Stumble under load becomes no start

[akaFrankCastle]

Problems started yesterday. As I got close to home the truck hesitated and stumbled under light throttle. Problem cleared up with more or no throttle. Today while pulling into the parking lot at school, same issues presented themselves. After class was cancelled, same issues on start up and parking lot speeds. Pulled over and popped the hood. Found a cracked rubber fuel line seeping fuel. Repaired that. Restarted truck. Let it run for about 5-10 minutes. Slight stumble still there. More noticeable with just a touch of throttle. Put in reverse. Truck died. Will not start.

This is Stroppe'd so it's a mostly stock 302 with 3 speed. Edelbrock 1406 on top. Manual fuel pump. In line filters.

Thoughts?

[Eck]

Rotting fuel lines clogging filters?

[TOOLMAN]

Something stuck in the idle circuit inside the carb? Runs like crap at idle and light throttle and once you get on the gas, it runs fine. That usually happens to me. Not sure about the no-start thing. Mine would only hard start when the idle circuit was clogged.

[akaFrankCastle]

The plot thickens.

Got it started and home. Barely.

Cruise/full throttle stumble now.

Oil pressure normally holds at 40+ but was down between 10-30 on the way home. Fed it two more quarts for good measure before I hit the highway.

Think I'll be pulling the trigger on the 5.8 build sooner than later now. Just wish this has happened before new tires so I could have put that money into the motor.

[Moab Mike]

Check to make sure your mechanical fuel pump diaphragm isn't leaking expensive fuel into your crankcase. It's even more expensive then!

[covan]

Sounds like fuel delivery problem. I'll second 76fordbronco's suggestion. Eliminate fuel tank, fuel line/s, fuel filter/s and fuel pump to trouble shoot. Mechanical fuel pump has to deliver correct pressure and volume to carb.
Test fuel pump volume and pressure at the carb. Disconnect fuel supply at carb and tap an extension line to get out of engine bay (safety issue) to a fluid measuring container. Volume should be 1 pint in 30 seconds of engine cranking/turnover according to Chilton's. Test the pump pressure via a fuel pressure tester obtained through Autozone or O'Reilly tool loaner program. Should hold steady at 5 psi.
I'm biased toward the fuel pump b/c the diaphragm in mine recently gave up the ghost causing similar problems. Mine just puked gas all over the garage floor as it died, not puking into the engine via the front cover.

[akaFrankCastle]

Good call Mike and Van. I'm going to pull the dipstick in a bit and see if I have foam or froth.

I did notice that after about 2 hours the inline fuel filter was empty. So, it had to have drained back down the line somewhere.

I went ahead and eliminated the carb by putting together a 1405 from pieces in a box. Yeah, I hoard Edelbrocks too.

[akaFrankCastle]

Oil looks good, smells good, and does not appear to be contaminated by fuel.

Installation of the new carb has cleaned up the idle a bit but there is still a stumble/miss.

[ZOSO]

replace fuel filters. Check fuel pressure. And/or check the coil. Is it getting hot? Ignition system checks?

[Moab Mike]

It's probably pissed you haven't driven it lately and spending too much time caressing TO!

[akaFrankCastle]

replace fuel filters. Check fuel pressure. And/or check the coil. Is it getting hot? Ignition system checks?

You might be on to something there. This weekend the tach was lazily bouncing around on a few occasions. It would suddenly and inexplicably right itself and go back to normal operation.

[akaFrankCastle]

It's probably pissed you haven't driven it lately and spending too much time caressing TO!

Could be. But it should be feeling better as TO has been put up for the winter.

[Colorado75bronc]

Sounds like there was some crap in the needle and seat on the other carb, as for the rest ZOSO has you on the right track


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[akaFrankCastle]

Things are getting worse.

Fuel filter has been replaced. Does not fill to capacity and maintains fluid level after shut down. So that is good news.

I replaced the coil, points, condensor, cap and rotor. Backfired leaving the Advance parking lot. Pulled into a gas station to trouble shoot. Idles okay until throttle applied. Small droplets of fluid coming from right exhaust pipe. Appear clear with a little brown droplet inside.

Starting to get quite frustrated with this thing.

[Eck]

Things are getting worse.

Fuel filter has been replaced. Does not fill to capacity and maintains fluid level after shut down. So that is good news.

I replaced the coil, points, condensor, cap and rotor. Backfired leaving the Advance parking lot. Pulled into a gas station to trouble shoot. Idles okay until throttle applied. Small droplets of fluid coming from right exhaust pipe. Appear clear with a little brown droplet inside.

Starting to get quite frustrated with this thing.

Do you have a fuel pressure gauge? What are you getting for pressure? I can't remember if you said-- do you have a mechanical fuel pump or electrical pump? Has it been replaced recently?

[akaFrankCastle]

Stand by. And cross your fingers.

[akaFrankCastle]

5 miles. Purring like a kitten.

[ZOSO]

Well what was it? Who was the closest to what the issue was?

[akaFrankCastle]

EARLY on I thought it was a carb issue. LATEr I suspected my points and condenser were bad. But in the end, it was all a matter of ______.

[Gunnibronco]

Timing?

[akaFrankCastle]

Boom. You got it.

Now, I'm sure there were plenty of other contributing factors. My points looked horrible. The cap and rotor were corroded like . And that carb hadn't been touched since back when you owned it. But, in the end I adjusted the timing and the original stumble and rough idle cleared up.

Now to figure out why my timing apparently changed.

[Moab Mike]

Three letters, EFI!

[Eck]

Three letters, EFI!

This seems to be the answer for everything!!

[akaFrankCastle]

Three letters, EFI!

Two numbers and one punctuation mark: 5.8

[Viperwolf1]

Three letters, EFI!

Two numbers and one punctuation mark: 5.8

10X better when you combine them into 5.8EFI.

[landshark]

Three letters, EFI!

Two numbers and one punctuation mark: 5.8

10X better when you combine them into 5.8EFI.

even better if its 6.6EFI

[EFI Guy]

I think you should go with the 6.8.

I want a guinea pig and I like spending other peoples money.

[akaFrankCastle]

I think you should go with the 6.8.

I want a guinea pig and I like spending other peoples money.

Sure thing. Just let me go cash in this Powerball ticket the news keeps talking about.

[ZOSO]

Timing change can be a couple of things. Timing chain stretch/jump. Distributor clamp loose. Drive gear worn. or drive gear pin sheared off causing the gear to rotate on the shaft throwing off the timing. I've had the latter on the 79. Took me some time to figure out what happened.