Re: Hard Starting Hot
 

So circling back to this.

A LOT has changed since October. New distributor/wires/RT44TS spark plugs, new fuel pump, and most recently a new PCV valve and electric divorced choke (which I love). Also the stop solenoid opertional. I am still waiting on my replacement carb that is being rebuilt to Performance Level 2 @ Quadrajet Power (I am in week 17 of my wait). Though without it, my the truck is really running fabulous in almost every way. Depending on my driving, I am getting 11~15 MPG.

...except starting after she is good and warmed up / hot and has set for a short bit of time. I would not call it hard starting but harder starting. So starting up, very cold, cold or after a good cool down period, she starts on one turn over of the key, every time.

After driving around, stopping and popping in a store or filling up. More or less the same, she starts on one turn over of the key, maybe two.

After driving around, stopping and waiting 15~30 minutes (let's say under a hour but more than 10 minutes). I'll need to turn her over 3~5 times. She idles a bit rough for about 5~10 seconds but slightly giving her some gas to 1k RPMs helps clear this up faster. After this all is good driving off down the road.

Is there a way to combat this? It isn't horrible but I find it annoying and I feel like a chump turning my engine over until she starts. The carb is not letting any fuel pool/run in after stopping, so it's not like she is flooding out.

Is this simply the fuel in the bowl getting warmed up from the intake manifold?

PS: Just yesterday, I started my 1st round of STA-BIL 360 Protection Ethanol Treatment And Fuel Stabilizer on my fill up. Even if it doesn't help this, I figured using this treatment for Ethanol is a good idea.

Re: Hard Starting Hot
 

Have you looked into the throttle bores to see if there is fuel on the floor of the intake manifold? Try that and see if there isn't fuel there, before starting it in these circumstances. It doesn't have to flow past the needle and seat. IIRC, your carburetor is a later model that doesn't have the well plug leakage issue?

Re: Hard Starting Hot
 

No I haven't.

This carb, I estimate is about 2 years "old", its from like a O'Riley's for a '78 Truck (I've matched the number) and it is a Carter make of a Qjet. Though I don't know if that means it couldn't have that problem at all.

This carb was rebuilt by my brother/friends - took three of them to decide on the jetting. I brought up the well plugs when they were diving into it and they reported no issues. This was done roughly a year ago. While I am not certain, I don't think this is the problem. And if it is, I am not fixing the wells since I am hoping to have my beast of a carb in the next month or so. LOL

Though to just know for certain, I guess I need to figure out how to see into the floor of the manifold!

Re: Hard Starting Hot
 

Just open the throttle plates and look down in. You will probably need a light. You can open the secondary air valve by hand if the choke is all the way open. You will get a squirt off the accelerator pump when you open the throttle as well, but if there is fuel puddled in the intake manifold, it'll be obviously more than that squirt.

Re: Hard Starting Hot
 

Steeveedee - thank you for those tips!

Re: Hard Starting Hot
 

Do you have a thermal insulator under the carb?

Re: Hard Starting Hot
 

there is something between the manifold and the carb - don't know if it is a simple gasket or a thermal insulator.... it's not very thick.

Re: Hard Starting Hot
 

perhaps I should be installing one of these that is talked about in this thread?

https://www.67-72chevytrucks.com/vbo...d.php?t=806982

Mr. Gasket 3406 Phenolic Thermal Insulating Carburetor Spacer?

$40 bucks shipped on Amazon, ordered. If it only 1/2 works on fixing my issue, I'd be happy. Best that I can tell there are any negatives.... Will report back on how it works out. If anything I need practice taking of the Carb ha!

Re: Hard Starting Hot
 

That should do the trick! :metal:

Not sure if it was mentioned earlier in this thread but a sticky 'exhaust gas heat riser valve' can also cause the intake manifold to get tooooo hot. Something to at least check.

Re: Hard Starting Hot
 

Something you have to consider when installing a spacer under a carburetor that has a divorced choke.. The spacer moves the carburetor farther away from the choke bimetal spring.. You'll also have to have a longer actuator rod or you'll have problems getting the choke adjusted and operating properly...

Re: Hard Starting Hot
 

Good point, hopefully it will be a little easier with my new electric divorced choke.

Thank you for bringing that up because it didn't even cross my mind. Though I am sure it would have been pretty clear once I started to install it!

Re: Hard Starting Hot
 

Have you tried a fuel pressure regulator? From the looks of your engine compartment I am under the impression you like more of a stock look, and that's cool .. but is there a section in your fuel line maybe somewhere out of sight you could install an in line regulator?

I had a very similar issue with an Edelbrock carb. They are really bad to do exactly what your truck is doing. People tend to use the heat spacer you mentioned in an earlier post to help the Eddy carbs too, but ultimately the fix is the fuel pump.

If you read in the Edelbrock tech documents it mentions the stock fuel pump produces around 12psi. Edelbrock says it is too much fuel pressure for their carbs and suggests (strongly) that you use their fuel pump. It is designed to produce around 5-6psi. This will resolve the 1406/1407 hard start issues. Ask me how I know. ..

So, perhaps the fuel pump combo you have now Qjet / stock pump is having a similar issue(?) What if you installed an inline fuel pressure regulator and backed the pressure down around 6psi? It really helps with a similar issue, but I understand its Edelbrock.. still a similar designed carb.

Mr Gasket makes an inline regulator I have used in the past, it has a dial on the top you can adjust.

Ultimately and as others have mentioned I feel like its dripping gas down into the intake after you stop. Too much fuel pressure will cause it. Hope this helps.

Re: Hard Starting Hot
 

Thank you for that information, I have read about fuel pressure on some of the search results but it seemed the critical fix for Edelbrock. Though to put one in I'll have to cut my hardline to make one fit. I have thought of this, though mainly for a external filter.

My fuel pump is a ACDelco, so I tried to get the best one possible but without a gauge I don't know what it is putting out.

Re: Hard Starting Hot
 

The stock ACDelco is right at 12psi.

With it idling, and warmed up good .. kinda peek down into the fuel bowls and see if its dripping gas down into the intake on idle. Then, shut it off. Check again .. I'd bet you'll have a slight drip. That would indicate the fuel pressure issue as the culprit. Too much pressure will impact the needle and seat combo in the carb and allow it to keep dripping raw gas.

Re: Hard Starting Hot
 

That is what I was thinking it should be around, out of the box.

BTW, my engine is stock, other than a light RV Cam on its rebuild last year. Other than careful improvements (generally around safety), she is stock all around.

Re: Hard Starting Hot
 

ugh, I just remembered I have that hose from the passenger valve cover to the air breather riser to deal with too.

I swear, nothing is easy! LOL

Re: Hard Starting Hot
 

Well, I ordered a ton more bits: Mr. Gasket Regulator, Gauge, a T and then from quadrajetparts.com two 5/8"-18 x 3/8" Barbed Nipple (2242). I'll do this first and with 3/8 rubber fuel lines for testing. Then if this helps in anyway, then I'll figure out how can cut my hardline.

Questions:

1. Do I T/gauge near the head of the Carb or near the output of the Fuel Pump or that doesn't matter so long as you are T'ed someone between Pump and Carb?

2. Can this regulator be at the bottom, near the fuel pump - rather than at the top? I rather not have this ugly thing up there staring me in the eye!

Re: Hard Starting Hot
 

If your pressure is within spec the ethonal in the gas can cause this also . Alchohol boils at a much lower point heat soak after shut down can boil the fuel in the bowl and raise the pressure. One of my cars uses low octane gas which has ethonal in it gave me this problem switched to the non ethonal high test gas and problem is gone . I was going to add an insulator plate but for the amount I drive it the 30 cents a gallon higher price is a non issue

Re: Hard Starting Hot
 

Getting non-ethanol gas isn't really option for me. The closest station that has it, is to far for me to for regular fill ups (even if it helps). Though I have started putting in STA-BIL 360 Protection Ethanol Treatment And Fuel Stabilizer just this week. I am not sure it has helped (or would help) this issue.

The Delphi Fuel pump is listed as 8 psi, so I assume that is to high? I don't mind trying things. At the very least I'd know 100% my fuel pressure after this and I'll have more tools in my toolbox.

Re: Hard Starting Hot
 

I realize you're deep in the rabbit hole but I'll still recommend getting an infrared thermometer. These are SUPER useful tools for chasing down thermal issues. I've used it for numerous household thermal issues and it works perfect for diagnosing thermal issues on engines.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Re: Hard Starting Hot
 

I actually have one. I didn't know I was suppose to point it to something for this issue. Where do I beam it to and what should I be watching for (temp wise)?

Edit - I totally missed your posting asking me if I have one! Doh!

So, yes I have one - what's next ;-)

Re: Hard Starting Hot
 

Check the manifold temp (right under the carb) and the carb float bowl. You can do this at 5-20 minutes after shutting down the hot engine. I've also used mine to find a stuck exhaust manifold heat riser which was putting too much heat into the manifold.

Note: reg gas (in the USA) will start to boil at just a bit over 120 degrees. You can actually hear a percolating sound when it starts boiling.

Re: Hard Starting Hot
 

I hope I don't have some "stuck exhaust manifold heat riser" - though I am not sure what that is LOL

Engine was rebuilt last year and I replaced my cracked manifold with a NOS one I got off of fleabay.

Re: Hard Starting Hot
 

You could start with while the truck is cold just reach down grab the heat riser weight and see if it moves. If it moves freely and the spring has some tension your golden.

Re: Hard Starting Hot
 

hmm, okay I looked up exhaust manifold heat riser, which seems I have asked about before when I saw a posting with a strange "pipe" coming off the exhaust to the stock air cleaner. I don't have that "stove pipe" thingy or anything to get stuck :)