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Old 07-19-10, 09:50 PM   #1
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I think I got a carb problem. Help!!?

I can't figure this thing out, my gas mileage is suffering and the car don't have that pep she used to have out on the highway. I noticed it about a month ago, pep gone, mileage down to around 320 mpt (I usually get 350 or better).

Here's a video of the cold car starting, when it's the worst. You can see she does not want to be bothered by the gas peddle, one time she just quit.

Nikki's, you gotta love them.



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Old 07-19-10, 09:58 PM   #2
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Hmmm, Runs sooo much better than mine and sweet engine bay. Could be gummed up a lill. You runnin seafoam through her? and any carb cleaner additives? could be a simple jet issue. But she pures soooo good
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Old 07-19-10, 10:10 PM   #3
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She doesn't purr like she used to. I'll put some Sea Foam in and see what happens, thanks for the tip.
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Old 07-19-10, 10:15 PM   #4
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does it act like that with the choke off?

i would warm it up, and reset the idle mixture, for starters
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Old 07-19-10, 10:31 PM   #5
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Possible plugged cat??
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Old 07-19-10, 10:44 PM   #6
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She doesn't have a cat and she dies with the choke off when cold. Adding gas to the idle mixture shouldn't be necessary, the car ran fine before. She has an issue.
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Old 07-20-10, 12:31 AM   #7
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do you still have the shutter valve in place and if so, have you ensured that its functioning properly? have you tested to make sure the coils were still in spec? how new are the plugs, fuel filter, air filter, cap, rotor, wires? have you rebuilt this carb?
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Old 07-20-10, 11:43 AM   #8
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+1 on ignition system

Replace fuel filter.
Inspect the jets to make sure you didn't get a piece of crap lodged in there.







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Old 07-20-10, 11:51 AM   #9
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Quote:
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She doesn't have a cat and she dies with the choke off when cold. Adding gas to the idle mixture shouldn't be necessary, the car ran fine before. She has an issue.
maybe its a choke pull off? and the idle mixture is seasonal, when its 100degrees out vs 40degrees, its going to be a little different. anyways its the first thing to check.

start with the basics first
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Old 07-20-10, 12:11 PM   #10
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Thanks for the suggestions guys, well worth checking those things in any event and I will give them one more look.

The shutter valve is disabled and wired open, but I'll check to make sure that's still the case.

The coils are the original stock 25 year old coils, but I've never had one of these go bad. How do you check them? Just do a visual on the spark jump?

j9 good point about the mixture changing, I'll reset that just to be sure.

I've replaced the plugs, cap, rotor, air and fuel filters while trying to figure this out, none looked all that bad and all were a no go on the low end stall issue.

So I'm back to the carb, which I rebuilt two summers ago and it was working great up until this problem showed up a few weeks ago. Looks like I'll be digging back into it this evening.

Kent may be right, something has gotten lodged in a jet, but I'm more suspicious at this point of the accelerator pump. I checked it this morning and if you depress the accelerator quickly you get good fuel squirts into the primaries (this is something I looked at early on and it seemed ok then). But when the accelerator is pressed slowly, very little if any gas shows up. I'm thinking I have a small leak in the pump diaphragm, a little surprising since it's only two years old but you never know.

I'll check it out this evening and post the results.
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Old 07-20-10, 01:33 PM   #11
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Make sure your fuel volume and pressure are good Ray.

Sounds like you already did the basics of filter change and tuneup.

Keep us posted on how it turns out. Maybe you need one of those Del Hortos now
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Old 07-20-10, 01:41 PM   #12
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A Del Horto is sounding pretty good right about now, but maybe my luck will change this evening. I'll keep you posted.
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Old 07-20-10, 02:32 PM   #13
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Quote:
Originally Posted by ray green View Post

Kent may be right, something has gotten lodged in a jet, but I'm more suspicious at this point of the accelerator pump. I checked it this morning and if you depress the accelerator quickly you get good fuel squirts into the primaries (this is something I looked at early on and it seemed ok then). But when the accelerator is pressed slowly, very little if any gas shows up. I'm thinking I have a small leak in the pump diaphragm, a little surprising since it's only two years old but you never know.

I'll check it out this evening and post the results.
the AP would be on my list as well...

does it always act like that, or only on cold starts?
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Your ideas frighten and worry me in ways that make me wonder if you're not "skiing" in Colorado right now.
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Old 07-20-10, 06:37 PM   #14
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It falters when it's warmed up too, just not as badly. As long as the gas peddle is not pressed to quickly it runs fine, even at speed out on the highway.

I'm heading out to the driveway now to take a closer look at that AP
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Old 07-20-10, 06:45 PM   #15
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Quote:
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...I'm more suspicious at this point of the accelerator pump. I checked it this morning and if you depress the accelerator quickly you get good fuel squirts into the primaries (this is something I looked at early on and it seemed ok then). But when the accelerator is pressed slowly, very little if any gas shows up. I'm thinking I have a small leak in the pump diaphragm, a little surprising since it's only two years old but you never know.
Ray, if there's a leak in the diaphragm, it'll leak to the outside.

Thinking maybe the pump inlet or outlet check ball is gummed up or got some debris in it & not sealing - - that'd behave as you are describing.
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Old 07-20-10, 07:47 PM   #16
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Thanks DD, it is not leaking outside and as I said, it would be strange for a two year old diaphragm to be giving out already. I must have some debris or gum some place, sounds like I need to pull the carb and take the top half off. Might not get this done this evening after all.
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Old 07-20-10, 11:56 PM   #17
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I feel your pain, sir.
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Old 07-21-10, 10:31 AM   #18
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Don't feel bad for me DD, once I get the hood up, hands greasy and carb out I'll be totally enjoying myself rebuilding the Nikki.

I took a closer look at the AP with a flashlight down the primaries and it actually doesn't look that bad. Gas pretty much dribbles and squirts like it should, depending on how much the gas peddle is depressed, and I'm not seeing any cut off of flow of gas from the AP ports when I get that stall problem happening.

So now I'm thinking it might be the progression circuits, I've had trouble with them before, which was the reason for the rebuild a couple years ago. Two years and 50,000 miles seems to not be enough to warrant another rebuild but it's an old car that was sitting for awhile, maybe some dirty gas from the tank is speeding the aging process, gumming up the works inside the Nikki.

In any case I'm tired of speculating, I'm going to get the GP Sorensen kit from autozone, pull the Nikki, give her a nice long scrub and soak in the Berryman's and put her back together.

After all, there is nothing like that new carb feeling!
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Old 07-21-10, 10:57 AM   #19
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I heard that... here's hoping your needles seat properly on the first fill after, with a minimum of carb-whacking!
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Old 07-21-10, 01:13 PM   #20
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There's nothing like that clean carb smell! Carb dip. Blech!
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Old 07-21-10, 03:11 PM   #21
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after looking at the video a couple times, it seems as if the issue is most definatly in the fuel system. how did the filter look when you changed it? have you checked the float levels in the sight glasses when the engine was running?
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Old 07-21-10, 04:40 PM   #22
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I'll give those needles extra tender loving care DD, I haven't had one stick yet.

Dave the fuel filter wasn't bad at all, which was surprising really. The first filter I ran on this car after taking it out of storage had all kinds of crap in it, mostly rust, no doubt from the fuel tank corroding. I expected more of that, but it was clean enough that I knew right away it wasn't the problem. And it wasn't, the fresh filter didn't help.

I checked the float levels with the engine off and they were OK. But good suggestion Dave, I'll check them again with the engine running. But I don't think fuel in the bowls is the problem, since when I ask for gas I can see it flowing freely into the venturi jets on the primaries and I don't have any problem with fuel starvation out on the highway, even accelerating at 80 mph.

It's just the low end, where the stumble is a real pain in the ***. It's getting so bad that if I put the peddle too far down the engine just stalls out. I'm thinking progression circuits all the way at this point ('course I'm usually wrong on my guesses).

I'm looking forward to smelling the Berrymen's, I picked up a fresh jug at autozone today, along with the GP Sorensen kit. I'll tear down the Nikki tonight and get it soaking, rebuild it tomorrow. I love rebuilding Nikki's.

And of course I'll take lots of pictures, to be posted soon.
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Old 07-21-10, 05:28 PM   #23
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before you pull it apart, you may wanna spend the 2 minutes, and spray around looking for vacuum leaks
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Old 07-21-10, 06:04 PM   #24
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I did spray for leaks early in the game, found one that I probably created earlier looking for leaks, but fixing it made no difference on the low end stall problem. Also this evening I tried readjusting the idle mixture but it was set right to begin with and turning it out a turn had no effect on the low end stumble.

So it looks like it's time for a re build, but I'm with you, check all the simple things first.
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Old 07-21-10, 07:18 PM   #25
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keep us posted. my 85 GSL, with a freshly rebuilt carb that i just rebuilt and installed runs similar to your car, in that a bit of gas when cold will stall the engine and it runs a bit rough until warm. once the engine is warm, there are no issues...so i'm looking forward to your progress. yo umay unearth something that could help my issue as well.
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Old 07-21-10, 07:18 PM
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