HELP---Engine won't throttle up---idles rough (1 Viewer)

[JC39232]

I don't have my manuals yet but they are on the way. Hope to have them next week. In the mean time, I could use some pointers. I have searched the forums and have not found anything much that would help.

71 FJ40 with 78 2F engine. Asian carb.

So, anyway, I bought it about 2 weeks ago and ran very well the first week, accelerated good, idled at 1000, apparently no problems. While driving it the other day, I pulled up to a redlight and it started idling rough and kind of missing and I thought it was running out of gas. Put gas in it still doing the same thing. So I changed the fuel filter and the rubber lines on either end of the filter, also replaced the air filter and plugs. PO replaced the plug wires, dist. cap, and coil wire.

Still having the same problem. It will start and idles pretty smooth. Idles around 1000, will start to idle kind of "rough" and down to about 600 sometimes as low as 500. It usually will recover if I don't try to give it any gas. It does eventually however idle so low it dies. It was running perfect for the first week and I drove it probably 25 or 30 miles, maybe a little more before this problem surfaced.

So, where do I start? I'm thinking in the carb, but what I know about carbs would take me about 30 seconds to tell. Plenty of gas in the tank and it flows very freely when i took the rubber lines off. I can also see gas in the viewing window, about half way up when I shut it off a minute ago.

Thanks for the help and if any of you know a thread I can look in I would look there too. My searches just haven't found anything so far.

Thanks for any and all help.

 

[FineWynsFJ40]

Double check your points, distributor cap, rotor, etc. I had a very similar problem due to the aforementioned, and found it out after I tried everything but rebuilding the engine. Mine would do the same, idle pretty decent, but any gas over idle and it would run rough, backfire, buck, etc. Never trust PO installed stuff, it can haunt you. Were the points ground to the proper setting, contacts good, ect? Good luck!

 

[JC39232]

I don't know what the proper setting would be to grind opints to. Guess I'll have to wait on the manual. Would it have ran perfectly fine. It appeared to have no problems when I bought it. It pulled great. accelerated perfectly, started easier than my 02 silverado cold, pushed choke in after about 30 seconds of running.

Thanks. I'll check all that I can in the AM considering it's dark here an I have no lights to work by.

 

[JC39232]

Also let me clarify. When I give it gas trying to rev the engine, it will spool up some if I pump it, but if I just go straight down on the accelerator it doesn't backfire it just sputters, acts like it's not getting any gas and then "catches up".

Also doesn't idle at what I would call "fine". I probably wasn't too clear. It has to turn over a more than normal to start, then it will idle ok then rpm's decrease idles rough and sputters and spits, will catch back up but eventually will do that three or four times and then die.

Thanks for any and all help.

I want to appoligize now if I am repeating threads. I found some things. But I really need my manuals. So i guess I won't do too much to it without them.

 

[FineWynsFJ40]

Yeah, because mine was running beautifully on the way back from Drummond Island, then I came up to a 4 way stop, and coming away it all of a sudden started having the problems you had and I described above. Just like that, bam no rhyme or reason, it just happens. Ran beautifully, then in about 5 seconds went to crap. Took me $550 to figure it out, learn from my mistakes!

 

[Robert LaDuke]

If it's a '78 2F you probably don't have points. Sounds to me like fuel starvation. Maybe your fuel pump, accelerator pump, clogged fuel line or filter?

 

[JC39232]

If it's a '78 2F you probably don't have points. Sounds to me like fuel starvation. Maybe your fuel pump, accelerator pump, clogged fuel line or filter?

Brand new filter, just installed it myself. I think it has points. It has a condenser. Of course the two could be unrelated. It has the old mechanical pump on it. How would I go about checking to see if it works. Where is the accelerator pump and how do i check it?

I was thinking fuel starvation too. gas was pouring out profusely from the tank when I removed the fuel pump. Could be clogged somehow though.

Also there is a braided steel fuel line between the hard line from the pump and the hard line that goes into the carb. Could this be the problem? I have never seen a set up like this. I plan on buying or borrowing a camera tomorrow to try and post pics. There is gas in the window on the carb about halfway up the window when I turned it off a while ago. I could get my roommate to watch it while I try to rev it up.

Thanks again. Everyone on here is real patient and very helpful tips.

 

[Mr. Toad]

What you describe is sometimes called "stumble" and it can be the result of several things.

Fuel starvation has been mentioned. Don't think that just because your fuel flows freely from the tank, thru the filter and to the carb that it's getting out of the carb freely. You could have a clogged carb jet. This sounds doubtful, however, since you say that the engine "catches up." It sounds like your accelerator pump might not be functioning properly. Take off the air cleaner assembly with the engine off, look into the carb body, and pump the accelerator once (just grab the linkage with your hand and work it quickly). You should see fuel squirting in a healthy stream. If you don't, the pump needs some help.

Also mentioned is electrical. A mis-timed engine or a distributor that does not advance will cause stumble. Just because the PO put some new stuff in doesn't mean that he did it right or that it's still right. For instance, what if he forgot to tighten up the distributor collar after (or if) he timed it and the distributor moved? The timing would most likely be retarded from where it should be, and the engine will stumble when accelerated. Go thru the electrical system. By the way, the electrical system of a cruiser is not vastly different from the system on other vehicles, so your receipt of the new manuals should not be crucial to an electrical system check.

Check vacuum. Sudden onset of poor idle is often related to a brand new vacuum leak. Have the brakes suddenly become very stiff? That booster runs on vacuum. The fact that it was set to idle at 1000 rpm (that's 25% higher than it should have been set) suggests that the idle was set high to mask something else that was going on. Just check for vacuum leaks everywhere there's vacuum. I'd bet that you'll find your problem there.

Finally, there's potential air starvation, but that's not likely since you say the engine "catches up." You could run it w/o the air cleaner assembly in a very clean, non-dusty setting for only long enough to determine whether it still stumbles to rule this out.

Get a good understanding of how this unbelievably simple engine works, and you'll be able to keep it running like a finely tuned . . . tractor.

 

[JC39232]

I pumped the accelerator linkage and one jet had a very good stream. It is a 2 barrel carb so should it have two jets and should both be expressing gas when I pump it like that?

Also I am weak on electrical. The last time I messed with points and condensors was on our old tractors and I was probably 12 or 11. It's been a while. But I won't ask someone to go into too much detail here. i will just wait for the manual. How am i to turn the engine to make the points open up? My fan has a clutch on it. Is there an easy way someone has found to do that? I would appreciate any and all help.

What exactly would I be looking for in the distributor cap and rotor? The electrodes on the distributor cap look a little blackened where the rotor contacts them but I think this is normal. How much would I need to file the points and is this something that should be done with all points when bought new?

Thanks, J

 

[azlar]

I pumped the accelerator linkage and one jet had a very good stream. It is a 2 barrel carb so should it have two jets and should both be expressing gas when I pump it like that?

... How am i to turn the engine to make the points open up? My fan has a clutch on it. Is there an easy way someone has found to do that? I would appreciate any and all help.

Thanks, J

I have a similar issue with the carb accel pump. I get one anemic squirt then have to wait for the pump chamber to fill again. The PO had the idle around 1000 so it was certainly masking something.

Good news is that he had the orig jack and 2-part jack handle. You can stick the handle thru the space just above the bumper and the hooked end will mate with the crankshaft, allowing you to turn the engine a rev or two by hand. Great for adjusting valves or setting the distributor, but I wouldn't want to try and start it that way....

L

 

[JC39232]

I need to make a slight revision. Even when it is idling smooth it still sounds as if it might be missing occasionally on one cylinder. And I can ease down on the accelarator pedal and it will rev to around 1200 or 1300 then it starts to fall off and spit and sputter. If I hold steady on the accelerator it will continue to fall off. Does this sound like a timing or electrical problem or a carb problem?

I hope that is clear.

And also about the carb jet question above? Does that carb have two jets or one? And are they both supposed to squirt when the accelerator is pumped when it isn't running?

 

[Robert LaDuke]

You should see gas in only the first barrel. The second barrel opens with vaccum and only at speed.

 

[poldo]

I vote for acc pump but since you're at it why don't you just take it off and get a rebuild kit it is
pretty easy to do replace jets all the gaskets etc..

 

[Mr. Toad]

JC39232: I pumped the accelerator linkage and one jet had a very good stream. It is a 2 barrel carb so should it have two jets and should both be expressing gas when I pump it like that?
...
And also about the carb jet question above? Does that carb have two jets or one? And are they both supposed to squirt when the accelerator is pumped when it isn't running?

Question 1: That's your accelerator pump, and it sounds like it's working. It only pumps into one barrel. Cross out the accelerator pump as a potential problem. (Question 2: Your "jets"--they're different from the accelerator pump--don't flow unless the engine is running, so you shouldn't see them when you pump the accelerator with the engine off. I'm not sure you can even see them when the engine is on--I've never looked)

How am i to turn the engine to make the points open up? My fan has a clutch on it. Is there an easy way someone has found to do that? I would appreciate any and all help.

Put it in 4th gear, take off the emergency brake, and bump/roll it. It's easiest if you turn the front passenger tire, since you'll be looking in the engine compartment there anyway.

Does this sound like a timing or electrical problem or a carb problem?

Not enough info. Could be either or neither.

One note: I mentioned vacuum in my earlier post. It's still worth looking at, but I'm not as confident any more, since increased RPMs usually decrease the symptoms associated with vacuum leaks, and yours seems to do the opposite.

 

[JC39232]

Thanks everyone that has posted and given me advice. I must admit it has been a while since I turned a wrench and I always had someone to call or go see for help just down the road. I really appreciate everyone helping and offering advice. I will check all these problems out when I get the chance. I am in medical school and it is difficult to get time to work on it. I will let ya know what happened here as soon as I get it fixed.

Thanks again. This site is awesome and the search option is great as well.

J

 

[JC39232]

Distributor

I hate to piggy back my posts like this, but I have a distributor question. Haven't had time to check on all the possibilities mentioned above, but would like to have some more knowledge going into this thing.

If I check the timing and for vacuum leaks. Let's say the timing has "jumped" somehow. I have read these things have gear drives on the distributor, no belt or chain like on some engines. So, if the timing is off should I go ahead and replace the entire distributor. I have a 2F engine that according to the block numbers was manufactured in Jan 78. The distributor in it has points and a condenser. That year model was supposed to have some kind of electronic ignition in it. Would it be wise to go ahead and replace the dist. in it even if it isn't the timeing? I have no idea where to set the points for this engine.

Thanks

 

[Mr. Toad]

JC39232: If I check the timing and for vacuum leaks. Let's say the timing has "jumped" somehow. I have read these things have gear drives on the distributor, no belt or chain like on some engines. So, if the timing is off should I go ahead and replace the entire distributor.

The distributor is gear driven, but it's unlikely that your distributor has jumped. Really, the only way it could do this is if the distributor was not seated all the way down in its housing. And if that was the case, then your oil pump probably would not be pumping because it's driven by the bottom of the distributor (looks like a flat-head screwdriver tip).

You can, however, remove the distributor and re-install it a tooth or two (or more if you want to) off from where it was. This will advance or retard the position of the distributor rotor relative to the cam (and thus crank) position. Given enough clearance to rotate the distributor after it is re-installed like this, the engine would still be "time-able". But if you do this you definately want to make sure that the distributor seats properly so that it drives the oil pump.

I have a 2F engine that according to the block numbers was manufactured in Jan 78. The distributor in it has points and a condenser. That year model was supposed to have some kind of electronic ignition in it. Would it be wise to go ahead and replace the dist. in it even if it isn't the timeing? I have no idea where to set the points for this engine.

I guess you could replace it if you wanted to, but I'm not sure I'd replace anything if it was working properly. The points gap should be .018" IIRC.

Good luck with the cruiser and the cadavers