Fuel pump not running.

[mmkkpro]

Hi guys, I have a question about the fuel pump/pumps.
Shouldn't FP1 be on with ignition switch on?
I have been chasing a miss, so I figured I would test each fuel injector by way of MH, procedure,grounding each pin at ecm connector A. However my fuel pump does not power up with switch on. When I start the car both FP1 and FP2 are working and I have 46 lbs. Idling. I have the FSM and have been studying it, and it says both pumps are energized on start. Every car I have worked on the fuel pump comes on with switch to the on position and shuts off when correct pressure is reached. Any help would be appreciated, thanks.

[Ccmano]

The fuel pump(s) should run for a few seconds when the ignition is turned on. Then turn off. It does not run continuously with the ignition on, engine not running. The circuit is controlled by the ECM via the fuel pump relays. So when the fuel pump is not running there is no power to the circuit including the fuses.
H

[mmkkpro]

Thanks CC, the red wire by the wiper motor is for testing fuel pumps right? I'm trying to test each primary injector, I can get them all to click but with no fuel pressure I can't hear them spray. I reckon I could turn the switch on and let fuel pressure build up and test a coupe at a time. Thanks, I appreciate you helping me out.

[Ccmano]

Originally Posted by mmkkpro

Thanks CC, the red wire by the wiper motor is for testing fuel pumps right? I'm trying to test each primary injector, I can get them all to click but with no fuel pressure I can't hear them spray. I reckon I could turn the switch on and let fuel pressure build up and test a coupe at a time. Thanks, I appreciate you helping me out.

No problem, yes the red wire is the fuel pump test lead. Apply 12v and the pumps should run. You won’t necessarily find a bad injector that way. They may be functioning but have a poor spray pattern, be clogged or have corroded electronics. About the only thing you can do is check the injector resistance with the plenum in place. Use Marks write up below. If the car is a 90-92 with original injectors don’t bother. Just replace them. They are either bad or will go bad.
http://www.zr1specialist.com/HAT%20W...in%20Place.pdf
H

[mmkkpro]

I put a remained set of injectors in it, don't want to say the name a while back.
It was running great, I stopped at a stop sign, pulled away kinda hard, second gear, moving out and all of a sudden it was like flipping a switch, just started missing. Since then I have installed new plugs, tried to test injectors and all are clicking, that's about all I could tell.
Work done before
Remaned injectors
Coils
Wires
Fuel pumps
Fuel filter
First new set of plugs
Repairs secondary vacuum system
Oil and filter
New pressure differential sensor
New o2 sensors
Compression check
200 Amp alternator
New oil in trans and rear end
New tires
Yesterday I put a new fuel filter on, because I had to clean the fuel tank when I got the car. Upon inspection of of old fuel filter, it was full of small rust particals, so I put a new filter on. Do you think some particals could have gotten past the fuel filter and stopped up an injector? The filters used are NAPA Gold.
I plan on buying new injectors and gaskets from Jerry soon, also a chip from MH with secondary delete. It's so frustrating, MH recommends not to pull individual plug wires off while the car is running, that's how I always found the dead cylinder in the past. I tried using a spark tester on each cylinder but can't really tell for sure which cylinder it is. Listening to the exhaust sounds like passenger side. It was running so good, smooth and powerful. I'm going to keep working on it, I mean all it needs is air, fuel, compression and fire, got to be one of those. Not giving up, thanks.

[dredgeguy]

If you had rust in the fuel filter, maybe the fuel pressure regulator could be the problem? I am certainly not as mechanical as others here but just making a possible suggestion to check. Good luck and thanks for keeping us posted.

[Ccmano]

I personally don’t have a problem with the “rebuilt” injectors that are available. Most are the Ford/Bosch type and generally work well. That said I’m not convinced the injectors are your issue.

How does it run since you changed the fuel filter? Unlikely the rust got past the filter.

How does it idle? Does the car idle at the correct rpm? Does it idle high?

Describe the “miss” more clearly and when it happens. Only at idle? On acceleration? On steady cruise throttle? Under load like going up a hill?

On the brisk acceleration that started this did the car backfire?
H

[mmkkpro]

Hi guys, first I want to thank you for you interest in helping me with this issue.
The engine idles around 7 or 800 rpm
The miss/skip can be felt at idle
Letting clutch out off idle really feel it
If I keep rpm above 1800 or so not so noticeable in any gear.
Driving at 60 mph in 5th gear it's ok but if I try to use 6th gear up 80mph it's very noticeable, very rough, for that matter any higher gear below 12 to 1500 rpm it's very noticeable.
It feels like a completely dead cylinder, I used a stethoscope to listen to fuel injectors while the engine was idling and all but one clicked, the injector on #6 is the one where there is no clicking. That's why I wanted to try MHs injector test at ecm. I could hear #2 cylinder spraying and the fuel pressure gauge dropped, but since the fuel pump won't come on I ran out of pressure before I got to cylinder#6. That's why I was asking if I could use the red test wire to power up the fuel pump to
rebuild pressure.
I have blue spark on all cylinders, checked with spark tester.
Compression numbers looked good all within like 5 pounds, I wrote them down, will see if I can find them.
New plugs, coils, wires.
When I was doing the ECM injector test all injectors clicked, but when running #6 is quiet, maybe a slight click but not like the rest.
The morning I was driving it when this happened, it was running great. As I pulled away from the stop sign, went through 1st gear to around 5k rpm, shifted to second gear, and half way to 5k, it dropped a cylinder. I was running exhaust manifolds only with cats, and when it happened I could feel the difference and hear it too, not near as responsive and sounds labored..
This is my first in depth dealing with fuel injection. I'm a carb guy, I have a 540 c.i. Pontiac 455 bored and stroked drag car, but it's a 850 holley, a lot simpler.
MH says not to pull the plug wires while running, when I did the spark test I could not identify the dead cylinder because of shutting the engine off to change the tester to the next plug wire, yall know while the engine is running and ya pull a wire, you can hear the difference or not immediately. I have read some posts where some guys with Zs have pulled plug wires while running to I'd the dead one but in afraid to do that, sorry for the long post. I'm going out right now to play with it a little, thank you guys very much, this has been an adventure.

[mmkkpro]

Just listened to all injectors with my stethoscope #6 is completely quiet, all others are ticking. Enclosed it two plugs.
The one on the right is #6
The one on the left is #4
I can see and smell gas on #4, actually looks rich.
I also pulled #6 wire and hooked up my spark tester, started the car and no difference in sound or vibration, I think this is the dead cylinder.
I reckon I could buy one injector and see if that's actually my problem. I mean all 7 of the others have a fairly loud tick, #6 nothing. If they were easier to get to I would switch it with one I know is working. I contacted the company, suppose to be a 3 year warranty but got no response. My thing with remanufactured injectors, you have no idea how old they are and from what I've read they do have a life cycle. I may buy one new one switch it out and see what happens. I should have bought them new SS ones Jerry has. Maybe I will try contacting the company agian, I don't know, bummed out. Nut ain't giving up, I have learned a ton from you guys, I knew it was going to be a steep learning curve. Wish I lived near a reputable LT5 guy. Maybe someday I will be that guy in my area!! Thing is it was running so good on all 8 cylinders, smooth, powerful, and sounds wicked. I really like this ole beast, with you guys help in going to get there. Thanks a million.

[-=Jeff=-]

Looks like 6 is not even Sparking.. I suggest checking plug #1.. they share the same coil.. see what 1 looks like, could be a bad wire.. Was the car sitting for a long while? maybe a mouse made lunch of the #6 wire