Fuel injector replacements

[Blue_streak]

This car was not taken care of by the PO. The owner before them replaced the floor pans, put an exhaust system on it and also got fiberglass quarter panels installed. It ran and drove when I got it 4 years ago, but I'm fairly certaint it was on its last legs the because of the sheer amount of things that needed replacing. The long list of stuff I replaced looks like I was just throwing parts at the problem but all those things where dead or dying on the car when I got it.

[S30Driver]

What has happened with the car in the last 4 years... When was the last time it started?

Has it sat for a long time? Have you made any recent changes and now it wont start?

[Blue_streak]

Ok, so year 1 it stopped running properly and was really hard to even get started. It ended up being the starter. Replaced that plus plug wires spark plugs cap and rotor while I was at it for good measure. Then it was running but killing battery, ok had a zx alternator that I had rebuilt so did the zx upgrade. Year 2 replaced alternator and it's no longer killing battery but now it will only run for 10 minuets at a time and need to cool down, kids and lack of cash gets in the way of much work, fuel pump also died this year. Year 3 replaced fuel pump, car fire right up till I gave it a little gas and sputtered and died. This year had been the most work so far. Got the tank cleaned and welded as it got a small leak from where PO whacked it off something. Initially I was not getting spark the new ignition relay fixed that. The fusible links where shot(the holders to) so I found a stinger max4 fuse block on eBay and did that upgrade to. Finally after it not starting it came to the injectors(which appeard to be the original ones) .

The car will start with starting fluid but not stay running. Fuel is getting to the rail. One thing I did notice is injector 1,2,3 had fuel in them when removing the rail where injector 4,5,6 didn't have much at all(numbered from front on engine back). My thoughts are clogged rail, fuel pressure regulator or failing that ecu.

[S30Driver]

The ECU needs pulse input from the ignition to fire the injectors. You need to check for continuity between the negative terminal of your coil and the #1 pin of your ECU.

Might be time to go through the EFI bible and sort things out ....

[Blue_streak]

Ya probably a good idea. Have been meaning to, whenever I'm about to I take a 2nd look at thing and notice something else broken that could be causing it

To.

[Zed Head]

S30Driver's suggestion is the way to go. You've run out of ideas it's time to do the tedious work. It's really not bad once you start, you'll find things that are not quite right and each small fix will make everything else better.

Here's a link to the book known as the Bible, below. Use the 1980 Electronic Fuel Injection Guide and find the tests for your car. Or just go directly to the 1975 Guide, it's probably close enough that nothing will be missing. Yes, ohms is the test. But the problem you described may not have anything to do with the EFI system, it sounds more like a cooling system problem. Saying that a clogged fuel rail or bad ECU causes overheating is kind of like saying that 2 + 2 = a circle. But the lack of fuel in three injectors doesn't indicate a clogged rail either. The fuel can feed from both sides. Anyway....

" but now it will only run for 10 minuets at a time and need to cool down,"

XenonS130 - S130 Reference

[Blue_streak]

Clogged fuel rail was more my thoughts on one set of injectors getting fuel but not the other. The ecu thought came from it just not starting based on what's been replaced. I have not encountered the 10 min run issue in a long time because it just won't start now. It's a 76. I'm gonna try the tests in the efi bible and go from there.

Edited July 22, 2014 by Blue_streak

[Zed Head]

I was just making a joke, but ECU and fuel system are pretty far apart themselves in operation, add in overheat and you're spread pretty thin.

If the problem now is that it won't start, you really want to begin even before the "bible" with the basic spark and fuel verification. You're at square one on the game board. Pull the small wire off of the solenoid and turn the key to Start. See if the fuel pump runs. Remove a spark plug, ground it, crank the engine and check for spark. Squirt some starter fluid in to the intake manifold.

It sounds like the engine hasn't been run much for three years? It could just be bad old gas. Might even have some water in it. Eurodat found a few gallons in his tank.

[Blue_streak]

Oh, fuel pump runs and I'm getting spark. Pulled the hose off the top for the fuel filter to a gas can just to see if it was pushing fuel to the engine and it is. Spark test was done to and the starting fluid. It will start with the fluid. Gas in it is brand new, was replaced when in ad to pull the tank for repairs.

[Zed Head]

Well then, S30Driver's comment about Pin #1 is important.

But here's an odd thing about the Z EFI system that I've experienced - if the tachometer is not installed, with its inline resistor, the ECU will not control the injectors. I think the tachometer may be acting as a pull-up resistor but I'm not sure. I do know that if I remove the resistor to the tach my engine will not start. I would only consider that if you've been messing around with other stuff though.

Before you get in to that, check for power to both sides of the injector pugs with the key on, and check for continuity from Pin 1 to the coil. And you might as well do as many of the Bible tests as you can while you're down there.

Good luck.

[EuroDat]

+1 for above advice and a couple of pointers on testing the pump.

You know it running, but there are some other test to tell the true condition of the pump and FPR. You will need a guage installed somewhere after the fuel filter and before the FPR.

1. Remove the solenoid wire from the starter. That way you can use your key in "Start" to test.

2. Hold key on start for 10 - 15 seconds. Pressure should read around 36psi. Thats the FPR pressure with no manifold vacuum.

3. Block the return line. I fitted a valve in the line so I could control it if the pressure went too high. Check maximum pressure. A good functioning OEM pump will reach about 55psi. Be carefull if you have a aftermarket. They can develop a lot more pressure and even damage something or blow off a fuel hose and spray fuel all over the place.

4. Check maximum flow from the return line after the FPR. You should get about 1/2 gallon (1.5 to 2ltr). That is with the fuel pump running under 36psi pressure.

5. Engine running: Pressure at idle should be around 28psi. If you give the throttle a quick rev. The pressure should briefly increase as the vacuum dips. Good indication that the FPR is functioning properly.

Note: The flow valve is from my testing on my pump. its not from a factory spec.

Here is some photos of my test.

Goodluck hunting.

Edited July 22, 2014 by EuroDat
Correction 46 ---> 36psi

[Zed Head]

Euro, I think that you meant 36 psi, not 46? You typed it twice. Fat fingers? No offense.