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HELP, Broke down Again !!!
My truck keeps leaving me along side the road broke down and having to be towed home.
I have a 2 and a half page document typed up of how it started and what its doing now if there is any interest in trying to help me. I have already replaced the ECM and had to jump around the Fuel Pump Relay this time to get her back home. AAA will only give you three tows before they start charging big time. I didn't want to add the the 2.5 page document as I figured no one would take the time to read it all. I can do this at two different ways, post the whole thing here and or put in on my website, which I did. http://www.joejohanesen.com/gmc/gmc.html I hope someone can help me on this. Thanks for taking the time to read this too. |
Re: HELP, Broke down Again !!!
I had a couple of incidents similar to yours. One was on a 90 GMC 2500 that was actually a Survey Crew truck for the Nevada DOT. It left me stranded a few times...and I would have to get a tow. One time, while waiting for tow truck, I checked the fuses in the inside fuse box, on the side of the dash. There was one blown fuse in there labeled 'ECM' if I remember correctly. I replaced it with a good one, turned on the key and I could here the fuel pump right away. I fired it up, called off the tow truck and drove back to the yard. Worked for me a few times. The second time was on my personal vehicle, a 93 Chevy Shortbed. It left me a few times... got towed home a couple times, other times I would let the truck sit for a few minutes and it would start up again. That one ended up being the fuel pump....I replaced it and the problem was solved for the rest of the time I owned it... only thing is, after I replaced the fuel pump, the gas gauge acted funky...
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Re: HELP, Broke down Again !!!
I used your link, and read it.
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The fuel pressure is tested by using fittings to “T” in a pressure gauge and must be tested with the engine RUNNING. I don’t have a schematic for your truck but this is my best educated guess at where the wires go. Orange wire, hot all the time. Power supply from junction block Red w\white, not hot. To ALDL terminal Black w\white, not hot. ground Red w\black, not hot, goes to Fuel Pump Fuse, didn’t expect it to come hot anyway. Out to fuel pump. This wire should have power for at least two seconds when you first turn the key on. It should also have power when the engine is cranking. If it does not get power the relay is most likely bad. Green w\white, hot Only with starter engaged and turning the engine over. From ECM – controls the relay The ECM controls the fuel pump relay. There will only be power to the fuel pump for a few seconds when you first turn the key to the on position. If you are turning the key on then walking around the vehicle testing for voltage to the fuel pump circuit there will be no voltage and should not be power to the pump. When the engine has oil pressure a redundant circuit supplies power to the fuel pump. This circuit goes through an oil pressure sensor/sender. Once the engine is running the fuel pump should get power from the redundant circuit and not need the fuel pump relay to keep running. |
Re: HELP, Broke down Again !!!
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Re: HELP, Broke down Again !!!
Thanks guys.
First thing I check was all the fuses and was not able to get power to run the fuel pump until I put a jumper around the Fuel Pump Relay.. Now that I let everything cool down, it started with the FPR hooked back up, like Nothing was wrong??? Does anyone know if the Distributor module is bad that it shuts off the fuel pump circuit ? Reason I ask this is now that I think about it more, its never acted up until after its been running for awhile. I was able to move it around the farm, hooking to trailers, moving them but just short running times. I called the parts store and told them I needed more prices on other parts as replacing the ECM did not fix the problem. He asked me, how many miles and have I ever replaced the distributor module on it. After saying no, he said pull it, bring it in and they can test it. He told me its a big seller and they always stock several of them. Again, the big question would be, can the distributor module not working cause the fuel pump circuit to fail? The thing that is making me nuts is it "won't" stay broken as to find it. Now that this truck is a high miler, makes me think I need to get my tail to GMC and purchase the "real" service manual for it. Thanks again for your help guys... |
Re: HELP, Broke down Again !!!
Before you go to the dealer for a manual, check Ebay. Then Google for '88 Service Manual. I got all 4 manuals from different places (Service Manual, wiring diagram manual, electrical trouble shooting, and emissions) off the internet and total was about $150. It took a little while, but you can find them.
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Re: HELP, Broke down Again !!!
I read your book. What I see from your description is something is overheating. My only question is which comes first? you are getting no signal to the fuel pump relay, but a ecm will shut down the fuel system if it isn't sensing fire from the ignition system. If I was working on it I would start with the distributer, and coil. test them and make sure they work properly. also check for corrosion on the contacts. corrosion causes resistance and so does heat. When you reassemble put dielectric grease on module connections and coil connections. after that is done take it for a drive. If it screws up, let it cool down, and try it again. If I'm right about a temp issue it will refire when it cools down. The bad news is if the distributer doesn't fix it I'm gonna bet the pump is overheating and shutting down. Have you checked the fuel filter? if it is mostly plugged it can cause the pump to work too hard and over heat.
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Re: HELP, Broke down Again !!!
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That was one of the main things I was looking for, the ECM shuts down the fuel system if the distributor module is screwy. I am not sure if I posted this but when the fellow put the crate motor in for me, his son was helping him (doing most of the work I would suspect) and the distributor was in wrong. It was a tooth off so instead of pulling it or moving the plug wires to the next holes to adjust for it, they just rammed it back to get it to time in. Doing this the wires were stretched Hard and I had to bend the coil back a tad to get the wires to relax some. When I did that, I noticed that the wires were right next to the coils primary and I seen what looked to be a hot spot or black spot ( possible rubbing mark) on the wires to the distributor module. I have that out and going to have it tested today.. Fuel pump filter, its been awhile so I will pick that up as well, Seems to me that was under the truck by the tank? Also the fellow about picking up the manuals on Ebay and other places, good call, I would never had gone to the stealership and paid retail plus anyway.. Good call.. Good answers everyone, Thanks Very Much !! |
Re: HELP, Broke down Again !!!
Clear the trouble codes that are in the ECM from you unplugging items like the Fuel pump relay. Then see if the system sets a trouble code the next time the vehicle won’t start or the next time it dies.
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The ECM controls the fuel pump relay. The truck has a fuel pump relay that supplies power to the fuel pump when: - Anytime the ECM receives a distributor reference pulse. (Engine running / engine cranking) - The key is turned on engine not cranking – relay applied for 2 to 20 seconds (most trucks 2 seconds), depending on emissions equipment. Trucks over 8500 GVW and some other vehicles have and electronic Fuel timer module that allows the pump to run up to 20 seconds. The key must be turned off for a certain amount of time before it will prime the system again when turned back on. Remenber, there will only be power to the fuel pump for a few seconds when you first turn the key to the on position, so if you are turning the key on then walking around the vehicle testing for voltage to the fuel pump circuit there will be no voltage and should not be power to the pump. The ECM should store a code 54 if the fuel pump relay fails. Quote:
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A bad module will not stop the redundant circuit from supplying power to the fuel pump once the engine has oil pressure. A bad module can cause the ECM the receive no distributor reference pulse during cranking, so after the prime timer has expired the fuel pump relay would not be energized. |
Re: HELP, Broke down Again !!!
Keep in mind, on a 20 year old truck, you could have 2 or more failing parts causing problems.
The redundant fuel supply circuit may not work so the fuel pump relay is the only item supplying power to the fuel pump. Sometimes the fuel pump current flow increases when the pump is getting bad. The high currant flow can damage the fuel pump relay, oil pressure sending unit and the terminals for the fuel pump wires on the fuel tank sending unit. It is common for the distributor module to fail. The module could be the cause of your vehicles problem, and not knowing how the fuel pump circuit works could be leading you astray. |
Re: HELP, Broke down Again !!!
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Seems I messed up the Quote some how? This might make it next to impossible to see my answers. Thanks... Joe |
Re: HELP, Broke down Again !!!
I have replace the distributor module and ready to try it again.
Fuel pump was replace about 2 years ago along with the filter (found the receipt) Should change it again just to be sure. We will see how the module replacement works as they tested it at the auto parts store and i was told it was failing on the Low side? When I asked the question, what IS the low side? All I got was, I don't know, the machine just says that ??? |
Re: HELP, Broke down Again !!!
If you put in an original equipment GM pump two years ago it should still be good.
If you used an aftermarket replacement pump, like some of them they sell at the local NAPA, that could be what is failing judging by what I have seen. |
Re: HELP, Broke down Again !!!
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I did that before we moved to the farm we have now so its a pain. It has a 6" drop which means when there is a flat, your on iron. Nevertheless, it came from Napa and I Do remember having a choice of getting a cheap one or the better one, I chose the better. No real driveway, just gravel to jack it up to get under it to drop the tank. The distributor module did test bad on the low side?? so I did replace that with the better one from Napa. Closest chev dealer is about 80 miles away from me so I have been using Napa. I guess I will know more as I am about to head to work with the truck so we will see. One thing I did notice is the time in between stalls is getting closer and closer. Another thing I did was use the hole saw to put two holes in front of the air dam as to get a tow chain in on each frame horn to at least pull her alone the side of the road if I need too. I am old school, old line mechanic from the early 80's so all this stuff is new to me. With the 700r, no faster than 35mph being towed with the wheels on the ground? Thanks again... Joe |
Re: HELP, Broke down Again !!!
If you ever have to replace the fuel pump again, consider removing or sliding the box back, instead of dropping the tank. I prefer moving/removing the box.
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Re: HELP, Broke down Again !!!
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Re: HELP, Broke down Again !!!
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This has got to be much easier than dropping that tank again.. So far, so good with today. I was able to drive it to work and back today, 70 some miles with no issues. I had Everything loaded into the truck just in case so I could do more testing. Think I will just keep that testing stuff along with the towing gear loaded as well. Will keep you posted. |
Re: HELP, Broke down Again !!!
Hopefully the truck is fixed.
Here is some more information if you have more trouble. Quote:
Here are some web sites with the basics on retrieving codes without a scan tool or code reader. Poor drawing of ALDL but ok instruction + codes http://www.cfm-tech.com/gm_tbi_trouble_codes.htm OBDI terminal identification http://robertpowersmotorsports.frees.../ALDL_plug.jpg OBDI illustration and instructions http://www.troublecodes.net/GM/ 1985 – 1990 trouble codes instructions http://www.iroczone.com/specs/TroubleCodes.htm Quote:
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Re: HELP, Broke down Again !!!
Good information !!!
I knew I had the service light that would blink the codes but never knew what they were, Good information for sure.. Fact it, I will go back to them and print them out to put in this worthless Chilton book. Thanks for all your help on this problem.. So far, so good, day two of driving to work and back with no problems. It will be awhile before I take the tools out just in case ;) Now I will go search the forum for some of my other issues to see what I can pickup. I have a hesitation accelerating, when cold. As soon as it warms up, its no longer hesitates. Another thing it has done ever since they replaced the motor is it seems to take a fair amount of gas peddle before it will shift into passing gear or out of overdrive in to direct drive. When I had another company rebuild the transmission, I had them check that and I was told all was well. Thanks again for all your help... Joe |
Re: HELP, Broke down Again !!!
You’re welcome. A thank you is always appreciated.
Let me know when you want to get in a discussion about your hesitation. I am way to tired to write a long reply tonight. |
Re: HELP, Broke down Again !!!
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Thanks again for your help !!! Next will be trying to figure out why I have been getting the hesitation for some time now too. Also ever since I had the crate motor installed, it seems as I have had to give it more gas peddle to get her to kick back into 4th gear and passing gear. When I had the 400R rebuilt, I had him look at that and can't remember what was said but it still is bugging me.. Thanks again for your time. Joe |
Re: HELP, Broke down Again !!!
I suggest checking the adjustment of the cable to the transmission. It not only controls the downshift – passing gear put it also affects the transmission fluid pressures.
The 4L60 and the 700R4 are same but do not confuse these with the 4L60E which is different. This site has very detailed information on adjusting the cable to the transmission: http://www.tvmadeez.com/article/index.php Here is another part of the same site: http://www.tvmadeez.com/article/part2.php Here is another good site: http://www.transmissioncenter.net/700r4.htm You should start a new thread for discussing the hesitation because it could get to be a very long discussion. |
Re: HELP, Broke down Again !!!
Wow, that is a cool site for sure.
Wonder why the transmission guy (a friend) never adjusted it. I will read the theory on how it works and do what I can with it. Its been messed up for a Long time.. Thanks for your help and Yes, I will search for hesitation before starting a new thread.. Joe |
Re: HELP, Broke down Again !!!
Many people fail to realize that if the transmission (TV) cable is out of adjustment it can affect the fluid pressure so much that the transmission can slip and burn up.
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Re: HELP, Broke down Again !!!
Thanks again Chevytech for all your help.
Just so you know, I have printed out all the information and added it to a 3 ring binder for the future possible needs. |
Re: HELP, Broke down Again !!!
You’re welcome
It’s a good idea to save information you run across. I save links / favorites, but I also copy and save useful information to a word file and save it on my computer. Links may not work in the future. My challenge is organizing what I save so I can find it easily. When I write a good reply to a post I also save it and improve it a little each time I reply to a similar thread about the same topic. |
Re: HELP, Broke down Again !!!
Well, lets see if I can get this old thread to work again.
Ran into some hard times and had to park my truck. Almost lost it in the divorce so she has been setting since May of 2015. I had started it every once in a while but the last time, I can't remember how long ago its been maybe a year. Now she would not start up. Can I just post what she is doing, not doing here? |
Re: HELP, Broke down Again !!!
drain fuel gas goes bad
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Re: HELP, Broke down Again !!!
You can try a shot glass or 2 worth of gas down the throttle body and if no start it's not fuel system.
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Re: HELP, Broke down Again !!!
Ok.
Looks as I can post on this thread even if it is old. As far as the fuel, it has a half tank of non ethanol fuel with the marine stabilizer in it. No drain on that tank for one. I took the car hauler over to get it and winch it up but tried one last time. Nothing, no fuel pump sound. I then jumped the fuel pump and could here it running. I then tried to start it and just rolled over. Tried it again, seen the oil pressure go up and she started. I let it run for about 30 minutes as I loaded her up on her own power. Brought it home, pressure washed the whole outside to clean her up. I tried to start her back up, no fuel pump sound, jumped the fuel pump again, watched the oil pressure come up and this time, did not start, just rolled over. I pulled the jumper form the orange wire to the center wire on the plug on the fuel pump relay. The notes that I had written down and in the Chilton book says it it was supposed to be a Gray wire to the pump, Mine is Pink going to the pump. I then had my friend work the ignition switch and I tested the Green/white wire which is supposed to be the prime I think its called. Anyway, No other wire in that plug was hot so the next step is go get to the ECU and test I that same color wire, Green/white to see if it comes hot (A1 in my notes). My hopes are its got 12 volts with the key on. This chilton book is really not that helpful. So, my thinking right now, with no special tools is to pull the fuel line from the throttle body, stick it in a quart bottle with a rag over the end, then make a LONG jumper wire (NO Sparks) plugged into the fuel pump relay plug. Its a 5 foot jump starter setup that I will just cut the alligator clips off and make sure its plugged in so No sparks, have my friend just tap that starter cable button to energize the fuel pump. I won't be able to measure the fuel but will now if its pumping. This book does not show the wiring so if anyone knows if that is A1 on the ECU I should be testing and where does it go, right to the fuel pump relay ? If I remember right the oil pressure switch is what tells the ECU to keep the fuel pump working, that green/white wire just primes and runs the pump until the oil pressure is up. I can't seem to find that information so hoping someone knows or has a real book to look at. There is also a module in the distributor that I think runs that fuel pump relay too but can't remember what it does. I can put a shot glass of fuel down in the throttle body and see if she will run on that. I will do that tomorrow in between snow showers ;-) Oh yeah. I have been plagued with a phantom draw on the electrical system which I will get into after I get her running again and off the trailer. Long story short, pulled the Alt wire, pulled fuses trying to find it. If she sits three days, it would pull a new fresh battery down to were it would need jumped. So, several issues to chase down. Right now, its got a marine power switch that disconnects the battery which means the ECU has not recorded any error codes. Real mess huh... |
Re: HELP, Broke down Again !!!
My 92 K2500 had an few issues when we bought it like yours. 1st was the every 4-5 day dead battery that was caused by an aftermarket stereo the PO installed that had a constant draw even though wired correctly, Second was the no start without a cup of fuel in the tbi every now and then that turned out to be a fuel pump with a dead spot, but as soon as it started on that cup of gas it (vibration?) worked.
The ignition module is not connected to the fuel pump circuit so don't waste time there unless no spark. This sounds stupid but did you check all fuses? You should be able to see fuel spraying from the injectors when cranking also. It seems strange to me after sitting 2 yrs to have these problems, it must be something simple. |
Re: HELP, Broke down Again !!!
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When I had this issue before, I replaced that module in the distributor plus the fuel pump relay only to find out the fuel pump was on its way to failing. Once it failed and stayed that way, found it and replaced it. One thing I do know, is while trying to start it, that one wire that is supposed to prime, does not come hot. Here is one I don't know for sure. It Does have some in line fuse looking things right up close to the fuel pump relay but they don't come apart, or if they do, I don't know how. I can take the light probe thingy and stab the wire before and after the barrel that looks like a fuse. All the other fuses under the dash I checked. |
Re: HELP, Broke down Again !!!
Ok, she Failed the Shot Glass test.
I put in a half of shot glass of gas, no start, dumped in the rest of the shot glass, no start. The Relay was plugged in just in case too. I also heard the fuel pump running after I quit trying, Pretty sure she is fueling. I didn't have help so I was not able to turn her over and watch to see if the EFI was spraying fuel in but never the less, heard the pump working. Not sure what to test next. Distributor module or maybe I had better dig out the ECU, make sure its got a good ground and the contacts do not have any corrosion on it from setting with mildew in the cab. Going to test A1 for 12 volts and hope the ol gray matter is correct. I think that is the primer signal wire to the relay... I also left the battery hooked up and will put the float charger on her. Maybe I can get a code once I figure out what the paper clip needs to be plugged into. This is first generation computer. |
Re: HELP, Broke down Again !!!
Ok-first I would take a good spark plug and hook up to #1 plug wire and ground it to the engine. Crank it over and see if you have spark. A shot glass of fuel should have got you a good pop or attempt to start.
Also- there are grounds on the back pass side of the engine for the ecm that need a good clean ground. If still no spark cap/rotor plus ign module are the main problem areas. |
Re: HELP, Broke down Again !!!
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As soon as I test that, I will report back in :-) |
Re: HELP, Broke down Again !!!
Ok, no spark to the plugs.
So, that is possibly the coil (which was replaced about a year ago) or the module in the distributor. I will look to see how to test the coil and go from there. |
Re: HELP, Broke down Again !!!
Coils don't normally fall but an old school cheater test was to hook a live wire to the + side and to the - side a wire with a bare end. Hook your spark testing screwdriver to the coil output wire and have your assistant tap the bare end on a grounded part of the engine like . . . . . . . and watch for spark.
O Reilly's and other parts houses have module testors but if your module failed DO NOT buy the cheap replacements as I've had those fail with alarming regularity on our daily drivers |
Re: HELP, Broke down Again !!!
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So, went back out, pulled the module out and noticed the pickup coil inside looked rusty. I just slid a piece of sand paper down inside that and kind of wiped it around and notice the rust on the sand paper when I pulled it up and out. I did that several times, but this worthless chilton book does not give a clue on how to test it, pretty much says replace the distributor at $140 bucks. Yeah maybe if had it to spare but I don't. The pickup coil does not come with it either. So, I have been looking for how to test that thinking its be ohms open, ohms closed so turning that engine over, it should be pulsing the ohm meter. Mine is a Fluke DMM and pretty fast reading anyway. I took the distributor module over to NAPA and my friend tested it and said No problems with it. New one (good one was 51 bucks) but didn't need it he said. So, what you said to test the coil, its a transformer so power to the plus, take the minus and ground it for a spit second and if the coil is working, spark will come out of the spark plug wire hole. I always get mixed up with primary and secondary circuits. Anyway, this does not have that and without a schematic, I have no idea once I pull the plug off that coil on which pin is which. I will get a picture of it as I think I remember a red and white wire coming from the distributor to the coil, then the other two go into the wiring loom. Kind of lost on what procedure to go after next. |
Re: HELP, Broke down Again !!!
This truck has just a tad over 300K.
I am going to pull the distributor and if the bushings are still ok, will pull it apart and just rebuild it with a new pickup coil. She is in dire need of a tune up anyway so might as well throw that in too. I pretty sure that pickup coil is what triggers the pulse to the distributor module and tells the coil when to fire. I can't find a description or diagram on what wire does what on that coil to really test it but will keep looking. |
Re: HELP, Broke down Again !!!
Got it. She fired right up. She rolled over maybe twice and lit right up.
Over the years there had been enough condensation in that distributor that it was rusty, so out and apart it came. Polished up things and added a new pickup coil. Use the old cap, old everything else and she is running so not its time to unload her off the car hauler. I was concerned about that distributor with 300k on it but the shaft is still snug fitting so it was a easy rebuild. Lots of other things to do to her now, tune up, serpentine belt, check all the hoses, license and title change back to Oregon. Next thing is to try and chase down that phantom draw. New battery, new alternator plus pulled the wires off to test for draw. I think I was pulling a bank of fuses at a time but now she is not required to be running every day so now I hope to chase that down and hook my alarm system back up. I am sure I can come up with a little device that can trigger a relay for a horn or whatever that once the current drawn is over what is normal, she will warn me. Then I can start pulling fuses and disconnecting things until I find it. The radio started acting up but its on a fuse that I think I had pulled but will start over finding that phantom draw she has. Does a 60 or 85 milliamp draw sound about right, don't exceed that ? |
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