81 FJ-40 - Hesitating / bucking under acceleration

[AYM707]

So I purchased a new distributor cap (mine was chipped) and a new rotor. I noticed the new rotor has a rough edge (black bit) at the tip. not sure if this is a protective coat or something that helps the current transfer. Feels alot like a match box but my old rotor did not ave it, or it wore out years ago. Am I supposed to rub it off or let it be?

 

[MatthewMcD]

So I purchased a new distributor cap (mine was chipped) and a new rotor. I noticed the new rotor has a rough edge (black bit) at the tip. not sure if this is a protective coat or something that helps the current transfer. Feels alot like a match box but my old rotor did not ave it, or it wore out years ago. Am I supposed to rub it off or let it be?

View attachment 3911586

Let it be.

 

[charliemeyer007]

I'm guessing its a conductive compound to wipe the aluminium contacts. I vote you leave it alone and just trust Mr. T. I like NAPA Echlin stuff - they were brass; not sure if they are still.

 

[65swb45]

I'm jumping back on this after a few weeks of "other" things.

I did do some preliminary investigations; opened it up, cleaned / sanded the copper connectors. I have also increased / overcome my fear with "playing" with the distributor. I also experimented with starting / turning the engine with the distributor open / disassembled. Problem is the dwell meter is always reading. When the engine is off, the meter shows ~60 degrees, but when you start / turn the engine, it drops to 36 degrees. This means....this is a 2 person job.

My distributor cap is also chipped where the cable #4 connects. Not a big issue, but ordered a replacement.

@pb4ugo / @65swb45 / @MatthewMcD

I re-read all the threads, so just to confirm what I'm doing one last time...my dwell angle is 36 deg and I need to increase the angle to min 40/41 deg. This means I have to decrease the gap; ie using a slot screwdriver in the slot near screw 2; move the points slightly closer to the cam shaft. I am assuming this is a hair's width adjustment.

Gap decrease = dwell angle increase?

Apologizes, I'm asking baby steps; but dont want to screw this up. Appreciate your confirmation / support.

What does your feeler gauge give for a point gap currently? Remember, as you close the gap, you're also increasing the likelihood that the points will arc and burn.

 

[AYM707]

Jumping back to this....

Finally got some time & courage to do this. After several attempts, I've ended with ...

I know I'm a bit out of spec (40-41 degrees); but thinking this is good enough for a solo / unexperienced person like myself. The angle slightly varies 41.3-41.5; but dont think that's a big difference. I need to take it out for a test drive later today.

@pb4ugo / @65swb45 / @MatthewMcD - thank you for your support & guidance.

I have also noticed my fuel pipe, upstream of the fuel filter is a bit long. In fact, it makes a loop before connecting to the fuel filter. I am going to shorten that, as it might disrupt the supply of fuel when there's a increased acceleration.

 

[65swb45]

While it’s apart, put a shot of air through the line back to the tank (gas cap off!) to make sure your pickup is clear.

 

[AYM707]

Well ...the test drive was very disappointing...

Yes, the hesitating was reduced...but now its misfiring!! mainly in 2nd gear & a few times in 3rd gear. Typically when I do a gear change. It feels like the brake is engaged when I reach the top of the 2nd gear. I hear it in the back, ie out the exhaust like a fire cracker; but you also feel it. My clutch was also acting up; need the bleed it again.

Recounting my steps :

1. Before I started, my engine would hesitate / struggle, typically after I would change into 2nd gear. No misfiring.
2. Cleaned the contacts of the existing distributor cap and rotor. The hesitating was significantly down / reduced. No misfiring.
3. Replaced the chipped distributor cap & rotor. The new distributor & rotor matched the old units. Also replaced the screws for the points. Noticed misfiring in 2nd & 3rd gears. Checked the dwell angle and noticed my dwell angle increased to 35 degrees (previously it was 36 degrees). I assumed I had over tighten the points and this was causing the misfiring.
4. Fixed / adjusted the dwell angle to 41.3 degrees; helped with the hesitation, but still feels like I'm driving with my brake engaged. Engine is still misfiring. Replaced the new distributor & rotor with the old units, and its still misfiring on 2nd gear.

I'm not sure what I should do ??? This is really frustrating.

Thinking of going with an electronic distributor, but not sure which product is best suited for my vehicle. I would like a plug 'n play unit.

 

[pb4ugo]

Did you readjust the timing after adjusting the points? Are your brakes actually dragging? The engine will seem sluggish if the timing is too retarded, advancing the timing the engine will run sportier. If the engine pings under load your timing is too far advanced.

 

[MatthewMcD]

Well ...the test drive was very disappointing...

Yes, the hesitating was reduced...but now its misfiring!! mainly in 2nd gear & a few times in 3rd gear. Typically when I do a gear change. It feels like the brake is engaged when I reach the top of the 2nd gear. I hear it in the back, ie out the exhaust like a fire cracker; but you also feel it. My clutch was also acting up; need the bleed it again.

Recounting my steps :

1. Before I started, my engine would hesitate / struggle, typically after I would change into 2nd gear. No misfiring.
2. Cleaned the contacts of the existing distributor cap and rotor. The hesitating was significantly down / reduced. No misfiring.
3. Replaced the chipped distributor cap & rotor. The new distributor & rotor matched the old units. Also replaced the screws for the points. Noticed misfiring in 2nd & 3rd gears. Checked the dwell angle and noticed my dwell angle increased to 35 degrees (previously it was 36 degrees). I assumed I had over tighten the points and this was causing the misfiring.
4. Fixed / adjusted the dwell angle to 41.3 degrees; helped with the hesitation, but still feels like I'm driving with my brake engaged. Engine is still misfiring. Replaced the new distributor & rotor with the old units, and its still misfiring on 2nd gear.

I'm not sure what I should do ??? This is really frustrating.

Thinking of going with an electronic distributor, but not sure which product is best suited for my vehicle. I would like a plug 'n play unit.

My brakes were dragging, but that only impacted my top speed, not the engine performance. (I can't drive 55)

Does it misfire when you rev the engine standing still?

I'd start back at the start.
Check the distributor timing, make sure it's pointing at #4 at TDC on #1 (refer to the FSM instructions on reinstalling the distributor if you are unsure. Make sure you are spot on and not 180* out.)
Recheck your dwell (or points gap)
Check your distributor cap and make sure the central electrode spring is working (I had mine seize up after a bad backfire.)
Set your ignition timing at the 7* ball bearing or a little better (advanced) (I don't recall if your distributor is vacuum advance or retard, but that should not be the issue at this point. But disconnect the vacuum while setting the timing.)

After this, if it hesitates when you rev the engine or after a few seconds at high RPM, see if you can watch the fuel level in the carb sight glass. If the level drops you may have a dirty needle valve or fuel delivery issue that's starving it at higher RPMs.

 

[AYM707]

My brakes were dragging, but that only impacted my top speed, not the engine performance. (I can't drive 55)

Does it misfire when you rev the engine standing still?

I'd start back at the start.
Check the distributor timing, make sure it's pointing at #4 at TDC on #1 (refer to the FSM instructions on reinstalling the distributor if you are unsure. Make sure you are spot on and not 180* out.)
Recheck your dwell (or points gap)
Check your distributor cap and make sure the central electrode spring is working (I had mine seize up after a bad backfire.)
Set your ignition timing at the 7* ball bearing or a little better (advanced) (I don't recall if your distributor is vacuum advance or retard, but that should not be the issue at this point. But disconnect the vacuum while setting the timing.)

After this, if it hesitates when you rev the engine or after a few seconds at high RPM, see if you can watch the fuel level in the carb sight glass. If the level drops you may have a dirty needle valve or fuel delivery issue that's starving it at higher RPMs.

It only misfires while driving; no misfiring when in neutral and engine is rev'ed.

Will go through the remaining items this weekend. Thanks for check list.

 

[firemanj92]

So I purchased a new distributor cap (mine was chipped) and a new rotor. I noticed the new rotor has a rough edge (black bit) at the tip. not sure if this is a protective coat or something that helps the current transfer. Feels alot like a match box but my old rotor did not ave it, or it wore out years ago. Am I supposed to rub it off or let it be?

View attachment 3911586

It's a RFI reducing coating but also to help reduce spark erosion

 

[AYM707]

My brakes were dragging, but that only impacted my top speed, not the engine performance. (I can't drive 55)

Does it misfire when you rev the engine standing still?

I'd start back at the start.
Check the distributor timing, make sure it's pointing at #4 at TDC on #1 (refer to the FSM instructions on reinstalling the distributor if you are unsure. Make sure you are spot on and not 180* out.)
Recheck your dwell (or points gap)
Check your distributor cap and make sure the central electrode spring is working (I had mine seize up after a bad backfire.)
Set your ignition timing at the 7* ball bearing or a little better (advanced) (I don't recall if your distributor is vacuum advance or retard, but that should not be the issue at this point. But disconnect the vacuum while setting the timing.)

After this, if it hesitates when you rev the engine or after a few seconds at high RPM, see if you can watch the fuel level in the carb sight glass. If the level drops you may have a dirty needle valve or fuel delivery issue that's starving it at higher RPMs.

I am just re-thinking my steps to how I got here. I did not adjust the timing while fixing the dwell, is it that now I've changed the dwell the timing is off? I had misfiring when my dwell was 35 degrees; and now at 41.3 degrees. Timing has to match the adjusted dwell? but then, why doesn't misfire in neutral. When in the garage, if I rev the engine, there's no misfire???

How do i check / know if the distributor is vacuum advanced / retarded? Looks like I have to purchase a timing light.

 

[MatthewMcD]

I am just re-thinking my steps to how I got here. I did not adjust the timing while fixing the dwell, is it that now I've changed the dwell the timing is off? I had misfiring when my dwell was 35 degrees; and now at 41.3 degrees. Timing has to match the adjusted dwell? but then, why doesn't misfire in neutral. When in the garage, if I rev the engine, there's no misfire???

How do i check / know if the distributor is vacuum advanced / retarded? Looks like I have to purchase a timing light.

I don't know why it misfires under load and not in neutral. That is what has me scratching my head.

If you don't have a timing light, how have you been adjusting your timing? This is a popular one on Amazon. Not the cheapest, but it does tach, dwell, and timing, with advance options. https://amzn.to/44qEV9D (Plus, Prime Days are next week so you might save a little.)

You can look at the vacuum can and based on which side of the diaphragm the tube is attached.

 

[charliemeyer007]

With dizzy cap off, you apply vacuum to the unit and see what direction the plate moves. If with rotor bug then its retard, into the rotor is advancing.

 

[MatthewMcD]

but then, why doesn't misfire in neutral. When in the garage, if I rev the engine, there's no misfire???

Once you verify the timing...

This is what I'd do. Ask what's the difference in neutral vs. driving? Is there something loose that is causing a vacuum leak? Can you push on the carb, manifold, hoses, and make it stumble?

 

[AYM707]

I don't know why it misfires under load and not in neutral. That is what has me scratching my head.

If you don't have a timing light, how have you been adjusting your timing? This is a popular one on Amazon. Not the cheapest, but it does tach, dwell, and timing, with advance options. https://amzn.to/44qEV9D (Plus, Prime Days are next week so you might save a little.)

You can look at the vacuum can and based on which side of the diaphragm the tube is attached.

View attachment 3942591

Well ... I think it is fair to say that I have not been checking the timing. That might be my problem. Ordered a similar unit from Temu (certified cheap-o here).

Based on the location of the vacuum tube, my unit is definitely a vacuum advance set-up.

 

[pb4ugo]

I am just re-thinking my steps to how I got here. I did not adjust the timing while fixing the dwell, is it that now I've changed the dwell the timing is off? I had misfiring when my dwell was 35 degrees; and now at 41.3 degrees. Timing has to match the adjusted dwell? but then, why doesn't misfire in neutral. When in the garage, if I rev the engine, there's no misfire???

How do i check / know if the distributor is vacuum advanced / retarded? Looks like I have to purchase a timing light.

When you alter the point gap you are slightly changing when the spark happens, which changes the overall timing. Always set the point gap then time it. I think i have the same timing light, it works great.

 

[MatthewMcD]

Well ... I think it is fair to say that I have not been checking the timing. That might be my problem. Ordered a similar unit from Temu (certified cheap-o here).

Based on the location of the vacuum tube, my unit is definitely a vacuum advance set-up.
View attachment 3942601

...and disconnect the vacuum line when you set initial timing.

 

[AYM707]

just an observation, I am comparing the distributor orientation between my FJ45 & FJ40.

It appears to be off by 1 cylinder; cylinder # 1 is at 12 o'clock (FJ45) vs 10 o'clock (FJ40). But I also checked it against TDC #1 and it was pointing to #1 (generally towards #4).

I also did the vacuum advance test and there was no change in RPM. Is this the culprit??? I am not sure if it can be adjusted alternatively looking for a supplier.

Noticed also my RPM was a bit low, roughly 570-590. I know the idle should be at 650 RPM. but it sounds OK. Either case, I will adjust / increase the speed to closer to 650. Will also check the vacuum at in inlet manifold.

 

[pb4ugo]

Hook a hose to the distributor vacuum advance port and suck on it. If you can suck air means its' diaphragm is bad.