Kentetsu

I have not done a compression test, but I did let her spin with the bottom plugs out (seperately) and had solid, loud, PSSST, coming out of each hole. I could not detect any variation in the levels that would indicate a bad seal. I agree, 190K is a lot of miles, but this baby was well cared for by the previous owner. He was a traveling sales guy and sold it to me when he retired. No smoke, no leaks, very smooth (at least it used to be).

The car still has the cats, but exhaust seems unrestricted. Thanks for the ideas guys.

Kentetsu

Correct me if I'm wrong, but when you move the little lever on the accelerator pump it should squirt a little go juice into the carb, right? I tried this while it was idling, and nothing happened. Bad accelerator pump?

I have not done a compression test, but I did let her spin with the bottom plugs out (seperately) and had solid, loud, PSSST, coming out of each hole. I could not detect any variation in the levels that would indicate a bad seal. I agree, 190K is a lot of miles, but this baby was well cared for by the previous owner. He was a traveling sales guy and sold it to me when he retired. No smoke, no leaks, very smooth (at least it used to be).

The car still has the cats, but exhaust seems unrestricted. Thanks for the ideas guys.

d0 Luck

yes, it can't be the muffler nor the catalytic.. even it cat is clogged, you would still be able to floor it and reach redline.. just slowly

the problem that i see here is a FUEL PUMP GONE BAD.. and you mentioned that your car bogs/struggles reaching redline, so do i. i plan on replacing mine's before 7stock though..

the most probable cause here is either a clogged/dirty fuel filter or a failing fuel pump

if it's not fuel filter, then your fuel pump's failing already.. might wanna check that out

Kentetsu

Well, fuel filter has been replaced. Fuel pump seems to be in good shape, it filled a 16 Oz bottle in about 20 seconds of cranking.

I think I might just take it into the shop next week. Thanks for your thoughts...

mar3

iTrader: (8)

It was about a year and a half ago, but that was exactly the same thing the other guy thought so he'd never check it....in the end, he pulled the cats and guess what...yea, that was it......it's the reason I mentioned it because his symptoms were exactly like this guys...

Kentetsu

Well, I started wondering if maybe it was the cat. After I got it running the first time, I ran some water through it via the power brake vacuum line (about a gallon), just in case there was a carbon buildup after the flooding. After I was done, I looked under the car and there was water running out of the cat. Turns out there were a lot of leaks (which I sealed up with muffler goop). Maybe the cat is plugged, but I'm not sure the symptoms confirm it. This is why....

The car is VERY drivable when it is cold, and the choke is on. As long as you don't actually "floor it" you wouldn't even know that there was a problem. But, once the choke pops back in that's all she wrote. It's still driveable, but you have to pay a whole lot of attention to the throttle and kind of fish around to find the power.

When she's cold and choked you can use about 75% of the throttle, but when she's warm you can only use about 25%. Anything beyond that and she just doesn't do much at all.

So, I'm thinking the fact that it runs better when cold would eliminate the possibility of clogged exhaust, bad fuel pump, clogged fuel lines, and ignition issues. It's beginning to look to me like I will be needing a new carb.

If anybody can think of something I've missed here, I'd be glad to hear about it. Or maybe someone has a good carb on the cheap for me? lol. Thanks for the help.

Kentetsu

Oh, I also tried swapping the coils around but there was no change. I pulled the spark plugs and inspected them, they were a little wet, but clean.

The Haynes manual suggests swapping the ignitors around. Are there two of them on my car? I'm not sure, but I will check in the morning before I leave work and if I can find them I'll try switching them around.

cdrad51

Yes, there are two, on the sides of the dizzy. Kinda PITA to unscrew.

Kentetsu

Would it be possible to just switch the wires around?

cdrad51

Don't know on that one, but just use an L shaped screwdriver and you should be able to unscrew them.

Kentetsu

Well, I switched the wires to the ignitors and there was no difference. Still looking...

mar3

iTrader: (8)

Please unbolt the cats and inspect them by looking at them physically...that's the only way, short of just replacing them or removing them, to know for sure if they are not the culprit. That's what the other guy ended up having to do.

Tom

Have to agree on 'check the cats'. My neighbors truck recently had similar symptoms. Loss of high end power. No problem until he tried to go over 35-40 mph then it just dogged out, misfired, etc..
Replaced the cats- voila. Problem solved.

It is worth a look-see.

Kentetsu

The only question I have is why does it run better when choked if the cats are clogged? Seems to me that the restriction would be there all the time, and would effect the engine the same way whether it was warm or cold. Does that make sense? Also, it doesn't matter if I'm going 10 mph and floor it or 60 mph, it reacts the same way.

I would love to pull the cats and install a RB header and exhaust system, but my cash flow is limited at this time. And since I live in Michigan, my current exhaust is very rusty. No way I would be able to just unbolt the cat and inspect it, I would have to hack it off and have something available to replace it with.

I'll take another look at the exhaust system, and if I can find a pipe that will work I'll go ahead and replace the cat. It's something I want to do anyway, so its worth a shot.

I don't feel that this is the problem though, because like I said, it runs nearly normal when the choke is on. To me, that would indicate a fuel/air mixture issue of some sort.

Thanks for your time and thoughts. :o)

Kentetsu

Car ran good enough (barely) to drive when I got home from work this morning. Tried to take it to work tonight and had to turn around and limp back home and just barely made it. I could barely keep her running at all by revving the hell out of her and slipping the clutch (ouch).

I didn't do anything to the car today, so the only thing that has changed is the weather (60 degrees and raining). This would seem to point to an ignition/electrical issue wouldn't it? Or will a carb be affected that much by the weather change?

Oh well, at least the 4 Runner was willing to haul my butt to work today! LOL.

I think I'll pull the dizzy tomorrow and give her a good cleaning and going over. I'll also look into the sizing for a pipe to replace the cat. Thanks for all the help guys!

cdrad51

I installed brand new spark plugs tonite, along with brand new NGK wires and a Blaster 2 coil for leading ignition. It improved the hesitation at cruising speed in the lower RPM band, but it's still doing it at higher RPMs (after 4-5K RPM).

Kentetsu

Have you checked your fuel filter and accelerator pump?

cdrad51

Changed fuel filter 8 days ago. Carb was just rebuilt by RX7Carl.

cdrad51

One good side effect of putting the new coil though was that the usually high idle went down about 200 rpm lol

Kentetsu

Damn! I almost bought a Blaster 2 coil tonight just for the heck of it (when all else fails, just start throwing money at the damn thing till it works again!). Maybe I'll grab it on the way home in the morning, sure it couldn't hurt any, right? LOL.

Kentetsu

I found an old Bosch Red Coil in my garage tonight that had come out of a '73 240Z I used to have. Replaced the lead coil and now it idles smooth as silk for the first time ever. Did not solve my driveability issues though.

I rechecked the ignition timing again, and noticed that the trailing timing mark would bounce around once in a while. It would read dead on but every couple of seconds I could see the timing mark light up about an inch further toward the top of the motor. Not sure how much this matters, since it is the trailing rather than leading ignition, but maybe its a symptom of something else?

It was raining again today, but I took her around the block about a dozen times and she was quite driveable as long as I went easy on the throttle, so I brought her to work tonight (45 miles). Had no issues, except that I pulled out in front of someone (he was about 1/4 mile down the road) and had a hard time getting up to speed before he caught up to me. No big deal though.

Since I have to fish around on the throttle to find the "sweet spot" and start producing any power, wouldn't this point to a carb issue? It seems that the carb is not handling the fuel/air ratio so I have to do it manually with the throttle. Anybody agree/disagree?

This has really got me stumped. Looking at some used Nikki's on Ebay, pretty cheap. Maybe I'll buy one and try swapping it out to see if that changes anything. Running out of ideas here though. Any input from someone more experienced would be much appreciated. Thanks for all the ideas and help so far!

Rx7carl

You already said that the accel pump doesnt squirt when you operate the linkage. Thats your acceleration problem. If its not leaking fuel then you have a clog. That tells me that you may have clogged passages elsewhere in the carb causing other problems. You can disassemble the carb just enough to remove the jets and bleeds to clean them to try and get it running right again. Look at Felix's FAQ page (sticky at top of forum). He talks about this there. Or just do the total rebuild and get it cleaned out.

Sterling

You can remove the secondary vacuum box fairly easily...just three screws. Don't even disconnect the linkage. Use compressed air and blow through the fourth hole that is the vacuum circuit port. If there is an accumulation of oil in ther (it happens) it'll blow out the front-most primary venturi.

You should see an unmistakeable dual stream of fuel squirt right into each primary venturi when you operate the throttle linkage.
There's only two reasons that this won't occur...you have no fuel in the rear-most fuel bowl (right behing the accelerator pump where it gets the fuel from...unlikely), or a checkball is stuck -probably the one under the nozzel.

Your problem seems to be getting worse throughout this thread, indicating to me that you do have clogged cats. Running water through the system won't "fix" clogged cats. Once they're cooked, they're not coming back.

You're going to have to do more extensive troubleshooting. Eliminate all other possibilities, and finally, simply disconnect your exhaust from the end of your manifold, and wire it up VERY WELL so it does not fall.
Go for a very LOUD drive.

You may very well have a combination of any of these problems. You must check each one off the list one at a time.

...But if you got no AP juice, you got no go.

Kentetsu

Thankyou so much for the info RX7carl! I will check into this first thing in the morning. Thanks for your time...

Kentetsu

I will most likely do a full rebuild on this carb, but was wondering if I should change the jets or anything else while I am in there. I have rebuilt a couple of carbs in the past, but it has been years, and I've never changed jets or anything fancy like that, so I don't know if this is difficult or easy.

I think I'll also rip out the rat's nest while I have her apart too. Thanks for the help!