Engine Trouble - Appears to be starving for gas

[Andy Illes]

Bummer Ray.  You said in another post you also had a similar fuel problem with your genny on the same trip.... that makes me think a clogged pick-up, fuel filter between the tank and fuel pumps.... or anything else the two fuel systems may have in commen.... start there.

Keep in mind... fuel pumps have very little "suction"... if they can't draw enough fuel (clogged filter, pinched line, etc) they just cavitate (an electric one will "race").  Be sure all fuel filters are on the pressure-side of the pump.  Can't always do that with a genny, though.

Rodney makes a great safety point.  You can run the electric pump off a relay..... stick a couple of plain 'ol house thermostat (or any other kind) mercury switches to it, pointed down in a "v".... run the relay coil through those, in series.  If either switch tips, no power to the pump... no gas spraying on the EMTs trying to pry that bourbon outta your hand.

[bigray]

Thanks gents. I'll keep you posted!

[terry and karen conkle]

in some cases if there is more air it seems to not be getting the correct amount of fuel. this could be the case, gasket seal between the carb and intake, or a simple vac line ,just a thought.



   tc

[bigray]

One thing I failed to mention is the fact that when I stopped (guys gotta have beer and smoke of his pipe when his Clipper is misbehaving) to let the engine cool it would operate fine for 20 miles or so.

[Horst]

You don't think you're getting vapor lock do you?
That sitting for 20 minutes, and then it works again has me suspicious about that.

[bigray]

I'd have to agree with you Horst. I mentioned vapor lock in my recent post. Like I said, when I was tightning a loose cable the other day I noticed how close the fuel line was to the exhaust manifold. I figured that was causing poor gas mileage as well.

Is there anything I can wrap the metal fuel lines with to reduce heat exposure? I think that is my problem!

[Horst]

lots of different ways to do this
1) put up a metal "shield" - certain shields exist just for this purpose, but you can make one I suspect
2) oldtimers trick - wrap your fuel line in foil - kind of crinkled - not rolled on tight
3) oldtimers trick #2 - put wooden clothes pins on your fuel line near where it gets hot - they absorb then dissapate heat
4) oldtimers trick #3 - wrap rubber hose (the kind that can take heat!) around your metal fuel line - cut the hose in half (lengthwise of course) and snap it over your fuel line with the slit facing away from the heat source - use zip ties to secure the hose - make sure you put zip ties as far away from heat source as well - or you can use metal screw clamps.

[bigray]

Thanks Oldtimer (oooooooops......I mean Horst) :lol:

'preciate the tips. I'll let you know how it goes.

A certain other ACOC member says my problem is to vapor lock. He thinks I have a restriction or opening somewhere in the fuel line. He shall remain nameless but he lives in Florida. Well .......sorta.

[Andy Illes]

More correctly.... what the mysterious HeWhoSorttaLivesInFloria actually said was to check for a clogged intake screen or in-line filter.. line leak... or bad pump.  Although roaming pieces of crud in the carb's float bowl could be partially blocking the jets - most likely, not enough fuel is getting to the carb.  

We've visited this issue several times before... but some people have short-term memory problems caused by alcohol/Cohiba abuse...  :lol:

Vapor lock is the LEAST likely culprit!!  That's almost exclusively a hot-start issue (except excessive hot-day idling).  Unless you've welded several feet of your fuel line to an exhaust manifold... moving fuel simply doesn't stick around long enough to vaporize.   Vacuum leakes?  Also not likely... he's not mentioning any over-lean symptoms.  Horst's fixes for that are all "right on".... just not the fix Ray needs.

First, make sure the pump is good.  Even brand new ones can be bad.  Unless the pump's check-valves are seating perfectly, no matter how well the pumping mechanism is working, it still can't deliver full flow or pressure.  However, while that problem CAN be intermittend like Ray's describing... it's almost invariably a go/no-go deal.

The main suspect when the engine starts sputtering at speed (even shuts down).. but restarts ok after a bit, or keeps running ok at a lower speed, is a restriction, most likely a clogged filter.  

Keep this in mind... a filter's JOB is to clog with suspended particles in the fuel.  Larger particles can get sucked against the element and clog it off while fuel flow/suction is holding it there... then drop off when the engine's shut down, or fuel demand/flow isn't enough to hold it against the element... engine runs again.  When fuel flow/suction gets high enough again, the stuff gets sucked back against the element and clogs it.  Can happen over and over again.  You see that most commonly in the tank pickup screen.  In an old steel tank, just look at the bottom, below the pick-up.... bettcha there's a little mountain of crud and rust flakes under it!!  

Ray cleaned his tank a year ago... but that's nearly impossible to do without "cooking" and power flushing the tank... and even then... you expose fresh steel to rust.  The filler hoses can also be flaking.  The pickup filter would be the FIRST thing I'd check... work forward from there till you find the problem.

Next... even the slightest amount of air-leak (which can be one-way... i.e. it will suck air, yet not drip fuel) can also cause Ray's problem.  Connections are the first suspect... then cracked, chafed lines.  Best fix... replace lines... ALL lines... s seemingly good line can be chafed through where it passes through a frame and you can't see it.  If you're SURE the lines are new/good... SNUG all clamps.. over-tightening worm-types can cut rubber hoses.  Also, be SURE to use the right size mini-clamps. Too-large ones WILL leave an unclamped area at the worm.

Tip #1.... Get the cheap, clear plastic filters... you can see what's in 'em, and they work fine.

Tip #2a.... If the charcoal canister/vapor recovery jobbie's not hooked up right... or the line from the tank's hooked directly to a vac port on the carb or intake manifold... it can generate enough "suction" in the tank to overcome what the fuel pump's trying to pull.

Tip #2b.... If you plug that vent line (like I did), you'll wind up with pressure in the tank (whoosh, loosening the filler)... flood the engine if it gets past the carb's float needle after you shut down.  NOT good for cylinder walls... or restarting.  Or Ye Olde Wallet.

[Rodney]

Another idea not sure if touched on is water in the fuel system. with all of the rain it seems you have gotten in the past month maybe some h2o could have gotten in to your tank from a fuel station with a tank with water in it? gas dryer is inexpensive and should be added every so often anyway as a precaution which is reminding me to add some to my Clipper since it will be sitting this winter. hope you get it figured out Ray

[Andy Illes]

Good point Rodney.   Water inna tank's not a happy deal and sure can make the 'ol engine REAL (un)cranky.

Don't think it's Ray's problem though, cuz of how long his trip was, he sez he had the problem the whole time, and only above a certain speed.... which is why I'm thinking a fuel starvation problem.   If he had that much water in there, it wouldda shut him down or at the very least caused him problems across the power band, not just over 50... plus, he sure coudn't have gotten easy restarts.... agree?

The only thing besides fuel delivery I'd be wondering about is ignition.  Bad/weak coil (and/or primary connections) can do that, or if his Chev has points, bouncing can do it.... if it's electronic, the wrong air gap.  A crack inna distributor cap.... shorting coil-distributor lead... stuff like that can also cause it to start cutting out when the voltage gets high enough.  But.. a) that should be happening at a slower speed, and; b} wouldn't disappear after a stop, like he's describing.  Didn't mention that cuz Ray said he went through his ignition, so I'm assuming it's ok.... that leaves him back with fuel delivery.

Ain't our little Clippers GREAT?!?!?   heeeeeeeeeeeeeee

[Rodney]

Yes there are a number of systems to check and the ignition as I think I mentioned in an earlier post could be an area to look at carefully, the chevys in those years are prone to the hi energy electronic ignition to burning caps and rotors due to the hot spark. Pull the cap and rotor and inspect for hot spots or holes where the spark may have burned. the ignition module in the distributor should be checked and that the grease under it is still making contact with the base of the distributor. process of elemination is all a person can do.
:wink:

[bigray]

my distributor cap has less than 4,000 miles on it. I didn't go through the ignition. Meaning I didn't change the distributor itself.

I'm going to change the fuel filter in the carberator and shield the fuel lines and see what that buys me.

My fuel strainer is new and I didn't have any settlement in the tank when I dropped it to include a separte pickup for my generator.

[terry and karen conkle]

another thought gas cap?











     terry

[bigray]

During the most recent ocurrence I stopped and opened the gas cap. It wasn't any pressure or anything so I replaced it and continued on.

And in case you are wondering, it took a long time to get home with all the troubleshooting stops.