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I've always suffered from hard starting when the vette sits for more than 24 hours. I thought this was ok but after researching realized it's not. So I read and read lars' paper on hard start. other than user error (which i suffer from no matter what we're talking about lol) I decided to start on the easiest of the steps. I changed my filter on the carb, specifically https://www.napaonline.com/en/p/FIL3...Input=fil+3052
There's a spring action to it that prevents gas from going back down it seems. I let the car sit 24 hours. After pumping the gas about 5 times it started right up.
Amazing.
I ordered the fuel pump getting ready to swap assuming such an easy fix wouldn't cut it. I'm letting it sit till saturday and see what happens. Thanks LARS for publishing your stuff.
before I get destroyed by the old timers on here, i'm not saying this will work for anyone else but me. I have no clue what i'm doing. I'm just a regular joe. I'm not a mechanic. Research LARS' papers on carbs and find your way. Just thought I'd share my experience.
Last edited by michael lamoglia; Jan 19, 2021 at 07:52 PM.
1978 c3 25th anniversary 350 vette.
I ordered the fuel pump getting ready to swap assuming such an easy fix wouldn't cut it. I'm letting it sit till saturday and see what happens. Thanks LARS for publishing your stuff.
Hey Michael, did you also order a new S hose for your fuel pump replacement?
Last edited by 71 Green 454; Jan 20, 2021 at 09:01 AM.
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
You should only need to push the gas pedal once to the floor to set the choke and then start up. That's how it came from the factory and it should be no different now for a properly setup carb. So you still need to investigate why you need 5 times as many pumps to start from cold. Have you tried just one pump? Have you setup the choke to specs?
I too have a 78 that was harder to start after leaving it sit for longer than 2 days. My issue turned out to be the 6 inches of fuel hose that was connected from the top of the fuel tank to the fuel line. It was split and sucking air in when the fuel pump was trying to suck in fuel. You can look for this by taking the fuel filler cover flap off and looking down to it from there.
I had to lower the fuel tank a bit so that I could get in to change it. However this caused a pin hole leak to start from one of the straps under the tank which required the removal of the tank to fix.
One thing leads to another but all good now.
I tried a few things and got to the stage of thinking an electric fuel pump would help. I temporarily plumbed it up before the mechanical fuel pump and noticed that it was sucking a lot of air with the fuel. I removed the fuel filler flap and looked into the area above the fuel tank. The rubber fuel line from the tank to the fuel tubing was swollen and split in multiple places. Replaced this piece of fuel line and all good now.
I also have a 78 with a Lars overhauled carb..
Not a daily driver by any means but after a day or two it usually does start after maybe one or two pumps but after a week or more it does require several more pumps to fire off..
I was and still under the impression that even though the fuel may not drain back for the filter assy the fuel in the bowls tend to evaporate from it being loaded with ethanol????
I've always suffered from hard starting when the vette sits for more than 24 hours. I thought this was ok but after researching realized it's not. So I read and read lars' paper on hard start. other than user error (which i suffer from no matter what we're talking about lol) I decided to start on the easiest of the steps. I changed my filter on the carb, specifically https://www.napaonline.com/en/p/FIL3...Input=fil+3052
There's a spring action to it that prevents gas from going back down it seems. I let the car sit 24 hours. After pumping the gas about 5 times it started right up.
Amazing.
I ordered the fuel pump getting ready to swap assuming such an easy fix wouldn't cut it. I'm letting it sit till saturday and see what happens. Thanks LARS for publishing your stuff.
before I get destroyed by the old timers on here, i'm not saying this will work for anyone else but me. I have no clue what i'm doing. I'm just a regular joe. I'm not a mechanic. Research LARS' papers on carbs and find your way. Just thought I'd share my experience.
I would like to say something here.......regardless of your skill set or knowledge of engines, you made an effort to research, make a list of possibilities, then came up with an action plan to tackle these possibilities one at a time starting with the simplest. You are 90% ahead of everyone who attempts to work on these. Your effort paid off. Approach any task in this manner and the chances for success go up exponentially. Kudos to you. It makes more of a difference on how you approach a situation rather than raw skill or knowledge. This is Ocham's Razor 101.
I would like to say something here.......regardless of your skill set or knowledge of engines, you made an effort to research, make a list of possibilities, then came up with an action plan to tackle these possibilities one at a time starting with the simplest. You are 90% ahead of everyone who attempts to work on these. Your effort paid off. Approach any task in this manner and the chances for success go up exponentially. Kudos to you. It makes more of a difference on how you approach a situation rather than raw skill or knowledge. This is Ocham's Razor 101.
Jebby
Jebby! what's up. thanks for the kind words. Remember when i started with an oil pan gasket and did half the vette? Thanks to you and others. I know what you mean. I was scared to death to touch the timing chain and ended up doing it no problems. This is no different.
I tried a few things and got to the stage of thinking an electric fuel pump would help. I temporarily plumbed it up before the mechanical fuel pump and noticed that it was sucking a lot of air with the fuel. I removed the fuel filler flap and looked into the area above the fuel tank. The rubber fuel line from the tank to the fuel tubing was swollen and split in multiple places. Replaced this piece of fuel line and all good now.
if original fuel lines (including rubber) on the feed side..chances are fair you have a leak..suction or drip. Also check in tank at sock etc..
short story, heavy visual inspection of lines (including under cap as noted above), pump flow and pressure with check valve operation (see if gas at carb line after off for a couple hours..) , filter, hoses all replaced if old or maybe looking back .. a pressure check? to see if it holds air? (lines)..
I learned that after above link and fix and Lars rebuilt carb..
it sat for a 1/2 month.. (see the actual video of this in the link below post #15) got carb, installed empty, started to crank no gas and within 5 seconds it was trying to start.. two pumps.. and bang (probably no pumps as choke was already closed).. tells me if all working as designed.. shouldn't be a problem and i'm done screwing with the fuel system.. for now .. Rebuilding "interpon's" '79 L82 Q-Jet - CorvetteForum - Chevrolet Corvette Forum Discussion
Last edited by interpon; Jan 22, 2021 at 10:02 AM.
So I got the fuel pump. Instead of researching fully, i decided to pop it in there and realized i bent the fuel rod (see pic) Off to Napa to get another one. While I was at it I bought a gasket for the plate which had none. someone had been in there before because one of the screws was missing a washer. Anyway, I bought high temp grease to keep the rod in place. I put everything back and noticed I wasn't getting any gas thru to the metal pipe going to the carb. Why? because I wasn't patient and didn't pump enough. I kept the pedal down with the metal pipe going to the carb unplugged to see if I got any gas flow. I finally did, as i can hear it spraying into my pan. I tightened it all together and it started up right away. I swapped out the pump to see if I can avoid a 5 pump start, instead of a 1 pump start. Lastly, the original pump did not have the white 'plug' the new one does. When I say original, i mean it. It's stamped and all. I bought an airtex one, as I can't find an ac delco anywhere. Good reviews.
You should measure pressure and flow at end of pipe prior to carb and see what you have.
pumping throttle will only pump what gas is in carb bowl..
i would check flow also did you use s hose for pump? ( pre molded)
also how did you bend rod?
Last edited by interpon; Jan 24, 2021 at 09:26 AM.
You should measure pressure and flow at end of pipe prior to carb and see what you have.
pumping throttle will only pump what gas is in carb bowl..
i would check flow also did you use s hose for pump? ( pre molded)
also how did you bend rod?
didnt change metal rod used original. Gonna swap it also rubber pipe from gas supply up to fuel pump is all crappy will order new ones. What a cheap butt I am that I would t order it all at the same time. I think I do it purposely so I have an excuse to be down there lol. Anyway this morning 5 pump again. Definitely lines. Lastly I want to send carb to Lars change all the rubbers etc thanks all as usual.
Hey Michael, did you also order a new S hose for your fuel pump replacement?
Originally Posted by michael lamoglia
didn't change the s pipe
Originally Posted by michael lamoglia
didnt change metal rod used original. Gonna swap it also rubber pipe from gas supply up to fuel pump is all crappy will order new ones. What a cheap butt I am that I would t order it all at the same time. I think I do it purposely so I have an excuse to be down there lol. Anyway this morning 5 pump again. Definitely lines. Lastly I want to send carb to Lars change all the rubbers etc thanks all as usual.
Some don't realize that the rubber S hose is preformed so it doesn't kink.
Good luck.
hard starting when cold after 24 hours
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