The Stovebolt Site Forums The Shop Area The Electrical Bay Turns over, but no firing

My 53 GMC was sitting for quite a while. I put in a new 6 volt battery (positive ground) and got it to turn over, but I can't get it to fire. I've put in new points, condenser, rotor and distrib cap; gapped the plugs; rebuilt the carb; replaced the electric fuel pump; and finally polarized the generator. I had not done that before.
I am wondering if I have a problem with my coil, or if the crack in my distributor's primary terminal could be the culprit. Any help appreciated, I am sure getting discouraged.

did you check for spark

then check the if its geting fuel

GMC53,

Welcome to the Stovebolt. It sure sounds like you have done everything right.

Have someone try and start the truck as you hold a plug wire to a ground on the engine, you can verify it has ACTUAL spark this way.

If it doesn't have spark, some item in the ignition system isn't proper. I didn't see the condenser mentioned in the replacement list...just an oversight!

If the truck IS showing spark, then it might be a fuel issue. Bad gas or no gas would be the first thought.

Your first task is to see if there is "fire" to the plugs...if so, think fuel. If no, go back and check points, coil/cap and condenser.

Nothing will happen if you don't have 6 volts to the coil [is the key on]. This can be checked with a little volt meter. The idea is to narrow down the possible causes through detective work. Take a day off, think about it, and start again with renewed spirit!

GMC's are much easier to work on than Chevrolets!

Stuart

when i have trouble starting any gas engine and it won't start i spray starting fluid, it makes it easier to start if it is a fuel problem. if that doesn't help it usually electical. ron

Half way there. I checked for spark using "Atomarc's" advice, and I do have spark! So now, thinking my carb rebuild skills might not have been so great, I loosened the fuel line out of the carb. I turned the engine over a couple of times,and lo and behold, no gas came out. None!
So I'm gonna go through the carb rebuild again, very carefully. I'd appreciate any tips or problems to look for.
On the road again!

GMC53,

I might have misread your above post, but didn't you indicate you loosened the fuel line INTO the carburetor, and no gas came out!

This means no fuel is reaching the carburetor from the fuel pump/fuel tank..this could be no fuel in the tank, a blocked line from the tank, a defective fuel pump or a plugged line from the pump to the carb.

Before you beat yourself up over a funky carb rebuild, get fuel up to it! Work your way back until you find fuel.

Several recent posts on this same subject have come up with a plugged fitting at the tank, and a empty fuel tank.

Be sure to check your fuel filter/filters if you have them.

Stuart

You said you replaced the electric fuel pump. Your truck didn't have one originally, but most modern electric fuel pumps are polarity sensitive and negative ground. Make sure the one you installed is a six volt positive ground pump. You should hear it if it's working.

Electric fuel pump....how did I miss that one!


Stuart

Because you were, as was I, so flabbergasted at the perceived direction of fuel flow, I believe.

Ho, ho! Sorry about the confusion. I meant to say I removed the fuel line between the carb and the engine, and nothing came out when I cranked her over. I do have gas coming into the carb. So I'm guessing I reassembled something incorrectly. We'll see ...

There is no fuel line from the carb to the engine. The fuel is mixed with air in the carburetor and gets to the engine through the carburetor throat to the intake manifold and then into the intake ports. I'm confused.

You do not need to crank the engine over to get fuel flow with an electric fuel pump. Is the mechanical pump bypassed or are you pumping fuel through it with the electic pump?

OK, I believe it was the vacuum advance line I disconnected, not an outgoing fuel line.
That said, I have checked, step by step, from the pump to the carb, to the fuel bowl, and down the throttle body. I pushed the pump piston and gas came out a hole, and the power jet assembly (I think) in the float bowl pushed down and sprang up. When I took off the throttle body there was gas going into the governor throat. So I think I am OK on getting gas to the engine. I sprayed some starter fluid in the carb and cranked her over. I got a couple of gasps and finally a small bang. That's all, but I could smell that something had caught! I can't get any more than this, though. What next?

GMC53;
It still sounds to me like you aren't getting enough fuel to your carb. Are you sure you have enough gas in the tank for the fuel pump to pick up? If you have at least 5 gallons in the tank,try pulling the gas cap off,loosen your fuel line and see if you get fuel flow. If so,try to put a clean bucket under the fitting you loosened and open the fitting. If the gas is flowing well,re-assemble the connection. If there's no gas or a very weak stream,coming from the gas tank,attach a piece of fuel hose and apply a little air pressure to the line going into the tank-just a short burst of maybe 5 pounds of air pressure. Does it flow now? If so,you might want to clean the tank out,and now would be the time to replace your sender if it isn't working,or at least the screen on the end of your fuel pick up tube in the tank.
If you had a good fuel flow from the tank and didn't have to go through all this so far,let's go back to the electric fuel pump. If it's wired right,you should hear it running for a few moments every time you turn your switch on. If not,loosen the the fuel line fitting at the carb and turn the switch on. Now you should hear it running,and gas should be coming from the loosened fitting. If you hear the pump running but there's no gas showing,have a second look at the pump and be sure it's installed the right direction. (this one caught me once-don't ask how) If that's right,is the line from the electric pump feeding into the stock fuel pump? If not,see if there's an inline filter that might be plugged. If it's feeding the stock pump,pull the oil dipstick and smell it;do you smell gasoline or stale fuel smell? If so,your electric pump is pushing gas past a cracked diaphragm in the stock pump and into the crankcase. Bypass the stock pump and see if you have fuel going to your carb. If so,do an oil change,tighten up all your lines and see if it'll run. If not,loosen the line at the carb again,and see if fuel is making it to the carb. If so,you may have to re-check your float level in the carb. Now you've been through pretty much the whole system,so,for all intents and purposes,it should run. One last possibility I just thought of,make sure your gas tank is venting properly,otherwise the fuel pump will pull vacuum against the tank to a point where fuel won't flow until you let it sit a while.(This probably won't apply,since this problem usually causes the truck to run fine for a couple of minutes and progressively get worse and worse until it runs out of gas, Once it sits for a couple of minutes,or you pull the cap to add more gas,it'll be fine for a couple of minutes,then...)
Speed

I want to thank everyone for the great advice. I have got the beast running for short periods!!!
I'm now working on timing and tune-up.

Craig, GMC53