Dave WM

for fun I am going to try turning power off to my pump on my test stand. It has several feet of rubber tubing. If nothing else should be interesting to see what happens. Any way back to the OP issue, I would look at the FSM and check the CTS to see if its gone high resistance. Always the 1st and easy thing to check.

8 to 10 minutes? with the pump off sounds impossible to me. the hoses are maybe a couple feet total, I just cant see them expanding enough to maintain any kind of pressure for more than a few seconds, even at idle. However I could be wrong but just cant see it happening for 8-10 min of idle. And if they are expanding enough, then I suggest a fire extinguisher be at the ready, really should have one on hand, but in this case, replacing the hoses would be 1st thing. agree with needing a fuel pressure gauge as a 1st step.

I suggest If you have not already you read the EFI section of the factory service manual. It has extensive trouble shooting and information on exactly how the EFI system works. Read is several times if need be until you have a through grasp of how the system works. Coming here for answers when you state the fuel pump is OFF and the car runs for 8-10 minutes is a waste of time.

impossible. The pump is running.

any glass out options? I agree that will look a lot better.

at the 6 week mark, I will try face book message again see if there is an update. will post what I find out. Left a message on face book, looks like he has been traveling, again will post what I hear back.

You really have to be careful about what you are doing, as stated before you need a proper set of gauges to monitor both high and low, you could have moisture build up causing a block in the expansion valve, could have junk in the filter, any number of issues. Not to mention you have to be careful about adding Freon into the low side to avoid liquid slugging into the compressor. The FSM has a rather extensive section on how to diagnose based on those pressures (low side/high side). Overcharging is bad a well as under charging. The only way to really know what is going on is with a proper manifold. The low reading may just be an indicator that the expansion valve is not working properly for what ever reason (moisture/or bad valve). The source of the Freon is not what accounts for the level of charge, its the condition of the entire system. I hope you are wearing safety glasses, compressed gases can be very dangerous. has the system ever completely lost is charge? if so you def want to replace the drier and do a vacuum, its the only way to get it to work if that is the case as surely it would have moisture inside.

if its a condenser leak, you may want to replace with a modern cheaper to source generic type and replumb to fit it. Or IIRC there are some new OE style ones being made but not cheap, would save on fitment cost.

your best bet would be to replace the drier, pull a vacuum, get some gauges on it and refill assuming no leaks. If leak (will not hold a vacuum) pressurize with nitrogen, and get some soapy water, spray down everything in site, look for bubble, and hope its not in the evap.

you really need a proper set of gauges to determine what is going on. Its could be a clogged evap if pressures are low and high, could be a faulty compressor if both are low, could be moisture inside the system icing up, many many things. the only correct way is to get some good gauges on it and someone that knows what they are looking for.

Lastly things that can cause issues, mainly moisture in the system. Best practice assuming it was properly converted would be to replace the condenser, replace the drier, check the filter screen on the inlet side of the fire wall connection, then pull a deep vacuum and charge to about 75% of he recommended R12. That is assuming it will hold the vacuum.

Next 20lbs on the low side maybe correct, depends on the ambient temp. lastly what is the pressure with the engine off and wait a few minutes.. then check the pressure to a chart for 134a given the ambient temp.

1st off was it converted to use R134?

yep, that's the same as mine. I got and aftermarket unit of ebay for 50$ IIRC, pulled my OE off to test it, left the aftermarket unit in place so I carry the hitachi as a spare. The aftermarket unit seemed to have fewer parts IIRC. I can see several electros in there that prob should be checked at least of not just shot gun replaced. I can't believe the engineers ever expected this kind of long term life.

took a trip a last weekend, drove back Sunday thinking less traffic (not) down 75 starting at Tifton, 260 miles of rain later, had a tiny bit of wetness on the floor board, under the carpet right around the back large floor plug. Now I mean rain like get started on the Ark type rain. I can't imagine how many millions of gallons must have fallen, but 260 miles for about 6 hrs of non stop, cant see, afraid to pull over and become a sitting duck type rain. I finally bailed out at Ocala and took some side roads home (never venture south of Ocala on 75 if you can avoid it). anyway passenger side was completely dry, so I guess the cowl vent is in good shape. I did purchase a new OE Nissan floor panel plug since the orig one was looking a bit ragged, I figure it could have been some water getting past it as I submarined my way home. checks all around the back, all good. some water dripped out of the weep holes on the doors, which is why they are there, I would have loved to look at the rear quarters but did not feel the urge to pull all the plastic trim, off to investigate. Anyway its passed its water test, so good to go on my longer trips where I will have to deal with bad weather at times. oh and the AC was on the whole way both up and back, up was no rain and upper 80's to mid 90's the whole way, never got past 1/2 mark on temp. I did check oil and I am burning about 1qt every 1100 miles or so. The book says more than 1Q in 750 miles is excessive, so I guess I can live with it. Any one else track oil usage?

ditto on a new pump, why trust it after sitting for two years, Personally I would get a new NISSAN pump, about 250$ but if the pump stops your are dead in the water, so I like OE.

I pulled one apart a long time ago, IIRC it was all mostly hi reliability type parts (metal film resistors, film caps, maybe some IC's but I bet they were not custom, prob things like 555 or 556 etc... I do not recall seeing any caps electrolytic types (they tend to dry out and open over time). So if anything I would guess maybe a physical problem, pin connections broken trace (if abused) or electrical damage from reverse polarity or some kind of short of the pins. I can see the power transistors leaking or shorting since they are under the greatest current draw. But I think its a long shot.

did you ever test the ign switch as mentioned before, I mean out of the car with a multimeter on tone?

I wonder if the show the lean/rich condition? Unless its just an idle thing. Did the color tune look the same above idle on all plugs?

for some reason I am thinking the ECU has two power transistors for grounding the injectors, 1 for 123 and 1 for 456. I could be all wrong about that, but if not, then its a valid test of the output from the ECU.

I would think its more likely a ECU thing than and injector thing, since its a 123 vs 456, hence the easy thing to do is swapping the injector harness plugs around.

did you try swapping the injector plugs 123 with 456 to see if the lean run follows the injector plugs. Also did you could try swapping the injectors themselves if no change with the plug swap. the richness of the AFM will have an effect on both idle and vacuum. a rich setting will increase both. I recently tested this and found that adjusting the AFM bypass screw could be used to optimize idle quality and vacuum, prob at the expense of emissions.

I torqued to 61 ft lbs.

I know that chem test is the only thing showing a problem... but it shows the no change in color on my other engine after it warms up and is flowing too. If it were not for that I would be more skeptical about it. all the bolts went in fine, I used a cheap HF torque wrench. The other thing to consider is the orig head came off with an OE head gasket that looked perfect, no issue at all on it. So I was hoping it would have been a smoking gun. The change to a different head was kind of "a lets see what happens" rather than a "I am pretty sure this is it". It was easy to do so I took a shot. This is a 1st for me (pulling heads) so I may have missed something or could be doing something completely wrong, live and learn.