GM GM TBI No Spark - No Fuel (1 Viewer)

[TwelveGravity]

So it wasn't very long ago I finally got my FJ40 (has a 5.7 TBI from a '93) going. I had been driving it periodically around town for a few weeks when one day I went to move it from the side if the house to the driveway. I got about 80 down the street to flip around and it just died and would not restart. Just crank and crank. Looking it over found no spark. Replaced the Ignition Coil... Still no spark. Replaced the Ignition Module... Still no spark. I replaced the Distributor... Still no spark. Also with that, the three parts I just replaced are less than 1 year old. During all this I also noticed that the injectors would not spray while the engine was cranking over. I verified that the fuel Pump (from Howell EFI) was in fact working and supplied enough pressure to the injectors. I read to unplug the Timing advance to bypass the ECM controlling the injectors. I did that and still no fuel through the injectors while cranking. Next I thought the ECM itself but it too is only a few months old. I contacted Howell EFI who I bought the ECM from and described the issue and was told its most likely the pickup coil in the distributor. So I sit with no spark and no fuel and not sure what to look at next.

 

[White Stripe]

So it wasn't very long ago I finally got my FJ40 (has a 5.7 TBI from a '93) going. I had been driving it periodically around town for a few weeks when one day I went to move it from the side if the house to the driveway. I got about 80 down the street to flip around and it just died and would not restart. Just crank and crank. Looking it over found no spark. Replaced the Ignition Coil... Still no spark. Replaced the Ignition Module... Still no spark. I replaced the Distributor... Still no spark. Also with that, the three parts I just replaced are less than 1 year old. During all this I also noticed that the injectors would not spray while the engine was cranking over. I verified that the fuel Pump (from Howell EFI) was in fact working and supplied enough pressure to the injectors. I read to unplug the Timing advance to bypass the ECM controlling the injectors. I did that and still no fuel through the injectors while cranking. Next I thought the ECM itself but it too is only a few months old. I contacted Howell EFI who I bought the ECM from and described the issue and was told its most likely the pickup coil in the distributor. So I sit with no spark and no fuel and not sure what to look at next.

Ha that's crazy I had the same problem on my 40 and I found the problem today. On the ignition module it has that weird 2 pin plug which comes from the distributor pick up coil. Well in that weird plug, the female pins were opened up too much and not making good contact with the male pins on the ignition module and the ecu wasn't getting a pickup coil signal. So I took a 45 degree pick a nd reached into the female pins and bent the springy tab so the opening had a much tighter clearance. Runs great. Took me many hours to figure it out. It could also be a bad TPS. If your TPS is stuck at WOT, the ecu won't power the injectors because of will be on clear flood mode. Also check your crank wire that goes from the starter to the ecu. Hope that helps.

 

[TwelveGravity]

Well I checked the two pin clip from the distributor pick up coil to the ignition module, they did not look like the tolerance was too far open but I went ahead and bent them a little as you described. I also checked the TPS. I have an OBD1 diagnostic computer that reads all live data from the ECU and it read 0%, then as I turned the linkage the TPS readout would increase from 0% to 100%. So I ruled out WOT, not that it would be an expensive part to replace. As far as any wire from the starter to the ECU, I am not sure I have that. I have previously installed a four pin, 12V 30A relay inline from the starter switch to the solenoid but I replaced that with the spare I had in the glove box. Also I think if that were defective, the starter would not crank over but I gave it a shot anyway.
So I am still at a no spark & no fuel problem. I wonder about taking a meter and trying to chase/troubleshoot each connection from upstream do downstream electrical path to see if I can identify anything from there but I'm not sure.

 

[Elbert]

Get on ebay or somewhere and buy a GM shop manual for a GM pickup/suv with the 5.7 TBI. I believe you can find that rather easy...as I recall there was one company that had the rights to publish some of those manuals on cdrom media. That way you can run down the circuits for the fuel pump and ign. Do all the dumb stuff about checking for blown fuses and shorts to ground on the wiring harness. (engine harness). You mentioned that you checked the fuel pump pressure...which I assume is that you hot-wired the fuel pump to see if it works, because as I recall you should hear the fuel pump energfize for about 2 seconds with ign on. I don't recall for sure but did those engines also have a oil presure cut off switch...where if oil pressure dropped too low the engine would not start/run.

I see the below... might be helpful for you.


1992 Chevrolet Light Duty Truck Shop Service Repair Manual CD | eBay

 

[spotcruiser]

TBI wiring diagram (partial). I don't know how your truck is wired, but have you got 12V (as designated by IGN or 12V IGN) to the fuel pump circuit, ECM fuse, and the primary coil (all as shown down the left side of the diagram) with your ignition on? Perhaps it's fused or perhaps it's hardwired and the connection(s) failed. Also make sure you have the Batt 12v as shown at pin B1 of the ECM.

 

[White Stripe]

So u replaced the whole distributor ?

 

[toyotaspeed90]

Start with the basics.....

You said it was a 93 motor, so it should be pretty straight forward. You said you're able to read TPS values - so that assumes that you are getting power to the ECU (might want to verify you have power to the ECU while cranking).

So - if you aren't getting fuel and you aren't getting spark, the problem lies with the ECU not getting a signal from the distributor. Start with that simple thought - the signal is missing... and move backwards.

Is there power to the distributor?
Is there an issue with the wiring from the dizzy 4 pin connector to the ECU?
Is the ignition control module bad?


The other possibility..... is this ECU one that has the early GM security system and does it need to either be reflashed or have a resistor placed in line?

 

[TwelveGravity]

So u replaced the whole distributor ?

Yes, I replaced the whole distributor. Glad for the lifetime warranty to replace the one I bought less than a year ago.
I also went nuts looking over many connections and checking every fuse I saw. I found this unknown fuse and found that it was blown. Replaced it and have not noticed any difference. I will have to find what it goes to.

I Checked connections at the ECM to ensure no wires came loose or backed out of the pin connectors and didn't find anything.


@toyotaspeed90 I am making an assumption to the year. I ran the block code and found the block to be '88-'95. I think there may be a difference in some of the color of wires within the wiring harness as I have found that to be the case when troubleshooting my previous ECM and fuel pump with Howell Engineering over the phone. But I cannot say 100% what year within that range.
I will have to check this weekend to see if I do get power to the ECM while cranking as you suggested.

I will also check signal from the distributor to the ECM, should I see 12V right away or only while cranking?
I am thinking that the early GM Security system would not necessarily be the issue since I had been driving it on a weekly basis for a little while and did not have any issues BUT this does highlight another unknown. The PO had an aftermarket security system put in. I haven't had any issues with that I know of but there are wires EVERYWHERE. iH8Wires! between the mated Toyota wiring harness, the GM wiring harness and all the after market crap installed. It makes it very troublesome trying to trace out wires. Did I mention iH8Wires?

Hopefully this weekend it is less than 100 DegF out and I will be able to work with it a little bit longer.
Greatly appreciate everyones insight.

 

[toyotaspeed90]

Couple things to note.....

Reference is a voltage reference signal - which is just a silly way of saying it's a lower voltage signal from the ecu usually its 5v.

Reference low is the ground that runs back to the ecu.

+ is 12v
C is to the coil


Like I said earlier- if you aren't getting fuel nor spark this is where I would look.... the only way the ECU knows what the engine is doing in order to provide fuel is through the distributor.

 

[TwelveGravity]

I am getting 12v while cranking from the distributor to the coil. While checking this I did notice that I would get a shot of fuel but usually when I depress the ignition switch after cranking. No fuel while cranking. I also verified power to the ECU while cranking.

 

[Mdz320]

I have at least a similar issue. 1991 p30 454 rv, no spark no fuel. Replaced cap and rotor, coil, ignition module, and pick up coil. Had a blown injector fuse. Might have done that while jumping rv. Please help. I need to sell this thing.

 

[TwelveGravity]

Its been so long now, I don't recall exactly what was the issue. I reached out to Howell Fuel Injection and got a new ECM. I recall that I also had a Knock sensor issue that they helped diagnose & get rid of.

 

[reddingcruiser]

This is going to sound way out in left field, but it happens: cracked or defective fuel injectors. Ask me how I know.

Do you have a set you can throw in, or a spare TBI? I did all the things you listed and spent days going through the electrical system. Changed out the TBI and vvvrrrrroom. Worked backwards from there.

 

[Mdz320]

This is going to sound way out in left field, but it happens: cracked or defective fuel injectors. Ask me how I know.

Do you have a set you can throw in, or a spare TBI? I did all the things you listed and spent days going through the electrical system. Changed out the TBI and vvvrrrrroom. Worked backwards from there.

This doesnt explain the no spark.

 

[reddingcruiser]

This doesnt explain the no spark.

Yes I does. Gas leaking internally in the injectors causes a ground fault. The ground fault will prevent ECM from sending a signal time the ICM, somewhat similar to what happens when the dielectric grease dries up under the ICM and there's oxidation between the distributor base plate and ICM, no spark. Both are ground issues.

 

[Babybrown]

I had the same issue with my 94 454. Replaced the distributor coil fuel filter and ignition module but still nothing. Uncle came over and said to check if the distributor is even spinning... long behold not spinning when cranking so timing chain issue.

 

[Joe W]

Hello. I have a 1990 350 tbi that runs great cold. After warms up it either dies or will not restart after shut down. Checked both spark and injector spray and nothing from both. Let cool off a couple hours and starts back up and runs fine.
ICM was replaced and still happens.
Any Help?

 

[haryv]

So it wasn't very long ago I finally got my FJ40 (has a 5.7 TBI from a '93) going. I had been driving it periodically around town for a few weeks when one day I went to move it from the side if the house to the driveway. I got about 80 down the street to flip around and it just died and would not restart. Just crank and crank. Looking it over found no spark. Replaced the Ignition Coil... Still no spark. Replaced the Ignition Module... Still no spark. I replaced the Distributor... Still no spark. Also with that, the three parts I just replaced are less than 1 year old. During all this I also noticed that the injectors would not spray while the engine was cranking over. I verified that the fuel Pump (from Howell EFI) was in fact working and supplied enough pressure to the injectors. I read to unplug the Timing advance to bypass the ECM controlling the injectors. I did that and still no fuel through the injectors while cranking. Next I thought the ECM itself but it too is only a few months old. I contacted Howell EFI who I bought the ECM from and described the issue and was told its most likely the pickup coil in the distributor. So I sit with no spark and no fuel and not sure what to look at next.

Well probably what you needed was a voltmeter. You're doing the wrong thing by replacing parts that's called shotgunning and it's a waste of money. What you need is a good fluke multimeter or equivalent. Also if you had a good scope one made by Snap-on. Those are being your most valuable tools that you'll ever use for troubleshooting electronic or electrical problems in your vehicle. Did you ever check the fuse? Did you ever troubleshoot from the circuit breaker back to the ignition pickup? Do you have to have VCC in electronics world that's called voltage source. Having a schematic diagram also helps a great deal and troubleshooting. You have to have a good ground to the ignition module. My guess is you have a hall effect sensor inside the distributor. First thing you could probably do is go on to all data and download the manual I think it's $13. I suggest you print out the entire schematic diagram. And use that to troubleshoot the electrical problem on your vehicle. Once you're done with that I'll put it in a plastic sleeve and always keep it inside the glove box.

 

[TwelveGravity]

Well probably what you needed was a voltmeter. You're doing the wrong thing by replacing parts that's called shotgunning and it's a waste of money. What you need is a good fluke multimeter or equivalent. Also if you had a good scope one made by Snap-on. Those are being your most valuable tools that you'll ever use for troubleshooting electronic or electrical problems in your vehicle. Did you ever check the fuse? Did you ever troubleshoot from the circuit breaker back to the ignition pickup? Do you have to have VCC in electronics world that's called voltage source. Having a schematic diagram also helps a great deal and troubleshooting. You have to have a good ground to the ignition module. My guess is you have a hall effect sensor inside the distributor. First thing you could probably do is go on to all data and download the manual I think it's $13. I suggest you print out the entire schematic diagram. And use that to troubleshoot the electrical problem on your vehicle. Once you're done with that I'll put it in a plastic sleeve and always keep it inside the glove box.

Thanks for the input. I did find the issue and was able to fix it but it has been so long ago that I do not remember what the fix was. I have since sold my 40 but was happy to see it go to another enthusiast that has taken great care of it and it is running great.

 

[haryv]

Thanks for the input. I did find the issue and was able to fix it but it has been so long ago that I do not remember what the fix was. I have since sold my 40 but was happy to see it go to another enthusiast that has taken great care of it and it is running great.

I've always had a strong troubleshooting skills. It's something I really enjoy and the same principles of a car made in the 80s is the same principles in today's cars with the exception that a lot of vehicles today have little computer modules depending on make and model of vehicle. Some of these modules don't fall asleep and they were all trained the current out of the battery. The car computer is probably not much difference then I Robot computer. I guess you don't remember what the fix was?