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Looking for some advice - blowing out fuel lines

Posted: Feb 12th, 2018 1:17 pm
by clrayjr
I have a 1971 454 C3 that was stored in a barn in 1995. It was running when it was put away but gas was left in the tank. Since having it at the house, I have replaced the gas tank, sending unit and the rubber gas lines from the tank to stainless steel lines. I have changed the spark plugs, the points and distributor as well as the oil and battery. At this point, the engine cranks but will not turn over. (I turned the engine by hand prior to any of the work I did).

I used a starter spray and sprayed it into the carburetor, the car turned over for about 3 seconds and then stopped. I am thinking that I am getting air and spark but I am not sure I am getting gas. I am thinking that I will need to change out the fuel pump as my next step but I am also wondering if I should blow out the gas lines. I should say that when I tried cranking it without using the spray, I could smell gas.

Any suggestions would be welcomed. I am hoping to get this back on the road this summer and the engine is a pretty big hurtle at this point!

Re: Looking for some advice - blowing out fuel lines

Posted: Feb 14th, 2018 11:18 pm
by MaineVette
Hi, and welcome to the forum! :cheers:

I suggest a few more tests to narrow down the issue. From what you describe it could be a spark or fuel issue.

First off check for fuel. After you crank the engine over for a while, pull a spark plug immediately after. If you're getting fuel chances are the plugs will be wet. You can also try completely draining the carb. Reconnect the carb and turn the engine for another 30 seconds or so which should fill the float bowls. If you try to drain it again and no fuel comes out you'll have your answer. If you find you aren't getting fuel you can isolate and test components to find the issue.

Your issue could also be due to a spark issue. If you pulled and/or replaced the distributor your timing could be off or your plug wires could be out of sequence. It's pretty easy to goof up. I've learned even an engine with really bad timing will turn over a couple times if you put enough starter fluid to it. I suggest verifying you're getting spark, that you're plug wires are all connected in the proper sequence, and that your timing is correct. You may find these two papers to be useful: ... lation.pdf ... ing101.pdf

Good luck, I'll be interested to hear what you find :thumbs:

Re: Looking for some advice - blowing out fuel lines

Posted: Feb 15th, 2018 6:10 pm
by rbryce1
Actually, testing for fuel in the carburetor can be done much easier that that. Assuming you have fresh gas, crank the engine for about 5-6 seconds. Remove the air cleaner. While looking down into the carburetor, pump the throttle a few times. If you see fuel squirting into the carburetor venturies from the accelerator pump, it has fuel. If not, no fuel.

Since the engine will fire with starting fluid, it's probably not spark. If you have fuel from the accelerator pump but the engine will not fire, now look at timing. If the timing is retarded enough, the engine can fire on starting fluid, which is essentially alcohol and ether, but not on gasoline.

If you do not have fuel at the accelerator pump, remove the fuel line from the carburetor and crank the engine for only a second or two. If you do not get gas from the fuel line, it's most likely the fuel pump. If you get gas from the fuel line, check the fuel filter inside the inlet of the carburetor. It's usually a stone filter that can easily get clogged by ethanol fuel sitting a long time.

Remove the stone filter, replace the fuel line and crank the engine for 5-6 seconds and retry the accelerator pump trick. Fuel means the filter is clogged, replace it. No fuel, rebuild the carburetor. Fuel and still no start, rebuild the carburetor.

Re: Looking for some advice - blowing out fuel lines

Posted: Feb 15th, 2018 11:41 pm
by Brookster
If the fuel lines sat with gas in them for 23 years - its most likely clogged with varnish and corrosion (suggest Replacement). Loosen the fuel line going to the gas tank at the fuel pump, see if you have good steady gravity fuel flow from the tank. If you don't, slightly pressurize the fuel tank at the gas cap with air, this will force the fuel feed to the fuel pump if the lines are dry and clear. Once completed, if you have good gravity fuel flow, re-attach to the fuel pump. Now remove the fuel line at the carburetor, clamp on a fuel hose and route it to fuel canister, turn the engine over and see if you have fuel flow from the fuel pump into the canister, if you don't. replace or rebuild the fuel pump. Next as mentioned earlier, carburetor and spark! I might suggest a fuel line pressure gauge after the inline filter just before the carb 0-10 psi.

The one great thing about these C3 engines is they are simple to troubleshoot. If it were my 71 C3 I would order me some new fuel lines, fuel pump, fuel filter, carburetor rebuild kit, new set of spark plugs, wires, distributor cap and points.

I wish you the best luck with your troubleshooting and welcome to the forum! Almost everyone here has gone thru the same issues - lots of good people and helpful advise here... :)

Re: Looking for some advice - blowing out fuel lines

Posted: Feb 16th, 2018 1:15 am
by rbryce1
When he said he had stainless steel fuel lines, I assumed he had already replaced it, since stainless steel fuel lines were never installed in Corvettes by the factory. But that brings up a good point. If the fuel lines are the old lines and the car had gas sitting in it since 1995, replacing the rubber fuel hoses and the fuel tank probably did not remove the old fuel from inside the fuel lines. Assuming the fuel lines are not clogged, you probably need to purge the entire fuel line to remove all the bad gas from the fuel line. You may have good gas in the tank and kerosene in the fuel lines. That actually happened to me on my boat. It sat in it's slip for 2 years and when I pumped out the fuel tank and filled it with new fuel, the 15 feet of fuel line was still full of bad gas. Had to spin the engines until I pumped about a quart of fuel through the fuel lines into a container and it started fine after that.

Re: Looking for some advice - blowing out fuel lines

Posted: Feb 17th, 2018 11:30 am
by Brookster
I just hope clrayjr returns with an update, and yes, if the fuel-lines are stainless steel they've been changed but may need cleaned or replaced. OP could also setup a gravity feed directly to the carb if he just wanted to start it, he'll just need to be real careful...