Running lean?

[Jerry G.]

Re: Running lean?

If I'm understanding correctly what your saying, the air flow back through the air meter when you apply pressure is normal, the air is just going back through the sensing ring annular opening.

[William C.]

Re: Running lean?

.026 is not really a problem, not what I would like to see, but not a problem. The leak you are getting is likely thru the cranking signal valve, that is one thing to check. Also check the seal between the diaphragm cover and the housing by blocking off the cranking signal line and using a mityvac to check the seal at the cover. The cranking signal valve should give a clean cutoff when vacuum is applied to the tube...

[George W.]

Re: Running lean?

After flow test, checking screen under thumb tack, inspecting all fittings, re-calibrating choke, re-setting idle mixture and idle screws to two turns out, doing some tweaking on one of the vacuum lines and anti-siphon solenoid plumbing (in order to get good fuel supply line clearance from valve cover), and shimming distributor to .003.

I re-installed.

Fired right up.


Re-set timing, re-set idle mixture, checked dwell, checked vacuum. Vacuum now 10 at idle and only 12 at 3,000rpm?

Let her get to 180 degrees and shut her down. Waited 3 or 4 minutes and tried a "hot" re-start.

Fired right up and idled.---- Cool!--- Shut her down again, waited another 6 or 7 minutes, and tried second "hot" re-start.

Fired right up. Yahoo!

Decided to go take a test drive.

While backing out of garage/driveway the engine seemed to not return to idle immediately when I released the throttle pedal. Hum? It did return, but not as responsive as it should have. Continued backing out and it happened again. I'm thinking maybe the return spring came off, or????

Pulled back into the garage and shut her down. Spring in place and throttle return operating properly. Surge? Don't know.

Tried another "hot" start---no go. Bummer!!!!!

Preparing my water squirt bottle to test for vacuum leaks. Waiting for engine to cool.

Oh, still running 100 aviation fuel.

Oh, one more thing: the "wet" look in the intake runners turned out to be oil???? Valve seals or guides?

Thanks in advance for any help,

George
210 748 4693

[William C.]

Re: Running lean?

Lets see what you find, but as to the vacuum readinbg, id the centrifugal advance in the distributor functioning properly?

[George W.]

Re: Running lean?

Bill.
timing goes to 36 degrees advanced when reved up, so I guess the distributor advance is operating properly?

How else can I check this?

Thanks,
G

[William C.]

Re: Running lean?

OK, are you talking 36 degrees at what RPM? Is the vacuum advance functioning properly? I assume you have a timing tape on the damper?

[George W.]

Re: Running lean?

Bill,
this is a '60 unit, so there is no vacuum can on the dist.

no degree wheel, but have "marks" on balancer

[Jim L.]

Re: Running lean?

Each time you ran the engine, how long did it run?

Loaded question.

If the FI unit isn't getting adequate fuel from the engine mounted pump, the engine will run for 3 or 4 minutes (perhaps longer) as the bowl slowly drains. Once the bowl is empty, engine will die and won't re-fire. However, if the inadequate fuel supply is due to some kind of inlet restriction (dirt.... a needle/seat that's coming unscrewed....clogged filter.... whatever), the bowl will slowly re-fill. After some time, the engine will re-fire and run briefly.

Regarding the lack of return to idle, that is consistent with worn throttle shaft bushings and/or a rough throttle shaft.

Jim

[George W.]

Re: Running lean?

Each time you ran the engine, how long did it run? ---Upon each cold start, unit runs as long as I want it to. Always have time to let engine warm up and go to 900 rpm idle----allowing me to perform vacuum, timing, mixture, etc. tests. This is usually 25-30 minutes.
Can take on test drive and unit does not "quit".
Unit "breaks up", "stumbles" under quick WOT, usually at 3,000 rpm, then "catches up " and goes to 6,000 rpm nicely.


Loaded question.

If the FI unit isn't getting adequate fuel from the engine mounted pump, the engine will run for 3 or 4 minutes (perhaps longer) as the bowl slowly drains. Once the bowl is empty, engine will die and won't re-fire. However, if the inadequate fuel supply is due to some kind of inlet restriction (dirt.... a needle/seat that's coming unscrewed....clogged filter.... whatever), the bowl will slowly re-fill. After some time, the engine will re-fire and run briefly.



Regarding the lack of return to idle, that is consistent with worn throttle shaft bushings and/or a rough throttle shaft.---sure hope not, as stated, this a unit that was recently gone through.

Jim

See above,
thanks,
g

[George J.]

Re: Running lean?

George,
I am starting to think like Jim. When I have had very weird things happen, like car runs perfectly and then stops. Runs again a few minutes later, may run fine for days, then stops, etc. It is the fuel pump on the engine. Now, if anything happens, I first pull a plug wire and try to start the car. If it is getting good spark, I pull a fuel line from one of the nozzles, put a plastic bag over the end, and have someone esle crank. If it doesn't get fuel, you know where to look. First the high pressure pump cable. Second the engine fuel pump. I have gone through an engine fuel pump every 5 years or so. The last time I ordered a rebuilt original one from LI and it is still going strong after two years. Good luck.

George

[George W.]

Re: Running lean?

George,
Fuel pump replaced and is working properly.
Needle and seat doubled checked and working properly.
Float in good condition and working properly.
Just performed a bench flow test and all nozzles flowing properly.

Unit ALWAYS starts right up when cold.


Unit will run nicely until engine reaches 180 degrees. (now using 100 av gas)

Unit will continue to run after warm up --takes about 5 min to reach 180 degrees---will run 25-30 minutes on "low" idle (850-900RPM). Longer if I were to let it.

Can drive the car and unit will continue to run, does not die, still idles, but is stumbling/breaking up at about 3000 RPM, then "catches" and runs up to 6000 RPM.

Unit does not like a quick WOT (will stumble/hesitate). Gradual throttle produce "okay", not great acceleration, but still "stumbles at the 3000 RPM point.

Unit does not "stumble" when revved or given a quick WOT in the garage (no load).

Unit will not re-start when hot.

Doing more tests this morning---checking for vacuum leaks. Vacuum seems to be low?

G.

[George J.]

Re: Running lean?

George,
I would not rule out the fuel pump. I have had very weird behavior with them when going bad. Much of the point of my provious post is to give you a point to start from. If an engine won't start it is either not getting fuel or spark. Check them as I explained to at least give us a benchmark. My guess is you're not getting one of them when it won't re-start.

George

[Jim L.]

Re: Running lean?

Can drive the car and unit will continue to run, does not die, still idles, but is stumbling/breaking up at about 3000 RPM, then "catches" and runs up to 6000 RPM.

Unit does not like a quick WOT (will stumble/hesitate). Gradual throttle produce "okay", not great acceleration, but still "stumbles at the 3000 RPM point..

By what means was the FI unit calibrated..... i.e. how were the positions of the ratio lever stop screws and the sensitivity of the enrichment diaphragm determined?

[George W.]

Re: Running lean?

By what means was the FI unit calibrated..... i.e. how were the positions of the ratio lever stop screws and the sensitivity of the enrichment diaphragm determined?

These were set by the re-builder.

I followed "Ram Jets that run" instructions to tweak, but ended up with the same settings as when the unit arrived.

I performed the "water" check for vacuum on every fitting, diaphragms, intake runners, etc, etc. and found no leaks. Idle vacuum is 10 (I think it should be higher).
Goes up to 12 with throttle increase, and "rebound" numbers are almost zero with quick throttle, back to 15 when quick release of throttle, then settles back to 10.

Have been playing with the choke settings. Engine now starts when hot. Only starts at half throttle. With no throttle or full throttle and it will not start. So, the air/fuel combo at "hot" is what I'm following now.

I did pull a couple of injector lines when hot, cranked engine, and found very little fuel ---drips, no stream. I then manually pushed choke tab to full choke position and got good stream. I think this tells me that the vacuum signal is not correct when hot.

I still have spark when hot.

Still stumbling under WOT and at about 3,000, but I now think it is a lack of fuel problem related to vacuum signal.

I might be getting closer, but......?

Thanks,
G

[Joe C.]

Re: Running lean?

George,

In post #14 you made the following statement: "But, when applying oral vacuum during flow test, there was not a complete "shut off". Also I could blow through the tube and air escaped at the air meter. I don't think this is supposed to happen?"
I don't think that you got an answer to it. Did you? In any event, that statement is what prompted me to make statement #1 in post #15. Although, not being familiar with mechanical fuel injection, I used the wrong terminology: instead of saying "flowmeter diaphragm", I should have said "fuel enrichment diaphragm". It seems to me that the enrichment diaphragm is ruptured or there's a vacuum leak in the passage. This would account for the low manifold vacuum at idle, as well as the poor performance and lack of power under load.

I would concentrate on THAT aspect, and ascertain from an expert the proper procedure to check it.

Also, at what idle speed are you quoting the vacuum readings? I would think that IF YOUR LASH IS SET ACCORDING TO SPEC, that a 283 with the 097 cam should develop about 15 in-hg vacuum at about 850 RPM.