I got an 01 blazer here that won't run on it's own. I think it is the fuel pump. It will start on brake clean and idle great. Give it more than 1/4 throttle and it bogs. Fuel pressure with the engine off is about 48-50psi and stays around 50 with it running. Also has lean codes for bank 1 and 2.
You have a scan tool?
Injectors pulsing?
If you have a scan tool. prime the system and use the tool to pulse one of the injectors and see if the fuel pressure drops.
Ian Adams Function>Form 1990 shadow scrapped, too rusty:( 1991 Spirit R/T Scrapped, parts sold:( 1989 Turbo Caravan Daily beater with built-[I]ish [/I]engine slowly evolving into weekend turbo beater.
Fuel pressure should be 60 to 66psi key on engine off
No scan tool. Just a little mac code reader.
You either need a pump, filter, or pressure regulator.
BTW, does the pressure stay or does it bleed off?
Bryan
86 GLHS #161, 2016 Impala
SDAC National Member, SDAC Buckeye Chapter Member
A man has got to know his limitations.....
Pressure will bleed off to about 40 and sit there for a while. I also noticed it will backfire through the intake along with bogging down when you step on the gas. I checked distributor timing and it was spot on.
Could be multiple issues, but think it's wise to get the fuel system in the clear first.
I've got half a thought that if it's the returnless pump it did something funky like have MAP see atmospheric because of a manifold leak, tune more fuel in for that, then see rich at the O2 and take it back way lean at the pump.
DD1: '02 T&C Ltd, 3.8 AWD. DD2: '15 Versa Note SV, replacing.. DDx: '14 Versa Note SV << freshly killded :( ....... Projects: '88 Voyager 3.0, Auto with shift kit, timing advance, walker sound FX muffler on 15" pumpers wrapped in 215/65/R15 H rated Nexens.... and a '95 phord escort wagon PnP head << Both may need to go :( ..... I like 3.0s ... so??? ... stop looking at me like I've got two heads!
that sounds like either a map or tps issue. the 4.3 in that truck uses the injector spider, any problems with that and you replace the whole assembly.
I checked the tps with a dvom and it was fine. I was thinking it could be some kind of sensor too, but it should still start fine on it's own if it was a map or maf or something.
Well unless the MAP is getting low ref voltage or high ground ref, or giving out low volts because of bad connections, and the key on baro read is telling the ECU it's flying at 20,000 feet.
DD1: '02 T&C Ltd, 3.8 AWD. DD2: '15 Versa Note SV, replacing.. DDx: '14 Versa Note SV << freshly killded :( ....... Projects: '88 Voyager 3.0, Auto with shift kit, timing advance, walker sound FX muffler on 15" pumpers wrapped in 215/65/R15 H rated Nexens.... and a '95 phord escort wagon PnP head << Both may need to go :( ..... I like 3.0s ... so??? ... stop looking at me like I've got two heads!
4.3L requires 60 to 66 psi fuel pressure to open the poppet valves on the injector spider. I had one that did the same time would not start with out starting fluid had low fuel pressure. I replaced the pump started and ran ok. I'm not saying that its going to fix your problem but you have to have the proper fuel pressure or it will not run.
That is why I asked if it was bleeding down. Sounds like the injector unit is ok, but it needs a fuel pump. Trust me on this.Originally Posted by slowneon
Bryan
86 GLHS #161, 2016 Impala
SDAC National Member, SDAC Buckeye Chapter Member
A man has got to know his limitations.....
That is what it's looking like. I just want to be 100% because fuel pumps for these aren't that cheap.
I know. Unless it is just the fuel filter clogged, it will be the pump or an electrical connection. Most likely pump.
Bryan
86 GLHS #161, 2016 Impala
SDAC National Member, SDAC Buckeye Chapter Member
A man has got to know his limitations.....
Correct... The fuel pump on these beasts are common for going out if it has been sitting for a while and sucks up a bunch of crud since it is so low in the tank(the filter is damn near on the bottom[piss-poor design]). Since you are saying that it is pulling 'some' psi at idle and not under load/rpm, I would bet the farm that it is partially gunked over. Was this vehicle sitting for any length of time?
-Nate- ''Sometimes I wonder whether the world is being run by smart people who are putting us on, or by imbeciles who really mean it.'' —Mark Twain
I don't believe it was sitting. Once it's started with brake clean, it will stay at 50psi fuel pressure no matter the load. With it idleing, the fuel gauge flickers a lot also.
I would check the ground wire should be on the cross member. Also you should have sure your getting a good 12 volt supply to the pump. If you have both that its more than likely the pump starting to fail
Thanks for all the help guys. A new pump and filter did the trick.
Yep, and I'll bet that in-tank filter had more crap in it than Oprah Winfrey's diaper....
-Nate- ''Sometimes I wonder whether the world is being run by smart people who are putting us on, or by imbeciles who really mean it.'' —Mark Twain
It was fairly dirty. I've done the intake gaskets and the fuel pump on this thing. Hopefully I never see this GM POS again.
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