1G Cranks but no spark and no fuel

[Turblown]

I am having an issue diagnosing my 1990 GSX. No Fuel, no spark, no start, CAS plug test failed.

Do you have to test the CAS differently on 1990? Because my plug looks different than what is listed in the haynes manual.

My compression is good and I have power at the MPI relay. Please help! What should I look for next?

 

[steve]

I hate to bring back the dead, but any update on the original poster's problem? I'm dealing with a similar issue, but I get no start.

Rather than post in every thread go read http://www.dsmtuners.com/forums/articles-miscellaneous/217951-how-diagnose-no-start.html and work through the list. I find it helpful to make sure your ECU works before starting the checklist since it a really common problem.

 

[Turblown]

Rather than post in every thread go read http://www.dsmtuners.com/forums/articles-miscellaneous/217951-how-diagnose-no-start.html and work through the list. I find it helpful to make sure your ECU works before starting the checklist since it a really common problem.

Hey steve, That was an attempt to see if the original posters ever solved their problems. I guess I should've just PMed them. I've already worked the list (great resource by the way) and I'm still stumped. I pulled the ECU and it is flawless. I swapped the ECU with a known working unit just in case and still no start. MPI Relay has power and tested good as well as another MPI Relay I swapped. I have a charged battery, compression is good, and timing belt is rotating. I know it has to be something electrical because I have no fuel, no spark, no warning lights with the key on acc, and there is no power to the CAS.

I could go on listing symptoms, but it's pretty much the same as this thread. I will continue to search, try what I can find, and post my results. Thanks for any suggestions.

 

[steve]

I pulled the ECU and it is flawless. I swapped the ECU with a known working unit just in case and still no start. MPI Relay has power and tested good as well as another MPI Relay I swapped. I have a charged battery, compression is good, and timing belt is rotating. I know it has to be something electrical because I have no fuel, no spark, no warning lights with the key on acc, and there is no power to the CAS.

Please describe how you tested the MPI Relay and verified that it has power.
Both the CAS and the ECU get power from the MPI relay and it gets power from the fuse on the battery, however the gauge cluster bulb test (since you say you get no warning lights not just no cel) is on a different circuit with the only common part being the battery and perhaps the ignition switch since the ECU needs to see 12v from the IG1 terminal to activate the MPI relay.

 

[Turblown]

Please describe how you tested the MPI Relay and verified that it has power.

Before I started I verified that the MPI fuse was intact.

I then just used my Hayne's Manual Section 4-3. With the ignition key ON, checked for battery voltage on MPI Relay (EFI control relay) connector on terminal 10. I then followed the instructions for energizing the relay and probing it for the appropriate voltage.

I was unsure about testing the CAS for power since the connector from my car (1990 = 4 terminals in a square) looks different than it does in the book (4 terminals in a row). So, I tested all of the terminals for power and none of them had power. Is there a better way to test the CAS for power? I already know about this post on testing the CAS, but there is no point if the CAS doesn't have power yet, right?

Would a bad Power Transistor be a possiblitly? I have yet to check that, but does the PT affect fuel as well as spark? Any help is appreciated.

 

[turboglenn]

Turblown.. are your cam gears spinning or not?

His aren't so you might wanna check your, btu if the CAS failed and you're gears are turning then you probably just need anew CAS or to check your wiring for breaks or shorts.

If the cam gears weren't turning it's a whole lot of things gone bad. Any update on the timng belt check?

hope to god you got luck enough that nothing hit, but that's about as rare as a whiteman in compton.

 

[Turblown]

are your cam gears spinning or not?

I know for sure that the timing belt rotates when I turn the key and that the belt has no visible damage (cover removed). I've been testing this car (cranking it) for a while and I just did a compression test which is within spec. So, I don't think the timing belt or cams are bad. I will double check tonight to make sure the cams are rotating too and the timing belt is not stripped.

 

[steve]

Before I started I verified that the MPI fuse was intact.

I then just used my Hayne's Manual Section 4-3. With the ignition key ON, checked for battery voltage on MPI Relay (EFI control relay) connector on terminal 10. I then followed the instructions for energizing the relay and probing it for the appropriate voltage.

Since I only have the factory manuals I can't say if the procedure you followed is correct without you describing it.

MPI Pin 10 is the power input to the relay and should have 12v all the time regardless of ignition switch position. Pins 4 and 5 are the switched output and they feed both the CAS and the ECU. Pin 8 is the "control line" from the coil of the relay. It will be 12v when the ignition is off and drop to ground (0v) when the ECU wants the relay activated. There is a diode between pin 10 and the coil so you will only get a resistance measurement in one direction and it will seem open in the other.

I was unsure about testing the CAS for power since the connector from my car (1990 = 4 terminals in a square) looks different than it does in the book (4 terminals in a row). So, I tested all of the terminals for power and none of them had power. Is there a better way to test the CAS for power? I already know about this post on testing the CAS, but there is no point if the CAS doesn't have power yet, right?

So unless you have a broken wire between the CAS and the MPI relay the relay doesn't seem like it turning on, or you would see 12v on one pin and if the ECU was powered up you would see 5v on the two signal wires when the CAS wasn't pulling them low.

Would a bad Power Transistor be a possiblitly? I have yet to check that, but does the PT affect fuel as well as spark?

Maybe and no.

Based on what you have said so far I don't think the ECU is running so nothing interesting it going to happen.

 

[Turblown]

Let me just inform you that I just bought this car (DSM #4 = angry wife) as a no start vehicle, so I don't know alot about it's history. The previous owner said he stopped driving it when it got hot outside (no AC) and it would not start back up again. I will try to mention any mods that I find that may be relevent.

I can see an electronic turbo timer/boost controller, but the display does not come on. I was told it has a Walbro 255lph fuel pump and I can see an AEM AFPR. I can see an aftermarket 3 wire ground coming off the battery.

When I turn the key without pushing the clutch, I can hear the MPI relay click and then a relay that has been added down near the pedals (possibly for the turbo timer or fuel pump) will click also. Once I push in the clutch and turn the key, the starter will crank but not turnover and then there is a grinding noise (for about 3 sec) coming from the starter area after I stop turning the key. All of this with no warning lights and no turn signals, but headlights, instrument panel lights, and hazards all work.

Since I only have the factory manuals I can't say if the procedure you followed is correct without you describing it.

For the harness it says to probe pin 10 to check for battery voltage and that's about it. Here is the short version of what it says to check for the relay.

Section 4-3, Fuel Injection Control Relay Check. (just the relay)
step 32 - Remove EFI relay
step 33 - Connect battery positive (+) to terminal 10 and battery negative (-) to terminal 8
step 34 - Connect voltmeter negative probe to the battery negative terminal, Connect voltmeter positive probe to terminal 4 and then to terminal 5, There should be 12volts at each terminal.
step 35 - Connect battery positive (+) to terminal 9 and battery negative (-) to terminal 6
step 36 - Check for continiuity between terminals 2 and 3, there should be continuity, next remove the ground lead from terminal 6 and check again, there should be no continuity.
step 37 - Connect battery positive (+) to terminal 3 and battery negative (-) to terminal 7
step 38 - Check for voltage between terminal 2 and the battery ground, there should be 12v
step 39 - If the test results are incorrect, replace relay with new part.

According to this my relay passed, but maybe not.

So unless you have a broken wire between the CAS and the MPI relay the relay doesn't seem like it turning on. or you would see 12v on one pin and if the ECU was powered up you would see 5v on the two signal wires when the CAS wasn't pulling them low.

This definitely helps me to understand the situation better. So what are my next steps? Should I be checking for voltage at the ECU? Checking the Power Transistor? Ripping up the dash to see what this guy did for the turbo timer install? Thanks for all the help!

 

[steve]

Here is the short version of what it says to check for the relay.

Section 4-3, Fuel Injection Control Relay Check. (just the relay)
This tests the MPI side of the MPI relay
step 32 - Remove EFI relay
step 33 - Connect battery positive (+) to terminal 10 and battery negative (-) to terminal 8
This should activate the one side of the relay causing it to connect pin 10 to pin 4 and 5
step 34 - Connect voltmeter negative probe to the battery negative terminal, Connect voltmeter positive probe to terminal 4 and then to terminal 5, There should be 12volts at each terminal.
if you do this before step 22 you'll see pin 4 and 5 don't have 12v before hand and do after

This tests the fuel pump side of the MPI relay
step 35 - Connect battery positive (+) to terminal 9 and battery negative (-) to terminal 6
step 36 - Check for continuity between terminals 2 and 3, there should be continuity, next remove the ground lead from terminal 6 and check again, there should be no continuity.
step 37 - Connect battery positive (+) to terminal 3 and battery negative (-) to terminal 7
step 38 - Check for voltage between terminal 2 and the battery ground, there should be 12v
step 39 - If the test results are incorrect, replace relay with new part.

According to this my relay passed, but maybe not.

What this doesn't test is that MPI relay is functioning in the car.

For that you need to check that you have 12v at the connector for pin 10 all the time, turn on the ignition switch and verify you have 12v at pins 4 and 5 when the ignition switch is in the run or start position.

If the the relay checked out but you done see 12v at pins 4 and 5 then you need to look at the ECU and the signals going to it.

 

[Turblown]

What this doesn't test is that MPI relay is functioning in the car. For that you need to check that you have 12v at the connector for pin 10 all the time, turn on the ignition switch and verify you have 12v at pins 4 and 5 when the ignition switch is in the run or start position.
If the the relay checked out but you done see 12v at 4 and 5 then you need to look at the ECU and the signals going to it.

I attempted to do this last night. I used this post to try and test pins 4 and 5 by testing ECU pins 102 and 107. I got no voltage. I then took the MPI relay, ECU and battery and put them in another 1990 GSX. The CAS connection worked just like you said. A 12v pin, two 5v pins, and a ground. So my CAS is just sitting there waiting for the signal, but it never gets there.

The previous owner must have jacked up the wiring. I will tear the dash apart this weekend to see what I can find. Thanks a lot for your help! I will post back with my findings.

 

[Turblown]

I will post back with my findings.

Okay, so I take the dash apart to find a bunch of wires and relays for the turbo timer...

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Then I notice two important connections that have come apart!

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I connected the wires, made sure I put the ECU and MPI Relay back and charged the battery. I retested the CAS connection to find the correct voltages.

I inserted the key and turned it to see the CEL test working. I turned it further and VAAAAROOOOOM!!! Car started!

There are still some issues with a fuel leak and the fact that the car hasn't been started in like a year, but It feels good to have made some progress.

Thanks for all the help Steve and everyone else!

 

[steve]

Congratz and thanks for staying with it. There is no way we could have guessed that somebody had goobered up the wiring. That's a tough one to diagnose over the internet.

One of the first things I do with "new" cars is go looking for all the aftermarket additions and either pull them out or make sure that they are up to snuff. That means no vampire taps and soldered or production quality crimped connections.

Good luck straightening that all out.