The Stovebolt Site Forums The Shop Area Engine Shop Starved for fuel - What to do?

Hi guys,
I am way over my head on this one. I tried to take the '54 to town the other day, and got as far as my mailbox. The engine just seemed starved for fuel. Even when I stomped it to the floor, it didn't make any difference. Prior to this, I'd been driving it 2 times per week (50 - 100 miles at a time), and it ran like a dream. I replaced the fuel filter, thinking that would solve my problem. No luck.

Dad, Jim, and I spent all afternoon working on it yesterday. My engine is a 1975 305. The problem went from barely running when I parked it to not running at all yesterday. So, we cleaned the Rochester 4BBL, then replaced everything. No change. Had spark and good gas pressure from the pump. Engine cranked and cranked but wouldn't catch.

We recently replaced the plugs and wires, as well as the rotor, cap, points, and condensor. Yesterday we also checked for vacuum leaks and ensured, using the Haynes manual, that everything was hooked up properly. No change.

So, we replaced the carb with a used 4BBL Rochester we had from another truck. Then it would start (barely) and run - terribly - for a short period.

We're down to theorizing that the timing is screwed up. Any ideas or advice? Thanks guys!!!

It is generally neccessary to retime after replacing or regapping the points. Sometimes condensers are bad out of the box, so you might try the old one.

You probably have a bad timing chain & sprocket.

Check the pick-up tube in the fuel tank. Sometimes rust or sludge will float into the fuel line and let very little fuel through,
Scott

look at the other post and it seems like we are all having a similar problem. i think it is caused by katrina and we should ask for government assistance,$$$$$$$$$$$$. RON

Just a tip that might help...Beings that I make most of my living repairing outboard motors I have a three gallon can with primer bulb to test run motors with a 50-1 mix...I do get into inboards and sterndrives some...When one of these has been sitting for some time and the fuel tank is suspected of having old and dead fuel I connect the hose from the 3GAL tank to the inlet fitting at the fuel pump and pump the system full to the carb ..If there is a leak problem..even at the float needle it will appear then..Since the hose is about five feet long it is safe to run the engine this way..And besides the 50-1 is a good top oil to help a dry engine......The same goes for older cars and trucks..If the flex line at the tank is the suspect the engine will stay running with the new supply...If it still dies..then maybe the pump is at fault...etc ...I have found this to be a quick way to find fuel supply problems...A great way to prime a carburetor too...no spill...On a 4BBL Q-jet I take the hose and put it over the bowl vent and fill the bowl to help get an engine going......AL..

I agree w/ 48bigtruck. You felt she was starving for fuel, so look into that and see if you have a clear line. I had this same thing happen and it turned out to be a chunk of rust caught @ the 90 degree elbow just 2'' out of the tank, b4 the fuel filter. thus restricting fuel to the engine.

Yup....like the other guys have suggested:

Fuel pump, fuel line, fuel filter...if you're running a quadrajet...well, rotsa ruck,

Other things to check: verify the firing order. Check for vacuum leaks or loose spark plugs.

Verify that the centrifugal advance weights aren't rusted solid.

Recheck the point gap...and seriously consider replacing the points with a Pertronix setup.

There's a whole buncha stuff to check out.

Ray

Thanks for all the info guys. We spent all day yesterday working on it too – even skipped the Vikings game! (Still had it on in the garage so Dad could swear at them, though). I forgot to tell you the fuel pump is new too, but I know its possible we might have a bad one.

We replaced the coil and the points (again). Then we replaced the temporary carb with the original carb and it now starts and runs for about 30 seconds. We're so out of ideas that we're planning to ohm test the spark plug wires and remove the fuel lines all the way back to the tank to see that they're clear.

We'll give all of your suggestions a try and post an update. Thanks again guys, I knew you'd have some great ideas!!!

I have also used an outboard tank (like Inlineal) when I coated the inside of my gas tank with the Bill Hirsch stuff and on a couple other occasions.

Kim,

The exact symptoms you describe occurred for me in my 1942 fire truck. I did everything, then finally checked the gas line (as 48bigtrucks suggests). Blew it out with air, and it fired right up and ran beautifully. Should have done that first--it would have save a heck of a lot of work and anxiety. I hope it's that simple for you.

Jim

Well, we blew another Saturday trying to get the truck running. We checked all the fuel lines, tested every plug wire, and everything else mentioned except checking the timing chain (too much de-construction involved for a cold Saturday). I'm afraid that since we've eliminated everything else, that's it. Boo.

Going to have it TOWED to a GARAGE for work by a PROFESSIONAL!!!! What a revolting development. I'll post whatever the smart guys do to get me back on the road . . .

I know you didn't do this but this was about my dumbest stunt ever.

I replaced the distributor cap on a 307. I wanted to get the wires back on correctly so I numbered them using masking tape. I just started in one position and number them clockwise.

A month later, I decided to replace the wires but used the numbers as if they were connected to the properly numbered cylinder. Get my point? No position on the cap was connected to the right cylinder.

I also had it towed to my ol' timer mechanic who had a good laugh out of it. He didn't charge me, the laugh was reward enough.

OK, back to basics!
You need fuel, air, spark, and compression, all at the right time.

Start with fuel- - - -does the fuel pump squirt a good stream when the engine is cranked over with the starter? Disconnect the fuel line at the carb, and plumb it into a catch container like a coffee can. It should squirt a good, solid stream of gasoline as the engine is cranked. If not, trace things back until you find the restriction. A reasonable amount of air pressure applied to the line from the pump to the tank should cause bubbles in the gas. Just blowing into the line should be sufficient to bubble air into the tank.

Next- - - -spark. If you've got a standard point-type distributor, the coil wire should jump a 1/2" spark or longer to ground as the engine is cranked. If it's weak or nonexistent, check out the points, condenser, and internal wiring in the distributor. The older ones were bad about getting breaks in the primary wire from the coil to the points. With the points open, there should be 12 volts all the way to the insulated side of the points. Points closed, ignition switch on, 9 volts at the coil (+) side, 0 volts at the coil (-) and to the points. If there's 12 volts at the insulated point with the gap closed, the point contacts are burned, and not conducting. On a HEI distributor, it's difficult to check anything but resistance of the coil, so substitution of known good parts like the module and pickup coil is the only option available to the non-professional without a shop full of fancy equipment. Look out for a distributor rotor with a hole burned through the middle to the dist. shaft.

Compression- - - -about 100 pounds on all cylinders is enough. If ALL cylinders have low compression, you're probably dealing with a slipped timing chain. Here's a quick cam timing check. Take the passenger's side valve cover off, and roll the engine over by hand with a socket on the crankshaft pulley bolt. It's easier to do this if the spark plugs are removed. Watch the third pair of valves from the front (#6 cylinder). The exhaust valve will be about halfway closed as the intake starts to open, and the Top Dead Center mark on the crankshaft pulley should line up with the timing mark just as that happens. That's called valve "rocking", and if the timing mark is much past top dead center when that happens, you've got a badly worn, or slipped timing chain. Another check is to rock the crankshaft back and forth, and see how far the pulley moves before the distributor follows. More than 10 degrees of movement at the crankshaft before the dizzy moves means the timing chain is stretched and/or the sprockets are worn out.
Jerry

Thanks Jerry! I appreciate you taking the time to help me out with so much detail. We did not do a compression test; I'll get to work.

Thanks to everybody for all your advice, and Wally, I'm OK with getting laughed at (as long as I learn something).

I think if you hooked up a timing light, varied the engine speed a bunch, you could watch the
timing mark walk all over the place indicating a sloppy chain. This requires no teardown. Can't
an exhaust restriction keep an engine from
running properly too!

Stuart.