jagevileye21

iTrader: (3)

Engine: LT1
Trans: 4l60E
Custom wiring harness by LT1350


Here's the story...

Last wednesday, I was kind of low on gas. So I stopped by the station to fill up. After doing so, I started the car, turned my lights on and I notice my high beams were on. So I hit the switch and they wouldn't turn off until I hit the switch pretty hard. Afterwards, I got out to clean the windows. While cleaning the windows the car sounded like the RPM's were dropping and the car finally stalled. So I get in a tried to crank it back up. The engine would turn but it seemed as if I wasn't getting any fuel. So I turn the key to the on position to see if I hear the fuel pump energizing. I didn't hear anything. Next I check all of the fuses. None of the fuses were bad. Finally, I check my fuel pump relay. I felt the relay clicking but just to be sure, I switched it with the same type of relay from my fan relay. The pump still did not energize and the car did not start. So I had to have the car towed home.

After the getting the car home I hooked up the fuel pres. guage. The result was 0 psi. So I was pretty sure it was the pump. However, I had forget to check the in-line fuse come off of power cable that goes to the alt. That fuse was bad. So I replaced the fuse and the engine started and then turned off. Still no fuel pressure.

Now I am almost certain the pump is bad. Eventhough, it gave no signs of failure i.e (hard start, stalling, or hesitation). So I changed the fuel pump yesterday. Still nothing. Pump does not energizes, no fuel pressure, no start.

It must be an electrical problem. So I use my test light to check to see if I even getting power to the relay. After checking my wires going the relay I see that I am getting power. However, no power is not coming from the relay wire that goes to the (+)fuel pump. So I believe that can eliminate a bad harness thereafter. The relay clicks when I turn on the ignition. So it must be grounded. I even bought a new relay and still no power is coming out.

I was thinking that the wire was bad, but I tested the wire and it turned out good. I also thought maybe there was a bad ground later in the harness from the fuel pump. But I grounded the old fuel pump(which is still good) and connected the + to the wire coming from the relay and the wire still has no power and the fuel pump did not work. The old pump works when I connect it to the battery.

If anyone could help me out that would be great.

The relay is a 5-terminal, 30A, 12vdc.
It has an input for battery power & 12v switched power.
It has a ground and power out.

Thanks in advance,
Jay

jagevileye21

iTrader: (3)

Anyone?

BigBadLou

iTrader: (3)

Sorry, I didn't see this thread sooner.
As I posted in your other thread, check out this short article on the FP circuit troubleshooting: http://www.austinthirdgen.org/index.php?pid=35

If you have a digital multimeter and know how to use it, it's a big plus.

You already did some good troubleshooting here. Kudos.
So now you know that the relay works but you still don't have power to the pump. Three posibilities here I can think of right now:
1) bad wiring on relay
2) dirty C313
3) bad pump

You can test #1 by cranking for a few seconds to build up oil pressure. If your oil pressure sender/switch is good, it will turn the fuel pump on.

You can test #2 by jacking up the rear and disconnecting and cleaning the connector above the rear differential.

You can eliminate #3 by putting 12V directly on the grey wire on C313 and ground on the black wire. If the pump won't run, it's likely bad.

Hope this helps.
Lou

jagevileye21

iTrader: (3)

Lou, thanks for the help.

I tested the ECM green/white wire. The test light lit for two seconds.

I rechecked the relay to make sure I was getting power to the relay. The relay has a good ground and the ECM wire is functioning correctly. However, still no power is coming from the relay. Tested three different relays.

Next, I connected 12V power to the grey wire (+) fuel pump. The pump did turn on. However, I still have no fuel pressure. The fuel filter is almost brand new. The injectors and fuel pressure regulator are brand new and I have braided stainless fuel lines.

Even if the fuel filter is clogged it should still show alittle pressure. I guess my next step will be checking the fuel injectors to make so they are firing.

Let me know if you have anymore suggestions.

Thanks,
Jay

BigBadLou

iTrader: (3)

Great troubleshooting!

You say 12V on the grey wire turns on the fuel pump, awesome.
Remove the relay from the connector. Test the orange wire for 12V. Use a paperclip (or wire) to connect the orange wire to the grey wire. If the pump turns on, the fault is either in all three relays or their connection. Try wiggling the connector with the paperclip in - does the fuel pump cut out?

Also, you mention that you're not building any fuel pressure with the pump running. That's not an electrical problem anymore but still very interesting. Try clamping the return line and see if you build up pressure - that would point to a faulty regulator.

Btw, what color is your vert? Mine's black.

Hope this helps.
Lou

uemf

I'm sure you checked this but...
you say that you can hear the relay actuate but you still don't get 12V out of it. did you verify that you still have 12V coming into the relay ? it sounds like a short (did the fuse blow again? ) or open in your wiring.
if the fuse blew again, replace it and make sure you have 12 v coming into the relay. then check from gray wire to ground ... if pump is connected you should read the pump resistance. if not you of coarse should read open/infinity.
on a hard to trace problem like this it's best to have your wiring diagram and start from one end working to the other...

I can't think of any way that the headlights / dimmer switch would kill power to the fuel pump but then I thought the cruise went out on my blazer ... turned out it was a bad ground on a trailer that I was pulling...the bad ground was on one tail light (when I turned on the headlights, the running lights on the right tail light found a ground thru the brake side... just enough to prevent my cruise from activating (sorry, off topic)

probably not much help but...

Tony

jagevileye21

iTrader: (3)

The fuse has not blown again. I'm getting power out of the orange wire going the relay. When I get home I will check to see if its a full 12V.

I know its not impossible but if all three relays are faulty that would be crazy.

I will try clamping the return line and see if pressure builds. How does a fuel pressure go bad?

Thanks,
Jay

BigBadLou

iTrader: (3)

The FPR can have a hole in it or can be stuck open or have another mechanical failure.

Let us know what you find on the relay and connector.

Lou

jagevileye21

iTrader: (3)

Where do I start...

Aftering, working on the car Friday and conducting all the test. I called the auto store to confirm they gave me the right fuel pump. They had given a fuel pump for a TBI which did not provide the adequate pressure needed to start the engine. So, I figured this was my problem and I dropped the tank again to put in the correct fuel pump. Afterwards, I go to check fuel pressure and I still get no reading. Next, I change the fuel filter eventhough my other filter is only a few months old. Still no reading. I am getting fuel up to the rail and the engine does crank but it cuts out thereafter. I tried to clamp the return line to see if pressure builds but it did not. Next, I take off the inlet to check for any imperfections and give it a few bursts of compressed air to see if anything came out. Now I guess my only choice will be get a new regulator eventhough I haven't had this one for more than a year.

Lou,

How do I test the injectors without a noid light? I use to have one but I can't find it. As far as the relay goes I tried tinkering with the connector but I still get no power out of the relay. By the way my vert is white but I still trying to decide if I want to paint it. Thanks for all the help.

BigBadLou

iTrader: (3)

You said you have power to the relay and it clicks but does not send any power to the pump. And you also said that you tried 3 different relays. In that case, I wouldn't suspect the relay, I would think the flaw is in the socket. If you get power in but not out, there must be a bad connection in there.

You can jumper the orange to grey wire with a paperclip (not sure if you've done it yet) and the fuel pump should run continuously. At that point, try to wiggle the socket and wires. If the pump runs without interruption, the connections are good and the problem must be between the relay and the socket.

Wish I could be there to look at it myself, it's driving me nuts.
Lou

jagevileye21

iTrader: (3)

I got the relay to work. I hear the pump energize for two seconds. I believe two out of the three were bad along with a bad connection. However, still no fuel pressure. I even changed the fuel pressure regulator. I tested all of the injectors and they are all getting power (11.5V). None of the injectors are leaking. I am getting 11V at the connector to the fuel pump. I removed the fuel rail and cleaned it out. No debris or anything came out. The fuel rail does not leak nor does any of my lines. I've checked everything in the fuel system. I dont know what else it could be. Maybe the auto part store just gave me a bad pump or the wrong part. When I removed the fuel rail only a little bit of fuel was present. The pump probably isn't pumping enough.

jagevileye21

iTrader: (3)

Nothing yet...

BigBadLou

iTrader: (3)

A very very very stupid question: do you have fuel in the tank?
Sorry for asking but I gotta cover that possibility.

If the electrical is fixed but your fuel pump is not building up pressure in the fuel rail, I'd take it to the right forum (TPI?), they'd have more answers.

Lou

jagevileye21

iTrader: (3)

Yeah I do have fuel in the tank. I just added some the other day.

jrs84ta

Anyone figure what was wrong cuase I seem to be having the same problem. I go to start the car and fuel pressure is barley around 20psi and i just put a new pump that pushes up to 80psi.

karl's-92'-z28

iTrader: (5)

Well I just found out that their is backup fuel pump switch that shuts the pump down when oil pressure drops. Its located next to the oil sending unit, its to protect the motor.

BigBadLou

iTrader: (3)

That is incorrect. (nothing personal, just making sure there is no confusion on this)
It works the other way around. It is a backup system that powers the fuel pump once the engine builds up oil pressure (is turning). This backup system is in place in case the ECM controlled relay fails to operate the fuel pump. It would suck to be stranded 100 miles from the nearest civilization because of a $5 relay.

Lou

karl's-92'-z28

iTrader: (5)

Ahh cool, thanks for clearing that up, well heres the link I got.

http://www.chevythunder.com/fuel%20i....%20pg%20B.htm

BigBadLou

iTrader: (3)

I see, I didn't know that somebody actually published that on their website.
That's why I never trust anything from an amateur sites. It's always recommended to double- and triple-check.

If anybody knows how to contact the owner, can you ask him to correct that information? Thx.

Lou

Bill/T/D/Y

Ok hello all.Still havin issues here.Heres an update.
I just came back inside from workin on the 90.Rechecked everything and this time around found the inline fuse #3 a 20 amp fuse was blown.Have replaced with a 25 amp fuse brand new out the case and still car would not fire up.(no fuel pump action).Then when I fliped the switch for the hotwire bypass for fuel pump the car started and ran.However the 25 amp fuse blew.(tried 3 times same results).I also notced that the indash batt gage was reading low and as i reved the motor it had backward swing.(2 hour old brand new batt BTW.)
The car does start and run with the hotwire bypass on.Heck I even drove it around the block.However I keep blowing the fuse.(there must be a dead short somewhere.)
I believe it comes down to me doing the following.1 buy more 25 amp fuses.2 buy yet another fuel pump relay.3 buy yet another new oil pressure switch.And then restart the whole trouble shooting thing again.Even consider a new fuel pump regardless of the fact that this one bench tests @ around 80 and does run the car.(even if only when it is hotwired)
In the meantime I plan to also get the alt bench tested.
This is just exactly why I hate , HATE fuel injection.A handfull of wires will run a carbed motor but ya need the ecm & other assorted other demons to run fuel injection.
Times like this I get sorely tempted to just gut the car and drop in an old carbed motor.

The_Phoenix

iTrader: (3)

I'm having the same problem on my '89 GTA except my SES light won't come on either. I replaced all 3 relays yesterday and still no f/p prime. Bypassing 12v directly to it gets it running but thats the only way. I might have to purchase a new ECM if its not the C313 connector which I'll take a look at later . Does your SES light come on Jagevileye???

Thanks later,

Phoenix

navyCM

iTrader: (3)

i believe if your SES light doesnt come on then your ECM is not getting a signal from the ALDL. it may be a bad ECM.

The_Phoenix

iTrader: (3)

Thanks for the info. Sorry about the post jagevileye21; I wasn't trying to steal the thread or anything. And now back to our regularly scheduled programming .

Thanks later,
Phoenix