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Engine runs sometimes, but idles poorly only getting heat to 1,3,5,7 and 2.
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Engine runs sometimes, but idles poorly only getting heat to 1,3,5,7 and 2.
Hey all I recently acquired a 1990 pontiac trans am GTA. I'm scratching my head trying to figure out whats going.
its a 305 tpi. Previous owner put a bbk throttlebody on it and Jett chip. My knowledge of a lot of things is fairly weak but I'm trying to get better.
Basically when I turn over the engine it will run sometimes but idles terribly, and eventually dies. 4 of the tubes get warm on driver side so cylinder what? 1,3,5,7? And sometimes the tube on cylinder 2 does. Sometimes not.
others do not get warm. I have done compression tests, tested wires,tested spark plugs. Played with the tps sensor.
It also seems like my fuel pump is not kicking on now. Which maybe the obvious issue. It just seems weird that only one side is really firing. I'm having a hard time finding diagrams for fuel pump relay fuses and such. As a lot of what I saw was for v6s. So my first check is to see if those fuses are blown but I cannot for the life of me figure where all the ones are. I will add some pics. I'm just praying I don't have to drop the tank and change the fuel pump.
Thanks for any help, I tried searching but everything I found was not accurate or old so the pics people posted didn't load.
Re: Engine runs sometimes, but idles poorly with only passenger side tubes heating up
Sounds like a fuse. Can't recall what it was called at that time; either INJ 1 or ECM 1.
If those are good (exchange them with xxx 2 and see if the problem moves to the other side) you probably have a shorted injector. If you get to that point, unplug them one at a time; if the other 3 cyls suddenly start to work with the 4th unplugged, that inj is fornicated.
Your photos contain basically no useful information whatsoever.
Not ANYTHING to do with the FP. (as far as the original symptom anyway... you may have boggered something in the process of dinking with stuff but I can't guess much about that) The same FP serves both banks. If one bank works, the FP circuit is working.
Last edited by sofakingdom; 06-16-2020 at 08:01 PM.
Re: Engine runs sometimes, but idles poorly with only passenger side tubes heating up
The pics are me wondering where the fuses are and if anyone seeing anything wacky... because some of the things i read issues could be there?? Sorry man thanks! I'll check those fuses.
Re: Engine runs sometimes, but idles poorly with only passenger side tubes heating up
Checked all the fuses under the dash everything seems to be ok.. puled them all just to check.. which fuel pump fuse relay. In the engine bay? Is it the one closest to passenger of the three?
Re: Engine runs sometimes, but idles poorly with only passenger side tubes heating up
Not sure about "puled them all just to check". Doesn't make sense to me. But I'm just an electrical engineer by trade, so... being stewpid and otherwise ignorant about things like this, I just work off of LOGIC.
If the engine runs AT ALL, the FP circuit is fine. Leave it alone. Both banks use the same FP. If the FP was bad, both banks wouldn't work, because BOTH would have no fuel. But since one bank works, the FP and EVERYTHING to do with it has to be good.
Looks like the ones in question are labelled INJ 1 and INJ 2. Swap em and see if the problem moves to the other bank. If it doesn't, unplug the injectors on the failed bank one at a time, looking for one that when you unplug it, the other 3 start to work.
Re: Engine runs sometimes, but idles poorly with only passenger side tubes heating up
Sorry I didn't mean to sound ignorant or disrepectful, I was trying to say I checked all the fuses there to make sure something else wasn't popped. So again sorry, and thanks for your help! I will go try what you said and let you know. Thanks again.
Re: Engine runs sometimes, but idles poorly with only passenger side tubes heating up
Originally Posted by sofakingdom
Not sure about "puled them all just to check". Doesn't make sense to me. But I'm just an electrical engineer by trade, so... being stewpid and otherwise ignorant about things like this, I just work off of LOGIC.
If the engine runs AT ALL, the FP circuit is fine. Leave it alone. Both banks use the same FP. If the FP was bad, both banks wouldn't work, because BOTH would have no fuel. But since one bank works, the FP and EVERYTHING to do with it has to be good.
Looks like the ones in question are labelled INJ 1 and INJ 2. Swap em and see if the problem moves to the other bank. If it doesn't, unplug the injectors on the failed bank one at a time, looking for one that when you unplug it, the other 3 start to work.
So i swapped the two and it fired up the same. Before the swap I was getting cylinder 2 firing as well so we are upto 5 total firing. One thing that did happen when I went to start it once, it was completely dead.
Pushed around on the ecm fuse and it started up again, and once I let off pressure it died again. Played around with it and made sure everything sitting correctly. So I got it idling again. Got the driver side bank firing as it has been, and cylinder 2 on passenger side firing as well.
I am still going to do what you mentioned with the pulling injector and seeing if one or the others fire up upon removal.
I just hope its not a weak fuel pump. Thanks again and I'll let you know what the results of the injectors test you mentioned.
Re: Engine runs sometimes, but idles poorly with only passenger side tubes heating up
Ok so, I re checked some of the ohms on the injectors. On passenger side. Once I disconnected injector 6. The remaining 3 fired up following the procedure you had mentioned. The ohms on injector 6 read 0 so it must be that one I assume, since I went through them and the others didn't cause any change to the system and read ohms.
So now am I looking at new injectors I imagine? I live in Canada so I will see what southbay can do thats the company everyone recommends now?
Thanks for the help! Now to see if this is the only thing holding me back.
Re: Engine runs sometimes, but idles poorly only getting heat to 1,3,5,7 and 2.
Yup, you found it.
Yes Southbay can hook you up. There are others as well but they're as good as anybody. I haven't a clue about shipping costs and all that but I guess at some level it just is what it is.
06-16-2020, 07:21 PM
