Dswoods3

I have been diagnosing my fans not working, prior to this the car ran great. I decided to start her up after checking resistance and toning wires. ...... cranks but no start. I have spark..... but I am missing two important things.... fuel pressure and injector pulse.... read it may be vats.... but my security light goes off when the key is in the ifnition.... it's reading the key enough for that and to enable the starter..... sooo... what can I check and how can I check it? I am not sure what else could control both fuel pressure and injector pulse.... all fuses that I know of locations were checked for resistance already, I also get power at the fuel pump... and it clicks when turning on the key... just no pressure at the schrader valve.

antfarmer2

Pump should hum and run for two seconds when you key on without cranking. So might be bad if not. And look for a bad connection on your distributor on the tach filter wire for the pulse and have your module tested.

Dswoods3

No place to test module here. Which wire is tach filter wire?

antfarmer2

Just about any auto part store can test them but go to more than one some do not know what they are doing. Just unplug the wires going to the distributor clean and check the connector. not sure what color LT1 here.

Dswoods3

It's kewl, found diagram through google, connector is good. Tried to run power through the alcl on g... but it's dark outside now... will check in the a.m. maybe I will call a few more shops in the a.m. too.... autozone was confused when I asked if they had the equipment to test the ecm....

antfarmer2

That was on you it is a ICM on mine and something else on yours. Try telling them ignition module.

Dswoods3

Well $***. I guess I'm confused.... I see what your saying, test the ignition module for the pulse? I thought that had more to do with the spark. My thinking, which may be horribly wrong, is the ecm is messing up because it control both fuel pump and pulse... receives signal from vats and has outputs for fuel pump, injector signal, and starter.... that's why when you said module, I assumed electronic control module. Problem with my theory is the starter has been "approved" by vats.... but I'm looking for somthing the fuel pump and injectors have in common since they both stopped working when I was testing fan circuit

antfarmer2

It could be but I would start looking at the cheaper stuff first. Does your fuel pump run for two secounds when you turn the key on without cranking? And you can jump some wires on the diagnostic port too. Not sure what ones. Shoot for one at a time first. Might have killed a fuse or a breaker. Does yours have fuseable links behind the battery?

Dswoods3

I tried jumping but couldn't see what I was doing, will check in the morning, the fuel pump clicks when turning on the key but it's not running. I tested the wires at the fuel pump.... only 1 is hot. Thanks for the help, I will respond more tomorrow after I try to jump the pins in the light.

ddahlgren

Get a factory service manual. At the rate you are going more liable to break something than fix it. If you have spark it is not the ICM or coil. Don't care about tach module either. Assuming there is fuel in the tank the pump need s +12V and GROUND. Assuming it ran before playing with fan wiring I would start by checking all the fuses to make sure you did not short something and blow a fuse. BTW don't try random combinations on the ALDL connector not a good idea. There should be a sticky here that will have them listed and what the accomplish.

Dswoods3

There is fuel in the tank, I already posted that I checked the fuses and the fuse links, I'm not jumping random stuff I am following the Haynes and Chilton and I also posted that the pump has 1 12v at the connecter by the fuel fill spot, and the ground on the pump was checked also the other 2 wires going to the pump I don't know what they are for.

WVZR-1

The suggestion for the FSM by "ddahlgren" is by all means the first thing you should consider. There are particular diagnostic tree and procedures for a "CRANKS NO START" - you start from scratch using the FSM and where it directs you.

I think I've seen you mention in other threads that you've had multiple ECMs in this car and conditions remained the same. You've got many things that are ECM controlled that you've mentioned don't work. Do I think you need an ECM? Likely NOT

The FSM I'd think a good move.

I believe that the suggestions previously in this thread be "AVOIDED" they're a WAG and you're wasting I believe time and the likely hood of ruining things.

Dswoods3

Yes, I need a fsm. Unfortunately, I don't have one yet, money limitations at the moment. I just come here hoping that I can get some guidance from others to try to save money and time. Maybe some one has had the problem before and can guide me in the direction I need. I have splices all over the car from previous owners. I am tackling each one after I fix one, returning the car to its former glory. Owned the car less than a month and have 1600.00 in parts already. By the time I am done here I will know every circuit in the car. I guess it's the way my family raised me but when I am done here, I will post every bit of knowledge I have learned, and if I have a fsm.... I won't hesitate to look it up for others. I will purchase one... but that will take a week to get the money, and another week for it to arrive with no chance of keeping my hands off the car while waiting for it.... lol

ddahlgren

I would not buy another part until the FSM arrived as at least a 50% chance of wasted money guessing. Tools are a safe bet wand will need them again at some point. I would suggest a noid light and fuel pressure gauge that will screw on to the test port. Until you have fuel pressure and injectors pulsing don't worry about anything else. I believe there is an ALDL jumper setting that will run the fuel pump if not a 12 ga. wire from the battery will, just hook it up temporarily and see if you have fuel pressure and if so it takes the pump and line out of the picture at least for starting. If you have fuel pressure spark and injectors pulse it should start or fire on some cylinders at least. If you don't have a timing light buy one to make sure the sparks are in the right place and time. Don't bother with the expensive high end lights they have as many problems as solutions. If you spend more than 30 bucks it probably has to many features. You need one with battery hook up a pick up no dials ***** or switched needed or wanted. There is a one pin weather pack connector neat the distributor if a L98 that is the bypass for ecm controlled ignition with this unplugged #1 should fire around 6 degrees before TDC and takes the ECM out of the ignition timing game and yes the car will start though not run all that well as far as power. These are all long term investments along with the FSM that are all needed to maintain the car and many others as well.

Dswoods3

Thank you for your recommendations. I have noid lights, I have fuel pressure gauges, and the car has a new permanent remote mount digital fuel pressure gauge from autometer.... the cobalt blue.... it's beautiful! Lol. I do need a timing light, all I can say for sure is checking it old school and verifying top dead center on cylinder 1 checks out to the button pointing to 1. But that doesn't speak of degrees. The timing light I will buy, but after I solve this issue. I wish I knew of a way to test the ecm itself.

Dswoods3

Just an update, the terminal listed by the repair manuals and else where say "g" on the alcl. Supplying 12v does nothing.... the connector that hangs out under the master cylinder when supplied 12v kicks my fuel pump on.... atleast I know my fuel pump is good. Next to check.... fiik.

ddahlgren

Unplug the bypass that will take ECM out of the loop for timing if you have fuel pressure and noid light fire it should run this is all assuming a L98 what year is the car?

Dswoods3

1990, l98. I swapped my relays with a known good one for fuel pump no luck. The wires into relay are all grounded but 1 12v in the 87 position. When I bypass the ecm for the fule pump it starts.... but that is also bypassing several other things, like relays. I have 12v on both wires to the injectors.... I thought only one should be 12 v and the other is supposed to pulse. ***** I need to find what the injectors and the fuel pump circuit share.... that is where the problem is. Somthing as stupid as a hot wire that they share that is grounded some where.

Dswoods3

I have a car full of messes like this..... lol i dont even know what those wires are supposed to go too.... any one wanna post a pic of their wires? Lol. If i jiggle it my key buzzer starts working.... lol

Dswoods3

And sorry, what bypass are you speaking of?