I am running way too lean

[menesesjesse]

All
My engine is running very nicely at idle.  I adjusted my dwell to 38 degrees and my idle is perfect.  I checked compression and it is 125 for 1-5 and 115 for #6.  I then went to check the plugs and the were all white with the exception of #2 .  I have tried to drive the car and the car starts to buck and miss at 3000 rpm and above.  My advance is working on my distributor is working and I even swapped out distributors to rule this out.  My timing is dead on and I have room to move the distributor for adjustment.  I have adjusted the idle screw in the back of the injection pump but this wont cure my higher rpm issues. What is the consensus here?  Can this be a fuel pump or is it more likely to be the injection pump.  Has anyone had this type of problem before and give me what their problem was. Is there an adjustment I can do to correct this problem before I burn up my motor?  Thanks for all the help so far.
Jesse

[ja17]

Hello Jesse,

Check to make sure that your fuel filter is clean, your linkage is correct and your warm running device (WRD) is not stuck.

Next your fuel pressure and volume should be checked. These are some possible issues which can cause your lean running problem.  Your high rpm miss is caused by shorted out spark plugs from running lean. You will need new plugs. Lean running kills them.  Try a set of NGKs they seem to handle lean running better than most.

If everything checks out ok, then just add an oval shim under the WRD, this will richen all speed ranges.

[Benz Dr.]

I agree with Joe that any one of those things could be the problem but I think it's something else. It's running lean because it's burning oil. This may not sound like it's makes any sense but after seeing it myself several different times I'm more inclined that way. This engine needs a rebuild.
Any cylinder that has just the right amount of oil getting in will run hot and then run lean. If you put a new plug in it will stay clean for a short while so it's not too rich. Run it a bit longer and the plug will turn dark. Not long after the plug will quit firing. No amount of testing will get you there and no amount of changing parts will make any real difference. It's worn out.

[menesesjesse]

Dr Benz and Joe
The motor is new and the head was rebuilt.  I am not burning oil as of yet.  It runs great at idle and will idle all day if I want it too.  The spark plugs are new NGK's(6hrs of use) but they have run been running hot since I started the motor. The engine temp when it was running is ok .  When I rebuilt the motor I replaced all the gas lines, cleaned the gas filter assembly, installed a new gas filter(now less then 2hrs old), I cleaned out the WRD and checked it for mechanical operation(good),  The WRD coolant lines both warm up as they should.  I have replaced the cap and rotor also.  My fuel pressure is at 15-18 psi but I have not done a volume check on it yet.  What type shim will i need and where can I get one if needed?
Thanks!!
Jesse 

[Benz Dr.]

You didn't say what engine you have but 125 - 115 PSI is very low on compression. The engine will still run but will lack any real power. Either you have a faulty tester or something went wrong with the rebuild.
If all cylinders are running lean the the pump is set too low. Something tells me you have more than just one problem.  Engines with low compressio have a tendancy to run on the rich side due to incomplete cumbustion.

[ja17]

Hello Jesse,

Here is a photo showing where the shims go.  Adding shim thickness will richen up the mixture at all speed ranges. I like this procedure since you can easily restore it to "as it was" by removing the shim if needed.

These injection systems usually "wear rich" so yours is acting non-typical.  This may suggest that the issue may be elsewhere as Dan suggests. Pump timing?

In any case, adding a shim is harmless and easily reversed if needed. It should improve the lean running situation.

[ctaylor738]

Hey Jesse,

Send me an email, I believe you have the address, or give me a call.  Maybe we can work out a way to put my CO meter on the car and see what's going on.

[menesesjesse]

Joe and Dr Benz
Thanks for the input. I have the older 230 motor.  It was rebuilt at Metric.  I picked up a older rebuilt injection pump(from Pacific)this weekend and installed it.  The car became drivable and  I believe my compression tester may be incorrect since the car does run so well at idle and it does pull hard when it is cool. I have no lack of power when it is cooler. I ran it for 25 miles yesterday.  The car ran well but after 10 minutes.  After warm the car would then sputter over 3k rpm. After the car cooled a little I could run it again for about 5 minutes and the same symptoms would flare up. I pulled the plugs and they were all clean with nor residue at all.  They looked lean but not like my first pump.  The car is really running well and I have it set for 38 degrees on dwell.  I will replace the spark plugs just in case I fried the last ones.  I would like to add some shims to the WRD but not sure where to get them.  Is there a source for them?  Thanks

[Benz Dr.]

OK, the more info you give us the more we can dail in on your problem.
It sounds like the engine is OK so it's less likely to be a mechanical problem. It sounds more like a bad fuel pump. They work well when could but start to slow down when hot. Shut the engine off for a while and it cools but so does the fuel pump.
Try a fuel volume test right after you get back from a longer drive while the engine and the fuel pump is still hot. Be extra careful working around the engine bay with everything so hot because spilled fuel will evaporate very quickly and can catch on fire if you create any sparks. Remember, it's the fumes that ignite.
 
You should have about 1 litre or a US quart in 15 seconds. The fuel should come out in a steady flow with some amount of force. Time it from the moment you see fuel coming out of your hose and not from the point of turning on the ignition switch ( a common mistake ) and then measure the fuel. Anything less than 750 ml and the pump is starting to drag or you have a restriction in a line. Do your test right after the fuel dampener in the engine bay.

[ja17]

Hello,

Yes, I agree a fuel volume test should be next.

[menesesjesse]

Thanks for the advice.  I checked the volume and it was way off.  I took the pump off and the inlet side was pretty restricted.  I had a used pump at the house and I bench tested it. The pump worked and I got about a gallon a minute.  I will install it today and let you know what happens.  Thanks for the attention and I believe I may have this thing solved.  Update to follow.
Jesse

[ja17]

Hello Jesse,

The filter screen in the fuel tank should be looked at also.  It comes out with the drain plug. It is the first line of defense against dirt and crud.

[menesesjesse]

Joe/Dr Benz
Thanks I have concluded that the fuel pump was clogged and I went ahead and changed the plug and filter at the tank.  The car now runs beautifully through all rpms.  I drove it for 50 miles and i love the car now.  6 months of work and I now have a dependable cruiser i can take anywhere.  I will now focus my attention on all the adjustments and the inside.  Thanks again and I am so glad the group is here.
Jesse