14 replies to this topic

[c00mes30]

hey guys, i am trying to get my project started while im working on it, its been sat for about a year but was running fine before i took it off the road, its a 1275 Sprite with a stage 1 kit

so... i am getting fuel to the carb but it wont fire, i have a spark at the plugs,if you spray WD40 into the intake it trys to fire, have tried a carb that came off a working metro to try and it does exactly the same,
i have put new plugs in, changed the fuel for fresh, have put new gaskets on the carb and tried with a new battery but all it does is turn over and not fire, am running out of ideas? 

[cal844]

timing?

[c00mes30]

well the car was running perfectly before it was taken off the road and nothing has been touched on the engine aart from the carb and fuel tank ?

[KernowCooper]

Air leak on the inlet manifold to head ? if you pour fuel in the air intake on the carb does it fire up and die away?

[c00mes30]

yes it does, so where would the leak be?

[dklawson]

Do not focus on leaks at this point.  You said the engine fires on fuel poured down the carb throat.  That identifies this as a fuel delivery problem. 

 

Start by confirming fuel delivery.  Disconnect the fuel line at the carb and aim it into a catch can.  Have a friend turn the engine over on the starter and observe whether or not the fuel pump is pumping.  If you observe a reasonable amount of fuel being pumped into the can, look for blockage at the float valve in the carb and be prepared to clean out the float bowl and jet.

 

If you do not see fuel being pumped into the catch can, look for any filters previous owners may have installed between the tank and carb.  Replace any you find.  If after replacing the filters you do not get fuel pumped through the system it could be a fuel pump issue or (less likely) a blockage in the fuel pipes.

[c00mes30]

Yeah im getting fuel pumping out when it turns over. So will have to strip the carb I think

[dklawson]

You did say that the car sat for a year so it would not be unexpected for there to be fuel gum/varnish built up on the float valve and the main jet and needle.  If you are very careful you can take the carb off and wash its float bowl and jet using spray carb cleaner without disturbing the mixture adjustments.  You may find that is all that is needed to get going again.

[c00mes30]

The problem is I tried it with another carb that I know worked and it still didnt start?

[dklawson]

For your sanity you can run through all the steps in a basic tune-up to exclude several things... but as you said, the car "ran when parked".  Mechanically nothing should have changed.

 

Adjust the valves with the engine cold.

Replace and set the points.  Replace the condenser. 

Set the static ignition timing.

Clean and gap the spark plugs.  Inspect and replace the plug wires if there is any apparent damage or cracking.

Inspect and replace the distributor cap and rotor as necessary.

Once you go through the above, do a compression test.

WIth all the above steps completed you will know that the problem should not lie anywhere but with fuel and/or the intake.

 

However, you did say that the engine runs when you pour a bit of fuel down the carb throat and that says you are dealing with a fuel problem.  By all means examine the intake manifold and carb gaskets to make sure you don't have a major air leak.  If you have a servo fitted, make sure its hose is connected to the intake or that its port on the intake manifold is plugged.  However, I doubt that is the issue since the thimble of fuel worked.  

 

I did see in your earlier post that you said you tried another known-good carb without success.  Combined with the fact that the engine runs on a thimble of gas, that points all the more to this being a fuel delivery problem.  There is a common thing done in car restoration that you can try "just to see".  Remove the fuel hose from the carb inlet and plug the hose.  Connect a supply bottle and hose to the carb inlet and hold the bottle above the engine (like an IV drip you would see at a hospital).  This is affectionately known as "bottle feeding" a carb.  By directly supplying fuel to the carb by gravity you eliminate the other parts of the fuel system.  If your engine will run on bottle feeding, you have a blocked fuel line or pump issue to deal with.  However... you said the pump is working.

 

Which carb do you have fitted?

[c00mes30]

Hi thanks for tajing the time with these explanation. I have a hif 44 carb on it at the moment

[dklawson]

I know you had the other working carb on and the problem didn't go away.   However, this still sounds like a fuel problem since you can get the engine to run by pouring fuel down the carb throat.  

 

Cleaning an HIF carb is more effort than an HS series.  If after going through the basic tune-up stuff you are still unable to get the engine to run and a thimble of fuel tipped into the carb intake does let it run briefly I don't see an option other than basic cleaning of the HIF carb.

 

I would really hate to see you unnecessarily have to remove the carb and take it apart.  Therefore, my advice would be to start with some simple steps that don't involve removal or major disassembly.  Remove the suction chamber, piston, and dashpot from the top of the carb.  Carefully remove them and be careful to not damage the carb needle.  Use spray carb cleaner to shoot cleaner down the carb jet into the float bowl.  Use the plastic spray straw inside the carb jet to make sure the jet is open and free of deposits (top to bottom).  Turn your attention to the carb needle.  Make sure it is clean.  Use the spray carb cleaner on a coarse cloth to wipe off any gum or deposits.

 

While the suction chamber is off the carb, carefully remove the piston from it.  Wipe both the outside of the piston and inside of the suction chamber with carb cleaner on a coarse rag.  When you put the two back together, make sure the piston can freely move up and down in the chamber.  If you find any binding, clean the parts more.  Finally, put the piston, suction chamber and dashpot back on the carb body.  Refill the dashpot with oil up to about 1/4" from the top of the inner tube.  Hopefully these cleaning steps will get your engine running again.  If not, it may be a blockage of the float valve which requires removal of the carb for replacement.

 

 

[gazza01]

Has the timing/dizzy been messed with at all?

Are the plugs getting soaked in fuel?

Edited by gazza01, 02 March 2014 - 08:30 AM.

[c00mes30]

no i have not touched them. the plugs are dry?

[Carlos W]

no i have not touched them. the plugs are dry?

The dry plugs go further to confirm a fuel delivery issue!

Dougs guide above is very comprehensive, once you've followed it come back and update!

Fuel these days seems to go stale far quicker than it used to! The more lighter volatile organic compounds are always going to evaporate off, (you can see this at the petrol station on a hot day) but you do seem to get this waxy tar like residue