SanTan Devil

Looking for some opinions here- my 1972 Cutlass with a 2bbl 5.7L 350 V8 has had a recent tuneup, new fuel tank/lines/pump, carb rebuild, new battery (kept on a tender) and a lot of other work under the hood including a new cooling system in the past 6 months. It starts right up after sitting overnight but, after a short jaunt (like 5 miles) to a restaurant and sitting 1 to 1.5 hours, its hesitant to start. It'll start but, it'll often take a second or third try of cranking it over. Any ideas?

VC455

Does it crank slower on the warm start?

SanTan Devil

No, I can't say that I've noticed that. It cranks pretty good just doesn't turn over the first or sometimes second time trying. When it takes on the second or third try, it's good to go.

I've had this happen driving the car four miles and putting fuel in it and trying to start just five minutes later. And I've had it happen going 6 miles to Cars and Coffee, talking for 1.5 or 2 hours and trying to restart. Definitely seems like a warm engine thing. I can start it from a cold (first start of the day) start, forget something, turn it off, run back in the house, come back and start it right up without problem.

Sugar Bear

Try pumping the accelerator once slowly all the way to the floor. Release the pedal and then hold the throttle open about one third with the pedal while cranking.

Could also need the choke thermostat tightened a bit.

Good luck!!!

SanTan Devil

I will try that. I had no idea about the possibility of the choke thermostat but will look into that as well, thank you.

It's so satisfying to have the car turn over nicely upon first start of the day and about equally as depressing to experience any kind of issue with the warm engine.

Sugar Bear

By tightened it means set one or two notches richer. The thermostat housing should have an index and adjustment reference notches. They break easily be careful.

BillK

How was it before all of the work ? Did you keep all of the factory vent lines, canister lines etc ? It sounds like it is vapor locking when it is hot. I dont think you want to "tighten" the choke thermostat. It should be totally open when hot. How long does it have to crank before it starts when you have the problem ?

oldcutlass

I push the pedal down about 1/4 to 1/3 while cranking but don't pump the gas and it starts after about 3 rotations when hot. I have no choke. I attribute it to todays fuel.

Fun71

Kinda the same here, but on a QJet with electric choke.

coppercutlass

Is your fuel system vented properly. Does it have a return ? Was the work done right ? Most importantly something no one else asked here is DID IT DO IT BEFORE lol.

SanTan Devil

Yes, it’s done this before the work. I’m starting to think that maybe all the vacuum type lines need to be looked at and have one in particular in mind.

My old fuel tank did not have a return line going back to it and my mechanic used a two line sending unit, closed off the return line.

SanTan Devil

I’d say that I try cranking it about five seconds. After the first no-start. I stop, pump the pedal a little, and crank another three to five seconds. Typically it will start either on the tail end of the second try between 3 and 5 seconds of cranking. Or, on the third try almost immediately

BillK

3 to 5 seconds ??? Shoot, that is nothing. Just try cranking it until it starts. Pump it a couple of times first. 10 seconds is not a big deal in my opinion. That's about how long my S-10 takes every time.

coppercutlass

Another thing to keep in mind is fuel boil. You could add a little electric fuel pump just to keep the system under constant pressure. My 750 HP Holley carbed 350 will always start right away but if it sits for an hr or so under temp i have to crank it and hold the throttle down. Other wise it wont do anything. This is the first carbed engine that has done this for me but due to the nature of then set up I can live with it

Fun71

Agree with BillK above. It isn't a fuel injected engine that fires on the first revolution.

coppercutlass

Not that i am disagreeing but my boss' 69 impala ss that i built a 454 for starts on the first turn if you press the pedal to the floor once before starting it. But for the most part it does take a few revolutions for any carbed engine to fire up.

tru-blue 442

Check and see if your carb filter has the check valve in it.

https://www.rockauto.com/en/catalog/...el+filter,6200

oldcutlass

Or the OP can just let the car sit for a couple of hours and then go out and look down into the carb and see if the throttle makes to solid streams of fuel.

SanTan Devil

Update from OP: I never really got to the bottom of the issue myself but, my Cutlass is in good hands right now with an Olds specialist. He's as much an expert's expert I've ever found.

He is doing a thorough check on my Cutlass and mentioned that he adjusted the choke and a few other things, has it dialed in... in terms of the original post issue.

Good news/bad news, he's also found a handful of smaller issues in addition to what I brought the car to him for and is correcting. I'm very happy to have befriended him and appreciative that he took on my vehicle as a project given that being a mechanic is not his main trade in particular. He and I have had fun conversations and determined the best was just for him to look it over. Very glad I got the car to him.

oldcutlass

All the choke does when the engine is warmed is completely open the flap and is not your issue.