2F loses power when warmed up, Ideas? (1 Viewer)

[Rick '79 FJ40]

I have just gotten my '79 FJ40 on the road after about 8 or 9 months of work on the steering and other stuff. I drove it to work today for the first time.

As background, this is a 2F with a Weber carb, headers and factory '79 electronic ignition distributor. There is also a fuel pressure regulator valve inline in the fuel line. I have a small to moderate exhaust leak that I am trying to get to, but haven't yet.

I noticed today that it seems to lose some power after the engine gets up to operating temperature. It isn't really noticeable at speed, but mainly when pulling off from a stop. I also noticed it dieseled a bit when I shut it off, which I thought I had fixed by increasing the fuel pressure through the fuel pressure valve.

Does anyone have any insights or ideas as to what I should check or how to go about diagnosing the problem? I would appreciate any help you can give me.

 

[FJ40Jim]

I have just gotten my '79 FJ40 on the road after about 8 or 9 months of work on the steering and other stuff. I drove it to work today for the first time.
As background, this is a 2F with a Weber carb, headers and factory '79 electronic ignition distributor. There is also a fuel pressure regulator valve inline in the fuel line. I have a small to moderate exhaust leak that I am trying to get to, but haven't yet.

I noticed today that it seems to lose some power after the engine gets up to operating temperature. It isn't really noticeable at speed, but mainly when pulling off from a stop. I also noticed it dieseled a bit when I shut it off, which I thought I had fixed by increasing the fuel pressure through the fuel pressure valve.

Does anyone have any insights or ideas as to what I should check or how to go about diagnosing the problem? I would appreciate any help you can give me.

The dieseling is because there is no anti diesel (idle cut) solenoid in the carb.
The sag in acceleration could be many things, though I want to blame it on a too small carb.

So it seems like a carb of the right configuration and size might make all the problems go away

 

[FJ40onNOS]

check your timing, and check your dis cap. see if that help, what weber do you have?

 

[Roadnoiz40]

Have you ever run Seafoam through the engine? This will help remove the built up carbon on the tops of the pistons and stem of the intake valve. Red hot carbon particles are known to cause run on when the key is turned off.

 

[ken_79-fj40]

I would guess timing too. I've spent way too much time this week chasing down a hesitation/skipping problem. I spent all week re-gapping points, re-timing my truck each time,going on multiple "test runs" only to finally discover last night my truck didn't agree with the w8dc bosch plugs I put in it. Sounds silly, but if you've got these plugs in yours pick up some ngk's. My truck ran great when it was cold. Re-gapped my points back to where I started, re-timed it, put ngk's back in, runs like a top now.

 

[FJ40onNOS]

nice, i have found the the smallest things that you never think of fxxx up

 

[Rick '79 FJ40]

My carb is a 38.

On the timing, I think I have heard that you need to advance a de-smogged 2F (I forgot to mention it's de-smogged, but you probably knew that because I have a Weber on it) How much advance should there be? I just bought a timing light, but haven't tried it yet. It's been a long time since I have used one and my eyesight is not what it used to be. I hope I can see the marks...

Thanks!
Rick '79 FJ40

 

[Rick '79 FJ40]

Loss of power after warm-up

Have you ever run Seafoam through the engine? This will help remove the built up carbon on the tops of the pistons and stem of the intake valve. Red hot carbon particles are known to cause run on when the key is turned off.

I've heard people talk about Seafoam, where do you get it? I've looked for it at my local autoparts store (Advance) but haven't found it if they have it...

Thanks!

 

[Rick '79 FJ40]

I would guess timing too. I've spent way too much time this week chasing down a hesitation/skipping problem. I spent all week re-gapping points, re-timing my truck each time,going on multiple "test runs" only to finally discover last night my truck didn't agree with the w8dc bosch plugs I put in it. Sounds silly, but if you've got these plugs in yours pick up some ngk's. My truck ran great when it was cold. Re-gapped my points back to where I started, re-timed it, put ngk's back in, runs like a top now.

Hmmm...that's interesting. I haven't been doing much to my engine so far. I've been working my way through "issues" in the order of most annoying to less anoying. The PO had just put plugs in, but I don't remember what they were. I don't think they were Bosch, but I don't think they were NGK either. Probably something common like Champion or Autolite... I'll look into that, though.

Did you replace the electronic ignition that came on your '79 with a points distributor? If so, do you like it better than the factory dist.?

Thanks!
Rick '79 FJ40

 

[Rick '79 FJ40]

Power loss after warm-up

The dieseling is because there is no anti diesel (idle cut) solenoid in the carb.
The sag in acceleration could be many things, though I want to blame it on a too small carb.

So it seems like a carb of the right configuration and size might make all the problems go away

Jim,

I forgot to ask, can an idle cut solenoid be added to a Weber carb? If so, is it expensive?

Thanks!
Rick '&( FJ40

 

[Rick '79 FJ40]

Power loss after warm-up

I would guess timing too. I've spent way too much time this week chasing down a hesitation/skipping problem. I spent all week re-gapping points, re-timing my truck each time,going on multiple "test runs" only to finally discover last night my truck didn't agree with the w8dc bosch plugs I put in it. Sounds silly, but if you've got these plugs in yours pick up some ngk's. My truck ran great when it was cold. Re-gapped my points back to where I started, re-timed it, put ngk's back in, runs like a top now.

I forgot to ask, do you know what the part number is on the NGKs you used?

Thanks!

 

[ken_79-fj40]

I didn't put the distributor in, that was 2 owners ago. If it were me I would have left the stock electronic distributor in it. The guy I bought it from actually didn't even notice it had points in it. But he only drove it about 15 miles in the six years he had it. My truck has a mallory centrifugal advance only points distributor in it. Which, when the points are properly gapped and it has the right plugs in it, seems to work fine.

 

[Rick '79 FJ40]

2F loses power on warm-up

I didn't put the distributor in, that was 2 owners ago. If it were me I would have left the stock electronic distributor in it. The guy I bought it from actually didn't even notice it had points in it. But he only drove it about 15 miles in the six years he had it. My truck has a mallory centrifugal advance only points distributor in it. Which, when the points are properly gapped and it has the right plugs in it, seems to work fine.

Thanks for the info...

I was just wondering if there was some reason I shouldn't be satisfied with my factory dist.

Thanks!

 

[Mace]

79 factory dist is awesome.


Do you have a header on it?
I am wondering if you have a hairline crack in the base of the intake manifold that when the motor warms up allows the crack to open up. Leaning out the motor. That would account for the dieseling too.

Hmm..

 

[Ian Rogers]

I've heard people talk about Seafoam, where do you get it? I've looked for it at my local autoparts store (Advance) but haven't found it if they have it...

Thanks!

Napa is one only place that sells if.... im not sold on it. I think that Seafoam is the reason that i burned out my 9mo O2 sensor in my truck

 

[jjhancock]

I did a seafoam treatment on my 81 fj40 and it didn't seem to do anything at all for me. There are also verious ways to administer a seafoam treatment, but I just pulled the air cleaner and poured it (very slowly) into the air horn in the "inside" barrel. I was expecting it to smoke like hell and to have to drive it around in the country so as not to offend my neighbors.

I got new ngk plugs, plug wires, dizzy cap, rotor, and have replaced pretty much all of the vacuum lines and some fuel line. I also did a BG44-K treatment which for 20 bucks didn't seem to help much either.

My carb is getting rebuilt by Jim C right now. In our conversations he has said to me what I have described sounds like a malfunctioning or worn accellerator pump.

You obviously have a different carb setup than me so this might not be that useful. However, if you plan to wheel this truck, it is my understanding that weber and edelbrock's on the 2F are very poor in off-camber situations. You could probably get a used carb fairly cheap and have it rebuilt if you do plan to wheel the truck. Good luck.

 

[FJ40Jim]

I forgot to ask, do you know what the part number is on the NGKs you used?
Thanks!

Rick, NGK BPR5EY or a ND W14EXR-U are both excellent plugs for a '79 2F.

 

[srafj40]

I would guess timing too. I've spent way too much time this week chasing down a hesitation/skipping problem. I spent all week re-gapping points, re-timing my truck each time,going on multiple "test runs" only to finally discover last night my truck didn't agree with the w8dc bosch plugs I put in it. Sounds silly, but if you've got these plugs in yours pick up some ngk's. My truck ran great when it was cold. Re-gapped my points back to where I started, re-timed it, put ngk's back in, runs like a top now.

Ditto and then a vacume leak and bingo (have not seen that mentioned yet).

 

[Rick '79 FJ40]

2F loses power when warmed up...

Rick, NGK BPR5EY or a ND W14EXR-U are both excellent plugs for a '79 2F.

Thanks Jim!

I'll try one of those.

 

[Rick '79 FJ40]

2F loses power when warmed up...

79 factory dist is awesome.


Do you have a header on it?
I am wondering if you have a hairline crack in the base of the intake manifold that when the motor warms up allows the crack to open up. Leaning out the motor. That would account for the dieseling too.

Hmm..

Yes, I have a header. I know I have at least one exhaust leak, I think on the collector pipe where it goes into the exhaust pipe, but I could have one in the manifold area, too. There could easily be a crack in the intake manifold as well.

I'm thinking of replacing the vacuum lines to try to eliminate that possibility. Do you know what the size is or what size will work for aftermarket vacuum hose?

I have a distributor cap and rotor I bought for spares. I will try replacing them tonight to see if that makes a difference, too.

I need to break out my timing light to see what it looks like. I'm hoping I can see the marks. My eyesight is pretty bad, especially when it comes to checking measurments and stuff like that...

Thanks for the help!