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Eric,
I want to thank you for what your doing helping DIY wrench heads like me. My wife has a 2002 Chevy Trailblazer, the other day I started the car and made it about half way down my street and the car just shut off. After pushing it back up the street and into the driveway I started to Dx. the problem. I check all of the fuses and relays # 41 is for the fuel pump, I switched it out with the horn relay and it just turned over. I check for fuel pressure and it was zero, so I assumed it was the fuel pump (in the tank) after spending $300.00 for a new one, I put it back together (I tested it before I installed it and it was fine) when I tried starting it…… nothing. I then removed the new fuel pump and returned it for another one, same thing…nothing. I checked the voltage at the wire harness and turned the key on and it read zero volts. I checked a bunch of forums to see if I could find an answer….One of them said it could be the oil pressure sending unit, so I changed it….NOTHING. I hit a wall. Will a bad ECM cause this? The car has over 200,000 miles on it and we really haven’t had problems with it. The Transmission is starting to slip and I have a rebuilt one to install. What would you suggest next?
Thanks,
Newcastle Utd.
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if there is no power to the fuel pump.Is there a red security
light on? If so that could be holding the fuel pump circuit off.
here is a video to help you.do you have a check engine light on?Did you see the test light or meter reading at the same time you turned the key on? It is only on a few sec. The video will help a lot. You can also jumper the relay terminals and test voltage at the pump. I doubt a security issue because with vts it would disable injectors.
I was frazzled and took it to a very good and honest mechanic I trust. He told me that the only way he could get the pump to run is jump the ECM. He told me it ran really bad, it was running perfect and I just check the oil and I didn’t see any signs of water. I asked w
“what codes did he get?” he said he didn’t get any. How can I check the ECM ?The only light is the “Check Engine” light. It turns but it sounds like it has no spark, I added “Starter fluid” and it started for a second. The Mechanic told me he wasn’t getting error codes at all
Well, we gotta know if you checked the voltage within 2 to 3 seconds of turning the key on. It’s only hot long enough to prime.
Second, will it run while spraying starting fluid in it past when it actually starts (keep spraying little sprays to try to keep it running)
3rd, have you checked spark?
I don’t think you should start pointing at the pcm. If ya can answer the questions in my last post it’d help me help you find a problem.
check if power is coming from ecm, by ehecking voltage on wire coming from ecm to the fuel pump during the first couple seconds of key on. NOTE: Verify you are using a known good ground. If no voltage, check for dirty/damaged pins on the ecm connector. If none found, verify ecm has all good powers and grounds going to it. If all is good – replace ecm
I’m with the group in that you should not condemn the PCM just yet, in fact, that would be the LAST thing to condemn. Why don’t we start at the beginning with diagnosing a no fuel pressure problem? BTW it would be a great idea to check to see if you have power and ground at the fuel pump connector if all the rest of these tests prove out.
I did check it twice, once with a digital and a multimeter just in case, now power both time, not even when it was cranking. I took it to a mechanic that said he was able to jump the PCM and it started but ran rough. I haven’t given up yet, the mechanic did.
Ok, well here we go. I never saw an answer but I’m ASSUMING you had someone turn the key on and checked the voltage (within 3 seconds) and nothing. If you can tell us that it would help (i know you’ve checked it several times, but the power is present for a split second)
Those also run a fuse along with the relay to the pump, make sure that’s good, if it is….
Watch this video for in depth information I can walk you through it, but this info will be a lot easier to understand than just reading the text.K so we have no fuel at the fuel at the fuel rail and when you check voltage at the pump u have zero. Well if we are positive its a fuel issue then the first place i would start is the fuse there should be a fuse and a relay if you have power at the fuse you should then also have power at one terminal of your relay k so i looked up the wiring diagram on alldata its kinda generic but i attached it i just assumed the truck was a 4×4 and a 4.2 so it looks like when you are cranking or the fuel pump relay should have power the pcm sends power to one terminal of the relay so if you have power there then your pcm is good.
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