Jekyll and Hyde engine frustration

[Slow Poke]

I have a 77 FJ40 with a desmogged 2F and what I believe to be the original Aisin Carb. The truck starts easily and warms up quickly. Within just a couple of minutes it’s happily idling with the choke completely off. I can drive it to town ( 10 miles ) shut it down and then 5 or 10 minutes later start it back up and head home. On the return trip it’s harder to start and idles poorly. It stumbles on acceleration and generally limps home. While it’s hot and unhappy I’ve been unable to adjust the carburetor and improve the situation. It feels like it’s just not getting enough fuel but I could be wrong about that.

So far I have pulled the manifolds off and had them machined. They put a new heat riser block off plate in and I installed the manifolds using a Remflex gasket. I also pulled the carburetor and rebuilt it myself twice. The engine pulls 17inHg at idle ( 1000 ft elevation) with the timing set at 7degrees advance. I’ve sprayed WD40 along the intake and carburetor base without any change. I’ve plugged the brake booster hose too but so far I haven’t discovered what the issue is.

Any suggestions about where else to look?

 

[charliemeyer007]

Warms up quickly? I think you are running lean and/or retarded perhaps both. Do the read the spark plug check. How old are your plug wires. Open the hood on a no moon night away from lights and start it up - look for dancing fire off the plug wires/dizzy. Dial in a little more timing 11 degrees. If your dizzy cap has aluminium contacts inside, scrap the scab of corrosion off with the small blade of a Swiss Army Knife. Aluminium Oxide is an insulator.

Warm days cold nights condenses water right out of the air in tanks yours and the station. A wet paper fuel filter will not pass fuel easily - add a bottle or two or the yellow gas drier to your tank. Put on a new fuel filter, set the old one in the sun for a few days - it will dry out and can be reused. Keep a new one in the glove box, and cycle the other 2 as needed.

A 10 mile drive - You need to give it an Italian tune up - take it on the road for an hour or so and drive it hard!

 

[Pighead]

I'd try advancing your timing a bit. It might bring your vacuum up

 

[Slow Poke]

The plugs don’t look lean to me. Maybe a little like it’s running rich. I found the accelerator pump boot has separated. It’s only a month old. I’ve had 3 of them and none of them last. Is that a possible vacuum leak source?

 

[Pighead]

Is that a possible vacuum leak source?

no.

 

[pb4ugo]

It's hard to tell with your plug pic, but the white porcelain indicates your close with mixture the darker side could be from contamination of some sort. It's hard to see the back side of the ground strap in the pic, but it looks like you might try advancing the timing a bit.

 

[Slow Poke]

I moved the timing to 11 degrees. It helped a little. Maybe. It still misses pretty bad when warm. It’s not really drivable anymore without arranging for someone to come get me. I’ve thought about trying another carb or a sniper but if it runs great when cold it doesn’t seem like the carb is the problem

 

[charliemeyer007]

Does the coil get really hot? Put a $9 electric fuel pump inline and see if it helps.

https://www.amazon.com/dp/B0DGQFTH1G?tag=ihco-20

 

[Pighead]

I moved the timing to 11 degrees. It helped a little. Maybe.

Some people say 17* is a good starting spot for timing...did your vacuum improve?

 

[aztoyman]

I don't have anything with a 2F but I do have old trucks with a carburetor and points ignition that has done this. Starts and runs great and dies a few blocks away. Let it cool of and it runs great again. It was the coil.

I've also had my truck die like it ran out of fuel because I replaced the gas cap and was given a non vented one.

 

[Slow Poke]

Some people say 17* is a good starting spot for timing...did your vacuum improve?

I was frustrated by the situation and just buttoned it up and went in the house and had dinner. So I’m not sure. Tomorrow I’ll get the gauge out and get a reading. 17 degrees sounds nuts. It’s worth a try though, its not like it’s hard to put back

 

[Slow Poke]

. It was the coil.

There’s something I haven’t checked. Good thought

 

[mattressking]

If your truck runs better with 17* of timing, you've got vacuum/tuning issues. Your truck should run smooth at 7* and see 20inHg. You only advance timing at elevation above 4k or for a little peppiness bump, but not to exceed 10-11* under 4k ft AGL.

Put the truck at 7* to get an accurate portrayal of vacuum at idle when cold then when hot. What you're actively doing is HIDING your issue by advancing timing, which leads to pinging and engine faults later.

 

[Pighead]

If your truck runs better with 17* of timing, you've got vacuum/tuning issues. Your truck should run smooth at 7* and see 20inHg. You only advance timing at elevation above 4k or for a little peppiness bump, but not to exceed 10-11* under 4k ft AGL.

Put the truck at 7* to get an accurate portrayal of vacuum at idle when cold then when hot. What you're actively doing is HIDING your issue by advancing timing, which leads to pinging and engine faults later.

I mis-spoke, 13* BTDC is where some people start. There are about a dozen threads on this, here's one; I like post #9

Thread 'How much Timing is to much?'

Sep 24, 2023

I did the tappet cover gasket on my 2F this weekend including pulling the distributor out. I made sure to put the distributor back in the same rotor position as when I pulled it out. I did not have a timing light on hand to verify timing, so I adjusted it by ear and set it at the smoothest idle. My girlfriend was a little confused as to why it was so much quieter haha. When I restarted the truck afterwards, it took a few extra cranks but otherwise started up and ran fine. Going for a test drive it ran like a raped ape with no odd noises or knocking of any kind.
I'm sure the timing...

• PVCsnorkel
• advanced distributor ignition power timing
• Replies: 28
• Forum: 60-Series Wagons

 

[mattressking]

I get what you’re saying but what I’m stating is that if it runs better when you add timing, you’re masking a fault. Simple, it’s standard engine theory If it runs poorly at 7* you need to fix the problem(s).

These trucks can run at altitude up to 13k smoothly at 7* they’re just ever so slightly slower to start….ive tried it with a few different trucks.

 

[Slow Poke]

I tested my coil while cold. 3.4 ohms primary and 7.6K ohms secondary. Some places suggest that it should be between.4 and 2 on the primary. I’m don’t know what the specs on this one are but I have and old one laying around that I’ll swap in and see if it changes anything

 

[pb4ugo]

Advancing the timing to a point can improve performance and fuel milage. It allows the engine to breathe a little better, just like advancing it for elevation. Don't advance it to the point of pinging. You can listen for pinging along with reading the plugs to check for to much advance without the engine pinging.

 

[mattressking]

Advancing the timing to a point can improve performance and fuel milage. It allows the engine to breathe a little better, just like advancing it for elevation. Don't advance it to the point of pinging. You can listen for pinging along with reading the plugs to check for to much advance without the engine pinging.

Correct but everyone is missing my point here, if you are correcting a fault, advancing the timing masks the issue, simple as that. Fix the issue, then tune.

 

[middlecalf]

I’m not missing your points () @mattressking, you’re spot on.

Rapidly scanned the earlier posts, didn’t obviously see anything about your distributor @Slow Poke. Is it still points, and if so, have you looked at them?

 

[Slow Poke]

The distributor is a small cap electronic distributor off a 1980 I think. I bought it from Jim C a few years back. The coil I’m using says “use without external resistor” but the old one in my parts box says it needs an external resistor. As I’m pulling this apart I see what looks like a resistor. Now I’m not sure what I have here.