86 Sierra cuts off while driving. Seems to flood.

[86SquaredUp]

1986 Sierra Classic. All original. 305, TH350, M4ME Quadrajet.

This truck sat for around 2 years before I bought it. Fuel tank was empty when I got it. I changed the plugs and wires, changed the oil, filled the tank, replaced the battery, and it fired up. It ran great for 2 months and then one day, while slowing down to turn onto a street it shut off. Then it wouldnt start. It acted like the carb flooded. After an hour or so if fired right up. A week later, it did the same thing while slowing down but this time in a straight line. Towed the truck home and it fired right up .

The truck has sat in my driveway since. I start it twice a week. Hard starts. Have to push it to the floor and crank for around 20 seconds.

The brake booster is good.

Anyone ever have this problem?

I'm about to just by a rebuilt carb from GuaranteedCarburetors.com. Its $244 altogether.

I would try the rebuild myself, but I am not very well versed in the sorcery that IS the quadrajet carb. I'd hate to spend my money and waste my time trying it.

 

[Crispy]

Might be something gummed up or otherwise wrong with the float. My Buick did this to me until i rebuilt the carb. Someone with more knowledge will lend their 2 cents shortly.

Time vs money. Do you wanna learn how to work on this truck and its quirks or throw cash at it? Rebuild kits are cheap and there are tons of videos on youtube to walk you through it. Most store bought rebuilt carbs will require some adjustments when finally on the vehicle.

 

[86SquaredUp]

It's not that I dont want to learn about the quadrajet, its that I cant find the time to. 2 jobs.

I just want the old girl to run and be dependable.

 

[Rusty Nail]

I dont think the carb is your culprit.
I'm at fuel pump / vapor lock.

Try it again until it dies and then take the gas cap off and see if it'll start. That is a fine place to begin.

Diagnose ?
First. Duplicate the symptom. Remove gas cap.

Second. If still no start, verify accelerator pump.

If you want to throw parts at it, there will be MANY supporters of THAT, here.

I may be here, but I am not with those guys.
Some people actually still try to fix stuff to avoid replacement costs..

You know what im saying?
I'm not 40 years old but I could help you fix a 40 year old truck.

 

[86SquaredUp]

I dont think the carb is your culprit.
I'm at fuel pump / vapor lock.

Try it again until it dies and then take the gas cap off and see if it'll start. That is a fine place to begin.

Diagnose ?
First. Duplicate the symptom. Remove gas cap.

Second. If still no start, verify accelerator pump.

If you want to throw parts at it, there will be MANY supporters of THAT, here.

I may be here, but I am not with those guys.
Some people actually still try to fix stuff to avoid replacement costs..

You know what im saying?
I'm not 40 years old but I could help you fix a 40 year old truck.

I didnt even think of a vapor lock!!! Tomorrow morning I will be testing, lol.

 

[Crispy]

It's not that I dont want to learn about the quadrajet, its that I cant find the time to. 2 jobs.

I just want the old girl to run and be dependable.

I get ya. Side note, i checked that website and found a rebuilt carb for my trans am for over $100 cheaper than what I was looking at so thanks for that!

Good luck on diagnosing the problem. Let us know how it goes.

 

[dvdswan]

I think you should drop the tank and inspect it. It sat for 2 years, left over gas evaporated, left a film and its clogging the sock reducing the flow to the pump. I would suggest cleaning the lines too. If you have dual tanks do both sides.

 

[Rusty Nail]

Good luck on diagnosing the problem. Let us know how it goes.

I see what you did there.
That veil is too thin! Lololo

 

[Crispy]

I see what you did there.
That veil is too thin! Lololo

Like a Vegas bride.

 

[Rusty Nail]

 

[gotyourgoat]

Runs fine in the yard...cuts off and leaves you stranded while driving. Sounds like a gas filter to me but what the **** do I know.

 

[bedwards]

Next time it shuts off, see if air rushes in when you open the gas cap.

 

[86SquaredUp]

Thanks for all of the ideas guys. I'll get to it in the morning and see what I come up with.

 

[Rusty Nail]

Gas filters fall into the $5 fix, good one.

 

[SquareRoot]

Mine did that. I replaced it with a $2000 efi.

Cheap, Fast, Reliable. You can choose two, but, you can't have three.