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Author Topic: No Check engine light at all???  (Read 11125 times)

Offline Buttabiscuit

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No Check engine light at all???
« on: November 13, 2014, 05:13:51 PM »
Okay I am having trouble with some electrical issues. I'm learning as I go never really chased wires before but I want to learn. Okay I have a 87 Chevy 5.7 TBI 2wd it ran when I first got it. Then it ran out of gas I put new fuel filter and fresh gas and it would only crank over. I'm not getting any spray out of the injectors. I swapped injectors nothing. Checked the fuel pumps (I have 2) the left one works if I run a hot wire from the battery. Right one doesn't. I tried to run the hot wire to the left tank and start it and nothing. I'm only getting a dim light on my test light to the left pump. I was thinking there was a short in the wire. That's where I'm at. I tried to get codes from it with a jumper but no check engine light. I am trying to get this thing running but I know I need the codes to get me going in the right direction any ideas of what to do next? Here are some pics how my truck sits now.
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Online bd

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Re: No Check engine light at all???
« Reply #1 on: November 13, 2014, 06:32:34 PM »
Begin by removing and inspecting the fuses.  Pay particular attention to ECM I (10 amp red) and ECM B (10 amp red).  Don't start connecting "hot wires" to get it to run or you'll run the risk of destroying the ECM.  By the same token, don't probe sensors or the ECM harness with a test light or analog meter for similar reason.  Checking for power at the fuel pumps using a test light is okay.
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Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Buttabiscuit

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Re: No Check engine light at all???
« Reply #2 on: November 13, 2014, 06:40:01 PM »
I did check the fuses but will double check tomorrow. Any other reason the check engine light won't come on? It worked before. I was thinking the bulb but wanted to check any other reason before having to take the dash apart.
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Offline Irish_Alley

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Re: No Check engine light at all???
« Reply #3 on: November 13, 2014, 11:03:03 PM »
i know on my 91 most of the bulbs that didnt work were good just had a bad connection
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If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

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Offline Buttabiscuit

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Re: No Check engine light at all???
« Reply #4 on: November 14, 2014, 05:15:00 PM »
Okay update I went to double check fuses, and ECMB was burned out. I replaced it and check engine light works. I jumped the test plug to see what codes it would shoot out and it only shot out code 12 over and over??? It still won't start it will only crank.  Here is some more info on what I have done to eliminate some of it. New cap, rotor, spark plugs, (it's getting spark), and fuel filter. I pretty sure it's not getting gas I don't see any coming out of the injectors. I'm pretty mechanically inclined but this thing has me stumped. What else should I check? Let me know if I need to provide more info or if you have a suggestion. Want to find out whats going on before I just start replacing things.
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Online bd

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Re: No Check engine light at all???
« Reply #5 on: November 14, 2014, 06:28:02 PM »
If ever there were any codes logged they were erased when the ECM B (battery) fuse blew.

Verify correct fuel pressure (9-13 PSI).  W/o it, TBI won't function.

Refer to the 1987 Fuel, Drivability and Emissions Manual for detailed troubleshooting information and refer to the 1987 Wiring Manual for wiring detail.  ECM B protects circuit 440 (orange), which may have developed an intermittent ground.  While you're poking around, look for any evidence of pinched or chaffed wiring.
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Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Irish_Alley

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Re: No Check engine light at all???
« Reply #6 on: November 14, 2014, 10:41:56 PM »
so when you first turn the key on do you hear the pump prime?
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If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline fitz

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Re: No Check engine light at all???
« Reply #7 on: November 15, 2014, 06:00:38 AM »
BD has you covered as far as chasing down the electrical end of it.
If you nott 100℅ sure its a fuel related problem, spray some starting fluid in the TB and see if it starts.
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Offline 78BIG-TEN

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Re: No Check engine light at all???
« Reply #8 on: November 15, 2014, 09:55:50 AM »
First thing I would check is ecm ground at t\stat.Remove nut ,then stud and check for corrosion.I've seen them powder white .Also put a test light across the injector harness,crank engine and see if light blinks.No blink and ground is good check for tps high volts,could be in clear flood mode.TPS ok,possible ignition module or ecm.My concern is why blown ecmb fuse,maybe it blew when poking around fuel pump circuit
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Offline VileZambonie

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Re: No Check engine light at all???
« Reply #9 on: November 15, 2014, 09:59:25 AM »
Agreed, verify injector pulse if you have verified spark.
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Offline Buttabiscuit

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Re: No Check engine light at all???
« Reply #10 on: November 16, 2014, 10:56:53 PM »
Thanks for all the suggestions I will check tomorrow the truck is at my work. I will update tomorrow.
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Offline Buttabiscuit

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Re: No Check engine light at all???
« Reply #11 on: November 21, 2014, 01:55:27 PM »
Okay sorry had a few unexpected jobs come up. I finally got some time to get out there and check out the truck. I don't have a fuel pressure gauge so I couldn't check that, But when I put the test light at the fuel pump the light is really dim. To be honest I looked through the Fuel, Drive ability and emission pdf you supplied me with bd, and it's hard for me cause I am trying to understand what it all means (not good with electrical :() let me know if I am doing this right. I got to page 3-18 Chart A-3 (in the pdf bd sent) I do have the SES light on with the code 12 so it is getting power to the ECM. I don't have a volt reader just a test light so I couldn't check the TPS volts of 2.5 volts to see if its in flood mode. I have new plugs and it is getting spark I shocked myself to check cause I don't have the tool getting good spark LOL. My injectors arn't spraying so to me it's telling me it is a fuel related problem. I checked the injector for the pulse with the test light. I put the ignition to the "on" position and the light does not pulse it just stays on the whole time. Is it supposed to pulse? I haven't tried to crank it cause I know for sure there's no fuel coming out of the injectors. Should I just buy a new fuel pump? Anyways Thank you all for all your help that is where I have stopped hopefully I'm on the right track not good with this electrical stuff (trying to learn). Well  I am going to be out of town for the weekend talk to you soon!
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Offline 78BIG-TEN

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Re: No Check engine light at all???
« Reply #12 on: November 21, 2014, 06:47:31 PM »
Take 1 injector connector and put test light across terminals that is ground to one post and probe to the other.Have someone crank it and watch test light to see if it flickers.Then do the other connector the same way.Where you are checking the pump circuit?If at the tank are you sure your on the pump wire.If on the sender wire it will be dim.The pump only runs for like 2-3 seconds when you turn the key on.Check the crank fuse in the fuse panel,I think its a 5 amp.
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Offline flips87c30

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Re: No Check engine light at all???
« Reply #13 on: November 21, 2014, 08:51:50 PM »
Sounds like the fuel sending unit to me. Try pouring some gas in the throttle body also check your oil pressure sensor mine kept blowing my ecmb fuse
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Offline Buttabiscuit

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Re: No Check engine light at all???
« Reply #14 on: December 12, 2016, 01:22:59 PM »
Sorry I haven't been on for a while. Just wanted to update you guys on my truck. I ended up taking it to a shop cause I couldn't figure it out. It ended up being the fuel pump and a gas line was plugged. I got it running and had to get it smogged in Ca. I bought 2 brand new cats and put a cherry bomb exahust. It sounds pretty good. I got it all running, tagged, and have been using it to go fishing. Thank you for all your help. I have a few issues, but I will make another post on that issue. Thank you for all your help.
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