Officially Stumped

[joemechengineer]

I just bought a 1986 c10 silverado with 80k miles for what I thought was a sweet deal.  Truck started and ran great, drove it an hour home without a hiccup.  No smoke or hesitation, ran like a champ.  Minimal rust on the body and the frame is solid without hardly any surface rust.  A southern truck no question.

When I got it home, it sat for about 3 days before I went out to take it for a drive and the thing wouldn't start.  Didn't seem like it was getting any gas, I tried the fuel line in the bottle and never got any fuel out of it.  Reading posts online, I thought it might have been the fuel pump, so that was the first thing to get changed.  No improvement.  Then I thought maybe the valve selector solenoid for the 2 gas tanks might be bad, so I bypassed that and went straight to one of the tanks that I know is full of fresh gas.  Still no luck.

When I sprayed carb cleaner in the carburetor, I can get the truck to turn over and it will run for a few seconds before it dies off.  It came with an edelbrock 1405 600 cfm carb.

I'm officially stumped.  It went from running fine the day I bought it to being a driveway ornament.  Hoping someone with more knowledge can guide me to some other things to try.

[Rapid Roy]

Welcome.

[big_al273]

ok not too be a smart ass but did you check if there was any fuel in the tank? did you try adding any fuel?

[joemechengineer]

ok not too be a smart  but did you check if there was any fuel in the tank? did you try adding any fuel?

Yeah, I mentioned that in the comment.  I filled one of the tanks on the drive home.  The fuel gauge wasn't working so to avoid being stranded I filled one of the tanks.

Also, I hooked a break bleeder pump up to the gas line near the carb and was able to pump gas up to it so there is no line blockage.

[joemechengineer]

Welcome.

Thanks Rapid Roy

[Rattler12]

At the risk of being pummeled by some of the guys on here   Edelbrock  is the root of your problem. If it starts with the carb cleaner it's a fuel issue and not ignition...…. my guess is a stuck fuel float. Have you determined if gas is making to the fuel inlet fitting on the carb ?

[Mario]

I 2nd that Rattler.  I would add or replace the inline fuel filter, and buy a overhaul kit for that carb.  I would soak it in hot soapy water, and then spray it down with carb cleaner.  Run soft wire into all the tiny passages, and blow compressed air through them.  I think it's the float valve.

[Irish_Alley]

2 questions

1. electric or manual fuel pumps?

2. are you sure you bypassed the valve and hooked the supply lines up together?

3. are you sure that line can reach the fuel? (blow on the line and hear bubbles or maybe try and siphon some fuel out of it before the fuel valve)

[joemechengineer]

I 2nd that Rattler.  I would add or replace the inline fuel filter, and buy a overhaul kit for that carb.  I would soak it in hot soapy water, and then spray it down with carb cleaner.  Run soft wire into all the tiny passages, and blow compressed air through them.  I think it's the float valve.

I'll check into that.  Thanks Mario

[joemechengineer]

2 questions

1. electric or manual fuel pumps?

2. are you sure you bypassed the valve and hooked the supply lines up together?

3. are you sure that line can reach the fuel? (blow on the line and hear bubbles or maybe try and siphon some fuel out of it before the fuel valve)

1.  Mechanical fuel pump

2.  Yes

3. Yes, as mentioned in the comments above, I connected a break bleeder pump to the end of the fuel line at the carburetor and was able to pull full to that point without an issue.

[bd]

...it sat for about 3 days ... and ... wouldn't start.  Didn't seem like it was getting any gas.  I tried the fuel line in the bottle and never got any fuel out of it.  ...I thought it might have been the fuel pump, so that was the first thing to get changed.  No improvement.  Then I thought maybe the valve selector solenoid for the 2 gas tanks might be bad, so I bypassed that and went straight to one of the tanks that I know is full of fresh gas.  Still no luck.

When I sprayed carb cleaner in the carburetor, I can get the truck to [start] and it will run for a few seconds before it dies off.

I hooked a brake bleeder pump up to the gas line near the carb and was able to pump gas up to it so there is no line blockage.

So, return to the basics and perform some standard tests.  Check f/p draw (should measure >20"Hg).  Check f/p transfer volume (should measure 1 qt in 20-30 seconds of cranking).  Check fuel pump pressure (should measure 5-9 PSI).  Disconnect the fuel line from the tank and plug it.  Use your suction pump to check the fuel supply line for perforations.  Will it maintain a vacuum that's drawn on it?  Physically remove and blow through the fuel filter to see if it is restricted.  Avoid making any assumptions (rationalizations) and you should be able to narrow down the cause.  Rely only on what you can physically verify (prove) to be true.

And, don't neglect to verify that the ignition is generating a strong, blue spark.