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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Ok I'll check that. What does the oil pressure do to spark?
Sorry i should have separated those sentences
1) Maybe you have an ignition issue instead.
2) Check your oil sensor. Maybe that thing is flaky.
Someone else can better explain the oil sensor than me because i always confuse myself with it, and demos/tests i see on youtube and how it works on GM vehicles in the 80s-90s conflict with each other. If I remember, the sensor sends oil pressure to the gauge and has a built in relay itself, and if the pressure is too low, the built in relay cuts power to the fuel pump. So then your car would only be running on the main relay, (the one on the firewall, drivers side, next to the other 2 relays). If the sensor is acting weird, maybe flipping on/off, maybe thats a reason for your flicker. Its just an idea.
I'll check the oil pressure switch. The pump comes on when key is on. It primes to 42psi and then falls down after a few seconds. When cranking the fuel is only at 20-30. I'll put a new pump in and oil pressure switch and hope for the best. I'll report back here with results lol. Thanks everyone for the input and advice.
Dont give parts stores all of your money. Just buy what you need.
You can test if the sensor is faulty like Will did in the 2nd video by jumping the connector. The pressure sensor completes the circuit when pressure is at the correct level (whatever PSI it is for a third gen). If your car stays running with good pressure when you have it jumped (pressure sensor bypassed) then u know you have a sensor problem.
He already bypassed the whole control scheme by jumpering the fuel pump relay. The oil pressure switch system isn't the problem. That one test will power the pump at all times regardless of ECM, oil pressure switch, or fuel pump relay. So either the issue IS the pump, or it is NOT the pump and the problem lies in another system such as the ignition.
I couldnt quite understand if when he said he jumped the relay he left it jumped when running it, or just jumped it then checked pressure.
Maybe the strainer is clogged who knows. My truck's pump with 175k was original and had pretty good pressure, but the strainer was absolutely failing apart. Hopefully he replaces that as well.
FWIW I'm chasing a problem right now where FP comes up at key on and then drops right to 20 and slowly to zero. Car will not start. Previously pressure would stay at 40 for 20 min after engine stop.
Oil pressure must build after pump prime or the pump will not pump any more until key off and back on to.
New regulator yesterday and Walbro 255 earlier this year. I pulled the fuel rail up to see the injectors are not leaking/dripping. These are new too.
I think the fuel pump has a bad check valve. Don't know where else pressure could be going.
I think I can start the car by hotwiring the relay to force FP to stay up with no oil pressure. Once the car starts then FP should stay up enough till I get to the replacing pump or finding something else out.
Oil pressure must build after pump prime or the pump will not pump any more until key off and back on to.
The oil pressure switch is redundant to the fuel pump relay, it alone will not stop the pump from turning on. This was just covered in another thread, the oil pressure switch is in parallel to the relay.
Ok 3rd gen ppl. I'm going to burn the freaking car to a crisp!!!! So I just replaced the fuel pump. And after all that crap still the same thing. I'm going crazy working on this dang car. I've still got a drop in pressure after initial pump prime. Don't know where I've looked at ever fuel line from the back to the front. No leaks or anything of nature. Like I stated before all timing is in check and msd ignition installed properly. I know due to it running for a moment. I put the new pump in and it won't start at all. I floored it to see if that would work putting the ecu in clear mode or what was stated in a previous reply. It acts like it wants to start and never does. I can hear a small back fire in exhaust probly due to fuel buildup. I also checked the oil and it was way over the full mark also.... I'm thinking due to fuel seeping after multiple weeks of trying to get this thing started. Another thing I thought was odd. If I jump the ALDL to check codes it does nothing. I appreciate yalls comments and direction on my not so fun adventure.
Ok so pinch off the return line going back to the tank, jump the relay and see if it holds pressure. if not, jump it again, then pinch the feed line while return is still pinched, then that should tell you there are injectors leaking. obviously do the rubber lines. I have no idea where the rubber ones are, Ive never had to go back that far.
If you have leaking injectors, youre probably going to have to remove spark plugs and crank the motor for a while and dry out the cylinders after all of what you have done lol
If you have no activity from jumping the ALDL terminals then as I stated before you probably have a cracked ECM circuit board. That's what mine acted like as well.
If the CEL is on then the ECM is powered. It provides the ground for the lamp. It should either be steady on, or flash codes. If it's flashing randomely and you can't get it to post codes then either there is a problem with the CEL circuit, AND a problem with the ALDL circuit, or the ECM is bad. Mine would work sometimes if I smacked the case. It's a known problem with the 165 ECM.
Ok so I pulled the ecu out tonight just to see if I could tell if there were any obvious problems. Well I'll let the photographs speak for themselves. I'm not sure if this is how the PO did the chip or if it burnt the connections or what. In some of the photos you can see it looks like a soldering iron or a test light was pushed into the connections for the prom. Input your ideas if you will and maybe lead me in the right direction o great 3gen gurus.
Well not being able to hook up a scanner to the ALDL port is quite annoying and if its due to that jacked up prom then personally i would replace it. But if its like the moats G1 that i use, when plugged in they just bypass the factory chip so you can use your own. So I would assume when you plug in the G1 into the ECM, the crappy solder job part of the prom will be ignored\bypassed, and the G1 will instead pass on to the ECM whatever chip you plug into the G1.
So, to go that route, you would need a G1, chip, and burner. I'm guessing around 140 bucks or so. Thats assuming you cant find a prom on ebay. I don't know how much they go for, ive never had to replace one.
Ok so problem has been resolved. I noticed the blue clip that hold the prom and other 2 chips on place was not all the way seated into the connection. I cleaned the connections and seated the chip properly. Turned the key and it fired right up and ran beautiful. Thanks for everyone's help. Appreciate it.
Ok so tonight I changed the oil. I set timing at 10° before tdc. I let the car warm up and like any gear head I gave it a generous rev or two. Well I noticed it had a little miss at 3500rpm. So I gave it another rev trying to get to about 4-4500rpm. Car would not rev past 3500rpm. The car just sat at 3500 and didn't go past at all. Still getting a somewhat rich condition and after the car is shut off it's hard to start. Any direction would be appreciated. I have not yet replace the ecu as it is a remanufactured unit already and the chip was loose as stated earlier in the thread.
How do you know it's a rich condition? Just by smell? Now that the ECU is good, can you hook up a scanner, even a cheap one from ebay, 75 bucks, and get fuel trims. Also is this a custom chip? It sounds like some dude tried to solder in one.
What I pasted was the unit that plugs into the circuit board and gets locked down with the whit and blue tabs. I'm unsure of where the eprom is located and what the difference between a zif socket and eprom are. I'll look through the sit and gather some knowledge on the matter and see what I can do tho
The eprom looked fine. No burnt section, all pins we're straight. Only crappy looking part was what I posted. Also is there a certain way the chip is placed in the zif socket.
So what's a stock ecu look like. From reading up in the tuning section it's been modified because from what I have gathered the zif socket didn't come in it and the crap solder job on the socket.
Put a stock PROM in it and see what happens. Maybe they just wanted a lower fan setpoint. It will be fine to run a stock chip. Ask in the wanted forum or there are plenty on ebay for cheap.
A stock prom and a cheap ebay scanner, so that you can finally see how your car is behaving.
And later if you want get a G1, burner, and a couple of chip so you can remove EGR, etc
Put a stock PROM in it and see what happens. Maybe they just wanted a lower fan setpoint. It will be fine to run a stock chip. Ask in the wanted forum or there are plenty on ebay for cheap.
GD
MorningWood , The General has given you some great advice here that you really should follow . It's obvious there has been hackery afoot within your ECM , so to establish a "baseline" from which further troubleshooting can continue your best bet would be to get a stock prom or better yet an entire unmolested ECM prom & all , from the for sale section here and put that in so your not "chasin yer tail" on problems that very likely reside within the confines of that shiny little metal box .....
I do appreciate all the advice and direction on this problem. It will be a week or two before I can gain some coin for a new ecu. When I get it I'll put it in and go from there as advised. When I find out further on this I'll report back here lol. Thanks again.
I truly believe that we as Americans are so money hungry that we in the 70s and 80s decided to give our job market to the Chinese and in turn made China what it is today that the USA is even worried about them being such a huge super power. I love the fact that you as an American can recognize were the flaws are. couldnt agree more with you on the subject.
Unfortunately that decision was already made for me...... In the most ugly way possible.
i used to have a hard top GTA and they previously changed the F. pump this way and it was disappointing to see someone take the easy route since these cars are really nice. I still have my t top car and the pump is over 20 years old and i am ready to change it and will do it the correct way. maybe if it was a disposable japanese car or any fwd car, i would cut it this way. make sure you reseal it good maybe with body seam sealer since the fumes tend to make their way into the cabin even thru the smallest opening.
11-30-2017, 10:38 PM
MorningWood , The General has given you some great advice here that you really should follow . It's obvious there has been hackery afoot within your ECM , so to establish a "baseline" from which further troubleshooting can continue your best bet would be to get a stock prom or better yet an entire unmolested ECM prom & all , from the for sale section here and put that in so your not "chasin yer tail" on problems that very likely reside within the confines of that shiny little metal box ..... 
