help!! 88 nostart
06-15-2008, 11:20 AM
#1
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help!! 88 nostart
Hi, as a new member, I did the recommended search of the archives to avoid asking a redundant question... I found several fuel pump related issues but none quite like what I'm experiencing.
car is an 88 auto, fuel pump won't run unless the relay is jumped. When it is however, there is still no start. However, the car will run on a small amount of starting fluid so I know there's spark, etc.
I pulled the elek panel forward and checked everything I could find, no moisture, no corrosion, no obviously broken wires. Using a DMM, I found that there is simply no signal from the ecu to the entire circut that triggers the FP relay.
Other clues???? there is no regular ticking noise from under the hood when the key is on, (injectors), and the ecu was done by JDS last year.
What should I be looking for as an input to the ecu to tell it that everything's ok for it to turn that circut on?
Any help would be greatly appreciated,
stumped in detroit,
Todd
car is an 88 auto, fuel pump won't run unless the relay is jumped. When it is however, there is still no start. However, the car will run on a small amount of starting fluid so I know there's spark, etc.
I pulled the elek panel forward and checked everything I could find, no moisture, no corrosion, no obviously broken wires. Using a DMM, I found that there is simply no signal from the ecu to the entire circut that triggers the FP relay.
Other clues???? there is no regular ticking noise from under the hood when the key is on, (injectors), and the ecu was done by JDS last year.
What should I be looking for as an input to the ecu to tell it that everything's ok for it to turn that circut on?
Any help would be greatly appreciated,
stumped in detroit,
Todd
06-15-2008, 01:07 PM
#2
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Hi and welcome!
How did this happen? You bought it like this or suddenly appeared?
Can you swap the LH relay (XXV) with another known good one? E.g. the relay for the horns (XII).
How did this happen? You bought it like this or suddenly appeared?
Can you swap the LH relay (XXV) with another known good one? E.g. the relay for the horns (XII).
06-15-2008, 01:09 PM
#3
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When was the fuel filter last changed?
The FP relay is the most common on the board; if the horn works use that relay to test the FP, LH and EZK relays.
Is there a running 928 close of same MY so you could wap the LH?
The FP relay is the most common on the board; if the horn works use that relay to test the FP, LH and EZK relays.
Is there a running 928 close of same MY so you could wap the LH?
06-15-2008, 01:23 PM
#4
Burning Brakes
There are 3 relays you want to jumper to confirm if it is relay related. You have jumped the fuel pump relay but the signal for the fuel pump is dependent on one or both of the other 2 (if I recall correctly).
Once you have confirmed that with all three relays jumped that they engine starts and runs then you can focus on which one is actually the problem. I have had and heard of several others that have done this and found that relays that are "known good" don't always work consistently. I think in many cases the process of removing and installing the relay improves the contact to the terminals while in other cases the "good" relay was not strong enough to work in all the common locations.
Once you have confirmed that with all three relays jumped that they engine starts and runs then you can focus on which one is actually the problem. I have had and heard of several others that have done this and found that relays that are "known good" don't always work consistently. I think in many cases the process of removing and installing the relay improves the contact to the terminals while in other cases the "good" relay was not strong enough to work in all the common locations.
06-15-2008, 01:37 PM
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Thanks for the quick replys,I'll take a look at the other 2 relays and post results. Out of curiosity, any alarm related issues that could interfere?
More history, Aryan asked if I bought it this way, inherited someone else's problem to be more accurate. I do know that the car has somesort of weird battery drain issue that was originally believed to be driver seat related. However that is now disconnected. During the PO's attempt to resolve the drain issue, the non working FP issue reared it's ugly head.
More history, Aryan asked if I bought it this way, inherited someone else's problem to be more accurate. I do know that the car has somesort of weird battery drain issue that was originally believed to be driver seat related. However that is now disconnected. During the PO's attempt to resolve the drain issue, the non working FP issue reared it's ugly head.
06-15-2008, 01:49 PM
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Don't know about a local running 928 same year.... what could the fuel filter have to do with a relay issue?
06-15-2008, 01:54 PM
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Do you know for sure its a relay?
From what you describe your issue is with a lack of fuel hence I suggested the filter, relays and then the LH brain. I didn't mention the pump as you said it runs with the relay jumpered but theres still no fuel to the engine.
From what you describe your issue is with a lack of fuel hence I suggested the filter, relays and then the LH brain. I didn't mention the pump as you said it runs with the relay jumpered but theres still no fuel to the engine.
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06-15-2008, 02:47 PM
#9
Drifting
When I got my '85 it ran like crap. After spending a lot of time and throwing a lot of money and parts in it, I realized the problem was the LH. So I got a replacement. I plugged it in, started the car and everything worked for about a minute. Then it shut down and wouldn't restart. So I started going through the wiring diagrams and diagnostic manual, and was almost literally pulling my hair out. On a whim I tried something totally crazy. I put gas in it. Sometimes it's the little details that make all the difference.
Not to sound like a dick, but does the car have gas? The senders for the fuel gauges do fail from time to time, and then you won't see if there's gas in it. Also, the fuel pump gets the signal to operate from the LH. You can tell the pump is working because it should run for a second or two after you release the key when trying to start it. Or if the cover is off, you can place your hand on it while someone else cranks it. You'll feel it running.
To check for fuel at the injectors you can remove the cap at the front of the passenger side fuel rail. You don't even need to remove it all the way as pressurized fuel will spray out if it is there.
Not to sound like a dick, but does the car have gas? The senders for the fuel gauges do fail from time to time, and then you won't see if there's gas in it. Also, the fuel pump gets the signal to operate from the LH. You can tell the pump is working because it should run for a second or two after you release the key when trying to start it. Or if the cover is off, you can place your hand on it while someone else cranks it. You'll feel it running.
To check for fuel at the injectors you can remove the cap at the front of the passenger side fuel rail. You don't even need to remove it all the way as pressurized fuel will spray out if it is there.
06-15-2008, 03:50 PM
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Do you know for sure its a relay?
From what you describe your issue is with a lack of fuel hence I suggested the filter, relays and then the LH brain. I didn't mention the pump as you said it runs with the relay jumpered but theres still no fuel to the engine.
From what you describe your issue is with a lack of fuel hence I suggested the filter, relays and then the LH brain. I didn't mention the pump as you said it runs with the relay jumpered but theres still no fuel to the engine.
As far as fuel in the tank, I put 5 gals in it before starting repairs.
06-15-2008, 03:56 PM
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ok.............now we're getting closer.
Have you tried the relay swap as suggested?.
Look at the relay chart on the 928SP site and you'll see the horn and defrost relays are the same as the FP and LH...............simply check to see if horn and defrost work and swap them.
After years of reading many issues resultant of relays I did the most easiest of manitenance; I replaced them all with new.
Have you tried the relay swap as suggested?.
Look at the relay chart on the 928SP site and you'll see the horn and defrost relays are the same as the FP and LH...............simply check to see if horn and defrost work and swap them.
After years of reading many issues resultant of relays I did the most easiest of manitenance; I replaced them all with new.
06-15-2008, 03:57 PM
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[QUOTE=JHowell37;5513056] edited....
Not to sound like a dick, but does the car have gas? The senders for the fuel gauges do fail from time to time, and then you won't see if there's gas in it. Also, the fuel pump gets the signal to operate from the LH. You can tell the pump is working because it should run for a second or two after you release the key when trying to start it. Or if the cover is off, you can place your hand on it while someone else cranks it. You'll feel it running.
QUOTE]
It does have fuel at the engine, I can hear the pump run when I jump the relay, it's got enough gas, etc.
I understand that the fuel pump get's it's signal to run from the ECU. I have verified that the signal from the ECU is not present in the trigger side of the relay.
My question is this, since the ECU was done last year by JDS, is it likely that it's bad again, or is it more likely that the ECU is looking for some sort of missing signal to tell it that everything is in order and it's ok to turn on the fuel pump circut?
Not to sound like a dick, but does the car have gas? The senders for the fuel gauges do fail from time to time, and then you won't see if there's gas in it. Also, the fuel pump gets the signal to operate from the LH. You can tell the pump is working because it should run for a second or two after you release the key when trying to start it. Or if the cover is off, you can place your hand on it while someone else cranks it. You'll feel it running.
QUOTE]
It does have fuel at the engine, I can hear the pump run when I jump the relay, it's got enough gas, etc.
I understand that the fuel pump get's it's signal to run from the ECU. I have verified that the signal from the ECU is not present in the trigger side of the relay.
My question is this, since the ECU was done last year by JDS, is it likely that it's bad again, or is it more likely that the ECU is looking for some sort of missing signal to tell it that everything is in order and it's ok to turn on the fuel pump circut?
06-15-2008, 03:59 PM
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ok.............now we're getting closer.
Have you tried the relay swap as suggested?.
Look at the relay chart on the 928SP site and you'll see the horn and defrost relays are the same as the FP and LH...............simply check to see if horn and defrost work and swap them.
After years of reading many issues resultant of relays I did the most easiest of manitenance; I replaced them all with new.
Have you tried the relay swap as suggested?.
Look at the relay chart on the 928SP site and you'll see the horn and defrost relays are the same as the FP and LH...............simply check to see if horn and defrost work and swap them.
After years of reading many issues resultant of relays I did the most easiest of manitenance; I replaced them all with new.
Incedently, anyone in metro detroit with a known good ECU from a good running car?????
06-15-2008, 04:09 PM
#14
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It is most unlikely one of my rebuilt ECUs would fail after such a short time..... does the tach flicker when you crank the engine ?
RPM pulses from EZK to LH arrive at LH pin #1. A 12v square wave. Check that is present. Those same pulses feed the tach.
Have you checked fuel delivery volume and pressure at the rail, as per the WS manual ?
RPM pulses from EZK to LH arrive at LH pin #1. A 12v square wave. Check that is present. Those same pulses feed the tach.
Have you checked fuel delivery volume and pressure at the rail, as per the WS manual ?
06-15-2008, 04:26 PM
#15
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The most common problem in a no-start situation on a 928 is a faulty relay. So far, there have been six suggestions that you check the relays...
If the injection relay is faulty, the injectors won't work. If the EZK relay is faulty, the LH ECU has no signal.
All three relays must work for the engine to run. While there are other possibilities, perhaps a good starting point might be to check Relays XXV, XVI and XX.
If the injection relay is faulty, the injectors won't work. If the EZK relay is faulty, the LH ECU has no signal.
All three relays must work for the engine to run. While there are other possibilities, perhaps a good starting point might be to check Relays XXV, XVI and XX.