a fit. If you are hearing fuel flow in the tank, would be a good bet that's what it is. The ethanol in today's fuel doesn't play nice with 30yr old rubber.

 

[Schurkey]

The rubber hose between fuel pump and the "hanger" has to be rated for SUBMERGED use in gasoline. There's a specific SAE standard for such hose. The hose should be rated SAE 30R10.

www.gates.com/us/en/fluid-power/engine-hose/fuel-line-hose.p.4219-000000-000012.html

Submersible Fuel Line Hose | Gates Corporation

Before you start your engines, equip them with Gates fuel hoses. We’ve engineered our fuel line hoses at the cutting-edge of fuel-efficient, environmentally-safe design, so your engine will perform with superior power.

www.gates.com

Some folks install cheaper hose inside the fuel tank, that fails due to not withstanding gasoline on the outside of the hose.

Be sure to use "fuel injection" clamps on that hose, too. Don't use the unshielded worm-gear clamps.

 

[Arctic Fox]

I had a chance to look into this problem further today and I hope I'm on to something now.

Does this look like it could be the cause of my problem?

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[Drunkcanuk]

Well...your rubber hose looks like it's in WAY better shape than mine was, there were big holes in mine. Hard to tell if that's a split in the hose or not.
I assume since you have it out already, that the new one is sitting close by ready to go in?? You have gone this far already!!! Lol
How does the inside of the tank look? Cleanish, or all cruddy and rusty?

 

[Arctic Fox]

Well...your rubber hose looks like it's in WAY better shape than mine was, there were big holes in mine. Hard to tell if that's a split in the hose or not.
I assume since you have it out already, that the new one is sitting close by ready to go in?? You have gone this far already!!! Lol
How does the inside of the tank look? Cleanish, or all cruddy and rusty?

I need to buy a replacement hose still. I'm not sure of the size, so I'll probably have to take this one apart to determine what to get.

Thankfully the inside of the tank looks quite clean!

 

[AuroraGirl]

There is a TSB for GMT 400 trucks for the inside tank hose going bad.

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[Arctic Fox]

I took apart the hose connecting the pump to the hard line and this is what I found. The large black glob next to the screwdrivers on the rag was in the end of the steel line.

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[HotWheelsBurban]

I took apart the hose connecting the pump to the hard line and this is what I found. The large black glob next to the screwdrivers on the rag was in the end of the steel line.

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Probably a piece of the line the TSB is talking about....

 

[Arctic Fox]

I got the replacement fuel hose that's rated for being submerged in fuel. Once I got everything put back together the truck runs again. :-D

Thank you for the help.