Methodical first start process? (1 Viewer)

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I am having a real bear of a time getting my freshly rebuilt motor to start and run. The motor was completely rebuilt and I have confirmed compression and leakdown. The ignition is a DUI version which seems to be giving spark consistently. Cranking timing is 9 degrees. Plugs are new and properly gapped. I do not think it is an ignition issue.

I also rebuilt the carb and set the various settings to what I found in my FSM and on this site. Gas is fresh and stays at the mid-mark on the sight window.

I have had it start and run for a few seconds a few times but as I corrected an overly-advanced ignition and various carb screw throttle, mix and choke settings I am admitting I need some help finding the proper methodical, orderly approach to getting it to start and run.

I started with 1.5 turns out on the air correction screw. I tried it at various settings from there with no success.
I started with 1.5 turns in past contact with the throttle screw. I tried it at various settings from there with no success.
I started with no choke and then in with various settings from there with no success.
I started with no pre-start pumps of the accelerator, then 1, then 2 with no success.
I tried "starter fluid" in the carb with no change.
I am running 2 big batteries in combination, it spins freely and there is plenty of current.

I know its getting gas in the cylinders: I can smell it on the plugs after trying to start.

The "best" results I can get are with 1.5 turns out of the idle air, 2 turns in on the throttle screw at idle, 2 pumps of the accelerator before starting. It will then usually start and sputter maybe 10-12 cylinder-fires. No amount of full or no throttle seems to keep it alive.

I feel like I am now just hunting in the dark now and would have to be very lucky to get the right combination of variables correct...

What is the proper order in which to adjust and diagnose the various things we do so start and run when starting from scratch? I think ignition is good...but what order of idle air correction, throttle screw, choke, pre-start pumps, etc and in which direction should I attempt?

1974 FJ40 with "F1.5" and stock Aisin carb, "RV" cam grind, DUI distributor, anything else needed to help diagnose?

Thanks everyone in advance!
 
How did you set the DUI rotor to TDC on the flywheel?

Plug #1 fires at 9 degrees before the TDC, about 3 degrees before the BB. I checked #1 is at TDC on compression stroke with a piston position measuring tool and checking the valves are closed and confirmed compression and then no/little leakdown.. I have a remote starter switch so I am cranking it over while watching the timing light and the flywheel. I get the same setting with the vacuum line plugged or connected; it doesnt pull enough vacuum at cranking to change advance, thought I also confirmed advance is changed when vacuum is applied to the distributor vacuum port. I also checked I didnt have it 180 degrees out.

Thanks!
 
Sounds like you might have 12 volts cranking but no voltage with the key on? Make sure you have power to the dui in the run position. Also carb solenoid working? These flood easily, check your plugs!!
 
How did you set the DUI rotor to TDC on the flywheel?
I set the rotor to just about at #1 plug wire then rotated the distributor until I consistently get the #1 plug firing at just before the BB. Here is a thread I also started and got good advice checking the timing. I pulled the distributor again and checked. I also switched the plug wires to see if I was 180 degrees out and that definately wasnt it.

 
Sounds like you might have 12 volts cranking but no voltage with the key on? Make sure you have power to the dui in the run position. Also carb solenoid working? These flood easily, check your plugs!!
Hi,
I have good voltage during cranking, my timing light has a voltmeter on it. The batteries don't run down even after cranking 20 times. I definately get wet plugs. Yes, the carb solnoid is engaging. I hear it click when I turn on the power at the battery isolator.

I think its a fueling problem, as in too much. Or too lean when trying to start but eventually still fouling the plugs. Should I start with the idle air correction screw, throttle idle stop screw, choke, starting with throttle or something else when the batteries are topped up and the plugs have dried out overnight?

Thanks all!
 
Maybe try an old points dizzy to verify it's not the D.U.I.?
I appreciate the idea, and I do have the old dizzy available. However I have no indication that spark is a problem here...the DUI distributor worked before the rebuil and I get consistent spark and no voltage dropoffs. I rebuilt the carb so I suspect maybe I didnt set up something right or have a baseline setting right on it. The carb did work before the rebuild, though very dirty.

Can we try some diagnosis on fueling mix and startup procedure and see if that works? I have no reason to suspect a spark or compression problem.
 
Are you sure you have a good ground from block to the battery? You could temporarily hook a jump cable from Batt - to engine block.

If you think it's flooded, peg the throttle wide open and crank without pumping.

As far as carb settings, I've seen fj40jim recommend 4 turns from bottomed out on the air mix screw. I'd back the throttle positioner screw out and then in til it just barely makes contact. Also would shine a light down carb see that both throttle plates look virtually closed.
 
If the issue isn't spark related, might not hurt to double check that your valves are still set to spec.
 
Have you pulled a plug, hooked it up to the plug wire and checked for spark? Regardless of any carb setting issue it should start and at least cough and puke and smoke? Wet plugs? =Ignition issue..... or the fuel is just dumping in? Hold the throttle wide open and crank til it fires!
 
All good ideas here...

@whitey45 suggested, “Make sure you have power to the dui in the run position”. As you stated, it’s cranking fine, but do you have power to the dui, when the ignition is in “run” position?

Your dui requires full battery voltage (e.g. no ballast resistor)... where are you getting power for the dui?

My (1978) dui power is fed from a relay, triggered (relay-86) by voltage on the 12ga BY wire.

When triggered, the relay provides full battery voltage to the dui, via relay(87). Battery-Pos to relay-30/51... ground to relay-85.

Speaking of battery... you mention two batteries. They are wired for 12vdc (parallel), not 24vdc (series)... right?

Performance distributors recommends spark plug gap at .050-055”... I gapped mine at .050”. They recommend timing at 12*BTDC... my timing is ~12*BTDC. My 2F screams with these settings.

Firing order (on my 2F) is. 1-5-3-6-2-4 is your firing order correct?

Does your dui have a vacuum advance module?


What fuel pump are you running? Does it pump enough volume? Should pump 1 cup in 15 seconds. Use @pin_head’s test instructions in post 2 —-> Fuel /air mixture problems?

If it doesn’t pump 1 cup in 15 seconds, the filter could be dirty, the carb may have a dirty screen at the fuel inlet, your hard fuel lines may have crud in them, your fuelmay be dirty, your fuel tank may be dirty, the fuel pickup may be blocked, by something floating into it, when fuel is pumped. With your symptoms, I would check/clean/replace each of the above.

That same post (above) has info about air-fuel mixture.

Always start with your fuel filter - make sure it’s clean... new is a cheap fix.

Set idle at 650rpm
... if you can’t get that low, it’s probably running rich and/or you have a vacuum leak.

For, Air-fuel mixture: use the lean-drop method: remove the screw and check the pointy end for deformation. If deformed, try to source a good replacement, or carefully reshape it. Screw it all the way down... be careful NOT to tighten it so much that it deforms the point. Unscrew three full turns, start the engine and screw it back down until the engine starts to die. Back it off, to a point where it idles smoothly and doesn’t ping.

Make sure you have NO vacuum leaks.

Good luck!!
 
If your float valve is stuck open you will have gas pouring out the bowl into the throttle bores and could cause a 'wet-plug'. If your slow circuit isn't working (no power to the idle cut solenoid, debris ect.) that would also cause trouble. Carbs are simple, and I wouldn't expect much on that front.

Have you tried capping all the vac lines from the intake?

Along the lines of Thebigredrocker's advice, valve spec can be checked, but you can also do a compression check.

Always make sure you have oil pressure when doing any cranking.
 
If the plugs are saturated, then obviously you have to much fuel in the cyldrs. Either by pumping the accelerator, closing the choke to long, pouring gas down the carb, or the carb is leaking fuel. Letting sit overnight is not enuff for it to dry out. You should pull all the plugs and crank the engine over with the throttle wide open to blow out the fuel in the cyldrs, blow the plug with compressed air, or use a lighter or propane torch to burn excess fuel off them. As Big Red mentioned, if it is truly flooded, you should try to start it with the choke and accelerator wide open to get more air in the cyldrs. Even if it trys to start to fire keep cranking the starter until it starts to accelerate. If it's really flooded it my have to be run for quite a while to burn the excess fuel. The oil should be changed once you get it running. Fuel is probably washing the oil off the cyldr walls and rings and contaminating the oil.
 
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Hi and thanks for all the replies. I am still about the same situation. It coughs and sputters for about 4 or 5 revolutions and dies. Here is what I did;

1. Verified good ground. 0 gauge cables from battery to frame, body and engine block.
2. Distributor gets 12.7v in start and run positions.
3. Verified compression in all cylinders.
4. Idle mixture screw 4 turns out from bottom.
5. Throttle idle screw just barely activting the throttle.
6. Throttle plates closed.
7. Accelerator pump works
8. Fuel level stays in the middle of the window. Float works.
9. I replaced the hard lines with new lines, they were clean.
10. Fuel pump is OEM new and veerified its flowing. I didnt measure the volume but it is putting out lots of fuel.
11. New fuel filter. Tank is freshly dipped and lined.
12. Dual batteries are in parallel with a Blue Sea Systems ACR and Off-Either-Both cutoff switch. I have a solid 12.8 resting voltage and very little drop. All the other electrical functions are working properly.
13. Plugs gapped to 0.045

Who was it up there that said carbs are easy ;0) I have a good deal of experience with Webers so I get the concepts but the linkages etc on these Aisins are different.

I tried starting it and same situation. I did this all with the choke all the way in (open).

1. Tried cold start x5.
2. Tried cold start 1 pump before.
3. Tried cold start 2 pumps before.
4. Tried cranking WOT.
5. Started at #1 again...

While I wait for another reply I'll go pull the plugs and check timing again.

Should I re-start my experimentation with different choke, throttle screw, mixture screw or other adjustments? I dont just want to keep blindly hoping to get the right combination...my mind needs order!

Thanks again!
 
how are you verifying good spark? Still think it’s ignition related. You cannot dial in carb settings until it runs!
 
On those 5 pin hei modules I know if you get the connections wrong it puts the ignition 10 degrees retarded [or advanced ?] . Is it all wired up exactly the same as before? Also the wires from the pickup coil have to be on their correct pins on the module.
Maybe whoever rebuilt the engine botched the cam timing lol. Just kidding, but I suppose it could happen.
 
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