74 fj40 low throttle response and running rough (1 Viewer)

[nitroid13]

Ok in the video is exactly what it's doing and I'm unsure why the carb is making the hissing sound and running rough. It's been running really well lately, but recently it's been giving me problems running and accelerating. It may be fuel or spark I not really sure.

On the fuel side of things its a new filter and electric pump. I took the top of the carb off and made sure it was visually clean and no water inside that i could see.

As to timing, I looked at the timing with my light (in picture), I had to turn the dial up to like 25 to 30 degrees before I could see the mark(not hole, but line on flywheel). If set correctly though it runs much worse will die. I found a post on here about cheaply recurving the dizzy and I have already ordered the spring kit and installed the new aluminum bushing on the pin in the dizzy. Question is the barring plate that holds the pickup available anywhere?(Pic included). Also I'll include another pic of the bottom of the inside of the dizzy where it seems its machining a Grove in the bottom. I'm sure it's not supposed to do that lol. any ideas as to why it's doing this?

On the vac advance vac lines I got the back port ran to carb and the front ran to a port on the intake?

Any help is greatly appreciated.

General info

1. 1.5f with 83 FJ60 valve cover, valves were set correctly to fsm specifications, however this was about 7 to 8 years ago
2. Original 72-74carb(rebuilt 5 or so years ago by a forum member), new gaskets as well.
3. 83 fj60 big cap dizzy, igniter, and dent side cover(in the process of recurving the dizzy)
4. New denso plugs, cap, rotor, coil, and wires
5. 83 fj60 transmission/transfer case, flywheel and clutch

 

[45Dougal]

Do you have an air leak?

 

[65swb45]

Check compression, vacuum, adjust valves and recheck. With that much advance on the timin, you should have a lot of vacuum, and no hesitation in acceleration.

 

[nitroid13]

Do you have an air leak?

Unless there is a problem with my insulator under the carb, I do know over time they can get warped or cracked. And to my knowledge it's not cracked and I got the hose ran to the pcv valve over on the other side. I am considering doing a efi swap and I know one of the things you need to do is make sure the intake surfaces are perfectly flat and even

 

[nitroid13]

Check compression, vacuum, adjust valves and recheck. With that much advance on the timin, you should have a lot of vacuum, and no hesitation in acceleration.

I'll look into doing a compression test tomorrow and maybe adjusting the valves tomorrow as well. Am I correct in assuming that the engine needs to be warm to adjust the valves? i know there is a procedure that you start at top dead center and do half the vavles in a numbered order and roll it over 180° and do the other vavles. it ls been a very long time since I did it last.

 

[nitroid13]

Check compression, vacuum, adjust valves and recheck. With that much advance on the timin, you should have a lot of vacuum, and no hesitation in acceleration.

I'll look into doing a compression test tomorrow and maybe adjusting the valves tomorrow as well. Am I correct in assuming that the engine needs to be warm to adjust the valves? i know there is a procedure that you start at top dead center and do half the vavles in a numbered order and roll it over 180° and do the other vavles. it ls been a very long time since I did it last.

 

[65swb45]

Time to research the FAQs.

 

[igotta40]

If you’re hearing a hissing sound and it’s running poorly then check for a leak in your brake booster.

 

[nitroid13]

I ran a compression test and it went as follows (throttle open and all plugs out)
1. 135
2. 130
3. 127
4. 125
5. 131
6. 120
The plugs are new denso' s from cruiser outfitters. However they had alot of black soot on them probably from running a bit rich. So i cleaned them and it is running better ish... it's still bogging under load. As to the break booster it's a fairly new unit from btb and takes a gm master cylinder. So unless the grommet is bad I don't think there is an issue there. The vac is tested from the port on the intake that is hooked to the outer port the advance on the distributor. If i rotate the distributor all the way counter-clockwise it stars to idle smoother and the vac goes up. And when I put a timing light on it you can't see the mark until you turn the dial to almost 40° of advance. And this is when i tested the vacuum. But if I turn it all the way the other way it puts the line on the flywheel on the needle and the setting on the light can be dropped to 7 degrees. But it runs really low and has a chopy idle. I think this may be a fuel problem in the carb.

I did finish the cheap recurve on the dizzy that I found on another post on here.

 

[65swb45]

Do a little more research on the faq. Manifold vacuum is NOT appropriate to run a vacuum advance distributor.

 

[nitroid13]

Do a little more research on the faq. Manifold vacuum is NOT appropriate to run a vacuum advance distributor.

Ok I see something I'm getting wrong and that's the ports on the dizzy advance and believe I need run the inner port on the advance to the side of the carb and just cap the other off. I don't think I need the extra advance especially since I'm basically at sea level lol

 

[fyton2v]

Not an expert at these things, but I’d block the vacuum ports on the dizzy and manifold until you get the motor running correctly. The extra advance at the wrong time will just make things worse. Compression looks ok. With those ports closed, first make sure you don’t have a vacuum leak. When you feel confident that you don’t, set your timing correctly and run through the “lean drop” method to set your idle and mixture. Make sure you’re pulling 15+ PSIG with that vacuum gauge. If it’s still running poorly … well, at least you ruled out the most basic problems.

 

[nitroid13]

Not an expert at these things, but I’d block the vacuum ports on the dizzy and manifold until you get the motor running correctly. The extra advance at the wrong time will just make things worse. Compression looks ok. With those ports closed, first make sure you don’t have a vacuum leak. When you feel confident that you don’t, set your timing correctly and run through the “lean drop” method to set your idle and mixture. Make sure you’re pulling 15+ PSIG with that vacuum gauge. If it’s still running poorly … well, at least you ruled out the most basic problems.

When I get home I'll will disconnect the brake booster and block it off to see if it's a problem. I may have a blown intake/exhaust gasket. It was new when I rebuilt the engine in 05 or so it may be that. I do appreciate everyone for all the suggestions with me on this

 

[nitroid13]

When I get home I'll will disconnect the brake booster and block it off to see if it's a problem. I may have a blown intake/exhaust gasket. It was new when I rebuilt the engine in 05 or so it may be that. I do appreciate everyone for all the suggestions with me on this

So what i did is disconnected the vac and pluged the lines and reset the dizzy, then hooked the inner port to the the port on the carb and left the other pluged. And its running better and it has power under load, but its still running rough and has rough accelerating. I did to a manifold vac test with my mityvac gauge and its running around 17 psi. Another thing i need to note is my idle air screw on my carb has absolutely no effect on idle if you go all the way in or out there is no change. Now I do run 10% ethanol in the gas I know its bad and horrible for the carb but its all i can get localy unfortunately. Are there any kits or builders that make them compatible with ethanol? I'm thinking about sending mine to trollhole

 

[fyton2v]

Did you check for a vacuum leak?

 

[nitroid13]

Did you check for a vacuum leak?

Ya I used some spray around critical areas manifold, carb base, booster grommet, etc. It didn't seem to affect anything.

 

[45Dougal]

Maybe you also have a slight fuel issue which exacerbated your timing?
Did you check the pressure output of the fuel pump was OK for your carb?
No water in the new filter?

Think you both mean In HG, not PSI btw

 

[nitroid13]

Maybe you also have a slight fuel issue which exacerbated your timing?
Did you check the pressure output of the fuel pump was OK for your carb?
No water in the new filter?

Think you both mean In HG, not PSI btw

Fair point I miss spoke lol. I don't have a fuel pressure gauge. I'll look into getting one. Bur it's just one of those clickty clack electric pumps because I'm poor . I need to find a good mechanical pump or at lest a kit. And no water in fuel filter I posted a pic of it above

 

[45Dougal]

Fair point I miss spoke lol. I don't have a fuel pressure gauge. I'll look into getting one. Bur it's just one of those clickty clack electric pumps because I'm poor . I need to find a good mechanical pump or at lest a kit. And no water in fuel filter I posted a pic of it above

Ah yea forgot.
Reason I asked is that this is exactly how my VF750 behaves when it has a blocked jet.

 

[nitroid13]

Ah yea forgot.
Reason I asked is that this is exactly how my VF750 behaves when it has a blocked jet.

It could absolutely have a blocked jet. My plan is to bench clean the carb and see if it helps. I rebuilt it not to long ago with a kit. Do they have a kit out there that's compatible with 10% ethanol fuel?