Fixing vapor lock now that I barely made it home, experience with 3 port filters?

[TotalyHucked]

Let's start with the basics of what you have. I see the truck is a '77 Camper Special, 454 I assume? What temp was the engine at when it started to act funny? What temp was it when you realized it was sucking the rad hose in on itself?

What you're describing in January in Oregon does not sound like vapor lock. Every time I've had vapor lock has only been sitting in traffic and the car would just start sputtering and coughing. I was always able to put into a parking lot to sit and wait, but I'd have to wait an hour or more before the symptoms would go away. It would hard start if I tried it too soon (just spin and spin, maybe cough a little and die).

The backfire out the carb is odd too.

What you initially described sounded like ignition/timing problems, like the chain stretched and jumped a tooth or the gear on the dizzy was wearing out. But if that were the case, it would likely always have the same issues. That truck should be HEI, correct?

 

[dkraven]

I don't know that you have a fuel issue. Especially with the behavior you're getting from the truck, in January, in Oregon.
I'm leaning towards Ignition Control Module... (maybe because I just dealt with that being my issue). My issues started out very similar, and I'm wondering if when you can't start it, if you were to tap on the distributor or distributor cap, if would maybe start then. Don't ask me how I know that one.

I got parts to put in a return line off the mechanical fuel pump. I did put a new module on it 6 months ago as part of a distributor rebuild kit, which of course could've been faulty. I know I put plenty of the heat sink goop on it, but yeah, if this return line doesn't fix it I might fire up the parts cannon and put a new module on.

 

[dkraven]

Let's start with the basics of what you have. I see the truck is a '77 Camper Special, 454 I assume? What temp was the engine at when it started to act funny? What temp was it when you realized it was sucking the rad hose in on itself?

What you're describing in January in Oregon does not sound like vapor lock. Every time I've had vapor lock has only been sitting in traffic and the car would just start sputtering and coughing. I was always able to put into a parking lot to sit and wait, but I'd have to wait an hour or more before the symptoms would go away. It would hard start if I tried it too soon (just spin and spin, maybe cough a little and die).

The backfire out the carb is odd too.

What you initially described sounded like ignition/timing problems, like the chain stretched and jumped a tooth or the gear on the dizzy was wearing out. But if that were the case, it would likely always have the same issues. That truck should be HEI, correct?

It's a trailering special but has a 350 SBC in it. I thought the same about the weather, I'm not exactly in Texas in July. But it does run okay after sitting for a couple of hours. My temp gauge isn't working right now, but I do have an infrared so I'll keep that in the truck for next time. If there is a next time. Like I mentioned, going to put in a return line and see if that makes a difference. Also means changing the fuel pump which could also be part of the issue. I'm not sure why it's only after a drive, park (heat soak), drive pattern. Others have mentioned sediment in the fuel system somewhere that clogs it up when under power, and I wonder if that could be it. I'll be blowing out the fuel line when I put in the return line.

If it was ignition system I too think it would just always happen. And if the timing chain jumped a tooth, once it did that, it would have consistent problems yeah? I have thought about just putting a new distributor in, and yeah the current one is an HEI. I did put a new rotor and cap on as part of the rebuild kit that had a new module.

 

[AuroraGirl]

I believe there’s a little confusion here…
The sending unit assembly at the tank can have one, two, or three ports, depending on the year of vehicle, or what someone has installed in the past.
These ports are 3/8” for fuel supply, 5/16” for fuel vapor recovery, 1/4” port for fuel return from the pump.
The mechanical fuel pump on the engine can have one, or two ports.
3/8” for fuel supply, and 1/4” for fuel return.

the mechanical fuel pump would have 2 or 3* one in one out, or one in, one out, and one return

 

[AuroraGirl]

It's a trailering special but has a 350 SBC in it. I thought the same about the weather, I'm not exactly in Texas in July. But it does run okay after sitting for a couple of hours. My temp gauge isn't working right now, but I do have an infrared so I'll keep that in the truck for next time. If there is a next time. Like I mentioned, going to put in a return line and see if that makes a difference. Also means changing the fuel pump which could also be part of the issue. I'm not sure why it's only after a drive, park (heat soak), drive pattern. Others have mentioned sediment in the fuel system somewhere that clogs it up when under power, and I wonder if that could be it. I'll be blowing out the fuel line when I put in the return line.

If it was ignition system I too think it would just always happen. And if the timing chain jumped a tooth, once it did that, it would have consistent problems yeah? I have thought about just putting a new distributor in, and yeah the current one is an HEI. I did put a new rotor and cap on as part of the rebuild kit that had a new module.

Fuel being pulled under vacuum from the tank , if the fuel line is hot enough, will vaporize before the pump. Pump cant pull vapor through the line. If the heat is only after the pump, a 3 port filter could potentially work. Do you have an HD emissions truck or is it got a sticker on the core support? HD emissions had it on air cleaner. you would have a vapor canister if you dont have HD emissions. If you have the vapor line, try the filter first.

 

[RaisedK5]

So. Just a crazy idea here. I've read back thru this topic and can't find any mention of how your tank is vented. Is the charcoal can intact? If not is the line open? or plugged?

I've seen before when people pull all the emissions stuff off and plug every open line that the tank starts to experience vacume after awhile from the pump pulling fuel out, without any way for air to get in. That interupts the flow of fuel. Kinda like a water jug needing to glug glug the air back in but it can't glug glug it back up the line. The quick solution is a vented gas cap in that scenario.

Maybe try driving with the gas cap off and see if it still does it.

 

[Termite_Delight]

^^^ What he said ^^^ If it happens again, check the cap for suction.