Starving for Gas and getting worse!
 

I'm at my wits end, guys, and I don't know where else to turn...

My '65 C10 has been experiencing an elusive and worsening case of bogging, choking, and now shutting down as if no fuel is getting to the carb. Carb is a Rochester Quadrajet sitting atop a refreshed 1970's 'Vette 350 engine with stock cast iron intake under the Rochester 4B. The engine also has HEI.

I've already performed the following over the past several months, but none have resolved the mysterious issue:

> replaced the (OEM) fuel filter
> replaced the mechanical fuel pump (twice)
> removed the gas tank "sock" (even though it was not clogged
> had the Quadrajet professionally rebuilt with all new parts by a carb rebuild shop
> NOTE: It hasn't been so hot that vapor-lock would be a diagnosis, because it did it during Jan/Feb too.
> I just tried starting it again, and it fired right up...but I know what will happen when I drive it again.

It used to run fine following its 2017 engine rebuild. Then, one day I floored it on the freeway from a 60 roll. It hit about 70 and suddenly stalled out and starved for gas. It's been doing that at high speeds since then. I'd let it settle down and she'd run fine at 45 or 50. But now it's been getting progressively worse & worse-- at 50, then at 45, then 40. Today, after installing the freshly rebuilt Rochester, I started it up and it idled perfectly. I took it on the road... within 5 minutes of driving it starved for fuel at 35mph. I tried to nurse it home, but it finally gave up ~2 blocks from the house, and it wouldn't restart. THAT was a first! The fuel indicator shown over 1/4 tank, and I can hear fuel in the cab's fuel tank when I rock the truck. Walking home I grabbed some fuel, then primed the carb, and it started up. I limped it back home at slow speed.

Any thoughts and/or suggestions from the experts would be very much appreciated.

Re: Starving for Gas and getting worse!
 

Check the flexible fuel line coming from the tank that runs under the truck or along the side of the frame. They can cave in when deteriorated.
If you are sure all the lines are clear and you did everything you said you did including new carb then check the fuel pump push rod. They can wear down believe it or not.

Re: Starving for Gas and getting worse!
 

By the OEM fuel filter do you mean the chunk of sintered whatever at the fuel line fitting on the carb? If so, that was always the first thing I canned on a Qjet. Also, get a pressure reading on the pump(s). Did you talk to the rebuilder?

Re: Starving for Gas and getting worse!
 

Another place to check since you have an HEI:

Break out the trusty multimeter and check the resistance on your coil and ignition module. A failing ignition system can make you think there's a carb problem

Re: Starving for Gas and getting worse!
 

Vented gas cap ?

Re: Starving for Gas and getting worse!
 

Ditto on the flexible lines, I'd replace all the rubber hoses.

Re: Starving for Gas and getting worse!
 

I 2nd this. Sounds like the Module is going out.

Re: Starving for Gas and getting worse!
 

If it indeed was the coil & ignition module, would it still allow me to start the truck after a period of 5-10 minutes? While the problem has gotten progressively worse -- meaning the "starving for fuel" symptom has now been occurring earlier and earlier at lower speeds -- it still starts hours later and the next morning as if nothing was wrong.

I'll be discussing with a mechanic today, then crossing my fingers that it can make the 3-4 mile drive without breaking down again. :waah:

Re: Starving for Gas and getting worse!
 

I had a very similar experience once and it was a bad pickup coil in the distributor. Do you have another distributor you could try and see if it makes any difference?

Re: Starving for Gas and getting worse!
 

Bears63 - That's another possibility! Thank you as well! While I don't have a spare HEI handy, I'll add that to the list of remaining sources when I take it in.

Re: Starving for Gas and getting worse!
 

You might also check into this - the fuel pump eccentric at the front of the camshaft that runs the fuel pump might be worn. This happened to a friend of mine with his Chevy van that had a 350 motor in it. He installed an electric fuel pump and all was well.

Re: Starving for Gas and getting worse!
 

You've probably already checked the float level in the carburetor,
because if there isn't enough fuel in the float chamber at higher speeds, the engines tend to starve and then pick themselves up again at low speeds.

Re: Starving for Gas and getting worse!
 

I've read here that the in-cap HEI distributors can overheat the coil. I think weak coils will lose spark as they heat up, and if it's dying then it would explain why it's happening sooner/at lower speeds.

Re: Starving for Gas and getting worse!
 

TheAstronaut- Thank you for chiming in! As a longtime veteran, your expert opinion is always welcome!

Your suggestion now makes for the THIRD reference pointing to the "HEI distributor coil" as the possible culprit. Realizing that this can deteriorate over time, causing the fail to occur sooner at even slower speeds... just may be the correct path.

I'm giving a list to the mechanic and crossing my fingers.

Re: Starving for Gas and getting worse!
 

Forgot to say this in my first post, check the plugs- if they're black its a sign of weak spark. Quick and easy way to see if it's weak spark or actually starving and running lean.

Re: Starving for Gas and getting worse!
 

Another thing to check- thermal paste should be used to help transfer heat out of the HEI module. It's not the same as dielectric grease like some people recommend/use.

https://www.thirdgen.org/forums/elec...-compound.html

Pulled plug #1. Seems to be a mess. It may be a weak coil. However, when it was starving for fuel, and I primed the carb, it fired right up and it got me home 3 blocks away. Is it therefore possible that I’ve got TWO issues causing this failure— a bad coil AND something fuel-related??
Posted via Mobile Device

Re: Starving for Gas and getting worse!
 

Next time it dies, try opening the gas cap and see if it sucks air in. If you have the wrong type of gas cap on the filler, it will create a vacuum that is difficult for the fuel pump to overcome. I've had this happen on motorcycles with gravity feed, worth a try. I also had an electric fuel pump suck rust into the inlet screen and kill the engine at highway speeds. Waiting a few minutes allowed the rust to settle and the car restarted. Ended up replacing the tank and putting in an inline filter. Good luck!

Pulled plug #1. Seems to be a mess. It may be a weak coil. However, when it was starving for fuel, and I primed the carb, it fired right up and it got me home 3 blocks away. Is it therefore possible that I’ve got TWO issues causing this failure— a bad coil AND something fuel-related??
Posted via Mobile Device

Re: Starving for Gas and getting worse!
 

Did you fill the float bowl after the engine died and you started it and drove it a ways? Did I read that right? If so, you definitely have a fuel flow problem.

Re: Starving for Gas and getting worse!
 

Steeveedee-

Yes, you read that correctly. Before I primed the carb with about 2 shots worth of fuel, I tried to start it one more time. It cranked strong, wanting to start. But you can tell it wasn't getting fuel.

Once I put just a little fuel in, it fired up and continued running long enough to get me home 3 blocks away. (It was still faltering, but it got me home nonetheless.)

I'm not sure if I have BOTH an electrical problem AND a fuel problem...or just a fuel problem.

Re: Starving for Gas and getting worse!
 

I wanted to thank everyone for all of your insights & suggestions over the past 24 hours.

Here's my plan:
1. I'm going to pull and clean all my plugs, having seen #1 looking sketchy.
2. In addition, my auto repair shop's lead mechanic has offered to come over with his arsenal of tools to the house Sunday A.M. to figure this out- electronic & fuel. (I suspect he's going over & above the norm because he was the one that suggested I get the Quadrajet rebuilt.) I'm impressed by such service!

I'll let you all know the ultimate source(s) once learned.

Re: Starving for Gas and getting worse!
 

Something in the tank plugging the suction?

Re: Starving for Gas and getting worse!
 

I'd test the fuel delivery from the pump and have a look at the spark to a plug.
The OP describes things done but no description of testing--a sign of shotgunning rather than troubleshooting, which is a waste of time and money.

Re: Starving for Gas and getting worse!
 

Don’t clean those plugs, replace them. Look oil fouled to me.
Do you know the casting number on your heads. Your plugs might be the wrong kind.
Do you have a dedicated 12v power for the hei.

What air cleaner? Crazy long air cleaner stud! The nut on the stud can hang up the secondary metering rods and air door causing a super big bog like you describe.

What year is the intake from? Could be the infamous hot slot intake. The wrong gasket causes super hot carb.

Does your manual choke hold the choke blade completely open. Or is that how it normally runs.

Have you checked timing? Checked weights and springs are intact and moving? Vacuum canister good?

Re: Starving for Gas and getting worse!
 

As franken said, check for fuel delivery. Not just pressure but volume. Get a 1 or 2 gallon gas can with gas, set it on the ground - it should fit between the radiator and the motor under the lower radiator hose. Get some gas hose and run it from the suction side of the fuel pump into your gas can - this will eliminate your fuel line fuel tank pick up etc. from the loop. Will the truck start? If not prime your carb and try starting again. Does the truck start now? If so, does revving it a little in neutral cause a fuel starvation problem? If so it can only mean one problem you have a bad fuel pump. Since you've replaced the fuel pump twice - we're back to the eccentric on the camshaft being worn - that's providing the fuel filter in the Q-Jet carb isn't in backwards and the spring in it is OK. You can also buy a fuel pressure gauge from Harbor Freight for $15.00 - but it's not just fuel pressure but fuel volume. https://www.harborfreight.com/fuel-p...pressure+gauge Dang, I just left the Ahwatukee area of Phoenix and am now home in edited by staff - I would have been more than happy to come over and help you trouble shoot & repair your fuel problem. I'm retired, so every day is a Saturday & I have nothing to do and all day to do it in.

Re: Starving for Gas and getting worse!
 

***UPDATE***UPDATE***UPDATE***UPDATE***UPDATE***

To all those who suspected it was the coil, you seem to be ahead of the crowd...

Master mechanic came over to the house last night-- checked the fuel delivery system, including pump, finding no issues whatsoever. Carb & choke was good, too. Carb was correct for the manifold (no hot slot). He approved of the (like-new) plugs being put to the wire wheel for a good cleaning. He then plugged his spark reader into #1 cylinder and we took the truck for a ride...

It only took 3 minutes for him to experience that dreaded bogging and choking sensation. He saw that the spark indicator was reading quite a weak spark, so we limped it home, took the distributor apart, and this is what we found: a ground strap that was rusty and an original (1976) coil that had seen better decades.

For the price of a new coil, rotor, cap, etc., it made sense to replace it all. We'll be installing an MSD Street Fire. The mechanic was confident this was the issue. Still, as a guaranty, he said, "If this isn't the cause, then I'll buy the MSD back from you 100%."

I'll keep you all apprised on its results.

Re: Starving for Gas and getting worse!
 

If it's not with the ignition, I'll recommend the float level in the carb be checked. Especially since it's been apart.

Had one that wasn't set right (was too low and not keeping enough fuel in the bowl) and it would go traffic light to traffic light just fine but would run out of fuel after a long acceleration on a climb or wound up at highway speed for about 2 minutes or less.

If you're not resolved yet, recommend that be checked like others have already mentioned.

Re: Starving for Gas and getting worse!
 

*******PROBLEM SOLVED*******FINAL UPDATE*******

I am embarrassed. I am humbled. But I learned the value of a true fellow car fanatic mechanic vs some shop mechanic. I realize I'm now exposing myself to a fair amount of flack and "told you so", but I believe in full transparency.

Turns out the cause of the bogging wasn't that old distributor, and it wasn't the carburetor or any of its inner components. The source of the bogging was a hidden SECOND (in-line) fuel filter tucked within the frame's front horn...and...AND...that inline filter was REVERSED! Yes! It was facing the wrong direction! It was discovered as soon as he heard it sucking for fuel when we took it for another ride at night. While I do not know just who installed that filter (not me) -- maybe the non-English speaking person who sold me the truck in 2014. That would make sense if he couldn't read English.

Still, my previous mechanic DID change the mechanical fuel pump recently. So he had to see it when he hooked up the hose off that 2nd filter. Because of how it was tucked away, I didn't even see that it existed, otherwise I would've turned it around so that it was properly facing the correct direction "---> TO CARB".

And ohhh, it was a mess inside! Years of grit, dirt and impurities going straight into the paper filter the wrong way! Yikes! We were stunned, laughing that the truck even ran as long as it did!

But the silver lining is that its brand new MSD Street Fire distributor that was just installed was a No Charge from this mechanic who kept his earlier promise. We still need to install a timing tab and dial it in (it runs jittery at low speeds), but I had it up to 80mph a few times already.

Thank you all again. I thought I had just 1 filter in the carb's inlet. I never knew I had another inline filter, let alone one facing the wrong direction! Like I said, I'm ashamed.

Re: Starving for Gas and getting worse!
 

No need to be ashamed, an additional filter like that was not stock, so no way to know it was there until you actually lay eyes on it. I just fought what I thought was a timing issue on my 81 that was actually just me not putting enough gas in the tank for the truck to run effectively :lol:

Glad you got it figured out and can get started on enjoying your ride!

Re: Starving for Gas and getting worse!
 

Found bugs and the truck runs,
a hidden and twisted fuel filter is also insidious.