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This is driving me nuts !!!

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Long story short, been having "carb" problems. Idles high intermittently and sputters intermittently above 4K. Seems to get worse if you let off and open the throttle again while it's still above 4K.

That was w/ the DGV, changed to euro SU's.....same thing BUT, when you pulled the choke out when it acted up it ran a bit better. I thought it was vapor locking. Youo could pull the line off and the pump wouldn't push. blow back through the line and it'd pump again. ( guage was screwwy at this time too, so never knew exactly how much fuel was left in it. Ran out @ 1/4 tank)

Changed to single DCOE.....same thing.

Figured electric pump was the problem, changed to Cater P4070 72 gph. And fixed guage. Tank is 3 years old and clean as a whistle.....same thing..


Got a gas cap from VB a while back and it was the wrong one. They sent another that fit, but wasn't vented. I figured the unplugged return line in my '79 was vent enough. I thought maybe it wasn't vent enough and was starving the pump. Put the old one back on and it ran GREAT.....till on my way home from FL. Same place it acted up comming from Fairhope.

Seems to do it more when hot. Got good fuel from line when it sputters now. Carb and line aren't hot.

I'm wondering if I'm loosing power to the pump or if I have an ignition problem.

New cap, rotor plugs, wires, MDS blaster II coil( newish) new GM 4 pin module ( cheapy) in original C.E.I box and original C.E.I distributor.

Since the old fuel cap and new pump it is better, but still giving me trouble.

Any thoughts?
 
One stuck float valve, not sure which but would check back first.

If I am right you owe me.
 
DCOE has only one float and no way it could happen w/ three completly different carb types. All carbs show the same symtoms.
 
Too much fuel pressure.
 
Nope, had a reg on the old unit and dialed it all the way up and down. Carter pump is good w/o one on a DCOE.
 
Wht do you have for an air filter?

m
 
How is the carb vented? which is to say, I accidently blocked the float vent line on mine (ZS) and it would not run - could you creating a bit of a vacuum in the float when flow is the highest?
 
Just a thought, I had a Honda do this. It was a very small intake leak causing lean mixture at high speed.
Check for vacuum leaks and use a vacuum guage to see what happens.

Dave :savewave:
 
14dna said:
Just a thought, I had a Honda do this. It was a very small intake leak causing lean mixture at high speed.
Check for vacuum leaks and use a vacuum guage to see what happens.

Dave :savewave:
Click to expand...

My first thought also. sucking air somewhere other than the carb. Intake gasket leak, vacuum hose leak,Manifold, distributor leak etc..spray some carb cleaner, WD40 or starting fluid around the motor as it is running. see if it idles up in a certain area. If it does that will be your leak
 
It's intermittent. No vacuum leak detected and it has done this with three different carb systems. Well, I just went out and checked and I did have two "loose" intake nuts a one ( actally two) carb nuts. Didn't respond to spray. Tightened them up and it does run better. Pulls clean past 4K and on up towards 5K. Weird thing is, it does it mainly in 4th gear. You didn't really notice it in the first three. I hope this does it.

It's kinda like the cars at work, after everytime you run 'em, you gotta go back and tighten EVERYTHING back up. I've been loctiting them and marking the fasteners on all the racecars. Might not be a bad idea on my car. I just put that DCOE on and didn't think it would have lossened that quickly, so it never even crossed my mind. Then again, I do have a vibration @ 4K, which may have been my leak manifesting itself or caused it. Hmmm. Thanks guys. Sometimes you can't see the forest through the trees.
 
it could be a bad rotor in the cap had this come and go
a lot on MG's or even just the wrong rotor not the right one to go with the cap you have
 
Do you have the O-ring plates between the DCOE and the manifold, Billy?

An ~old~ issue with a DCOE setup. The vibrations generated have actually BROKEN the intake manifold on more than one 1275/DCOE racing Mini. There are side stays on those installs as result. Can ya post a photo of your setup?
 
Yeah I got the soft mount from the Alfa on it. I had the bolts a little loose cause I read don't tighten them too much and leave some wiggle room. I got 'em tight now and it runs great, but probably too tight for the soft mounts to do anything. So I need to fab a brace up then?
 
Add "wobbly-washers" under the carb mounting (NYLOC!!) nuts and the stays shown in the "Competition Tuning Manual" for a DCOE manifold.
 
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