Fuel injector Prob. 77 280z

[jagnew3]

, I have the bible on cd and printed form, as well as the 77 FSM. I have read a bunch, and have tested some. I am kinda on new ground in many ways, but particularly in the throwing $ and parts at it vs. testing out everthing battle. I have always been the latter, but now with two young childern...one only about 7 weeks old, I have lest time to test, less cash to throw, and have to wiegh which I do at what junction, So far I have done a bit of each, and unfortunatly the throwing cash part hasn't been very sucessful, and the testing keeps leading me to more questions.. In the end it will get warm enough here to spend a great great deal of time testing stuff, but until them I have to do quick checks, get ideas, form theroies, and act on those things...right now I think what is happening is a supply problem, but will have to wait til Saturday to even get a crack at checking it out Dang responsibility! I will update, and ask more stupid stuff...as long as you guys are still willing to answer them.. Thanks again to all.

[jagnew3]

Okay, the G3 was installed...air was blasted into the pick up line prior to install....a new std fuel filter was installed..after a long priming period, it was running again. But, only at 30 psi idle. A few observations.

The G3 never is completely full of fuel while the car is running, or not running.

The psi goes up as I give it gas To around 38-40..then comes down as I sustain throttle to about 26, as I let off the gas, it dips to around 22, and as it finds idle it rests at 30-32 again.

I did find an air leak (about the size of a pencil in the hose between the AFM and the throttle housing. Also the adjustment bolt (with the white cap) on the AFM has been tampered with.

[jagnew3]

Did some read, and the adjustment bolt I was talking about id the altitude adjust..it's in about 18 turns from the top.

Got the hole plugged, but won't get to reinstall thing til tomarrow. I suspect the air flow meter too Stephen..and the TPS, though it seems to be kicking the fuel in and out.

[jagnew3]

The plot thickens..I managed a bit of time and reinstalled my newly sealed AFM hose, and the air fuel meter, car ran good, as always. Ran it around the block..ran good..then as it sat in the driveway it started to stumble and died, like always and the fuel pressure went to zero...but here's the thing, I went back and looked at the G3 filter.....still had the same amount of fuel in it as it had had while running, and still looks clean . i tried and tried to get that baby to pump fuel..and it would just run..w/o pumping..but I'll bet in an hour..it will w/o really trying..and it will run good...and then it won't My main point is that there is fuel just before the pump when this happens...hmmmm

[jagnew3]

Yup..20 min. later...I turn the ignition on, I trip the AFM.....suck suck....and pressure to 36. Start the engine...30-32 psi, gun it jump to around 40, sustain 2500 rmp..pressure to 24-26 sustained let off fuel.. pressure drops to 18-20 for a few swconds and recovers to 30 at idle. then after the car has been running a while...the pressure slowly drops to 0 as the car comes to a sputtering backfiring death.. wait 20min/ 30 min.. repeat as nessisary..

Car runs like a raped ape, until this happens.

How does the TPS contribute to the amount of fuel going into the system? Does it simply tell the ecu how long to hold the injectors open? Does it tell a relay what voltage the pump should get, there by slowing down the pump? A combo of the two? The whine of the old factory pump would change pitch when all this was going on. I wondered if something was telling the pupm to slow down for way too long, causing it to dry out as the engine used the remaining fuel.and comming to a point where it couldn't prime running at low voltage, until it was givin' the voltage back (about 20 min. later, ) I don't know

[jagnew3]

One other thing...what do you think the Hissssssssssss that I hear comming from the rear, underside of the intake manifold is? I can hear it as it runs, and when I turn the engine off It lasts about 10-15 seconds. It shounds like it's comming from the steel tube running out of the in. manifold to the ex. manifold...is this normal?

[sblake01]

No, that's not normal. Are you talking about the EGR tube? If so, and the sound is coming from that general area, it's more likely that the EGR valve itself would be suspect. If the tube was leaking, it would be an exhaust leak.

[jagnew3]

I suspect the egr and will confirm today...would this lessen the manifold pressure enough to cause my fuel regulator to stay partially closed?

[sblake01]

I suppose that's possible. A vacuum leak is a vacuum leak wherever it occurs..

[jagnew3]

Something is very...very wrong. I believe the egr leak is in the tube. But that's not what is interesting. For some reason, I decided it would be fun to pinch the vacume line that goes to the fuel pressure regulator. At once my pressure gauge went to just a tick over 36....Hmm I thought, so I removed the line, and capped the tube...car ran great..I'd gun it.36 lbs, I'd idle..36lbs..constant 36 lbs w/o the vacume line hooked up..Now to make it even more strange, the car did eventually begin to lose pressure..just like always, but it took longer (higher pressure took longer to lean I suspect) Here is the wierd thing. When it started to happen I started playing with wires. Here's what I found. I goofed with the wires going to the thermotime switch..but when I started messing with the water temp sensor I was able to get the fuel pressure to recover..until I pulled the connector off by accident..then the car would barely run. eventually after many futile attempts...the car shut down. It took about 1/2 hour to get it to pump again..though the pump would run as always. When it di I ran it for a long time, and played with the wires going to the water temp sensor..each time I unhooked them..the engine would race, then runlike crap..hook em up..ran good. Finally when the car heated up..the problem began, only this time by playing with the plug, and the wires..I was able to recover the pressure...wierd huh?

[jagnew3]

been quiet today...too quiet.. I didn't get back out there to work on the wiring. but I put a new connector on a week or two ago. now I am noticing some of the wire in the harness to that sensor is cracked. I think I will take the senser out, clean it and test it. Then replace the wiring. I'll feel bad in a way if this is it, because we talked about it a while back in the thread, and though I changed the connector..I really prolly blew by it too fast.

[jagnew3]

tank all along gents. I ran a hose to a 5 gal tank,got it primed...ran w/o a problem...until it had sucked the 5 gal dry...note to self..the unused fuel has to go someplace...duh.....make sure there is room for at least 5 gal in the car's fuel tank. doesn't take long to go through 5 gal. I noticed as the tank started going down the problem would happen much faster..when the tank is full the car runs long w/o the trouble.. BTW I did get all new connectors an everything out of the deal..and that aint bad. Looks like the tanks comes out this weekend.