prettyood

I have an 84 Civic that has recently had its carburetor and fuel pump replaced. It turns over well but there is no gas getting to the engine. The tank has been drained and cleaned and it did run immediately after doing so, but that led to discovering that the idle screw and socket were completely stripped, hence the new carburetor.

Is there anything in the tank end of the fuel line that could be malfunctioning to the point of sometimes working? I plan on draining the tank again to see if there's any nastiness that keeps blocking valves soon, I might as well check anything else that could be giving me grief.

ezone

Some thoughts:

Put a hand-vacuum pump on the fuel line in the engine compartment (at the pump inlet, leading to the tank), see if you can pull a solid vacuum---- or if it bleeds off as though there is an air leak. (rust?) If there is an air leak during suction somewhere between the mechanical fuel pump and the liquid in the tank, it may suck only air and no liquid. (like a small hole in a straw makes it tough to get liquid in your mouth)

Maybe test the mechanical fuel pump for pressure and vacuum. New doesn't always mean good.
Also, if the cam lobe for the pump is worn then it won't be able to move the arm on the pump sufficiently to make it work..
Seems like I remember something about if the spacer between the pump and the head is missing it doesn't work right but I can't remember what happens, that was decades ago.

See if lines will flow and have no blockage from tank to engine compartment.

There is supposed to be an inline fuel filter between the pump and carb, see if it is clogged up.

There should be a strainer or sock on the end of the fuel pickup tube in the tank.

prettyood

The pump is definitely pulling gas from the tank, when the out line is disconnected it ran it out into a bottle. Somehow it still isn't getting into the carburetor. It will start when gas is directly poured into the carb, but dies as soon as that is all used up. The filter is clean, we even installed a smaller one inline before the pump for good measure.
Turns over just as well as before, but only attempts at firing every couple seconds, not enough to keep it going.

ezone

You've got some 33+ year old hoses that may have deteriorated inside (unless you've replaced everything), so rubber fragments could be clogging any narrow spots in the system. Is the inside of the tank rusty?


So manually verify everything one area at a time in an order from the tank to the carb.......

You've got the pump that pulls a vacuum on the line to the tank, so while the engine is cranking can it pull liquid fuel all the way up from the tank to the pump? I assume that's what you explained already----but does the pump need to be primed with gas?

Assuming the pump can draw the gas out of the tank.... With the engine cranking, Can the pump then spit fuel out its outlet fitting toward the carburetor line?

Can you blow through the line from the pump to the carb with your mouth just to verify it will be able to flow once liquid reaches it?

Inline filter actually flows air?
Does the float needle and seat allow air movement when you blow through it?
Does the cab have a sight glass on the side of the float bowl?

prettyood

So the car now works and drives alright, my father in law did some work on it, although he didnt really explain to me what he did. The only problem is that it diesels if driven for more than about twenty minutes. Common advice seems to be adjust the idle speed and install a solenoid, along with clearing the valves of the carbon deposits (which is outside my expertise and tool capabilities).
My short term solution is carrying vice grips in my glovebox, and pinching the fuel hose shut right before the intake on the carburetor. Its annoying to do at gas stations.

ezone

Manual transmission? Just stick the shifter into gear, hold the brake pedal down with one foot--- and let the clutch pedal out to force the engine to stall.


Idle speed too high was a big factor in dieseling, and many people would just crank that up after the various factory controls to do that job quit working (when equipped).

(generalizing here) If there was a throttle stop (or idle up) solenoid there from the factory, it was usually intended to turn on when the key turns on so it "props" the throttle slightly open and maintain a regular idle speed while the engine is running,
then when the key is turned off the solenoid also turns off and makes the throttle close all the way. This forces a drastic restriction to incoming air flow, thus reduces or eliminates the dieseling problem.

Vacuum leaks may cause high idle speed too.



To add to the list..... check for running too hot, which could be influenced by things like thermostat, low coolant level, electric radiator fans operation, 3 decades worth of bugs and dirt packed into the radiator fins, lime and calcium deposits inside the cooling system, etc.

An inoperative EGR valve or system causes elevated combustion temperatures which may be a factor in dieseling.



"Techron" added to the tank can help reduce carbon deposits over a long period of time.
Very careful use of plain water can literally steam clean the carbon deposits from the pistons and combustion chambers quite quickly, but beware doing this can cause lots of damage to the engine if you don't know what you are doing.
If your father in law got this running for you, does that mean he has experience with old school carbureted cars? See if he knows about the water tricks.