Fuel Flow issues?

[SLOroadster]

I have not checked to see if I have a broken spring in the bottom of the dizzy. I don't think thats is becaue if I open both the chokes, it will rev higher, but still falls on its face, just at a slightly higher RPM. If I floor it, it will rev, but then immediatly stumbles and dies. I will try to check the springs tomorrow.

Thanks,
Will

[TR]

Will,

You have something really weird here...Some thoughts:

Have you confirmed the fuel pressure maintains sufficient at RPM?

Have you confirmed that you have spark at RPM? (Take an old spark plug wire and cut a small gap in it. With the smallest of gap, you'll see the spark jump this gap when the plug fires. Put the gap where it is easy to see. If you are unsure of which cylinder is giving fits, put the gap in the coil to distributer wire)

Have you confirmed that all of your vac and mechanical advance is kicking in evenly as RPM climbs?

Is there any noise associated with the engine stumbling?

Does it stumble back to idle or die completely? Does it restart immediately?

Do the plugs still look rich?

Let us know and we'll all think some more...TR

[SLOroadster]

I cant be positive that the fuel pump is pushing a sustained 5 psi at greater than idle. I did pull the hose and checked to make sure I was pushing some fuel with the starter. I do have sustained spark when it cuts out, I verified this with a timing light, on all cylinders. It makes no strange sound except for the sound an engine makes when it is turned off while driving down the road. It restarts immediatly after it quits, turn the key, its running, starts faster than the miata that I am driving. I can generially get it to come back if I pump the gas a few times before it completly quits. If I had a second fuel pump I would swap it in and try it, but I don't. The plugs do still appear to foul, every time I pull them I wipe the soot clean and try it again.

My guess is that the fuel pump is going bad, but I cant be sure.

Thanks,

Will

[TR]

Remember that most timing lights are sensitive enough to pick up anything, even if it is not strong enough to make the plug fire.

Does it always stumble at the exact same point? If so, that points more toward ignition.

If it varies and pedal play gets it to behave differently, more likely fuel. You are on the right track.

Seal up a gas can with your pickup line directly to the carbs and a bicycle tire pump (I know you have one of these!). Have a friend keep 5 psi on the can by pumping the bike pump and see if the car runs any better...

Be careful, you are creating a gas bomb, but a good test till you can secure a second pump.

Hard to believe the pump deid during an engine out and back in, but who knows? I'm still thinking something ignition/dizzy related makes more sense, but what you are describing sounds fuel related. Hard to tell without hearing/seeing it in person...

[Datrock]

Will, have you tried hooking up an inline electric pump, just for troubleshooting purposes? Bill

[SLOroadster]

Well the fuel pump is attached to this engine, and seeing as how everything else attached has gone bad, this really wouldn't surprise me. The way I have the ignition set up now I just undo the coil and 1 other wire and thats it. Nothing else to disconect/reconnect other than the starter leads and a ground strap that attches to the block. The fuel pump wouldn't happen to be the same on a 510 would it?

I have to give the miata back tonight so I will be carless again until I get it figured out. I just hate riding a $5000 bike to work in the rain.

Will

[Datrock]

When I had a fuel starvation problem on my s/u U20 installation startup it was the new fuel pump, I left it on the engine block and hooked up an elect one and engine ran fine, took the electric one back off and put the old original pump back on the engine and no more fuel problems. The arm on the new pump was slightly straighter and would not pump or ride against the jackcam lobe as the old one would. Box said srl311 but not for mine! I will eventually switht the arms.
I take it you have solexes and I know nothing about them but to me is seams if your engine was not pumping enough fuel at higher rpms, wouldn't it run fine then slowly start to crap out. Not all at once and not always at the same rpm.
Once I bumped my distributor with the battery on a sharp right and killed the engine, I got it going but had it towed home by a friend. Found out the rotor split on the bottom and rotated on the distributor shaft a few more degrees than my engine liked. These are just a couple things that may be worth looking at... Bill

[SLOroadster]

I stuck a fuel pressure gauge on the car while it was running, and saw a constant 6lbs as the engine cut out. I checked the dizzy, the springs are fine, it advaces nicely, showing about 30 degress advace at 2500 rpm. The plugs are no longer fouled, but the engine doesn't run any differently. Tried a different coil, it made no difference.

Will

[TR]

So...

Shouldn't be a fuel issue as you have gone through the carb, but that might be worth triple checking.

You have fuel pressure.

Normally an air leak won't start right back up without fiddling with the choke or gas pedal...You have sprayed around the carb and insulator to see if it is sucking?

Can you run the car on one solex like you can with SU's? If so, see if it runs the same on each carb. If one is crapping out, it will be obvious.

Swapped the coil, so it should be good.

Did you check spark at RPM by slitting an old wire?

Advance appears to be kicking in smoothly and at the right time?

Make sure your dizzy connections are not shorting due to vibration, etc. Also, you should have a ground lead to the body of the dizzy. Not a bad idea to make a ground strap connecting your dizzy body, coil body and a spot on the frame.

The last time you had trouble with the car, you said you jiggled some wires near the ignition, have you done that again? Is there something there that isn't right?

Hope some of this helps, it sure is hard to diagnose from far away...TR

[Datrock]

Will, I would start the car in complete darkness and see if there is any electrical arcing around the distibutor or anywhere under the hood, plus are you using the fedico points in the yellow box that are selling on e-bay, I here they are junk.
Might check the point lead inside the dist. housing and see if it is touching the side of the casing, it might be shorting out. You might have a mounting screw washer under one side of the points, this will make the car run bad.
Also look at the ignition wire that connect to the starter tab it may be just hanging on by a thread and vibrates loose on acceleration.
These are just a few more idea's that have crossed my mind. I too am still using points but I use them to trigger my MSD box. Bill

[dbrick]

I'll go with Bill, only when you check the wires, use a spray bottle plant mister and get all the spark plug cap and wires damp. If there is High voltage leaking to ground, it will either show up as arcing or misfire, worse when wet.

hook up a vacuum gauge and watch the reading. Look in any Chilton manual for a vacuum diagnosis chart, or call me and I'll send it to you.

Easiest thing is see if someone can loan you a complete distributor and drop it in for a test, even a smogger if you set timing to TDC.

Also, check the small leads, ground and point inside the distibutor. Best way is with an Ohm meter. Flex them like crazy and see if the resistance changes. This was a real common problem back when points were current technology the copper in the wire is very small and fatigues from the point plate moving.
For a quick check, disconnect the condensor and run it and see if a change. Don't forget to put it back, or the points will burn quickly

See if the center contact fell out of the distributor cap (mine did) Clean contact surfaces if coroded.

You should be able to put a test light from "+" battery to coil negative, it will flash every time the points close. If it stops flashing when the engine craps out, you are losing the points.

Timing light looking at the timing mark will tell you if advance is working properly and if spark is cutting out as you rev through the range where it misses.
Also acts like a strobe light to look down the carb throat to see if it's dumping fuel or starving.

I'm betting it will be a simple problem, but not an easy one to find.

[SLOroadster]

Here is a thought; could I have a blown headgasket? When I drove the car over, I think I had a big air bubble or a stuck thermostat. The gauge was reading cold, and then after I shut the car off, it sounded like it was percolating. I pressed the coolent pressure release, and it suddenly was hot, even though I had shut it off. The gauge didn't peg, and the car only ran for about 10 minutes at the most. I don't see any oil in the coolent, nor coolent in the oil, so if it is leaking, its very small. I can't smell any coolent in the exhaust either.

Any thoughts?

Will

[dbrick]

Can't see how head gasket would get all 4 plugs wet. If you fill up the coolant and run it with the radiator cap off, you should hear or see the pressure escaping through the coolant. An extreme lean condition or retarded timing will make it run very hot, and cause a misfire and power loss.

Does it do the same thing driving it as it does sitting still, break up at the same RPM? does it do the same thing hot or cold?

Cooling could also be a seperate issue altogether.

I would take a systematic aproach and eliminate one step at a time.

intake compression power exhaust (suck squeeze bang blow)

Intake/fuel seems like you checked most things, but look again.

Compression is self explanatory. Might want to check the timing marks on cam and crank just for the hell of it. compression check and leakdown will rule out the head gasket

Power is harder, lots of variables

Divide ignition into primary (12v) and secondary (high volt after coil)
You said you get very short point life, replace the condenser, it prevents the points from burning. Check voltage to the coil, if it is too high, will burn points, too low, no spark at high rpm. Check resistance of the ballast resistor, if you took it out put it back in, that will fry the points too. Check for a crushed or damaged wire or connector from when the engine was removed and put back in. It could just be vibrating loose at that particular rpm. The copper can break inside the plastic wire jacket or at the crimp terminal. Recheck the timing and the advance.
Easiest thing is to drop in a complete working distributor and see.

Same with the secondary, cap rotor coil and wires. Whatever part you can swap without alot of work will eliminate something.

It will be something basic and simple, you didn't really change much by pulling the engine and putting it back in, not like you tore half the car apart and changed a bunch of parts.

[SLOroadster]

Ok, the plugs arn't wet anymore. I can't smell any coolent anywhere. The level hasn't changed, and it doens't bubble while running. As for the points, I have a 45,000 volt coil, its going to fry the points. The balast resistor is new Again I wish I had another working roadster to cross reference with. I'm going over there tomorrow to work on it some more. I'll see if I can find another set of eyes to look it over.

Will

[TR]

Good luck with it, have you checked to see if you are still getting spark at the RPM that the engine is cutting out at?